The document discusses marine electrical systems and electric propulsion systems for ships. Key points include:
- Marine electrical systems include power generation, distribution, and consumption of electric power on various vessels. Electric propulsion has increased for vessels with multiple large power consumers like cruise ships.
- Electrical transmission consists of mechanical energy converted to electrical energy by generators, electrical energy converted to mechanical energy by motors, and power conversion in between via converters.
- Electric propulsion provides advantages over conventional systems like increased efficiency and flexibility in component placement. Integrated electric drive propulsion with advanced technologies can further improve efficiency.
- High voltage distribution systems above 440V are needed to reduce cable sizes as power demands on ships increase. Components
The cylinder liner forms the cylindrical space in the engine where the piston reciprocates. It is manufactured separately from the cylinder block using an alloy that has better wear resistance at high temperatures. This allows for replacement of just the liner if it wears. The liner is cooled, often with tangential bore cooling, to maintain an optimal temperature for lubrication and reducing thermal stresses. Proper lubrication and minimizing abrasive particles are important to reduce liner wear over the life of the engine.
Ships Using Different Propulsion Systems Are discussed.The Ships are:
1:KMS BATTLESHIP- BISMARCK
2:QUEEN ELIZABETH-CLASS AIRCRAFT CARRIER
3:USS ENTERPRISE (CVN-65)
Prepared by:Vipin Devaraj,
38Th RS,
Dept Of Ship Technology,
Cusat,INDIA
contact:vipindevaraj94@gmail.com
Electrical Isolation procedure onboard shipShoaib Ahmed
Electricity is a hidden and soundless killer. So, dealing with electricity is inherently hazardous and it is tough to assure that safe working conditions are in place. Undoubtedly, safe electrical isolation is the first prior onboard ship. Both the seafarer and the company have responsibilities to ensure a safe working environment.
Shipboard employees face various problems that can make servicing operations more
challenging, such as:
# Large and complex vessel and vessel machinery, facilities, and systems;
# Machinery, equipment, and systems having multiple power sources, insulating points
and energy types; and
# Difficulty in identifying all energy sources due to faulty engineering drawings and
schematics.
The document discusses various marine propulsion systems. It describes how ships are typically powered through a propeller connected to an engine that transforms an energy source into mechanical power. Common energy sources discussed include fossil fuels like diesel powering most ships, as well as alternative sources like solar, wind, nuclear, hydrogen, and wave energy being explored. The document also examines different types of engines like steam, diesel, gas turbine, and their use in marine propulsion applications.
The document discusses various types of deck machinery and equipment used on ships, including:
- Windlasses and mooring winches used for anchoring and mooring.
- Hatch cover openers, winches, derricks, and cranes used for cargo handling.
- Pumps and other equipment used on specialized ship types like LNG carriers.
- Components and operation of typical anchoring systems including the anchor, chain, and windlass.
- Electric, hydraulic, and other drive systems used to power deck machinery.
- Cargo winches and derrick/crane systems and their use in cargo handling.
- Types of hatch covers including hydraulic folding and rolling varieties.
The cylinder liner forms the cylindrical space in the engine where the piston reciprocates. It is manufactured separately from the cylinder block using an alloy that has better wear resistance at high temperatures. This allows for replacement of just the liner if it wears. The liner is cooled, often with tangential bore cooling, to maintain an optimal temperature for lubrication and reducing thermal stresses. Proper lubrication and minimizing abrasive particles are important to reduce liner wear over the life of the engine.
Ships Using Different Propulsion Systems Are discussed.The Ships are:
1:KMS BATTLESHIP- BISMARCK
2:QUEEN ELIZABETH-CLASS AIRCRAFT CARRIER
3:USS ENTERPRISE (CVN-65)
Prepared by:Vipin Devaraj,
38Th RS,
Dept Of Ship Technology,
Cusat,INDIA
contact:vipindevaraj94@gmail.com
Electrical Isolation procedure onboard shipShoaib Ahmed
Electricity is a hidden and soundless killer. So, dealing with electricity is inherently hazardous and it is tough to assure that safe working conditions are in place. Undoubtedly, safe electrical isolation is the first prior onboard ship. Both the seafarer and the company have responsibilities to ensure a safe working environment.
Shipboard employees face various problems that can make servicing operations more
challenging, such as:
# Large and complex vessel and vessel machinery, facilities, and systems;
# Machinery, equipment, and systems having multiple power sources, insulating points
and energy types; and
# Difficulty in identifying all energy sources due to faulty engineering drawings and
schematics.
The document discusses various marine propulsion systems. It describes how ships are typically powered through a propeller connected to an engine that transforms an energy source into mechanical power. Common energy sources discussed include fossil fuels like diesel powering most ships, as well as alternative sources like solar, wind, nuclear, hydrogen, and wave energy being explored. The document also examines different types of engines like steam, diesel, gas turbine, and their use in marine propulsion applications.
The document discusses various types of deck machinery and equipment used on ships, including:
- Windlasses and mooring winches used for anchoring and mooring.
- Hatch cover openers, winches, derricks, and cranes used for cargo handling.
- Pumps and other equipment used on specialized ship types like LNG carriers.
- Components and operation of typical anchoring systems including the anchor, chain, and windlass.
- Electric, hydraulic, and other drive systems used to power deck machinery.
- Cargo winches and derrick/crane systems and their use in cargo handling.
- Types of hatch covers including hydraulic folding and rolling varieties.
This document summarizes key aspects of rudder theory and design. It discusses how rudders generate force through pressure differences on each side, and how this force has both lift and drag components. It describes different types of rudders based on the position of the center of effort relative to the axis of rotation, including balanced, semi-balanced, and unbalanced rudders. It also discusses rudder construction materials, pintle bearings, and considerations for rudder stock sizing based on the type of rudder.
The document discusses electric propulsion systems for marine vessels. It provides an overview of conventional power plants and their disadvantages. It then discusses the history and development of electric propulsion systems, including early experimental systems from the late 19th century through modern commercial applications starting in the 1920s. The document outlines several types of electric propulsion systems and their components. It discusses the advantages of electric propulsion systems, including improved efficiency, emissions reductions, and operational flexibility compared to conventional systems.
This document discusses ship rudders, including:
- Rudders are fitted at the aft end of ships to provide directional control and derive benefit from increased water velocity from the propeller.
- There are three main types of rudders - balanced, unbalanced, and semi-balanced. Balanced rudders have a portion of blade area forward of the stock to reduce torque on the steering gear.
- Size, shape, and type of rudder is governed by the ship's stern shape, required rudder area, steering gear capacity, and service conditions.
- Special rudders like spade rudders, Flettner/Becker rudders, Borg
Fresh water generators produce fresh water for domestic and auxiliary use aboard ships by distilling or desalinating sea water. They are essential aboard ships where fresh water consumption can be over 30 tonnes per day. There are two main methods - distillation and reverse osmosis. Distillation involves boiling sea water under vacuum to evaporate it, then condensing the vapor to produce fresh water. Reverse osmosis uses semipermeable membranes to filter out salt and other ions. Fresh water generators recover waste heat from sources like the main engine to economically produce fresh water as needed.
This document discusses ship propulsion systems. It begins by defining key terms related to propeller horsepower, including:
- Brake Horsepower (BHP): Power output at the engine shaft before reduction gears.
- Shaft Horsepower (SHP): Power output after the reduction gears.
- Delivered Horsepower (DHP): Power delivered to the propeller.
- Thrust Horsepower (THP): Power created by the screw/propeller after losses.
It then discusses propeller types, key parts like the hub and blades, and terminology such as diameter, pitch, revolutions per minute, and whether a propeller is right-handed or left-handed. The
A gas turbine, also called a combustion turbine, is a type of internal combustion engine. It has an upstream rotating compressor coupled toa downstream turbine, and a combustion chamber in-between. Energy is added to the gas stream in the combustor, where fuel is mixed with air and ignited. In the high-pressure environment of the combustor, combustion of the fuel increases the temperature. The products of the combustion are forced into the turbine section
Visit https://www.topicsforseminar.com to Download
Auxiliary marine machinery systems are essential for proper ship functioning. They include pumps, compressors, and blowers for fuel, water, and air systems. They also include separators, steering machinery, winches, cranes and other deck equipment. The machinery space houses these systems and its size depends on the equipment installed. Common auxiliary equipment includes engines, steering gear, deck machinery, blocks, pulleys, pumps, masts, derricks, rollers, gantries, and various types of winches used for specific fishing methods and vessel operations. Proper maintenance of critical components like engines is important for auxiliary system reliability.
The document discusses various piping systems on ships including bilge, ballast, air/sounding, firefighting, fuel oil, lubricating oil, cooling water, compressed air, domestic water, steam, and cargo systems. Key details provided include requirements for pump capacities, pipe sizing formulas, tank arrangements, safety features such as quick closing valves and alarms, and material considerations for high pressure/temperature applications.
The document discusses electrical hazards in marine environments. It classifies hazardous zones into Zone 0, 1, 2 and non-hazardous based on the likelihood of explosive gas-air mixtures being present. It describes the protection schemes of flameproof (Exd), intrinsically safe (Exi), pressurized (Exp), and increased safety (Exe) equipment suitable for different zones. The document also provides definitions and maintenance considerations for these protection schemes.
The document summarizes the machinery arrangement in a ship's engine room. It describes that the engine room contains main machineries that provide propulsion and auxiliary machineries that support operations with electrical power, cooling, and heating. Major machineries are categorized as critical because if they become inoperable, they can endanger ship operations. The document then lists and describes various main and auxiliary machinery located in the engine room, including the main engine, diesel generators, pumps, heat exchangers, refrigeration systems, and electrical equipment. It also lists storage tanks located in the engine room for liquids like fuels, oils, and water.
The document outlines the procedure for overhauling the pistons in a two-stroke marine main engine. Key steps include: isolating the engine, draining water from the cylinder, removing the piston and inspecting components for wear, cleaning and replacing parts as needed, reassembling the piston, and installing it back in the engine. Safety precautions are emphasized, such as permitting work and confirming it is safe to turn the engine.
Types, Operations and Maintenance of Air Compressor PlantsNejat Öztezcan
The document discusses maintenance and operation of air compressor plants. It provides information on different types of compressors used on ships, including:
1. Main air compressors which provide high-capacity air storage for starting engines.
2. Deck compressors which are smaller and more portable for tasks like pneumatic tools.
3. Emergency compressors which serve as a backup air source in emergencies to start auxiliary engines if the main compressor fails.
