This document provides a summary of production processes, power distribution systems, preventative maintenance procedures, and electrical improvements at the Nchanga copper smelter in Zambia. It describes the complex process of producing copper, acid, and cobalt alloy from concentrate using various furnaces. Electricity is supplied via 11kV and 33kV systems from the national grid and regulated before distribution to substations across the smelter site. Preventative maintenance is performed monthly and quarterly, including inspections and tests of motors, panels, cables, and earth pits to maintain equipment reliability and safety. Electrical improvements have also been implemented at the smelter.
This document provides a report on the 400/220 KV Nelamangala power station near Bangalore, India. It includes a single line diagram of the substation, details of the bus bar scheme, and descriptions of the main equipment including capacitive voltage transformers, current transformers, circuit breakers, isolators, transformers, and reactors. It also covers substation auxiliaries, control rooms, earthing systems, and provides specifications for the main transformers. The power station was established to integrate new power sources into the southern grid and reduce grid failures in the region.
Vocational Training Report (Rajdhani Express)shovandey07
The document provides details about the Rajdhani Express train service in India, including:
- Rajdhani Express trains offer fast connections between New Delhi and state capitals, first introduced in 1969.
- They have the highest priority on the Indian railway network and are fully air-conditioned. Meals are provided to passengers.
- The trains use electric locomotives powered by overhead lines, with diesel generators providing power for lighting, air conditioning, etc.
- Coaches include AC bedrooms, AC open berths, and AC closed berths of various configurations depending on the train.
This document discusses various busbar arrangements used in substations including:
- Single busbar system
- Single bus with sectionaliser system
- Double busbar system
- One and half breaker system
It provides diagrams and explanations of how each system works, their advantages and disadvantages. It also discusses the different busbar configurations adopted by the Andhra Pradesh Transmission Corporation (APTRANSCO) at various voltage levels.
Vocational training Report (Train Lighting)shovandey07
1. Train lighting systems have evolved over time, transitioning from axle-driven dynamos to various brushless alternator systems providing 110V DC power.
2. There are currently four main types of train lighting systems in use: axle-driven producing 110V DC, mid-on generation with 415V 3-phase generation and 110V utilization, and two end-on generation systems with either 415V or 750V 3-phase generation and 110V utilization.
3. All new coaches are being built with the 110V DC axle-driven system, which has proven more reliable and capable of meeting increasing load demands.
This document provides information about the design and components of a 220kV switchyard. It discusses:
1. The double main bus with transfer bus scheme used, which has two main buses (Bus-1 and Bus-2) and one transfer bus for maintenance.
2. The key equipment used including circuit breakers, current transformers, capacitor voltage transformers, isolators, lightning arresters, and insulators.
3. The testing procedures for current transformers, which include insulation resistance testing, polarity testing, excitation testing, ratio testing, and winding resistance testing.
This document proposes a micro-inverter configuration for high power phosphoric acid fuel cell systems as an alternative to conventional configurations. In the proposed system, each fuel cell stack is connected to an individual micro-inverter containing a three-level boost converter and off-the-shelf three-phase inverter. This allows independent operation of fuel cell stacks for increased efficiency and modular design. The document models and analyzes the operation of the three-level boost converter in the micro-inverter, including its two modes of operation and efficiency improvements from stage-shedding at lower loads. Simulation and experimental results demonstrate the viability of the topology for commercial fuel cell power plants.
The document discusses torque ripple minimization in BLDC motors. It describes how torque ripples occur during current commutation between phases in BLDC motors due to mismatched current rise and fall times. A proposed PWM switching strategy uses modified PWM signals to speed up or slow down the energized phase current during commutation based on motor speed, minimizing torque ripples. Experimental results show that the modified PWM approach reduces current spikes and dips during commutation, resulting in lower torque ripple compared to conventional PWM control.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
This document provides a report on the 400/220 KV Nelamangala power station near Bangalore, India. It includes a single line diagram of the substation, details of the bus bar scheme, and descriptions of the main equipment including capacitive voltage transformers, current transformers, circuit breakers, isolators, transformers, and reactors. It also covers substation auxiliaries, control rooms, earthing systems, and provides specifications for the main transformers. The power station was established to integrate new power sources into the southern grid and reduce grid failures in the region.
Vocational Training Report (Rajdhani Express)shovandey07
The document provides details about the Rajdhani Express train service in India, including:
- Rajdhani Express trains offer fast connections between New Delhi and state capitals, first introduced in 1969.
- They have the highest priority on the Indian railway network and are fully air-conditioned. Meals are provided to passengers.
- The trains use electric locomotives powered by overhead lines, with diesel generators providing power for lighting, air conditioning, etc.
- Coaches include AC bedrooms, AC open berths, and AC closed berths of various configurations depending on the train.
This document discusses various busbar arrangements used in substations including:
- Single busbar system
- Single bus with sectionaliser system
- Double busbar system
- One and half breaker system
It provides diagrams and explanations of how each system works, their advantages and disadvantages. It also discusses the different busbar configurations adopted by the Andhra Pradesh Transmission Corporation (APTRANSCO) at various voltage levels.
Vocational training Report (Train Lighting)shovandey07
1. Train lighting systems have evolved over time, transitioning from axle-driven dynamos to various brushless alternator systems providing 110V DC power.
2. There are currently four main types of train lighting systems in use: axle-driven producing 110V DC, mid-on generation with 415V 3-phase generation and 110V utilization, and two end-on generation systems with either 415V or 750V 3-phase generation and 110V utilization.
3. All new coaches are being built with the 110V DC axle-driven system, which has proven more reliable and capable of meeting increasing load demands.
This document provides information about the design and components of a 220kV switchyard. It discusses:
1. The double main bus with transfer bus scheme used, which has two main buses (Bus-1 and Bus-2) and one transfer bus for maintenance.
2. The key equipment used including circuit breakers, current transformers, capacitor voltage transformers, isolators, lightning arresters, and insulators.
3. The testing procedures for current transformers, which include insulation resistance testing, polarity testing, excitation testing, ratio testing, and winding resistance testing.
This document proposes a micro-inverter configuration for high power phosphoric acid fuel cell systems as an alternative to conventional configurations. In the proposed system, each fuel cell stack is connected to an individual micro-inverter containing a three-level boost converter and off-the-shelf three-phase inverter. This allows independent operation of fuel cell stacks for increased efficiency and modular design. The document models and analyzes the operation of the three-level boost converter in the micro-inverter, including its two modes of operation and efficiency improvements from stage-shedding at lower loads. Simulation and experimental results demonstrate the viability of the topology for commercial fuel cell power plants.
The document discusses torque ripple minimization in BLDC motors. It describes how torque ripples occur during current commutation between phases in BLDC motors due to mismatched current rise and fall times. A proposed PWM switching strategy uses modified PWM signals to speed up or slow down the energized phase current during commutation based on motor speed, minimizing torque ripples. Experimental results show that the modified PWM approach reduces current spikes and dips during commutation, resulting in lower torque ripple compared to conventional PWM control.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Vocational Training Report ( Sealdah Power House)shovandey07
The document provides information about the power distribution system at Sealdah Power House in Kolkata, India. It describes the key components of the power house including transformers, switchgear, bus bars, isolators, circuit breakers, and protective relays. The power house receives 6KV high voltage from CESC which is stepped down to 415V by transformers before being distributed to Sealdah railway station for lighting, equipment, and facilities. There is also a backup diesel generator at one of the substations in case of outages.
Biến tần trung thế ứng dụng trong công nghiệp cho các ngành như: Xi măng, nước, khai thác mỏ, sắt thép, nhà máy điện hóa chất, … Thiết bị giảm đáng kể dòng hài trên nguồn điện, độ tin cậy cao và dễ dàng bảo trì.
CÔNG TY CỔ PHẦN HẠO PHƯƠNG
Trụ sở chính:
Địa chỉ: Số 88 đường Vĩnh Phú 40, Kp. Hòa Long, P. Vĩnh Phú, Thuận An, Bình Dương.
Văn phòng Hà Nội:
Địa chỉ: Số 95 TT4 – KĐT Mỹ Đình Sông Đà – Phường Mỹ Đình – Q. Nam Từ Liêm – Hà Nội
Chi nhánh Cambodia:
Địa chỉ: The Park Land SenSok, Borey Chip Mong, House Number 22, P11.Sangkat Phnom Penh Thmey, Khan San Sok, Phnom Penh.
Email: cs@haophuong.com – Website: haophuong.com
Facebook: https://www.facebook.com/haophuongcompany/
HOTLINE: 1800 6547
Power Supply System - Single Line DiagramKamran Hassan
The document outlines the power supply system from the utility to a data center. Electricity is delivered at 13.8kV from the utility and stepped down through multiple transformers to 500kV, 132kV, 11kV, and finally 440V for the data center equipment. The data center is supported by backup generators that supply power through an automatic transfer switch if the utility power fails.
This document summarizes two motor starting simulation studies using ETAP software. The first case studied the starting of a large induction motor under full voltage with different pole configurations. The second case compared the starting of a synchronous motor under full voltage versus reduced voltage using a soft-starter. Both simulations evaluated thermal limits. Field test oscillography of the synchronous motor demonstrated the need for a soft-starter to avoid voltage depression affecting other loads. The simulations showed the induction motor required low-speed starting to stay within thermal limits, while the synchronous motor required reduced voltage starting to maintain acceptable voltage levels.
Low Cost Automatic Speed Control of Single Phase AC Fan MotorsSouvik Dolui
The document discusses a new TRIAC motor controller called the SmartFan MMC series that provides precise control of single phase AC fan motors. The MMC uses a microprocessor to precisely time TRIAC firing for improved speed control of fans and other small motors. It monitors output voltage in real time to maintain a stable speed even under varying loads. This allows the MMC to control a wider range of motors more effectively than conventional TRIAC controllers.
Development of a Microcontroller Based 12/24 Volts Push-Pull Inverter Systemiosrjce
Conventional power inverter systems are normally specified to work with a single nominal battery
voltage. This is somewhat restrictive and causes downtimes when d.c power sources of specified voltages are not available.
In this work, a push-pull inverter circuit that generates its rated output voltage from either a 12Volts or 24 Volts d.c source
was developed. The circuit, based on a PIC 16F877A microcontroller, determines the battery voltage and generates the
required MOSFET gate drive signals required to generate a 240 volts r.m.s modified square wave output waveform. The
developed circuit and the associated microcontroller firmware were designed and modelled using proteus® software and
MicroC software respectively. The circuit was constructed, programmed and then tested. The circuit generated 240 volts
r.m.s output waveforms when it was powered from either a 12 volts or a 24 volts d.c voltage sources.
Two-Feeder Converter Based Interline Unified Power Quality ConditionerIRJET Journal
This document describes an interline unified power quality conditioner (IUPQC) that is placed between two feeders in an electrical distribution system. The IUPQC consists of two voltage source converters (VSCs) with a common DC bus. One VSC is connected in shunt with one feeder and regulates the voltage on that feeder. The other VSC is connected in series with the second feeder and protects a sensitive load from disturbances occurring upstream on the second feeder. The IUPQC aims to maintain constant voltages on both feeders despite faults, sags, swells or other power quality issues affecting either feeder. It does so by allowing power to be absorbed from one feeder and supplied to the
Estimation of Synchronous Generator Parameters from On-line MeasurementsMohammadHasanmosadde
The main objective of this research work is to develop a method to identify synchronous generator parameters from on-line measurements.
Secondary objectives of the research include
• Development of an observer for damper currents
• Calculation of the error characteristics of the estimation
• Development of an index of confidence
• Calculation of a range of values for each estimated parameter
• Study of which machine parameters can be estimated, and which can not
LOAD FREQUENCY AND VOLTAGE GENERATION CONTROLPreet_patel
LOAD FREQUENCY AND VOLTAGE GENERATION CONTROL
Load frequency control
Automatic Generation Control
Voltage Control
Primary regulation.
Secondary regulation
real power
Why voltage control is important?
Enhancing Power Quality in Transmission System Using Fc-TcrIJMER
FACTS methodology is totally based on power electronics devices which are used to increase the transmission capability. To make the power system flexible, FACTS technology is used to attain entire control of power system i.e. transmission, distribution and generation. This paper is mainly concerned about the significance of Fixed Capacitor Thyristor Control Reactor (FC-TCR) acquiring automatic power and steady state voltage stability with the help of fuzzy logic controller. In transmission systems, the fuzzy rules are set to generate the required firing angle of FC-TCR to maintain a flat profile of steady state voltage and stability. The fundamental model is simulated in MATLAB along with the fuzzy logic control strategy. The results obtained are trust worthy and it can be used for controlling the voltage and reactive power in any electrical transmission system.
Sensorless Control of a Fault-tolerant Multi-level PMSM DriveTELKOMNIKA JOURNAL
This paper presents a new technique to track the saliency position in a permanent magnet synchronous motor (PMSM) post a single phase open-circuit fault. The PMSM is driven by a fault-tolerant multi-level inverter that is utilized to implement a fault-tolerant control strategy to minimize system performance degradation post the fault.The fault-tolerant multi-level inverter is consisting of a number of insulated-gate bipolar transistors (IGBTs). The dynamic current reponses of the PMSM motor due to the switching actions of these IGBTs are used extract the saliency position. This process is not introducing any modification to the operation of the fault-tolerant multil-level inverter as it uses only the fundamental pulse width modulation (PWM) waveform. Moreover,it considers the modifications introduced to the PMSM motor and the multi-level inverter post the fault.Simulation results are provided to verify the effectiveness of the proposed strategy of saliency tracking of a PMSM motor driven by a fault-tolerant four-leg multi-level inverter over a wide range of speeds in the case of a single-phase open circuit fault.
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Fire Pump Transfer Switch Application and Design Criteria
Static ward leonard drive - dual converterManju Karthick
This document discusses speed control methods for DC motors using a dual converter. A dual converter takes a three phase power supply and converts it to DC power for a separately excited DC motor. The dual converter uses chopper control to vary the duty cycle of the DC power supplied to the motor, allowing for speed control of the DC motor.
Research Inventy : International Journal of Engineering and Science is publis...researchinventy
This document describes a system for controlling the speed of an AC motor remotely using a mobile phone and DTMF signaling. An embedded controller is used along with a DTMF decoder to receive digit tones from the mobile phone and control the speed of the motor. The system allows the motor to be turned on/off and its speed varied by pressing buttons on the mobile phone. The document discusses the components used, including the DTMF decoder, embedded controller, motor control circuitry, and an LCD display to show the motor status. It provides block diagrams of the system and descriptions of how it operates to remotely control the AC motor speed via DTMF tones sent from a mobile phone.