The document outlines compressor systems, components, efficiency factors, and procedures for checking bumping clearance on main air compressors.
The document discusses marine air compressors used on ships. It describes the various uses of compressed air on ships, including starting main/auxiliary engines, automation/control, pneumatic tools, fog horns, and more. It provides details on compressor requirements, operating principles, intercooling benefits, maintenance procedures, and common issues like low efficiency.
The stern tube is a hollow tube running through the bottom of a ship that contains the propeller shaft. It connects the main engine to the propeller and supports the large weight of the propeller. Stern tubes are designed to keep water from leaking into the ship while allowing the propeller shaft to rotate freely. They contain bearings lubricated with oil or water to reduce friction and prevent leakage between the stern tube and propeller shaft. Modern systems aim to improve lubrication and reduce contamination of lubricants with water for more efficient propulsion.
An engine indicator is used to record indicator diagrams from engines, which represent the work done per cycle. There are two types of indicators: mechanical indicators record diagrams on paper up to 150 rpm, while pressure indicators measure only maximum combustion pressures without limit. An indicator consists of a small cylinder connected to the engine that records pressure variations during the cycle as diagrams. Different types of diagrams like power, compression and light spring can detect various engine faults.
Ship refrigeration plants play a vital role in transporting perishable cargo by maintaining the appropriate temperatures. The main components of refrigeration plants include compressors, condensers, receivers, driers, expansion valves, evaporators, and control units. Refrigeration plants use the vapor compression cycle to remove heat from cargo holds or crew areas, circulating a refrigerant through the components to absorb, compress, condense, expand, and evaporate heat.
The document discusses gas turbines used at an NFL power plant in Vijaipur. It provides details on the models, ratings, and loads of three gas turbine generators (GTGs). It then discusses heavy duty gas turbines from GE in terms of their configurations, frame sizes, speeds, and applications. The rest of the document goes into extensive technical details about the components, workings, inspections, and factors that influence gas turbines, including compressors, combustion systems, turbines, bearings, and more.
This document provides information about shipboard incinerators. It defines an incinerator as machinery used to burn various wastes generated on ships, such as oily rags and galley waste. It describes typical incinerator features like refractory lining and automatic controls. It provides details on normal incinerator operation procedures, the types of wastes that can be incinerated according to IMO regulations, and emission standards for type approval testing. The document also outlines safety requirements for incinerator design, operation, controls, and fire protection in waste storage spaces.
Marine electrical distribution system and control engineeringZeeshan Ahmed
The document discusses the electrical systems and components onboard ships, including marine electrical distribution systems, generator parts, high voltage cables, switchboards, motor starters, and control systems like PLC and DCS. It also outlines the various electrical repair and maintenance work performed by marine engineers, such as overhauling motors and generators, working on control valves, and training in an electrical and electronic shop. The author introduction provides background on the author's marine engineering education and training with the Pakistan National Shipping Corporation.
This document summarizes key aspects of marine electrical systems including:
1. Electrical safety hazards such as electric shock, overcurrent, and thermal hazards.
2. Common electrical instruments for measurement such as ammeters, voltmeters, and ohmmeters.
3. Procedures for testing continuity, resistance, and insulation of wiring, cables, and equipment.
4. Types of tests including continuity tests to check current paths, resistance tests for equipment windings, and insulation resistance tests to check insulation quality.
This document discusses electrical safety and protection on ships. It notes that most merchant ships have a 440V 3-phase 3-wire power system. Larger loads require higher voltage systems. Switchboards distribute power and include open and dead front types. Safety requirements to prevent electric shock are described, including types of neutral connections and operational considerations when connecting to shore power.
This document summarizes key aspects of rudder theory and design. It discusses how rudders generate force through pressure differences on each side, and how this force has both lift and drag components. It describes different types of rudders based on the position of the center of effort relative to the axis of rotation, including balanced, semi-balanced, and unbalanced rudders. It also discusses rudder construction materials, pintle bearings, and considerations for rudder stock sizing based on the type of rudder.
The document discusses electric propulsion systems for marine vessels. It provides an overview of conventional power plants and their disadvantages. It then discusses the history and development of electric propulsion systems, including early experimental systems from the late 19th century through modern commercial applications starting in the 1920s. The document outlines several types of electric propulsion systems and their components. It discusses the advantages of electric propulsion systems, including improved efficiency, emissions reductions, and operational flexibility compared to conventional systems.
This document discusses ship rudders, including:
- Rudders are fitted at the aft end of ships to provide directional control and derive benefit from increased water velocity from the propeller.
- There are three main types of rudders - balanced, unbalanced, and semi-balanced. Balanced rudders have a portion of blade area forward of the stock to reduce torque on the steering gear.
- Size, shape, and type of rudder is governed by the ship's stern shape, required rudder area, steering gear capacity, and service conditions.
- Special rudders like spade rudders, Flettner/Becker rudders, Borg
Fresh water generators produce fresh water for domestic and auxiliary use aboard ships by distilling or desalinating sea water. They are essential aboard ships where fresh water consumption can be over 30 tonnes per day. There are two main methods - distillation and reverse osmosis. Distillation involves boiling sea water under vacuum to evaporate it, then condensing the vapor to produce fresh water. Reverse osmosis uses semipermeable membranes to filter out salt and other ions. Fresh water generators recover waste heat from sources like the main engine to economically produce fresh water as needed.
This document discusses ship propulsion systems. It begins by defining key terms related to propeller horsepower, including:
- Brake Horsepower (BHP): Power output at the engine shaft before reduction gears.
- Shaft Horsepower (SHP): Power output after the reduction gears.
- Delivered Horsepower (DHP): Power delivered to the propeller.
- Thrust Horsepower (THP): Power created by the screw/propeller after losses.
It then discusses propeller types, key parts like the hub and blades, and terminology such as diameter, pitch, revolutions per minute, and whether a propeller is right-handed or left-handed. The
A gas turbine, also called a combustion turbine, is a type of internal combustion engine. It has an upstream rotating compressor coupled toa downstream turbine, and a combustion chamber in-between. Energy is added to the gas stream in the combustor, where fuel is mixed with air and ignited. In the high-pressure environment of the combustor, combustion of the fuel increases the temperature. The products of the combustion are forced into the turbine section
Visit https://www.topicsforseminar.com to Download
Auxiliary marine machinery systems are essential for proper ship functioning. They include pumps, compressors, and blowers for fuel, water, and air systems. They also include separators, steering machinery, winches, cranes and other deck equipment. The machinery space houses these systems and its size depends on the equipment installed. Common auxiliary equipment includes engines, steering gear, deck machinery, blocks, pulleys, pumps, masts, derricks, rollers, gantries, and various types of winches used for specific fishing methods and vessel operations. Proper maintenance of critical components like engines is important for auxiliary system reliability.
The document discusses various piping systems on ships including bilge, ballast, air/sounding, firefighting, fuel oil, lubricating oil, cooling water, compressed air, domestic water, steam, and cargo systems. Key details provided include requirements for pump capacities, pipe sizing formulas, tank arrangements, safety features such as quick closing valves and alarms, and material considerations for high pressure/temperature applications.
The document discusses electrical hazards in marine environments. It classifies hazardous zones into Zone 0, 1, 2 and non-hazardous based on the likelihood of explosive gas-air mixtures being present. It describes the protection schemes of flameproof (Exd), intrinsically safe (Exi), pressurized (Exp), and increased safety (Exe) equipment suitable for different zones. The document also provides definitions and maintenance considerations for these protection schemes.
The document summarizes the machinery arrangement in a ship's engine room. It describes that the engine room contains main machineries that provide propulsion and auxiliary machineries that support operations with electrical power, cooling, and heating. Major machineries are categorized as critical because if they become inoperable, they can endanger ship operations. The document then lists and describes various main and auxiliary machinery located in the engine room, including the main engine, diesel generators, pumps, heat exchangers, refrigeration systems, and electrical equipment. It also lists storage tanks located in the engine room for liquids like fuels, oils, and water.
The document outlines the procedure for overhauling the pistons in a two-stroke marine main engine. Key steps include: isolating the engine, draining water from the cylinder, removing the piston and inspecting components for wear, cleaning and replacing parts as needed, reassembling the piston, and installing it back in the engine. Safety precautions are emphasized, such as permitting work and confirming it is safe to turn the engine.
Types, Operations and Maintenance of Air Compressor PlantsNejat Öztezcan
The document discusses maintenance and operation of air compressor plants. It provides information on different types of compressors used on ships, including:
1. Main air compressors which provide high-capacity air storage for starting engines.
2. Deck compressors which are smaller and more portable for tasks like pneumatic tools.
3. Emergency compressors which serve as a backup air source in emergencies to start auxiliary engines if the main compressor fails.
The document outlines compressor systems, components, efficiency factors, and procedures for checking bumping clearance on main air compressors.
The document discusses marine air compressors used on ships. It describes the various uses of compressed air on ships, including starting main/auxiliary engines, automation/control, pneumatic tools, fog horns, and more. It provides details on compressor requirements, operating principles, intercooling benefits, maintenance procedures, and common issues like low efficiency.
The stern tube is a hollow tube running through the bottom of a ship that contains the propeller shaft. It connects the main engine to the propeller and supports the large weight of the propeller. Stern tubes are designed to keep water from leaking into the ship while allowing the propeller shaft to rotate freely. They contain bearings lubricated with oil or water to reduce friction and prevent leakage between the stern tube and propeller shaft. Modern systems aim to improve lubrication and reduce contamination of lubricants with water for more efficient propulsion.
An engine indicator is used to record indicator diagrams from engines, which represent the work done per cycle. There are two types of indicators: mechanical indicators record diagrams on paper up to 150 rpm, while pressure indicators measure only maximum combustion pressures without limit. An indicator consists of a small cylinder connected to the engine that records pressure variations during the cycle as diagrams. Different types of diagrams like power, compression and light spring can detect various engine faults.
Ship refrigeration plants play a vital role in transporting perishable cargo by maintaining the appropriate temperatures. The main components of refrigeration plants include compressors, condensers, receivers, driers, expansion valves, evaporators, and control units. Refrigeration plants use the vapor compression cycle to remove heat from cargo holds or crew areas, circulating a refrigerant through the components to absorb, compress, condense, expand, and evaporate heat.
The document discusses gas turbines used at an NFL power plant in Vijaipur. It provides details on the models, ratings, and loads of three gas turbine generators (GTGs). It then discusses heavy duty gas turbines from GE in terms of their configurations, frame sizes, speeds, and applications. The rest of the document goes into extensive technical details about the components, workings, inspections, and factors that influence gas turbines, including compressors, combustion systems, turbines, bearings, and more.