The document summarizes the key components and specifications of an LHB power car. It includes details about the 500 KVA alternator, 800 A air circuit breaker, voltage transformers, contactors, safety loops, batteries, transformers, switchboard cabinet, diesel alternator specifications including output voltage and capacity, insulation classes, regulation, gauges and controls. It also provides an overview of the hotel load supply from locomotives and battery charging system.
Troubleshooting of Electrical Switchyard & Substation EquipmentsMarcep Inc.
The document discusses substations, switchyards, and transmission lines. It describes different types of switchyard configurations including single bus, double bus, one and a half breaker, and gas insulated switchyards. It also discusses the major equipment found in switchyards/substations, safety procedures and minimum clearances. Maintenance procedures like routine, preventive, and breakdown maintenance are also covered. Finally, it touches on annual maintenance contracts, manufacturers, and the engineering, procurement, and construction of transmission lines.
This document provides an overview of automatic generation control (AGC) in power systems. It includes:
1) Block diagrams showing the components of AGC including speed governors, turbines, generators and load control. The diagrams model the dynamics of these components.
2) Descriptions of the turbine speed governing system, including flyball governors, hydraulic amplifiers and linkage mechanisms used to control steam flow based on generator speed.
3) Equations modeling the dynamics of the speed governor, turbine, and generator-load system and their interaction under different conditions like a load change when the speed changer is fixed.
4) Explanations of concepts like droop characteristic and steady-state frequency deviation from a load
Automatic generation control problem in interconnected power systemsAlexander Decker
This document discusses automatic generation control (AGC) in interconnected power systems. It begins by describing the structure of modern power systems and identifying AGC as an important control problem. It then provides details on the duties of AGC, including maintaining frequency and regulating power flows between interconnected areas. The document describes different types of frequency deviations and the associated primary, secondary, and emergency control responses needed to maintain reliable system operation. It also outlines the hierarchical timescales of different control functions, from governor response to economic dispatch. Diagrams are included to illustrate typical AGC control loops and the dynamic response to a generation trip event.
This document provides information about Indian Railways, including its history, organizational structure, and technical details about Linke-Hofman & Busch (LHB) coaches. It discusses how the railways were introduced in India and later nationalized in 1951. It also outlines the hierarchical organizational structure with the ministry of railways at the top. Finally, it describes various technical components of LHB coaches such as the alternator, rectifier, batteries, switchboard cabinet, and air conditioning system.
Este documento resume los términos "Corte", "Rigidez" e "Isostática" que son importantes para la arquitectura. El corte muestra la sección vertical de un edificio para conocer su estructura y organización espacial. La rigidez permite que una estructura resista las cargas sin deformarse. La isostática significa que una estructura mantiene el equilibrio a pesar de cambios en las fuerzas.
Reem El Ghamrawy has over 25 years of experience in marketing communications and management. She currently owns and manages her own agency, ANTS Communications, which provides world-class marketing services to international and local clients. Prior to this, she held senior marketing roles at Telecom Egypt, Leo Burnett Egypt, The Charles Yamine Company, J.Walter Thompson, and Tarek Nour Communications/DDB. She has extensive experience developing branding, communication, and marketing strategies across various industries.
Vocational Training Report ( Sealdah Power House)shovandey07
The document provides information about the power distribution system at Sealdah Power House in Kolkata, India. It describes the key components of the power house including transformers, switchgear, bus bars, isolators, circuit breakers, and protective relays. The power house receives 6KV high voltage from CESC which is stepped down to 415V by transformers before being distributed to Sealdah railway station for lighting, equipment, and facilities. There is also a backup diesel generator at one of the substations in case of outages.
Biến tần trung thế ứng dụng trong công nghiệp cho các ngành như: Xi măng, nước, khai thác mỏ, sắt thép, nhà máy điện hóa chất, … Thiết bị giảm đáng kể dòng hài trên nguồn điện, độ tin cậy cao và dễ dàng bảo trì.
CÔNG TY CỔ PHẦN HẠO PHƯƠNG
Trụ sở chính:
Địa chỉ: Số 88 đường Vĩnh Phú 40, Kp. Hòa Long, P. Vĩnh Phú, Thuận An, Bình Dương.
Văn phòng Hà Nội:
Địa chỉ: Số 95 TT4 – KĐT Mỹ Đình Sông Đà – Phường Mỹ Đình – Q. Nam Từ Liêm – Hà Nội
Chi nhánh Cambodia:
Địa chỉ: The Park Land SenSok, Borey Chip Mong, House Number 22, P11.Sangkat Phnom Penh Thmey, Khan San Sok, Phnom Penh.
Email: cs@haophuong.com – Website: haophuong.com
Facebook: https://www.facebook.com/haophuongcompany/
HOTLINE: 1800 6547
Power Supply System - Single Line DiagramKamran Hassan
The document outlines the power supply system from the utility to a data center. Electricity is delivered at 13.8kV from the utility and stepped down through multiple transformers to 500kV, 132kV, 11kV, and finally 440V for the data center equipment. The data center is supported by backup generators that supply power through an automatic transfer switch if the utility power fails.
This document summarizes two motor starting simulation studies using ETAP software. The first case studied the starting of a large induction motor under full voltage with different pole configurations. The second case compared the starting of a synchronous motor under full voltage versus reduced voltage using a soft-starter. Both simulations evaluated thermal limits. Field test oscillography of the synchronous motor demonstrated the need for a soft-starter to avoid voltage depression affecting other loads. The simulations showed the induction motor required low-speed starting to stay within thermal limits, while the synchronous motor required reduced voltage starting to maintain acceptable voltage levels.
Low Cost Automatic Speed Control of Single Phase AC Fan MotorsSouvik Dolui
The document discusses a new TRIAC motor controller called the SmartFan MMC series that provides precise control of single phase AC fan motors. The MMC uses a microprocessor to precisely time TRIAC firing for improved speed control of fans and other small motors. It monitors output voltage in real time to maintain a stable speed even under varying loads. This allows the MMC to control a wider range of motors more effectively than conventional TRIAC controllers.
Development of a Microcontroller Based 12/24 Volts Push-Pull Inverter Systemiosrjce
Conventional power inverter systems are normally specified to work with a single nominal battery
voltage. This is somewhat restrictive and causes downtimes when d.c power sources of specified voltages are not available.
In this work, a push-pull inverter circuit that generates its rated output voltage from either a 12Volts or 24 Volts d.c source
was developed. The circuit, based on a PIC 16F877A microcontroller, determines the battery voltage and generates the
required MOSFET gate drive signals required to generate a 240 volts r.m.s modified square wave output waveform. The
developed circuit and the associated microcontroller firmware were designed and modelled using proteus® software and
MicroC software respectively. The circuit was constructed, programmed and then tested. The circuit generated 240 volts
r.m.s output waveforms when it was powered from either a 12 volts or a 24 volts d.c voltage sources.