This document provides information about shipboard incinerators. It defines an incinerator as machinery used to burn various wastes generated on ships, such as oily rags and galley waste. It describes typical incinerator features like refractory lining and automatic controls. It provides details on normal incinerator operation procedures, the types of wastes that can be incinerated according to IMO regulations, and emission standards for type approval testing. The document also outlines safety requirements for incinerator design, operation, controls, and fire protection in waste storage spaces.
Marine electrical distribution system and control engineeringZeeshan Ahmed
The document discusses the electrical systems and components onboard ships, including marine electrical distribution systems, generator parts, high voltage cables, switchboards, motor starters, and control systems like PLC and DCS. It also outlines the various electrical repair and maintenance work performed by marine engineers, such as overhauling motors and generators, working on control valves, and training in an electrical and electronic shop. The author introduction provides background on the author's marine engineering education and training with the Pakistan National Shipping Corporation.
This document summarizes key aspects of marine electrical systems including:
1. Electrical safety hazards such as electric shock, overcurrent, and thermal hazards.
2. Common electrical instruments for measurement such as ammeters, voltmeters, and ohmmeters.
3. Procedures for testing continuity, resistance, and insulation of wiring, cables, and equipment.
4. Types of tests including continuity tests to check current paths, resistance tests for equipment windings, and insulation resistance tests to check insulation quality.
This document discusses electrical safety and protection on ships. It notes that most merchant ships have a 440V 3-phase 3-wire power system. Larger loads require higher voltage systems. Switchboards distribute power and include open and dead front types. Safety requirements to prevent electric shock are described, including types of neutral connections and operational considerations when connecting to shore power.
This document describes a preliminary design and prototype testing of an offshore floating structure for seaweed ocean farming. Seaweed farming has economic potential but existing cultivation systems are not suitable for deep or open waters. The paper outlines a design for a floating structure based on improving the existing long line cultivation method. Key factors considered in the design include determining hydrodynamic coefficients through static and dynamic model tests to inform the design of the mooring system, which is needed to prevent excessive movement of the floating structure.
This document summarizes a paper presented at the International Conference on Marine Technology in Kuala Terengganu, Malaysia from October 20-22, 2012. The paper discusses a study that performed hydrodynamic model testing and simulation of a mooring system for a very large floating offshore aquaculture system used for ocean plantation of seaweed for biomass. The study aimed to determine coefficients required for designing and simulating the mooring system to ensure the system's reliability and safety. The results of the hydrodynamic testing were used to model the static and dynamic behavior of the mooring system under different environmental conditions.
This document discusses the need to maintain navigation channels to accommodate increasingly large container ships. It focuses on the case of Port Tanjung Pelepas (PTP) in Johor, Malaysia. Ship sizes have been rapidly increasing, with some now over 18,000 TEU, but navigation channels have not been maintained accordingly. Without proper maintenance dredging, siltation reduces channel depths and poses risks to ship safety. The document analyzes trends in ship sizes, risks of groundings and collisions if channels are not deep enough, and environmental impacts of dredging and disposal of contaminated sediments. It argues for sustainable, frequent maintenance dredging to balance growing ship sizes with safe navigation in restricted waters like the Strait of Malacca near
The document discusses rules of integration, including:
1) The definite integral calculates the area under a curve between two bounds a and b.
2) If the function is negative in some intervals, the integral is the sum of the areas of regions where the function is positive minus the areas where it is negative.
3) The fundamental theorem of calculus relates the definite integral to antiderivatives.
Baltimore is a city located in Maryland known for industries like shipbuilding, aircraft construction, and automobile manufacturing. It was established in 1729 and named after the Barons Baltimore, founders of the colony of Maryland. Commerce and shipping brought the city prosperity. The national anthem "The Star Spangled Banner" was inspired by the sight of the American flag still flying over Fort Henry after bombardment. Popular attractions in Baltimore include the Walters Art Museum, Oriole Park at Camden Yards, and the Basilica of the National Shrine of the Assumption of the Blessed Virgin Mary.
This document summarizes a paper presented at an international conference on marine technology in Malaysia in 2012. The paper discusses quantifying greenhouse gas emissions from ships to support decision making and rulemaking by the International Maritime Organization. Specifically, it measures the concentrations of carbon dioxide and nitrogen dioxide emitted from a university research vessel during different operating modes to validate models for calculating emissions. Reducing greenhouse gas emissions from shipping is important because the industry accounts for a growing share of global emissions.
This document summarizes key aspects of marine electrical systems including:
1) Electrical safety hazards such as electric shock, overcurrent, and thermal hazards.
2) Common electrical instruments for measurement such as ammeters, voltmeters, and ohmmeters.
3) Procedures for testing continuity, resistance, and insulation of wiring, cables, and equipment.
4) Types of tests including current injection, pressure, and earthling testing to evaluate electrical system integrity and performance.
This document outlines a course on engineering mathematics that covers integration. The course aims to provide students with the fundamentals of calculus required for engineering problems and solutions. Specifically, it will cover integration as the reverse of differentiation, integrating common functions, evaluating constants of integration, definite integrals, and applications of integration like finding areas, volumes, work, and centroids. The course will be 40 hours long and cover these topics through lectures and practice assessments, evaluating students with three class assessments and a final exam.
This document discusses a risk and reliability analysis study of offshore aquaculture ocean plantation systems. The study aims to qualitatively assess system risks and quantify mooring failure probability, forces, and required mooring numbers. Offshore aquaculture is an emerging industry that could help meet growing seaweed demand. However, reliability studies are needed to ensure offshore floating structures can withstand harsh ocean environments. The study will evaluate risks through methods like FMEA, FTA, and HAZID to recommend safety measures and integrity levels for mooring structures.
This document discusses modeling collision risk frequency for inland waterways. It proposes a safety, environmental risk, and reliability model for collision accident frequency that considers factors like vessel characteristics, traffic characteristics, environmental conditions, operator skill, and quality of information available to operators. The probability of collision per year predicted by the model is acceptable in maritime industries but may be high for waterways with less traffic. Providing measures like traffic separation and vessel traffic management could help maximize sustainable use of the waterway by restoring safety. The goal is to develop a fundamental, sustainable transit risk model to support decision-making around reliable and sustainable inland water transportation development and regulation.
High voltages can cause overvoltage events that exceed the design limits of electrical systems. There are two main types of overvoltage: lightning overvoltage from natural sources, and switching overvoltage caused by changing loads on a system. Lightning overvoltage occurs when a lightning strike induces high voltage in a system. Switching overvoltage happens when large inductive or resistive loads are connected or disconnected, causing voltage spikes. Both types of overvoltage can damage equipment and should be controlled through various techniques like resistors, phase control, and reactors. Uncontrolled overvoltages present a danger, so protection methods are important for system reliability and safety.
The document discusses power electronics and regulators. It covers topics such as semiconductors, doping, PN junctions, transistors, silicon controlled rectifiers, zener diodes, and regulator circuits. The key points are:
- Semiconductors like silicon can be doped to create N-type or P-type materials which form the basis of diodes and transistors.
- A PN junction is formed when P-type and N-type materials are joined, creating a depletion region.
- Transistors involve two PN junctions and have three terminals - base, collector, emitter. Darlington transistors have very high current gain.
- Zener diodes
This document outlines the marine electrical standard requirements for electrical machinery and systems on ships. It discusses SOLAS regulations regarding main and emergency electrical power sources. Equipment like generators, circuit breakers, switchboards, cables, and motors are subject to periodic surveys to check they are maintained according to classification standards. The objectives are to understand general requirements for electrical power provision and ensure safety.
This document discusses maritime law as it relates to cargo documentation for the carriage of goods by sea. It begins by outlining key areas of maritime law and then focuses on objectives related to familiarizing marine engineers with legal aspects of cargo documentation. It defines important terms, describes various cargo documents like bills of lading and waybills. It also discusses the Hague-Visby Rules and Hamburg Rules which provide international regulations for carriage of goods and bills of lading. The document closes by outlining requirements for issuing and contents of bills of lading.
The document discusses different types of grounding systems used in high voltage systems, including: equipment grounds which connect metal parts to earth to protect from electric shock; system grounds which connect one point of an electrical circuit to earth to protect equipment and aid fault detection; and solidly grounded systems where the neutral is directly connected to ground without impedance. It notes factors like voltage level, equipment type, and safety that influence grounding method selection.
Shipbuilding activity in Russia is centered in St. Petersburg, where 40 shipbuilding companies are located. Russian shipbuilding is forecast to order 70 new vessels between 2015-2020, with Sovcomflot ordering 30 vessels. Major shipbuilding projects in Russia include construction at the Kerch Bay, Bolshoi Kamen, Severnaya Verf, Baltiyski Zavod, and the Zvezda Shipyard. The United Shipbuilding Corporation (USC) owns most of Russia's major shipyards and designs and builds military and civilian ships. Business opportunities exist for Finnish suppliers to the modernization of Russian shipyards and in providing equipment and components.
This document provides an overview of ship construction and outlines a 7-week course on the topic. It will cover ship structure, types of ships, construction processes, regulatory bodies, and key components. Students will learn about structural members, terminology, and framing systems. The document lists learning objectives and navigation for the course, which will cover construction overview, the construction process, ship dimensions and forms, development of ship types, ship structure, outfitting, and a final assignment project.
Marine propulsion, alternative propulsive devices.pptSaptarshiBasu23
This document discusses various ship propulsion systems and their components. It provides statistics on the global shipping industry and breakdown of vessel types. It then examines the key components of propulsion systems including the propeller, engine, steering and maneuvering systems. Different machinery arrangements are analyzed like single and multiple engine configurations. Emerging technologies like electric, nuclear and magneto-hydrodynamic propulsion are also mentioned. Criteria for evaluating propulsion systems include the hull, propulsion, prime mover and their interaction. Advantages of electric propulsion include increased reliability, flexibility and reduced maintenance needs.
Neil Garrigan: Electric Drive Technology Considerations for Aircraft Propulsion EnergyTech2015
EnergyTech2015.com
Track 2, Session 3 HYBRID ELECTRIC POWER FOR AERONAUTIC PROPULSION PANEL Monday, November 30
Moderator: Michael Heil, Ohio Aerospace Institute
This panel explored benefits and technology challenges associated with distributed, hybrid electric propulsion for future subsonic aeronautic vehicles. Panel members included aeronautics propulsion industry, NASA, and the DoD.