Two-Feeder Converter Based Interline Unified Power Quality ConditionerIRJET Journal
This document describes an interline unified power quality conditioner (IUPQC) that is placed between two feeders in an electrical distribution system. The IUPQC consists of two voltage source converters (VSCs) with a common DC bus. One VSC is connected in shunt with one feeder and regulates the voltage on that feeder. The other VSC is connected in series with the second feeder and protects a sensitive load from disturbances occurring upstream on the second feeder. The IUPQC aims to maintain constant voltages on both feeders despite faults, sags, swells or other power quality issues affecting either feeder. It does so by allowing power to be absorbed from one feeder and supplied to the
Estimation of Synchronous Generator Parameters from On-line MeasurementsMohammadHasanmosadde
The main objective of this research work is to develop a method to identify synchronous generator parameters from on-line measurements.
Secondary objectives of the research include
• Development of an observer for damper currents
• Calculation of the error characteristics of the estimation
• Development of an index of confidence
• Calculation of a range of values for each estimated parameter
• Study of which machine parameters can be estimated, and which can not
LOAD FREQUENCY AND VOLTAGE GENERATION CONTROLPreet_patel
LOAD FREQUENCY AND VOLTAGE GENERATION CONTROL
Load frequency control
Automatic Generation Control
Voltage Control
Primary regulation.
Secondary regulation
real power
Why voltage control is important?
Enhancing Power Quality in Transmission System Using Fc-TcrIJMER
FACTS methodology is totally based on power electronics devices which are used to increase the transmission capability. To make the power system flexible, FACTS technology is used to attain entire control of power system i.e. transmission, distribution and generation. This paper is mainly concerned about the significance of Fixed Capacitor Thyristor Control Reactor (FC-TCR) acquiring automatic power and steady state voltage stability with the help of fuzzy logic controller. In transmission systems, the fuzzy rules are set to generate the required firing angle of FC-TCR to maintain a flat profile of steady state voltage and stability. The fundamental model is simulated in MATLAB along with the fuzzy logic control strategy. The results obtained are trust worthy and it can be used for controlling the voltage and reactive power in any electrical transmission system.
Sensorless Control of a Fault-tolerant Multi-level PMSM DriveTELKOMNIKA JOURNAL
This paper presents a new technique to track the saliency position in a permanent magnet synchronous motor (PMSM) post a single phase open-circuit fault. The PMSM is driven by a fault-tolerant multi-level inverter that is utilized to implement a fault-tolerant control strategy to minimize system performance degradation post the fault.The fault-tolerant multi-level inverter is consisting of a number of insulated-gate bipolar transistors (IGBTs). The dynamic current reponses of the PMSM motor due to the switching actions of these IGBTs are used extract the saliency position. This process is not introducing any modification to the operation of the fault-tolerant multil-level inverter as it uses only the fundamental pulse width modulation (PWM) waveform. Moreover,it considers the modifications introduced to the PMSM motor and the multi-level inverter post the fault.Simulation results are provided to verify the effectiveness of the proposed strategy of saliency tracking of a PMSM motor driven by a fault-tolerant four-leg multi-level inverter over a wide range of speeds in the case of a single-phase open circuit fault.
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Fire Pump Transfer Switch Application and Design Criteria
Static ward leonard drive - dual converterManju Karthick
This document discusses speed control methods for DC motors using a dual converter. A dual converter takes a three phase power supply and converts it to DC power for a separately excited DC motor. The dual converter uses chopper control to vary the duty cycle of the DC power supplied to the motor, allowing for speed control of the DC motor.
Research Inventy : International Journal of Engineering and Science is publis...researchinventy
This document describes a system for controlling the speed of an AC motor remotely using a mobile phone and DTMF signaling. An embedded controller is used along with a DTMF decoder to receive digit tones from the mobile phone and control the speed of the motor. The system allows the motor to be turned on/off and its speed varied by pressing buttons on the mobile phone. The document discusses the components used, including the DTMF decoder, embedded controller, motor control circuitry, and an LCD display to show the motor status. It provides block diagrams of the system and descriptions of how it operates to remotely control the AC motor speed via DTMF tones sent from a mobile phone.
The document summarizes the key components and specifications of an LHB power car. It includes details about the 500 KVA alternator, 800 A air circuit breaker, voltage transformers, contactors, safety loops, batteries, transformers, switchboard cabinet, diesel alternator specifications including output voltage and capacity, insulation classes, regulation, gauges and controls. It also provides an overview of the hotel load supply from locomotives and battery charging system.
Troubleshooting of Electrical Switchyard & Substation EquipmentsMarcep Inc.
The document discusses substations, switchyards, and transmission lines. It describes different types of switchyard configurations including single bus, double bus, one and a half breaker, and gas insulated switchyards. It also discusses the major equipment found in switchyards/substations, safety procedures and minimum clearances. Maintenance procedures like routine, preventive, and breakdown maintenance are also covered. Finally, it touches on annual maintenance contracts, manufacturers, and the engineering, procurement, and construction of transmission lines.
This document provides an overview of automatic generation control (AGC) in power systems. It includes:
1) Block diagrams showing the components of AGC including speed governors, turbines, generators and load control. The diagrams model the dynamics of these components.
2) Descriptions of the turbine speed governing system, including flyball governors, hydraulic amplifiers and linkage mechanisms used to control steam flow based on generator speed.
3) Equations modeling the dynamics of the speed governor, turbine, and generator-load system and their interaction under different conditions like a load change when the speed changer is fixed.
4) Explanations of concepts like droop characteristic and steady-state frequency deviation from a load
Automatic generation control problem in interconnected power systemsAlexander Decker
This document discusses automatic generation control (AGC) in interconnected power systems. It begins by describing the structure of modern power systems and identifying AGC as an important control problem. It then provides details on the duties of AGC, including maintaining frequency and regulating power flows between interconnected areas. The document describes different types of frequency deviations and the associated primary, secondary, and emergency control responses needed to maintain reliable system operation. It also outlines the hierarchical timescales of different control functions, from governor response to economic dispatch. Diagrams are included to illustrate typical AGC control loops and the dynamic response to a generation trip event.
This document provides information about Indian Railways, including its history, organizational structure, and technical details about Linke-Hofman & Busch (LHB) coaches. It discusses how the railways were introduced in India and later nationalized in 1951. It also outlines the hierarchical organizational structure with the ministry of railways at the top. Finally, it describes various technical components of LHB coaches such as the alternator, rectifier, batteries, switchboard cabinet, and air conditioning system.
Este documento resume los términos "Corte", "Rigidez" e "Isostática" que son importantes para la arquitectura. El corte muestra la sección vertical de un edificio para conocer su estructura y organización espacial. La rigidez permite que una estructura resista las cargas sin deformarse. La isostática significa que una estructura mantiene el equilibrio a pesar de cambios en las fuerzas.
Reem El Ghamrawy has over 25 years of experience in marketing communications and management. She currently owns and manages her own agency, ANTS Communications, which provides world-class marketing services to international and local clients. Prior to this, she held senior marketing roles at Telecom Egypt, Leo Burnett Egypt, The Charles Yamine Company, J.Walter Thompson, and Tarek Nour Communications/DDB. She has extensive experience developing branding, communication, and marketing strategies across various industries.
Universal Design Learning: Fundamental Conceptsjleprice
Presents an overview of Universal Design Learning Principles
Presented by Leann Price, Marshall University, July 2016
College of Education and Professional Development
WVSTC Conference, Morgantown, WV
La ergonomía es una ciencia aplicada que adapta los métodos de trabajo, herramientas y condiciones ambientales a la anatomía, fisiología y habilidades humanas para reducir esfuerzos innecesarios y fatiga. La evaluación de riesgos identifica peligros en el puesto de trabajo y propone medidas para eliminar o reducir riesgos. La LOPCYMAT establece deberes para trabajadores y empleadores como proveer equipo de protección y mantener registros de seguridad.