James Felder, NASA Glenn Research Center
John Nairus, Air Force Research Lab, Chief Engineer Power & Controls Division
Neil Garrigan, GE Aviation
Meyer Benzakein, OSU - Aeronautic
Track Two: New Technologies for Solving the Energy Puzzle Where are the breakthroughs? How will new and emerging technologies provide solutions for society energy needs? How can these be effectively integrated with existing legacy systems?
1) The document discusses wind energy and provides an introduction to basic principles of wind energy conversion including the nature of wind and power in wind.
2) It describes various wind electric generation schemes such as constant speed constant frequency, variable speed constant frequency, and variable speed variable frequency systems.
3) The document also discusses important considerations for site selection of wind energy conversion systems and lists the basic components of wind energy conversion systems.
This document provides an overview of various energy storage technologies. It discusses mechanical storage technologies like pumped hydro and compressed air. It also covers electrical storage technologies like batteries, flywheels, capacitors and superconducting magnetic storage. Thermal, chemical and electrochemical storage technologies are also described. The document provides details on the working principles, applications and classifications of different energy storage systems.
This document provides an overview of various energy storage technologies. It discusses mechanical storage technologies like pumped hydro and compressed air. It also covers electrical storage technologies like batteries, flywheels, capacitors and superconducting magnetic storage. Thermal, chemical and electrochemical storage technologies are also described. The document provides details on the working principles, applications and classifications of different energy storage systems.
Download Link (Copy URL):
https://sites.google.com/view/varunpratapsingh/teaching-engagements
Syllabus:
Introduction
Need of Cogeneration
Principle and Advantages of Cogeneration
Technical Options for Cogeneration
Gas turbine Cogeneration Systems
Reciprocating Engine Cogeneration Systems
Classification of Cogeneration Systems
Topping Cycle
Bottoming Cycle
Factors Influencing Cogeneration Choice
Important Technical Parameters for Cogeneration
Typical Cogeneration Performance Parameters
Relative Merits of Cogeneration Systems
Case Study
MARINE DIESEL ENGINES & Engine in DSV.pptxSarath40652
Seminar on Marine Diesel engines with example of diesel engine used in 120m long DSV Ship. This is pure academic related. This is from an real time experience in Shipyard on Naval Ships. Very useful and Authentic information. This also gives an idea about the engine size requirement for a particular ship size & speed.
This document summarizes the key components and operation of hybrid electric vehicles (HEVs). HEVs combine an electric motor and batteries with an internal combustion engine to improve fuel efficiency. There are two main types of HEV configurations - parallel and series hybrids. Parallel hybrids allow both the engine and electric motor to power the vehicle simultaneously, while series hybrids use the engine to charge batteries which power the electric motor alone. Key HEV components include electric drive motors, auxiliary power units like engines, generators, energy storage batteries, regenerative braking systems, and control systems. Fuel cell HEVs use hydrogen fuel cells instead of engines to charge batteries. HEVs provide benefits like reduced emissions and fuel usage compared to
This document provides information about the components and working of wind energy conversion systems (WECS). It discusses the key components of WECS including the rotor, windmill head, transmission system, control system and supporting structure. It explains how the kinetic energy of wind is captured and converted into mechanical and electrical energy. The document also covers wind energy basics such as power in wind, forces on turbine blades, site selection criteria, classification of WECS, and advantages and disadvantages of wind energy.
This document discusses energy conservation opportunities in railway coach lighting and air conditioning. It begins by introducing the electric loads in coaches and the need for lighting and air conditioning. It then describes the unique design challenges of air conditioning in coaches compared to buildings. The document outlines different coach classification systems and existing air conditioning and power supply arrangements. It evaluates the merits and limitations of various power supply systems and discusses the potential for improving lighting efficiency through use of more efficient bulbs and fixtures. In summary, the document performs an analysis of energy use in railway coaches and identifies technical approaches that could reduce energy consumption and costs.
This document provides an overview of electric locomotives, including their main components and systems. It discusses how electric locomotives are classified and divided based on their power source. The key systems of an electric locomotive are then described, including the transmission system consisting of the pantograph and circuit breaker, the transformer, rectifier, DC link, and Arno converter. It also outlines the main traction components like the traction motors. In conclusion, it notes the advantages of electric locomotives in terms of efficiency and potential for renewable power sources.
Presentation on Ship Electric Propulsion.pptJegadeeswariG
Electric propulsion uses variable frequency drives to convert fixed line frequency power to variable frequency power that can match the required propeller speed during different ship operations. It offers quieter operation and maximizes usable space. Common systems include gas turbines powering generators that power synchronous or induction motors. The U.S. Navy is committed to electric propulsion. Key advantages include redundancy if cables are damaged instead of drive shafts, and flexibility in ship component placement. Azimuth pod drives locate propellers in pods that can rotate 360 degrees for maneuverability without rudders or steering gear. This saves space versus long drive shafts.
- Pumped storage hydro involves using excess electricity to pump water to an upper reservoir and releasing it to turbines to generate electricity during peak demand periods. Modern trends include variable speed pumps/turbines, sea water systems, and coordinating with wind power.
- Retrofitting existing plants with modern equipment like variable speed induction generators presents challenges like managing hydraulic transients and integrating new components while avoiding cavitation. Coordinating pumped storage with wind power through optimization reduces operating costs and increases renewable energy usage.
This document discusses advanced rotating machines like flywheels for energy storage. It summarizes past and current programs developing flywheels for applications like renewable energy buffering, electric vehicles, aircraft launch systems, and pulsed power. Flywheel technology has improved significantly due to advances in materials, magnetic bearings, and safety systems. Future work aims to develop utility-scale flywheel energy storage to enable high renewable energy penetration as well as novel superconducting motors.
Electric power systems involve generation of power at high voltages, its transmission over long distances via transmission lines, and distribution to consumers via lower voltage distribution lines. Historically, direct current power systems were limited in transmission range but the development of alternating current systems enabled economical long distance transmission using transformers. Modern power grids involve large interconnected networks of generation, transmission, and distribution infrastructure to reliably supply electricity.
A Study and Research on the use of Power Electronics and its Relationship on ...Haq Nuzul
This document summarizes a study on the use of power electronics in ship propulsion systems. It discusses how electrical propulsion systems are increasingly being used due to advantages like easier speed and direction control of the propeller. Electrical propulsion systems use a prime mover like a diesel engine to power a generator, with electric motors then used to drive propellers. Power electronics play an important role by enabling control and regulation of electrical propulsion components. The document reviews different types of propulsion systems and concludes by considering the benefits of using power electronics for ship propulsion.
Introduction to energy storage requirements in Hybrid and.pptxAdwaithDinesh2
This document discusses various energy storage technologies for hybrid and electric vehicles, including batteries, ultracapacitors, and flywheels. It describes the characteristics and applications of each technology. In particular, it notes that batteries provide high energy density but low power, while ultracapacitors provide high power density but low energy. A hybrid energy storage system combines the two for improved overall performance.
Improved efficiency of gas turbine by Razin Sazzad MollaRazin Sazzad Molla
This document discusses ways to improve the efficiency of gas turbine engines through various design modifications and upgrades. It describes how increasing turbine inlet temperatures, improving compressor and turbine components, adding modifications like intercooling and regeneration, and utilizing advanced cooling techniques can boost efficiency. Other methods covered include inlet air cooling systems, compressor and turbine coatings, supercharging, and comprehensive component replacements. The goal of ongoing research is to enhance power output while reducing emissions and fuel consumption.
Similar to Hv genration transpformation - converson & distribution - revisedl (20)
The document discusses watchkeeping duties and responsibilities in marine engineering. It provides an overview of relevant maritime law conventions like STCW and details of engine room watch systems. A typical engineering crew is listed, with chief, assistant, and junior engineers as well as qualified ratings. Watchkeeping involves monitoring machinery, making rounds, and being alert to changes to prevent problems. Normal watch rotations at sea and in port are described.
The STCW establishes standards for watchkeeping on ships. It requires the chief engineer to assign watchkeeping duties and establish standards. It aims to improve training requirements and make countries accountable for enforcing training standards. Countries must provide information to IMO about their training programs and are subject to quality assurance requirements to ensure the proper implementation of the Convention.
The document discusses maritime law relating to facilitation of international maritime traffic and documents required to be carried onboard ships. It provides background on problems with excessive paperwork requirements that led IMO to adopt the Convention on Facilitation of International Maritime Traffic (FAL Convention) to standardize and reduce documentation. The FAL Convention aims to prevent unnecessary delays by establishing maximum information requirements for key documents like cargo and crew manifests. It also provides a list of certificates and documents required to be carried onboard ships.
- International regulations and agreements are needed to properly regulate the global shipping industry. Key organizations that set standards include the International Maritime Organization (IMO) and International Labour Organization (ILO).
- The IMO establishes minimum standards for ship construction, operation, safety, and environmental protection. It adopts conventions through a lengthy process of proposals, committee review, adoption, and ratification.
- The ILO focuses on working conditions, labor standards, and social protections for seafarers. It has adopted numerous conventions and recommendations covering issues like minimum age, hours of work, wages, and accident prevention. Compliance depends on ratification and national implementation.
The document discusses emissions to air from ships and strategies for reducing air pollution beyond regulatory compliance. It outlines various air pollutants emitted from ships, such as nitrogen oxides (NOx) and sulfur oxides (SOx), and regulations from the International Maritime Organization (IMO) to limit these emissions. Methods for reducing ship emissions are discussed, including using low-sulfur fuel, exhaust gas cleaning systems, and operational measures like slow steaming. The document emphasizes that reducing emissions requires approaches throughout the combustion process, from fuel preparation to exhaust cleaning.
The document discusses developing a predictive and reliability based collision risk model for inland waterways, specifically for Malaysia's Langat River. It aims to estimate collision frequency based on waterway variables and risk factors. The analysis considers dimensions of the waterway as well as factors like vessel characteristics, traffic, environment, and operator skills. Based on the available data for Langat River, the estimated collision frequency is 5.3 accidents in 10,000 years. While acceptable for maritime industry standards, it is considered high for a waterway with less expected traffic. Implementing safety measures like traffic separation could help optimize sustainable use of the channel.
This document summarizes a study on installing Magneto Electric Co-generator Plants (MECPs) on a marine vessel to reduce fuel usage. MECPs would be located on the propeller shaft and main engine flywheel to harvest rotational energy. Numerical modeling was used to analyze the power generated. MECP1 on the propeller shaft produced 3.74 kW, enough to power auxiliaries and reduce fuel usage by 1054 liters/hour. MECP2 on the flywheel produced more power due to higher rotational speed. Overall, MECPs could save costs while reducing carbon dioxide emissions and supporting the maritime industry's climate change commitments.
This document summarizes a research article that presents a collision aversion model and cost benefit analysis for inland water transportation.
The key points are:
1. The model analyzes collision risk for inland waterways by estimating collision probability and quantifying consequences like damage, loss of life, and economic losses.
2. It applies the model to Langat River in Malaysia to estimate historical collision rates and predictive costs for implementing collision avoidance measures.
3. The cost benefit analysis compares costs of safety measures to reduced risks and economic benefits to evaluate options for improving safety and environmental protection for sustainable inland water transportation.
This document discusses the use of simulation for enhancing training in engineering fields such as maritime academies. It argues that simulation provides opportunities for training that traditional instruction cannot by allowing students to experience complex real-world scenarios. The maritime industry has institutionalized the use of simulation in training programs to develop competent ship personnel and meet safety standards. Simulation is becoming a central part of maritime competency-based education to provide knowledge, understanding, application and integration required for outcome-based learning. The document examines how simulation has been incorporated in maritime training in Malaysia and discusses challenges to further developing simulation-based training programs.
This document discusses the utilization of simulation for enhancing training in engineering fields such as maritime studies. It provides an overview of how simulation has been adopted in maritime training to improve competency-based education and meet safety and environmental goals. The document also describes ALAM's investment in advanced simulators certified by DNV, including a full mission ship simulator and engine room simulator. These simulators are used to train maritime cadets by replicating real-world tasks in a safe environment and helping to close the gap between theory and practice. Simulation is seen as a valuable tool for competency-based education across many fields by providing realistic, interactive learning experiences.
This document summarizes a review on the potential for waste-recycled based bioenergy for marine systems. It discusses how biomass has the potential to influence the marine industry. The use of waste biomass to generate power could allow ships to power onboard systems and even dump waste ashore to power coastal infrastructure. The paper also examines trends in biomass development, classification of biomass sources, and best practices from other industries utilizing biomass.
This document presents a study on modeling gas turbine co-propulsion engines to improve the sailing speed of ecotourism vessels. Thermodynamic properties of diesel engines, simple gas turbines, and regenerative gas turbines are modeled and their thermal efficiencies are calculated. Numerical calculations are performed to determine the appropriate power rating of a gas turbine co-propulsion engine needed to achieve a maximum speed of 35 knots. Results from the modeling and calculations will provide support for deciding whether to implement a gas turbine co-propulsion engine on ecotourism vessels.
This document summarizes a study on the potential for using solar energy as a supplemental power source for the diesel engines on landing craft. The study analyzed the reduction in fuel usage and diesel exhaust that could result from adding solar panels, and performed an economic analysis. Data was collected on the power needs, solar radiation levels, and fuel costs for a specific landing craft. Calculations were made to determine the power output from solar panels over different seasons and reductions in generator use. Tables show estimates of generator output and fuel savings in kilowatt-hours per year from using solar to partially meet power demands. The economic analysis considered costs of the solar system versus operating costs without it.
Biological screening of herbal drugs: Introduction and Need for
Phyto-Pharmacological Screening, New Strategies for evaluating
Natural Products, In vitro evaluation techniques for Antioxidants, Antimicrobial and Anticancer drugs. In vivo evaluation techniques
for Anti-inflammatory, Antiulcer, Anticancer, Wound healing, Antidiabetic, Hepatoprotective, Cardio protective, Diuretics and
Antifertility, Toxicity studies as per OECD guidelines
Introduction to AI for Nonprofits with Tapp NetworkTechSoup
Dive into the world of AI! Experts Jon Hill and Tareq Monaur will guide you through AI's role in enhancing nonprofit websites and basic marketing strategies, making it easy to understand and apply.
A review of the growth of the Israel Genealogy Research Association Database Collection for the last 12 months. Our collection is now passed the 3 million mark and still growing. See which archives have contributed the most. See the different types of records we have, and which years have had records added. You can also see what we have for the future.
Main Java[All of the Base Concepts}.docxadhitya5119
This is part 1 of my Java Learning Journey. This Contains Custom methods, classes, constructors, packages, multithreading , try- catch block, finally block and more.
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আমাদের সবার জন্য খুব খুব গুরুত্বপূর্ণ একটি বই ..বিসিএস, ব্যাংক, ইউনিভার্সিটি ভর্তি ও যে কোন প্রতিযোগিতা মূলক পরীক্ষার জন্য এর খুব ইম্পরট্যান্ট একটি বিষয় ...তাছাড়া বাংলাদেশের সাম্প্রতিক যে কোন ডাটা বা তথ্য এই বইতে পাবেন ...
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This presentation was provided by Steph Pollock of The American Psychological Association’s Journals Program, and Damita Snow, of The American Society of Civil Engineers (ASCE), for the initial session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session One: 'Setting Expectations: a DEIA Primer,' was held June 6, 2024.
This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.
June 3, 2024 Anti-Semitism Letter Sent to MIT President Kornbluth and MIT Cor...Levi Shapiro
Letter from the Congress of the United States regarding Anti-Semitism sent June 3rd to MIT President Sally Kornbluth, MIT Corp Chair, Mark Gorenberg
Dear Dr. Kornbluth and Mr. Gorenberg,
The US House of Representatives is deeply concerned by ongoing and pervasive acts of antisemitic
harassment and intimidation at the Massachusetts Institute of Technology (MIT). Failing to act decisively to ensure a safe learning environment for all students would be a grave dereliction of your responsibilities as President of MIT and Chair of the MIT Corporation.
This Congress will not stand idly by and allow an environment hostile to Jewish students to persist. The House believes that your institution is in violation of Title VI of the Civil Rights Act, and the inability or
unwillingness to rectify this violation through action requires accountability.
Postsecondary education is a unique opportunity for students to learn and have their ideas and beliefs challenged. However, universities receiving hundreds of millions of federal funds annually have denied
students that opportunity and have been hijacked to become venues for the promotion of terrorism, antisemitic harassment and intimidation, unlawful encampments, and in some cases, assaults and riots.
The House of Representatives will not countenance the use of federal funds to indoctrinate students into hateful, antisemitic, anti-American supporters of terrorism. Investigations into campus antisemitism by the Committee on Education and the Workforce and the Committee on Ways and Means have been expanded into a Congress-wide probe across all relevant jurisdictions to address this national crisis. The undersigned Committees will conduct oversight into the use of federal funds at MIT and its learning environment under authorities granted to each Committee.
• The Committee on Education and the Workforce has been investigating your institution since December 7, 2023. The Committee has broad jurisdiction over postsecondary education, including its compliance with Title VI of the Civil Rights Act, campus safety concerns over disruptions to the learning environment, and the awarding of federal student aid under the Higher Education Act.
• The Committee on Oversight and Accountability is investigating the sources of funding and other support flowing to groups espousing pro-Hamas propaganda and engaged in antisemitic harassment and intimidation of students. The Committee on Oversight and Accountability is the principal oversight committee of the US House of Representatives and has broad authority to investigate “any matter” at “any time” under House Rule X.
• The Committee on Ways and Means has been investigating several universities since November 15, 2023, when the Committee held a hearing entitled From Ivory Towers to Dark Corners: Investigating the Nexus Between Antisemitism, Tax-Exempt Universities, and Terror Financing. The Committee followed the hearing with letters to those institutions on January 10, 202
A Survey of Techniques for Maximizing LLM Performance.pptx
Hv genration transpformation - converson & distribution - revisedl
1. High Voltage for Ship
Generation, Conversion ,
Transformation and Distribution
2. Marine Electrical System
• Maritime electric systems include power generation, distribution and
control, and consumption of electric power on supply- service- and fishing
vessels as well as offshore installations.
• Electric propulsion has increased especially for vessels with several large
power consumers, for example cruise ships, floating production systems,
supply- and service vessels.
• Maritime electric systems are autonomous power systems. The prime
movers, including diesel engines, gas- and steam turbines, are integral parts
of the systems.
• The power consumers are large compared with the total capacity of the
system, as for example thruster and propulsion systems for DP operated
vessels, drilling systems, HVAC systems on board ship
3. Marine Electrical System
• The overall power train efficiency with DEP is around 87-
90%. Use of permanent magnets in electric generators and
motors as well as general advances in semiconductor
technology may improve this figure to around 92-95% in the
near future. Electrical transmission will consist of three basic
energy conversions:
• From (rotating) mechanical energy into electrical energy: E-
generator
• From electrical energy into (rotating) mechanical energy: E-
motor
• Some form of fixed or controlled electrical conversion in
between: power converter
4. Systematic overview of existing types
E-generator
• Mechanical ==> Electrical: E-Generators
• - DC Generators
• - AC Generators
E-Motors
• Electrical ==> Mechanical: E-motors
• - Driving motors
• - Synchronous Motor
• - Positioning motors
Power converters
Electrical ==> Electrical: power conversion or transformation
• - Fixed transformers
• - Controlled converters
• - Static converters
• -Inverter
6. Electric Propulsion System (AES)
• Electric propulsion of ships has been know for a long time to human
• Dynamic changes in human discovery has given several up and down in
history
• Recent time have seen a a lot of Passenger ships being built with all
electric system for various advantage that over the conventional prime
movers
• Early large passenger vessels employed the turboelectric system which
involves the use of variable speed, and therefore variable frequency, turbo-
generator sets for the supply of electric power to the propulsion motors
directly coupled to the propeller shafts. Where, the generator/motor system
was acting as a speed reducing transmission system.
• Electric power for auxiliary ship services required the use of separate
constant frequency generator sets. System with generating sets to provide
power to both the propulsion system and ship ancillary services.
• However fixed voltage and frequency system are suitable to satisfy the
requirements of the ship service loads.
8. Electric Propulsion System (AES)
• Other complication associated with earlier systems is difficulties in using multiple
motor per shaft when required propulsion power was beyond the capacity of a single
d.c. motor .
• Developments in high power static converter equipment have – presented a very
convenient means of providing variable speed a.c. and d.c. drives at the largest
ratings likely to be required in a marine propulsion system.
• The electric propulsion of ships requires electric motors to drive the propellers and
generator sets to supply the electric power. It may seem rather illogical to use electric
generators, switchgear and motors between the prime-movers (e.g. diesel engines) and
propeller when a gearbox or length of shaft could be all that is required.
• In the light of the above, hybrid of gas turbine or Diesel with electric couple with dual
fuelling that include natural gas, is explorable option for existing vessels, all electric
ship using natural gas is also a good option.