Este documento presenta los resultados de un análisis de heces de conejos realizado por estudiantes de la Universidad Francisco de Paula Santander. El resumen incluye la determinación de la materia seca, cenizas y humedad de las muestras a través de métodos estandarizados. Los resultados mostraron que el contenido de humedad de las heces era muy bajo y que el aprovechamiento de los alimentos por parte de los conejos estaba dentro de los rangos reportados previamente en otras investigaciones.
El documento proporciona instrucciones en 4 pasos para descargar imágenes, música, videos y archivos de sitios web como Google, YouTube y otros convertidores. Se explica cómo buscar el contenido deseado, seleccionarlo y guardarlo localmente dando clic derecho y eligiendo la opción de descarga.
Raj's Security Force is a leading private security services agency in Mumbai, India that has over seven years of experience and 50 clients. It provides specialized security solutions and services customized for each client. The company aims to deliver high-quality security and risk management through its integrated security services portfolio. It has a robust organizational structure and places emphasis on customer satisfaction, quality assurance, and staff training. The document provides details on Raj's vision, services, clients, processes, and contact information.
This document provides information about the benefits of studying and working in Germany. Some key points include:
- German universities offer 100% scholarships and are ranked higher than IITs in India. Proficiency in German leads to scholarship opportunities.
- Germany has a large economy and over 100,000 engineering/IT jobs annually with average salaries of Rs. 30 lacs.
- Studying in Germany allows travel across Europe and has recognized degrees worldwide. Over 15,000 programs are available.
- Learning German is made easier with knowledge of English, and the language can be learned to a high level within 9 months in Germany.
Este documento resume los principales recursos administrativos establecidos en la Ley Orgánica de Procedimientos Administrativos de Venezuela. Explica que los recursos administrativos son medios de impugnación ante actos administrativos y establece los recursos de reconsideración, jerárquico y de revisión. Detalla que el recurso de reconsideración se interpone ante el funcionario que dictó el acto dentro de 15 días, y el jerárquico procede si no se modifica el acto impugnado en reconsideración. El de revisión puede darse si hay nuevas
El hardware se refiere a los componentes físicos de una computadora, a diferencia del software. El hardware básico necesario incluye la memoria RAM, el microprocesador y la memoria ROM. Otros componentes esenciales son la tarjeta madre, dispositivos de entrada y salida de datos como el teclado, ratón y pantalla, y el gabinete. El hardware se clasifica en hardware de almacenamiento, proceso, entrada, salida y bidireccional.
Material handling is an integral part of any industrial activity. With growing business, a greater emphasis is laid on productivity, profitability as well as resource conservation and ecological preservation. Material handling plays a very crucial role in sustaining efficiency in financial and human resources.
In India, Material handling witnessed a revolution by the introduction of Plastic crates. This revolution was pioneered by NILKAMAL.
Aram Peralta Vivar is seeking an office position utilizing skills in Microsoft Office, organization, communication, and database programs. He has over 5 years of experience in office administration and cargo handling roles. His experience includes encoding reports, preparing time records, inventory management, answering calls/emails, and ensuring regulatory compliance. He is proficient with the Oryx Cargo System and has experience handling customer queries and daily operations. Vivar has a certificate in Marine Transportation and references available upon request.
This newsletter provides information to residents of the Grandview Palace Condominium Association. It highlights recent developments including new staff, ongoing renovations around the building, and upcoming improvements like new pool furniture. The manager expresses gratitude for the community's support and outlines goals for continued progress over the next 6 months and 25 years. A trivia section with facts about the U.S. flag is also included along with advertisements from local businesses.
1. The document discusses creativity - it defines creativity as the ability to create something original that solves a problem. It argues that creativity is an innate human ability that can be developed through practice, rather than only possessed by a select few.
2. It discusses how to be more creative both at home and at work. At home, engaging in intrinsically motivating activities you enjoy can help get in a "flow state" and experience creativity. At work, understanding your interests and strengths through personality assessments can help you find a fulfilling career and be more innovative.
3. Today's business world values creativity and innovation, so developing your creative skills can make you more valuable and marketable as an employee.
Training report of secl , khairha coal mine , sohagpur area for electricalPiyush Dwivedi
This document provides details about a trainee's summer training report at the South Eastern Coalfield Limited (SECL) underground mine in Khairha, India. It includes:
1) An overview of the 33/11kV substation at Khairha mine and the underground electrical power system.
2) Descriptions of different types of transformers used in substations, including power transformers, instrument transformers, and autotransformers.
3) Specifications of the current transformers used in the 33/11kV substation.
4) Information about substation components like busbars, insulators, circuit breakers, metering equipment, and miscellaneous equipment.
5) Details
This document summarizes a practical training report on a 132 kV gas insulated substation (GSS) in Jalore, submitted in partial fulfillment of a Bachelor of Technology degree in electrical engineering. The 30-day training took place at the 132 kV GSS Jalore and covered topics like the single line diagram, bus bars, isolators, insulators, protective relays, circuit breakers, power transformers, current and potential transformers, transformer oil testing, lightning arrestors, the control room, earthing systems, and power line carrier communication.
The document discusses heavy maintenance activities carried out by the CEB in Sri Lanka. It describes the organizational structure with a Chief Engineer overseeing three sections: hot line maintenance, cold line maintenance, and substation maintenance. Hot line maintenance involves inspecting and maintaining 33kV power lines while they are live. Cold line maintenance and substation maintenance involve maintenance when power is shut off. The document provides details on the types of distribution lines, tower identification, primary substations, transformers, circuit breakers, surge arrestors, isolators, auto-reclosers, and drop down lift off switches used in the electrical distribution system.
The document is a summer training report submitted by Sunil Kumar detailing his training from June to July 2015 at the Electric Locomotive Shed in Gomoh, Dhanbad. It includes an acknowledgement, contents listing the topics covered, and sections about the company providing an overview of electric locomotive maintenance. Key topics discussed include the operation of electric locomotives, equipment such as the pantograph and traction motors, and the installation process for carbon brushes.
This industrial training report provides an overview of NTPC Barh power plant. It discusses NTPC as a company and provides details about coal availability and transportation, construction power requirements, and power evacuation systems for the Barh plant. The document also includes summaries of the key equipment used in the plant, including the boiler, turbines, cooling systems, and switchyard components. It provides specifications for the various transformers used, such as the generating, interconnecting, and station transformers.
The document provides information about a summer training program at NTPC Barh power plant in Patna, Bihar, India. It includes the following key details:
- NTPC is the largest power generation company in India, with over 31134 MW of total installed capacity.
- The summer training was conducted at NTPC's Barh power plant, which provides power to states in Northern and Western India as well as Bihar.
- The document describes the power generation process at the plant, including components like the boiler, turbines, condenser, and switchyard equipment. It also explains the voltage levels used at different stages of power generation and transmission.
Power cars provide power to End-On Generation coaches in Indian Railways. Earlier models had single engines but now have twin engines rated at higher power outputs. The power supply arrangement includes alternators, transformers, and air circuit breakers to control output. Engine accessories include items like oil coolers, pumps, governors and injectors. Modifications have improved safety, such as adding a neutral current reactor to reduce harmonics and interlocking the fire alarm with generator circuit breakers. Maintenance includes cleaning radiators, thermo imaging, and modifying control circuits.