• Currently there is interesting development for new ship need exploration on
technologies to improve integrated full electric propulsion with advanced power
management systems:
• Improved converter and power electronics technology
• Improved generators and motors
9. Electric Propulsion System (AES)
• The AES give widespread electrification of auxiliaries and the opportunity
to use upgradeable and flexible layouts. It will include a low risk, cost
effective and comprehensive Platform Management System that has a
standardized Human-Computer Interface supportable for its entire service
life and the goal to be an Environmentally Sound Ship.
• The fit into the goals of the Environmentally Sound Ship where : freedom
of operation in MARPOL special and restricted areas; unrestricted littoral
operations; port independence; minimum onboard storage of waste and
reduced manpower whilst reducing cost of ownership and port reception
costs.
• the also promise potential for replacing the current traditional systems used
in steering gear, fin stabilizers with compact, power-dense actuators.
• They also offer potentials for possible use of electric valve actuators that
will simplify system architectures systematic integration of upper deck to
machinery.
10. Power generation
• A 2001 study concluded that fitting a Navy cruiser with more energy-
efficient electrical equipment could reduce the ship’s fuel use by 10% to
25%.
• Ship fuel use could be reduced by shifting to advanced turbine designs such
as an intercooled recuperated (ICR) turbine. Shifting to integrated electric-
drive propulsion can reduce a ship’s fuel use by 10% to 25%.
• There is Potential alternative hydrocarbon fuels Like biodiesel and liquid
hydrocarbon fuels made from coal
• Recent time has seen firms offering kite-assist systems to commercial ship
operators.
• Solar power might offer some potential for augmenting other forms of
shipboard power.
• Talking about the question now the electric propulsion , especially with
hybrid system offer the best answer to problem of energy
11. Power generation
• Integrated electric-drive system derived from a commercially available system that
has been installed on ships such as cruise ships requires a technology that is more
torque-dense (i.e., more power-dense) .
• Candidates for a more torque-dense technology include a permanent magnet motor
(PMM) and a high-temperature superconducting (HTS) synchronous motor.
• In addition, electric drive makes possible the use of new propeller/stern
configurations, such as a podded propulsion ... that can reduce ship fuel
consumption further due to their improved hydrodynamic efficiency
• Podded drives offer greater propulsion efficiency and increased space within the
hull by moving the propulsion motor outside the ships hull and placing it in a pod
suspended underneath the hull.
• Podded drives are also capable of azimuth improving ship maneuverability. Indeed,
podded drives have been widely adopted by the cruise ship community for these
reasons.
• The motors being manufactured now are as large as 19.5 MW, and could provide
the total propulsion power.
15. Prime movers
Gas Turbines
• Gas turbine have been selected as the future prime mover primarily because
of their high power to weight ratio.
• 4. Weight sensitive ship designs favor gas turbines and projected light
weight fuel cell power plants such as PEM.
• They also provide significant reduction in the amount of routine
maintenance required when compared with diesel generators.
• The other significant factor is the low emissions.
Diesel engine
• Diesel engines offer fuel costs savings of 50% if heavy fuels can be used,
and if emissions can be maintained at acceptable levels.
• Maintenance may include engine modifications such as dual fuel capability
for in-port use, water injection, and timing retard, and exhaust treatment
such as selected catalytic reduction and oxidation catalysts.
• Heavy fuel use also requires careful selection of cylinder material and lube
oil
16. Turbina
• A gas turbine, also called a combustion turbine, is a rotary engine that
extracts energy from a flow of hot gas produced by combustion of gas or
fuel oil in a stream of compressed air.
• It has an upstream air compressor radial or axial flow mechanically coupled
to a downstream turbine and a combustion chamber in between.
• Energy is released when compressed air is mixed with fuel and ignited in
the combustor.
• The resulting gases are directed over the turbine's blades, spinning the
turbine, and, mechanically, powering the compressor.
• Finally, the gases are passed through a nozzle, generating additional thrust
by accelerating the hot exhaust gases by expansion back to atmospheric
pressure.
• A steam turbine is a mechanical device that extracts thermal energy from
pressurized steam, and converts it into useful mechanical work.
19. COGAG
• Combined gas turbine and gas
turbine (COGAG) is propulsion
system for ships using two gas
turbines connected to a single
propeller shaft.
• A gearbox and clutches allow either
of the turbines to drive the shaft or
both of them combined.
• Using one or two gas turbines has the
advantage of having two different
power settings.
• Since the fuel efficiency of a gas
turbine is best near its maximum
power level, a small gas turbine
running at its full speed is more
efficient compared to a twice as
powerful turbine running at half
speed, allowing more economic
transit at cruise speeds.
21. Prime movers
Electric drive
• Electric drive transmissions have a higher specific fuel consumption, specific
weight and volume than mechanical drive systems, but has advantages in
arrangement which may compensate for these disadvantages.
• Advanced technology motors can be located very close to and on line with the
propulsors, at the extreme aft end of the ship, or in external pods.
• Electrical generator sets can be optimally spaced around the ship and electrically
connected. In the longer term, combined with fuel cells, SFC, specific weight and
volume are comparable with gas turbine and diesel prime movers for direct drive
systems.
Zone Concept :
• The concept of dividing future classes of ship into zones to maximize survivability
also extends to the power system.
• Each zone would be autonomous and include ventilation systems, cooling systems,
power distribution and other services which could be affected by damage to another
part of the ship.
• At least two supplies would be provided for all essential loads. Current classes,
using split generation and distribution, rely on the provision of normal and
alternative supplies via Automatic Change-Over Switches
23. Fuel cell
• The fuel cell stack operates by utilizing electrochemical reactions between an
oxidant (air) and a fuel (hydrogen), with two electrodes separated by a
membrane.
• The voltage of the fuel cell output can be controlled by a converter and it is
therefore able to connect to any point in the ship service or propulsion
distribution system.
• The fuel cell stack is modularity give redundancy advantage. It also has the
additional advantages of zero noxious emissions, and low thermal and acoustic
signatures.
• In the short term the fuel cell system is required to use marine diesel fuel.
Diesel fuel will require reforming within the fuel cell stack, or using an external
process, to produce a hydrogen rich gas which the fuel cell stack is capable of
processing.
• The reformer will clearly add both size, weight and complexity to the fuel cell
system. In the longer term technologies such as the Solid Oxide Fuel Cell
(SOFC) are contenders, which are more forgiving of impurities and can use a
fuel available world-wide, either methanol or gasoline.
24. Storage option
• The technologies being assessed for energy storage include are electro-
chemical batteries (both conventional and advanced), regenerative fuel
cells (otherwise known as redox flow cells ) Superconducting Magnetic
Energy Storage (SMES) and Supercapacitors.
• Regenerative fuel cells store or release electrical energy by means of a
reversible electrochemical reaction between two salt solutions (the
electrolytes). The reaction occurs within an electrochemical cell.
• The cell has two compartments, one for each electrolyte, physically
separated by an ion-exchange membrane.
• In contrast to most types of battery system, the electrolytes flow into and
out of the cells and are transformed electrochemically inside the cells. The
power is therefore determined by the size of the cell but the endurance is
determined by the size of the two electrolyte tanks
26. Prime movers
• All primemovers are potentially compliant with emerging emission
requirements, however, complexity for achieving compliance varies with
prime mover and fuel type.
• Diesels require the most attention to emissions control followed at some
distance by gas turbines, where ultra low emissions levels have been
achieved for land-based systems.
• Fuel cells emit the lowest levels of pollutants of all the primemovers
• Heavier fuel cell systems and diesels represent larger machinery and
structural weight.
• Fuel cells can be used as a prime mover in an Integrated Full Electric
Propulsion (IFEP) system providing DC electrical power output, and are
being developed as a replacement for diesel generators and gas turbine
alternators.
29. Propulsion motor
• For efficient operation of propulsion motor there is a
requirement for a compact, power dense, rugged
electrical machine to be utilized for the propulsion
motor.
• For the full benefits of electric propulsion to be
realized the machine should also be efficient,
particularly at part load,
• In order to achieve suitable compact designs rare
earth permanent magnet materials may be required.
• The machine topologies available for PMM are
deemed to be those based on radial, axial and
transverse flux designs.
31. Power for LNG ships
• These alternatives are more economical and offer greater overall efficiency
with an added advantage of providing greater flexibility and redundancy
• Diesel plant also raises are inherited with problem of vibration on
membrane
• LNG carrier it is necessary to understand the interaction between the
structural resonance that is excited by the diesel engine and the separate
resonance that is created within the membrane containment system
interacting with LNG.
• The traditional application of gas fired boilers for steam turbine propulsion
systems is no longer the only available option for LNG Carriers,”
• Direct drive, slow speed diesel plants, coupled with an on-board
liquefaction plant to handle the cargo boil off, or 4 stroke medium speed
diesel electric propulsion or gas turbine with diesel electric drive appear to
offer the greatest operational efficiencies for the new designs of large LNG
carriers.
32. Power generation for LNG ships
• Although slow or medium speed diesel engines have been selected for some of the
recent LNG carriers with dual fuel installation option that uses both gas boil-off and
ordinary bunkers.
• Variations of the dual fuel arrangements include:
-diesel engine or gas turbine driven generators with one propulsion shafting system and
a liquefaction plant;
-diesel engine or gas turbine driven generators with two propulsion shafting systems
and a liquefaction plant;
-diesel engine or gas turbine driven generators with two azimuth thrusters and a
liquefaction plant.
• To date, slow speed diesel with re-liquefaction plant as well as a gas combustion
unit, and medium speed dual fuel diesel with gas combustion units, are the
preferred options for the new large LNG carriers recently ordered in Korea.
• It would appear that gas turbine with simple and combined cycles using heat
recovery units to drive steam turbo alternators are another alternative being
explored. Industry is currently developing the fuel gas systems for these gas turbine
options.
33. Power generation for LNG ships
• A dual fuel diesel-electric system uses forced boil-off from the cargo tanks
as the primary fuel and marine diesel oil as back-up fuel. The arrangement
can also be adapted to current LNG carrier designs.
• Shipbuilders and engine designers that are proponents of dual fuel systems
point out that a gas-electric propulsion plant is more compact than the
traditional steam turbine plant used for LNG carriers, increasing cargo
capacity within the same dimensioned hull.