Understanding operation of shunt capacitors and oltc for transmissionIAEME Publication
This document discusses the operation of shunt capacitors and on-load tap changers (OLTC) to reduce transmission losses in the power system of Rajasthan, India. It presents two case studies:
1) Adding a fourth shunt capacitor bank at a 33kV bus improved the voltage profile, reduced transformer and line loading, and cut transmission losses by 0.35MW annually, saving 61.32 lakh rupees.
2) To control high voltage at a 33kV bus, either switching off a capacitor bank or lowering the transformer ratio via OLTC were compared. OLTC operation reduced reactive power flow and losses more with less impact on voltages and loading. Proper coordination of sh
This document provides a training report on a 33/11 KV substation in Lucknow, India. It discusses various components of the substation including transformers, bus bars, insulators, circuit breakers, metering equipment, protection systems, and earthing methodology. The report provides specifications for components, describes the types and functions of substation equipment, and outlines the trainee's experiences during their training at the facility.
1. An industrial plant experienced electrical failures and power quality issues that forced shutdowns. Harmonic analysis revealed unstable power and common mode voltage issues.
2. Harmonic filters were installed to eliminate failures at the plant and auxiliary systems. This allowed increasing production capacity by 30%.
3. A new unexpected problem emerged with a VFD drive tripping. The root cause was found to be conductive air forming inside an acrylic sheet used for touch protection, causing an earth fault and VFD damage. This finding will change electrical panel engineering practices.
1. The document provides an overview of electric power systems, including generating stations, transmission systems, distribution networks, and grid substations.
2. It describes the single line diagram and equipment details of a 132kV grid substation in Jodhpur, India, including transformers, circuit breakers, feeders, and control systems.
3. The substation receives power via two 132kV transmission lines and distributes it through eight 33kV and 13 11kV feeders serving the local area.
Condition based monitoring (CBM) has been implemented at Adani Power Maharashtra Limited to monitor electrical equipment and detect issues before failures occur. CBM involves regularly monitoring key parameters of equipment like transformers, circuit breakers, and insulators. This has helped replace faulty equipment like a wave trap and isolator contact tip during scheduled outages. CBM also detected heating in circuit breaker clamps and leakage in a lightning arrestor, avoiding potential outages. By trending gas levels in transformers, degassing was performed before failure. Overall, CBM is an effective tool for improving system reliability and performance by identifying issues early and planning maintenance.
This document provides an overview of maintenance of equipment at a 33/11kV substation. It discusses key components like transformers, busbars, insulators, circuit breakers, metering equipment, relays, miscellaneous equipment, and protection systems. It also covers substation design considerations like earthing methodology and materials. The document aims to give an understanding of maintenance needs for high voltage substation equipment.
A Three Phase AC-AC ZCS Resonant Converter for Induction HeatingIJMTST Journal
Generally, domestic induction-heating technology requires a high output power levels with less number of
components in a compact size. To satisfy these requirements, the basic circuit configurations are considered
based on the combination of a rectifier and a inverter. The main disadvantage of this method has low-efficient
and economic problems. This paper proposes a new concept unlike previous method, i.e the direct conversion
of ac–ac converter for reducing the component count, reduce cost, improve reliability, and also efficiency.
Generally, the proposed converter is a voltage-source based series-resonant converter used for controlling
output power, and minimizing the control complexity. This paper also proposes a concept of AC-AC converter
based three phase Induction Heating applications.
This document provides information on different shops in a railway workshop, including the air conditioning shop, power shop, production control organization (PCO) shop, and train lighting shop. In the air conditioning shop sections, it describes the specifications and safety protections of roof mounted package units used for air conditioning trains. The power shop section outlines the substation and protective devices used. The PCO shop discusses the electrical inspections conducted on trains. Finally, the train lighting shop explains the fan and battery sections, including the types of fans and maintenance of lead acid and VRLA batteries.
Electrical loco tripshed,sawai madhopurAkash Karol
Indian railways and loco tripshed ppt. it's my college ppt.in this ppt all information about Locomotives and indian Railway. The history of Indian railways is awesome. This ppt is helps you to make a better ppt.
Best of luck
Thank you.
Industrial training report on dlw varanasi for Main Receiving Substation, Tra...Devendra Kumar
Industrial training report on dlw Varanasi for Main Receiving Substation, Traction assembly shop, Maintenance area 2 and Loco Testing Shop(LTS).The industrial training report of DLW (DIESEL LOCOMOTIVE WORKS) is a different trade. i.e. Electronics and Communication, Electrical, Mechanical, Electrical & Electronics and many engineering holders have participated. The content of my industrial topic Main Receiving Substation, TRACTION ASSEMBLY SHOP, Maintenance area 2 and Loco Testing Shop
2. 1
CONTENTS
1) PRODUCTION AT THE NCHANGA SMELTER………………….2
2) POWER DISTRIBUTION…………………………………………...3
THE 11kV SYSTEM………………………………………………....3
THE 33kV SYSTEM………………………………………………....6
3) PREVENTIVE MAINTENANCE…………………………………....7
MONTHLY PM……………………………………………………....7
QUARTERLY PM……………………………………………………8
4) PREVENTIVE MAINTENANCE ON EARTH PITS………………..8
5) TYPES OF STARTING CONNECTIONS AT THE SMELTER…...10
STAR CONNECTION OF THE MOTOR WINDINGS…………....11
DELTA CONNECTION OF THE MOTOR WINDINGS………….11
6) ELECTRICAL IMPROVEMENTS AT THE SMELTER…………..13
7) TROUBLESHOOTING …………………………………………….15
REFERENCES
3. 2
PRODUCTION AT THE NCHANGA SMELTER
This is a very complex process in which copper, acid and cobalt alloy is
produced, the concentrate comes from a lot of different places namely the
underground and other sources given the current situation where the
underground section has been put on care and maintenance meaning no
mining is going there.
The process starts by sending the concentrate via a very efficient
conveyer system to the steam dryer where the concentrate is dried by the
use of steam, after the drying process the concentrate is later transferred
to the flash smelting furnace (FSF) where the process of smelting starts
from by the use of oxygen from the oxygen plant together with other
fuels necessary for flash smelting. Three main resultants come from the
FSF namely blister, sulphur dioxide and FSF slag. The blister is later sent
to the anode furnaces for the production of copper anodes which are later
sent to the refinery for the production of copper cathodes generally
known as copper. The sulphur dioxide is transferred to the acid plant for
the production of sulphuric acid and the slag is later processed for the
extraction of colbalt alloy in the cobalt recovery furnaces and the
remaining blister is transferred to the anode furnances while the waste is
later passed on as granulated slag. The flow sheet below illustrates the
full process at the nchanga smelter
4. 3
POWER DISTRIBUTION
An electric power distribution system is the final stage in the delivery of
electric power; it carries electricity from the transmission system to
individual consumers. In this situation the final stage of transmission is
when the electricity reaches the smelter where it is later stepped down
and distributed to other substations for use. The smelter has 5 main
substations namely substation 1(SS1), (SS2), (SS3),(SS4) and (SS6). The
lack of SS5 was due to planning issues when the smelter was being
constructed given the smelter is a modern day plant that was completed
and commissioned in 2008. All the power comes from ZESCO the
biggest energy company in Zambia, later the power is regulated by the
Copperbelt Energy Cooperation (CEC) inorder to give a more stable form
of electricity to KCM. CEC have 2 substations around KCM namely
Avenue and Stadium. The Avenue Substation steps down 66/11kV and
distributes it to SS1 where it is later distributed to other substations
THE 11kV SYSTEM
11kV incomers from Avenue to SS1
The Avenue substation steps down 66/11kV using two 20MVA and
three 15MVA thus feeding SS1 through 4 incomers namely I/C1, I/C2,
5. 4
I/C4 and I/C5. I/C3 has been rerouted to TLP, thus leaving SS1 with 4
incomers . SS1 has BUS A,B,C,D,E and F with BUS E and F having been
equipped with all the emergency loads incase of a power failure. Each
substation has two transformers, a main transformer and a back up
transformer that kicks in whenever there is a power failure. The back up
transformer gets its power from the Diesel Generators (DG) which
becomes operational 3-4 secs when the power from CEC has a fault.
Basically when power is limited in I/C4 and I/C5 a signal is sent to the
main control system that authorizes the opening of B/C 4 and the closing
of bus section B/C5 that’s after 2 or more DGs are operational thus
supplying power to the loads that are on bus E and F which mainly are
used for cooling and lighting. This is because the DGs can only produce
up to 8MW when running at full capacity thus can not sustain the full
load of the smelter in turn can only manage to run a few loads, the critical
loads
Switching on and off of equipment in the 11kV is done by using a
vacuum circuit breaker which can be seen in the picture below
VACUUM CIRUIT BREAKER
6. 5
11kV BUS E
The above figure illustrates emergency bus E with bus section B/C4 and
B/C5. It also shows incomer 4 (IC4) and the loads on bus E
The figure below shows emergency bus F where a capacitor bank, loads
on bus F and all the emergency transformers namely 12,14,17,19,21 and
23 are located. All these emergency transformers get their power from the
diesel generators (DGs) when there is a power failure. Power failures are
categorized in numbers, the worst of them is known has category 3 (cat
3). A category 3 power failure is when there is a nation wide blackout.
That’s when the DGs kick in automatically like explained earlier. When
there is insufficient power in I/C4 and I/C5 a signal is relayed to the main
control panel which authorizes the DGs to start running inorder to
provide power to the loads that need power at all times. The main control
panel is always on thanks to an effective UPS system
8. 7
The 33kV system gets its power from the CEC Substation called
stadium where power is stepped down 66/33kV with a current rating of
1250A and fed to substation 2 SS2 at the smelter via I/C1 and I/C2 which
is equipped with sulfur hexafluoride circuit breakers. There onwards
power is fed to the electric furnaces transformers namely Slag cleaning
furnaces (SCF) and Cobalt recovery furnace (CRF) transformers. The
CRF furnaces are on the 33kV bus A system and the SCF on bus B. The
electric furnaces use transformers that step down the voltage from
33kV/0.32kV using two 15 MVA transformers for the Cobalt recovery
furnace and one 20MVA transformer for the slag cleaning furnace. The
transformers step down 33kV/0.32kV producing up to 46kAmps. The
current increases substantially in-turn using the current heating effect for
slag cleaning and cobalt recovering. The 33kV system is also used to
supply power to some auxiliary equipment, mainly pumps, cooling fans
etc around the electric furnaces. Their motor control centre (mcc) and
(pmcc) power motor control centre for bigger equipment are located in
respectable substation
PREVENTIVE MAINTENANCE
Preventive maintenance in KCM is a procedure carried regularly to
ensure equipment around the plant stays in tiptop condition. Maintenance
at the smelter electrical department can be broken down in 2 parts,
namely quarterly pm and monthly pm. Monthly pm is carried out once a
month and quarterly pm is carried out every after a 3 month period hence
the name quarterly.
MONTHLY PM
Mainly there is checklist with procedures that need to be followed for
example, the characteristics of a monthly pm on a motor rated 185kWatts,
RPM 1475 on the motor side there is need check motor and local
pushbutton station cleanliness, check for slip ring cleanliness, check for
carbon brush worn out, check for power & control cables cerawool
covering, check for motor TB & JB sealing properly, check for bed bolt
tightness and earthing cable tightness, observe for smooth run/no noise.
On the panel side not much work is done, mainly check for the
feeder/module cleanliness, check for spare gland holes sealed properly,
observe for any burnt out/Terminal colour change, check for SFU handle
operation and check for indication lamps (ON, OFF, TRIP, etc)
9. 8
QUARTERLY PM
The quarterly checklist has everything that can be found on the monthly
pm checklist and more tasking procedures that cant be done everytime
you carry out preventive maintenance. Example of a quarterly pm
checklist on a motor air compressor (MAC) B filter fan motor in the
oxygen plant is as follows, the first thing that can be done on the motor
side is checking for power cable tightness, earthing cable tightness, check
for power cable tightness at jbs , check for motor space heater cable
tightness. So basically what needs to be done is to check for tightness on
all cables on the compressor. Also check motor and local pushbutton
station cleanliness, check for slip ring cleanliness, check for carbon brush
worn out, check for power & control cables cerawool covering, check for
motor TB & JB sealing properly, check for bed bolt tightness
On the panel side check for power cable tightness, control cable
tightness, check for main contactor fixed contactor tightness, check for
moving contact spring tension, check for main & moving contacts
cleanliness. There is also need to check for feeder/module cleanliness and
observe for any burnt / terminal colour change, check for SFU handle
operation and also check for indication lamps (ON,OFF TRIP etc)
These are the tests that need to be carried out during the quarterly pm
schedule. The most vital of all the procedures is checking for Insulation
Resistance Test that is carried out using an insulation resistance tester
commonly known as the megger. The first step is to carry out an IR test
with the power cable and motor together Red phase-Earth, Yellow phase-
Earth and Blue phase-Earth. If the insulation is ok the megger will show
give an infinite reading. The same procedure is repeated with the control
cable and the motor without the control cable.
These are examples of the procedures set up by KCM to ensure all the
equipment is tip top condition at all time
PREVENTIVE MAINTENANCE ON EARTH PITS
The main reason for doing earthing in electrical networks is for safety.
When all metallic parts in electrical equipment are grounded then if the
insulation inside the equipment fails there are no dangerous voltages
present in the equipment case. What makes earthing work are earth pits
below shows an illustration of an earth pit
10. 9
EARTH PIT
Preventive maintenance is carried out on earth pits by the help of an
instrument known as an earth tester that checks the resistance of the soil.
The earth resistance test is done by using a 3 point system test In this
method earth tester terminal P1 and P2 are shorted to each other and
connected to the earth electrode (pipe) under test. Terminals E1 and E2
are connected to the two separate spikes driven in earth. These two
spikes are kept in same line at the distance of about 25 meters due to
which there will not be mutual interference in the field of individual
spikes. After the tests are carried out the resistivity should be at its
minimum so that the soil should be able to conduct any over current for
safety purposes, it is the resistance of soil to the passage of electric
current. The earth resistance value (ohmic value) of an earth pit depends
on soil resistivity. It is the resistance of the soil to the passage of electric
current. To reduce the resistivity, it is necessary to dissolve in the
moisture particle in the Soil. Some substance like Salt/Charcoal is highly
conductive in water solution but the additive substance would reduce the
resistivity of the soil, only when it is dissolved in the moisture in the soil
11. 10
after that additional quantity does not serve the Purpose. And make sure
all Oxidation is removed from joints and joints should be tightened
EARTH RESISTANCE TESTER
TYPES OF STARTING CONNECTIONS AT THE SMELTER
The objective of star-delta connection is this starting method is used
with three-phase induction motors, is to reduce the starting current. In
starting position, current supply to the stator windings is connected in star
(Y) for starting. In the running position, current supply is reconnected to
the windings in delta (∆) once the motor has gained speed.