• The IMO Gas Carrier Code requires two means of utilizing boil-off gas on
all LNG carriers. Conventional systems use the main boilers for generating
steam for propulsion. When this cannot be used, excess steam is redirected
to the condensers. Similar arrangements are required for the diesel
propulsion systems. Current industry proposals for the alternative means of
boil-off gas utilization are a liquefaction plant or a gas combustion unit.
• Risk assessment methods are recommended for option selection
34. Power Distribution
• As the demand for electrical are 3.3 kV or 6.6 kV but 11 kV is
used on some offshore platforms and specialist oil/gas
production ships e.g on some FPSO (floating production,
storage and offloading) vessels.
• By generating electrical power at 6.6 kV instead of 440 V the
distribution and switching of power above about 6 MW
becomes more manageable.
• As for electrical Power increases on ships (particularly
passenger ferries, cruise liners, and specialist offshore vessels
and platforms) the supply current rating becomes too high at
440 V.
• To reduce the size of both steady state and fault current levels,
it is necessary to increase the system voltage at high power
ratings.
35. Component parts of an HV
• The component parts of an HV supply system are standard equipment with:
HV diesel generator sets feeding an HV main switchboard.
• Large power consumers such as thrusters, propulsion motors, air-
conditioning (A/C) compressors and HV transformers are fed directly from
the HV switchboard.
• An economical HV system must be simple to operate, reasonably priced
and require a minimum of maintenance over the life of the ship.
• Experience shows that a 9 MW system at 6.6 kV would be about 20% more
expensive for installation costs.
• The principal parts of a ships electrical system operated at HV would be the
main generators, HV switchboard, FV cables, HV transformers and HV
motors.
• An example of a high voltage power system is shown
37. HV Systems
• In the example shown the HV generators form a central power station for
all of the ship's electrical services.
• On a large passenger ship with electric propulsion, each generator may be
rated at about 10 MW or more and producing 6.6 kV, 60 Hz three-phase
a.c. voltages.
• The principal consumers are the two synchronous a.c. propulsion electric
motors (PEMs) which may each demand 12 MW or more in the full away
condition.
• Each PEM has two stator windings supplied separately from the main HV
switchboard via transformers and frequency converters.
• In an emergency a PEM may therefore be operated as a half-motor with a
reduced power output. A few large induction motors are supplied at 6.6 kV
from the main board with the circuit breaker acting as a direct-on-line
(DOL) starting switch.
38. Ship high voltage systems
These motors are:
o Two forward thrusters and one aft thruster, and
o Three air conditioning compressors
• Other main feeders supply the 440 V engine room sub-station (ER sub)
switchboard via step-down transformers.
• An interconnector cable links the ER sub to the emergency switchboard.
• Other 440 V sub-stations (accommodation,galley etc.) around the ship are
supplied from the ER sub.
• Some installations may feed the ships sub stations directly with HV and step-
down to 440 V locally.
• The PEM drives in this example are synchronous motors which require a
controlled low voltage excitation supply current to magnetise the rotor poles.
• This supply is obtained from the HV switchboard via a step-down
transformer but an alternative arrangement would be to obtain the excitation
supply from the 440 V ER sub switchboard.
41. Solid State Switching Principle
• The power systems engineers is interested in high voltages primarily for
power transmission, and secondly for testing of his equipment used in
power transmission in laboratory
• High voltage can be obtained locally from power generating plant through
the use of solid state
• In many testing laboratories, the primary source of power is at low voltage
(400 V three phase or 230 V single phase, at 50 Hz). From which high
voltage can be obtained
• On board ship the same technology can be used to use high voltage
• Laboratory test are aimed to design the required high voltage
• Since insulation is usually being tested, the impedances involved are
extremely high (order of M ohm and the currents small (less than an
ampere).
• High voltage testing does not usually require high power.
• Thus special methods may be used which are not applicable when
generating high voltage in high power applications.
42. Solid State Switching Principle
• In the field of electrical eng. & applied physics, high voltages are required for
several applications As:
-a power supply (eg. hv dc) for the equipments such as electron microscope and
x-ray machine.
-Required for testing power apparatus – insulation testing.
-High impulse voltages are required for testing purposes to simulate over
voltages due to lightning and switching.
• Sometimes, high direct voltages are needed in insulation test on cables and
capacitors. Impulse generator charging units also require high dc voltages of
about 100-200kV.
• Normally for the generation of dc voltages of up to 100kV, electronics valve
rectifiers are used and the output currents are about 100mA. The rectifier
valves require special construction for cathode and filaments since a high
electrostatic field of several kV/cm exists between the anode and cathode in
the non-conduction period.
• The ac supply to the rectifier tubes maybe of power frequency or maybe of
audo frequency from an oscillator. The latter is used when a ripple of very
small magnitude is required without the use of costly filters to smoothen the
ripple.
43. Half and Full Wave Rectifier
• Rectifier circuits for producing high dc voltages from ac sources
maybe
a. Half-Wave
b. Full-Wave
o The rectifier can be an electron tube or a solid state devices.
Nowadays, single electron tubes are available for peak inverse
voltages up to 250kV and semiconductor or solid state diodes up
to 250kV.
o For higher voltages, several units are to be used in series. When
a number of units are used in series, transient voltage
distribution along each unit becomes non-uniform and special
care should be taken to make the distribution uniform.
44. RL
Vin V out
Half Wave Rectifier
V
p
V
AVG
0
T
Mean Load Voltage or Average Value of half wave output
45. D1
+
to t1 t2
RL
D2
-
Full wave Rectifier Circuit
figure 1.7 : Full-wave rectifier circuit
Vp
V AVG
to t1 t2
Mean Load Voltage or Average Voltage Full-wave output
46. Voltage Multiplier Circuits
• Both full-wave as well as half-wave circuits can
produce a maximum direct voltage corresponding to
the peak value of the alternating voltage.
• When higher voltages are required voltage multiplier
circuits are used. The common circuits are the voltage
double circuit
• Used for higher voltages.
• Generate very high dc voltage from single supply
transformer by extending the simple voltage doubler
circuit.
47. Types of high voltages;
• High d.c. voltages
• High a.c. voltages of power frequency
• High a.c. voltages of high frequency
• High transient or impulse voltages of very short
• duration - lightning overvoltages
• Transient voltages of longer duration – switching
• surges
48. • The voltage doubler circuit makes
use of the positive and the
negative half cycles to charge two
different capacitors. These are
then connected in series aiding to
obtain double the direct voltage
output. Figure shows a voltage
doubler circuit.
• In this case, the transformer will
be of small rating that for the
same direct voltage rating with
only simple rectification. Further
for the same direct voltage output
the peak inverse voltage of the
diodes will be halved. Voltage doubler circuit
49. High Alternating Voltages
• Required in laboratories and a.c. tests as well as for the
• circuit of high d.c. and impulse voltage.
• Test transformer are generally used.
• Single transformer test units are made for high alternating voltages
up to about 200 kV.
• However, for high voltages to reduce the cost (insulation cost
increases rapidly with voltage) and make transportation easier, a
cascade arrangement of several transformers is used.
• For higher voltage requirement, series connection or cascading of
the several identical units of transformer is applied.
52. Cascade arrangement of transformers
• A typical cascade arrangement of transformers used to obtain up
to 300 kV from three units each rated at 100 kV insulation. The
low voltage winding is connected to the primary of the first
transformer, and this is connected to the transformer tank which
is earthed.
• One end of the high voltage winding is also earthed through the
tank.
• The high voltage end and a tapping near this end is taken out at
the top of the transformer through a bushing, and forms the
primary of the second transformer.
• One end of this winding is connected to the tank of the second
transformer to maintain the tank at high voltage.
• The secondary of this transformer too has one end connected to
the tank and at the other end the next cascaded transformer is fed.
53. Cascade arrangement of transformers
• This cascade arrangement can be continued further if a still
higher voltage is required.
• In the cascade arrangement shown, each transformer needs
only to be insulated for 100 kV, and hence the transformer can
be relatively small. If a 300 kV transformer had to be used
instead, the size would be massive. High voltage transformers
for testing purposes are designed purposely to have a poor
regulation.
• This is to ensure that when the secondary of the transformer is
short circuited (as will commonly happen in flash-over tests of
insulation), the current would not increase to too high a value
and to reduce the cost. In practice, an additional series
resistance (commonly a water resistance) is also used in such
cases to limit the current and prevent possible damage to the
transformer.
54. Cascade arrangement of transformers
• What is shown in the cascade transformer arrangement is the basic principle
involved. The actual arrangement could be different for practical reasons.
• In the cascade arrangement shown, each transformer needs only to be insulated for
100 kV, and hence the transformer can be relatively small. If a 300 kV transformer
had to be used instead, the size would be massive. High voltage transformers for
testing purposes are designed purposely to have a poor regulation.
• This is to ensure that when the secondary of the transformer is short circuited (as
will commonly happen in flash-over tests of insulation), the current would not
increase to too high a value and to reduce the cost. In practice, an additional series
resistance (commonly a water resistance) is also used in such cases to limit the
current and prevent possible damage to the transformer.
• What is shown in the cascade transformer arrangement is the basic principle
involved. The actual arrangement could be different for practical reasons.
55. High D.C. Voltages
• Generation of high d.c. voltages is mainly
required in research work in the areas of pure
and applied physics.
• Needed in insulation test.
• Use rectifier circuit (diode) to convert a.c. to
d.c.
• voltage. – vacuum rectifiers, semiconductor
diodes
56. Impulse High Voltage
• Impulse voltages (IVs) are required in hv tests to simulate the
stresses due to external and internal overvoltages, and also for
fundamental investigations of the breakdown mechanisms.
• Usually generated by discharging hv capacitors through
switching gaps onto a network of resistors and capacitors.
• In hv technology, a single, unipolar voltage is termed an
impulse voltage.
• Rectangular and wedge-shaped IVs are normally used for basic
experiments while for testing purposes, double exponential IVs
are used.
• Standard test of impulse voltages can be represented as double
exponential wave, and its mathematical equation is defined as
follows;
V = Vo [exp(-αt) – exp(-βt)]
Where α and β are constants of microsecond values.
57. Controlled Rectification
• The generated three power supply on a phase a.c. electrical ship
has a fixed voltage and frequency. This is generally at M0 V and
60 Hz but for high power demands it is likelv to be 6.6 kV and
60 Hz.
• Speed control for a propulsion motor requires variable voltage
for a d.c. drive and variable frequency * voltage for an a.c. drive.
• The set bus-bar a.c. voltage must be converted by controlled
rectification (a.c.--d.c.) ind/or controlled inversion (d. c. * a. c. )'
to match the propulsion motor type.
• A basic rectifier uses semiconductor diodes which can only
conduct current in the direction of anode (A) to cathode (K) and
this is automatic when A is more positive than K.
• The diode turns-off automatically when its current falls to zero.
Hence, in –a single-phase a.c. circuit a single diode will conduct
only on every other half-cycle and this is called half-wave
rectification.
59. Controlled Rectification
• In this circuit an inductor coil (choke) smooth the d.c. load current even
though the d.c. voltage is severely chopped by the thyristor switching action.
• An alternative to the choke coil is to use a capacitor across the rectifier output
which smooths the d.c. voltage. Full wave controlled rectification from a
three-phase a.c. supply is achieved in a bridge Circuit with six thyristors a
shown
• Other single-phase circuits using a biased arrangement with two diodes and a
centre-tapped transformer will create full-wave rectification Similarly, four
diodes in a bridge formation will also produce a full-wave d.c. voltage output.
• An equivalent three phase bridge requires six diodes for full-wave operation.
A diode, having only two terminals, cannot control the size of the d.c. output
from the rectifier.
• For controlled rectification it is necessary to use a set of three-terminal
devices such as thyristors (for high currents) or transistors (for low - medium
currents).
61. Three-phase controlled rectifier bridge circuit.
• A basic a.c.-d.c. control circuit using a thyristor switch is shown in the
next slide. Compared with a diode, a thyristor has an extra (control)
terminal called the gate (G).
• The thyristor will only conduct when the anode is positive with respect to
the cathode and a brief trigger voltage pulse is applied between gate and
cathode (gate must be more positive than cathode).
• Gate voltage pulses are provided by separate electronic circuit and the
pulse timing decides the switch-on point for the main (load) current. The
load current is therefore rectified to d.c. (by diode action) and controlled by
delayed switching.
• In this circuit an inductor coil (choke) smooth the d.c. load current even
though the d.c. voltage is severely chopped by the thyristor switching
action.
• An alternative to the choke coil is to use a capacitor across the rectifier
output which smooths the d.c. voltage. Full wave controlled rectification
from a three-phase a.c. supply is achieved in a bridge Circuit with six
thyristors a shown
62. Three-phase controlled rectifier bridge circuit.
• The equivalent maximum d.c. voltage output is taken to be about 600 V as
it has a six-pulse ripple effect due to the three-phase input waveform.
• Controlled inversion process - A d.c. voltage can be inverted (switched)
repeatedly from positive to negative to form an alternating (u.c.) voltage by
using a set of thyristor (or transistor) switches. A controlled three-phase
thyristor bridge inverter is shown
• The inverter bridge circuit arrangement is exactly the same as that for the
rectifier. Here, the d.c. voltage is sequentially switched onto the three
output lines. The rate of switching determines the output frequency.
• For a.c. motor control, the line currents are directed into (and out of) the
windings to produce a rotating stator flux wave which interacts with the
rotor to produce torque.
• The processes of controlled rectification and inversion are used in
converters that are designed to match the drive motor.
64. Converter Types
The principal types of motor control converters are:
- >a.c.-d.c. (controlled rectifier for d.c. motors) . a.c.-d.c.-a.c. (PWM for
induction motors)
- >a.c.- d.c.-a.c. (synchroconverter or synchronous motors) .
-> d.c.-a.c. (cycloconverter for synchronous motors)
These are examined below:
a.c.- d.c. converter
• This is a three phase a.c. controlled rectification circuit for a d.c. motor
drive.
• Two converters of different power ratings are generally used for the
separate control of the armature current and the field current which
produces the magnetic flux .
• Some systems may have a fixed field current which means that the field
supply only requires an uncontrolled diode bridge
65. Converter Types
• Shaft rotation can be achieved by reversing either the field current or the
armature current direction.
• Ship applications for such a drive would include cable-laying, offshore
drilling, diving and supply, ocean survey and submarines.
a.c.- d.c.-a.c. PWM converter
• This type of converter is used for induction motor drives and uses
transistors as the switching devices.
• Unlike thyristors, a transistor can be turned on and off by a control signal
and at a high switching rate (e.g. at 20 kHz in a PWM converter).
• The input rectifier stage is not controlled so is simpler and cheaper but the
converter will not be ablg to allow power from the motor load to be
regenerated back into the mains supply during a braking operation.
68. Converter Types
• From a 440 Y a.c. supply, the rectified d.c. (link) voltage will
be smoothed by the capacitor to approximately 600 V.
• The d.c. voltage is chopped into variablewidth, but constant
level, voltage pulses in the computer controlled inverter
section using IGBTs (insulated gate bipolar transistors).
• This process is called pulse width modulation or PWM. By
varying the pulse widths and polarity of the d.c. voltage it is
possible to generate an averaged sinusoidal ac. output over a
wide range of frequencies typically 0.5-120Hz.
• Due to the smoothing effect of the motor inductance, the
motor currents appear to be nearly sinusoidal in shape.
• By sequentially directing the currents into the three stator
windings, a reversible rotating magnetic field is produced with
its speed set by the output frequency of the PWM converter.
69. Converter Types
• Accurate control of shaft torque, acceleration time and resistive braking are
a few of the many operational parameters that can be programmed into the
VSD,usually via a hand-held unit.
• The VSD can be closelv tuned to the connected motor drive to achieve
optimum control and protection limits for the overall drive.
•
• Speed regulation against load changes is very good and can be made very
precise by the addition of feedback from a shaft speed encoder.
• VSDs, being digitally controlled, can be easily networked to other
computer devices e.g. programmable logic controllers (PLCs) for overall
control of a complex process.
70. Converter Types
a.c.*d.c.+a.c. synchroconverter
• This type of convert is used for large a.c. synchronous motor
drives (called a synchrodrive) and I is applied very
successfully to marine electric propulsion.
• A synchroconverter has controlled rectifier and inverter stages
which both rely on natural turn-off (line commutation) for the
thyristors by the three phase a.c. voltages at either end of the
converter.
• Between the rectification and inversion stages is a current-
smoothing reactor coil forming the d.c. link.
• An operational similarity exists between a svnchrodrive and a
d.c. motor drive. DC link synchroconverter and a dc motor
drive.
73. Converter Types
• This view considers the rectifier stage as a controlled d.c.
supply and the inverter/synchronous motor combination as a
d.c. motor. with the switching inverter acting as a static
commutator.
• The combination of controlled rectifier and d.c. link is
considered to be a current source for the inverter whose task is
then to sequentially direct blocks of the current into the motor
windings
• The size of the d.c. current is set by the controlled switching of
the rectifier thyristors.
• Motor supply frequency (and hence its speed) is set by the rate
of inverter switching.
• The six inverter thyristors provide six current pulses per cycle
(known as a six-pulse converter)
74. Converter Types
• A simplified understanding of synchroconverter control is that
the current source (controlled rectification stage) provides the
required motor torque and the inverter stage controls the
required speed.
• To provide the motor e.m.f. which is necessary for natural
commutation of the inverter thyristors, the synchronous motor
must have rotation and magnetic flux in its rotor poles.
• During normal running, the synchronous motor is operated
with a power factor of about 0.9 leading (by field excitation
control) to assist the line commutation of the inverter
thyristors.
• The d.c. rotor field excitation is obtained from a separate
controlled thvristor rectification circuit.
75. Converter Types
• As the supply (network) and machine bridges
are identical and are both connected to a three-
phase a.c. voltage source, there roles can be
switched into reverse.
• This is useful to allow the regeneration motor
power back into the mains power supply which
provides an electric braking torque during a
crash stop of the ship.
77. Converter Types
a.c.- a.c. cycloconverter
• While a synchroconverter is able to provide an output
frequency range typically up to twice that of the mains input
(e.g. up to 120 Hz), a cycloconverter is restricted to a much
lower range.
• This is limited to less than one thtird of the supply frequency
(e.g. up to 20 Hz) which is due to the way in which this type of
converter produces the a.c. output voltage waveform.
• Ship ropulsion shaft speeds are typically in the range of 0-145
rev/min which can easily be achieved by the low frequency
output range of a cycloconverter to a multi-pole synchronous
motor.
• Power regeneration from the motor back into the main power
supply is available. A conventional three phase converter from
a.c. to d.c. can be controlled so that the average output voltage
can be increased and decreased from zero to maximum within a
half-cycle period of he sinusoidal a.c. input.
78. Converter Types
• By connecting two similar converters back-to-back in each line an a.c.
output frequency is obtained.
• The switching pattern for the thyristors varies over the frequency range
which requires a complex computer program for converter control.
• The corresponding current waveform shape (not shown) will be more
sinusoidal due to the smoothing effect of motor and line inductance.
• The output voltage has ripple content which gets as the output frequency it
is this feature that limits useful frequency.
• There is no connection between the three motor windings because the line
converters have to be isolated from each other to operate correctly to obtain
line commutation (natural) switching of the thvristors.
• The converters may be directly supplied from the HV line but it is more
usual to interpose step-down transformers. This reduces the motor voltage
and its required insulation level while also providing additional line
impedance to limit the size of prospective fault current and harmonic
voltage distortion at the main supply bus-bar.
84. The future
• Propulsion of ships by help of standard diesel engines
usually gives a non-optimal utilization of the energy.
• Today an increased use of diesel electrical propulsion
of ships can be seen. New power electronics and
electrical machines will be developed for propulsion
and thrusters, as well as other application on board.
• Knowledge has to be developed about how such large
motor drives will influence the autonomous power
systems on-board.
• Even development of new integrated electrical
systems for replacement of hydraulic systems (top-
side as well as sub-sea) are becoming areas of need.
85. Typical system of all electrical ship
• Generator sets complete with prime movers and engine controls
• HV/LV Switchboards, distribution systems and group starter boards
• Propulsion and thruster motors complete with power electronic
variable speed drives
• Power conversion equipment
• Shaft braking
• Power factor correction and harmonic filters
• (as necessary)
• Power management
• Machinery control and surveillance
• Dynamic positioning and joystick control
• Machinery control room and bridge consoles
• Setting to work and commissioning
• Operator training
86. Future electrical ship
• Future HV ships systems at sea may require voltages up to
13.8 kV to minimize fault levels
• It is therefore essential that all Marine Engineering personnel
are trained in safe working practices for these voltages.
• The Electrical officers of the near future must be fully trained
to carry out maintenance and defect rectification on Medium
Voltage (MV) systems.
• This will mean a considerable increase in the electrical content
of all training.
• Training will also need to be given to non-technical personnel
to ensure everybody is aware of the dangers of these higher
voltages.