As the name suggests, direct-on-line starting means that the motor is
started by connecting it directly to the supply at rated voltage. Direct-on-
line starting, (DOL), is suitable for stable supplies and mechanically stiff
and well dimensioned shaft systems – and pumps qualify as examples of
such systems. Direct-on-line (DOL) starting motors only require adequate
12. 11
motor protection, whereas star-delta starting implies a more complex
circuitry composed of several relays and contactors.
The following two images demonstrate the different possibilities for
electrical connection:
The following images show the electrical circuitry of the three motor
windings and their phase voltages
STAR CONNECTION OF THE MOTOR WINDINGS
13. 12
DELTA CONNECTION OF THE MOTOR WINDINGS
As shown in the above illustrations, the difference in connections is not
just limited to the different circuitries, but also in the resulting voltages of
the windings. Where as in the DOL connection the windings are supplied
by the voltage they are designed for permanently, the STAR connection
is operated at a voltage reduced by the factor √3. Following principles
result from this, which have to be respected by all means for a continuous
operation of a STAR-DELTA motor
The motor-current (Amps) of a STAR-DELTA motor during start (IҮ) is
reduced roughly by factor 0,58; a motor with a nominal starting current of
550A will consume only 317 A in STAR – connection. This fulfills the
requirement of a current reduced start. The available mechanical
performance on the shaft to drive the pump or whatever equipment
is being run, is also reduced to 1/3 of the nominal performance. To
avoid an overloading of the motor, it is necessary to observe the
power demand of the equipment during startup in comparison with
the start current of the motor.
The available shaft torque (MҮ) also reduces while start to 1/3 of the
nominal torque. This also raises the necessity, to compare the demanded
starting torque of the equipment to the available torque of the motor, and
to do the right selection.
14. 13
THE ADVANTAGES OF STAR DELTA CONNECTION
Normally, low-voltage motors over 3 kW will be dimensioned to run at
either 400 V in delta (∆) connection or at 690 V in star (Y) connection.
The flexibility provided by this design can also be used to start the motor
with a lower voltage. Star-delta connections give a low starting current of
only about one third of that found with direct-on-line starting.
Star-delta starters are particularly suited for high inertias, where the load
are initiated after full load speed.
ADVANTAGES OF DOL
DOL starting is the simplest, cheapest and most common starting
method. Furthermore it actually gives the lowest temperature rise within
the motor during start up of all the starting methods.
ELECTRICAL IMPROVEMENTS AT THE SMELTER
At the smelter the electrical department is slowly moving over to a
more complex and efficient way of starting equipment by the introduction
of a soft start device. This device ensures smooth starting by torque
control for gradual acceleration of the drive system thus preventing jerks
and extending the life of mechanical components. It also helps in the
reduction of the starting current to achieve break-away, and to hold back
the current during acceleration, to prevent mechanical, electrical, thermal
weakening of the electrical equipment such as motors, cables,
transformers & switch gear.
A motor soft starter is a device used with AC electrical motors to
temporarily reduce the load and torque in the power train and electric
current surge of the motor during start-up. This reduces the mechanical
stress on the motor and shaft, as well as the electro dynamic stresses on
the attached power cables and electrical distribution network, extending
the lifespan of the system.
It can consist of mechanical or electrical devices, or a combination of
both. Mechanical soft starters include clutches and several types of
couplings using a fluid, magnetic forces, or steel shot to transmit torque,
similar to other forms of torque limiter. Electrical soft starters can be any
control system that reduces the torque by temporarily reducing the
voltage or current input, or a device that temporarily alters how the motor
is connected in the electric circuit.
Soft starters can be set up to the requirements of the individual
application. In pump applications, a soft start can avoid pressure surges.
Conveyor belt systems can be smoothly started, avoiding jerk and stress
on drive components. Fans or other systems with belt drives can be
started slowly to avoid belt slipping.. In all systems, a soft start limits the
15. 14
inrush current and so improves stability of the power supply and reduces
transient voltage drops that may affect other loads. Like seen at the
smelter acid plant, a blower of rating 1850kW using a soft starter system
to enable the blower starts smoothly avoiding any pressure surges. The
pictures below show examples of a soft starter for the 4650kW blower
found at the acid plant. The soft starter is located inside of Substation 6
(SS6)
SOFT STARTER FOR 4650KW BLOWER
16. 15
4650 kW BLOWER AT THE ACID PLANT
TROUBLESHOOTING
Troubleshooting in electrical engineering means tracing, finding and
rectifying a fault in an electrical system. In a complex electrical system at
the smelter it is inevitable not to have problems. We face enough
challenges but we have enough competent people to tackle any problem
that can come alone the way. One of the most common troubleshooting
techniques taught to technicians is the so-called “divide and conquer”
method, whereby the system or signal path is divided into halves with
each measurement, until the location of the fault is pinpointed. However,
there are some situations where it might actually save time to perform
measurements in a linear progression (from one end to the other, until the
power or signal is lost). Efficient troubleshooters never limit themselves
to a rigid method if other methods are more efficient. Here is an example
of troubleshooting encountered at the smelter by the lighting crew. An
electrician is troubleshooting a faulty light circuit, where the power
source and light bulb are far removed from one another
17. 16
As you can see in the diagram, there are several terminal blocks (“TB”)
through which electrical power is routed to the light bulb. These terminal
blocks provide convenient connection points to join wires together,
enabling sections of wire to be removed and replaced if necessary,
without removing and replacing all the wiring.
The electrician is using a voltmeter to check for the presence of voltage
between pairs of terminals in the circuit. The terminal blocks are located
too far apart to allow for voltage checks between blocks (say, between
one connection in TB2 and another connection in TB3). The voltmeter’s
test leads are only long enough to check for voltage between pairs of
connections at each terminal block.
In the next diagram, you can see the electrician’s voltage checks, in the
sequence that they were taken
18. 17
Based on the voltage indications shown, you can determine the location
of the circuit fault. The fault is located somewhere between TB3 and
TB4. Whether or not the electrician’s sequence was the most efficient
depends on two factors not given in the problem. The distance between
terminal blocks and the time required to gain access for a voltage check,
upon reaching the terminal block location.
Another of problem encountered at the smelter that needed
troubleshooting was with SCF bottom cooling fans. The problem was that
the earth leakage relay kept showing signals of an earth leakage in turn
resulting in the bottom cooling fan going off. So we had to troubleshoot
by carrying out a continuity test. A continuity test is a test carried out to
determine weather they are any cables touching thus a complete pathway
for electric current. So we had to start from the power source to the VFD
valuable frequency drive. The circuit showed continuity, we later tried to
carry out continuity from the VFD to the motor, the circuit showed
continuity. The diagnosis was that the earth leakage relay malfunctioned
and that it had to be replaced. The image below shows an example of
valuable frequency drive that can be found at the smelter
VALUABLE FREQUENCY DRIVE