This document provides guidance on sizing and protecting dynamic braking resistors for AC drives. It discusses calculating the resistance, wattage, and protection scheme needed. For resistance, the minimum allowable for the drive must be met. Wattage is based on application details like machine type and stopping frequency. Protection can be via a manual motor protector sized based on peak current and a trip time to safeguard the resistor. The drive software can also limit full power braking time and periodic use to prevent overuse. An example calculation is provided to demonstrate the process.
This document discusses factors to consider when selecting a servo motor and drive for an application. It outlines key sizing factors like inertia ratio, speed, maximum torque at speed, and RMS torque at speed. An inertia ratio between 2:1 and 5:1 is typical, with higher ratios requiring a motor with more inertia or changes to reduce load inertia. It also provides information on synchronous vs induction servo motors and their relative advantages. In general, a modest motor oversizing of up to 20% is acceptable.
The document discusses motor protection and motor control centers. It provides details on sizing conductors that supply single and multiple motors, sizing overload protection devices based on motor nameplate ratings, and protecting motors from short circuits and ground faults. It also describes the components, construction, and wiring classifications of motor control centers, which are used to control and provide protection for motors and connecting cables.
This document discusses a presentation on variable frequency drives (VFDs). It includes sections on load profiles, motor and load torques, control methods for drives, VFD components and working principles, advantages of VFDs, and a case study on potential energy savings from installing VFDs at a power plant. The case study estimates total annual energy savings of 2,350,000 kWh and payback period of 41 months for a VFD installation project with a total investment of 1,758.6 lakhs.
A variable frequency drive (VFD) converts incoming 60 Hz power to DC then converts it back to a variable voltage and frequency output to control the speed of an AC motor. It is composed of a rectifier that converts AC to DC, a DC bus, and an inverter that converts the DC back to AC. The rectifier causes harmonic distortion but devices like reactors and filters can mitigate this. While individual nonlinear loads may have high harmonic distortion, the total harmonic distortion on a system depends on the percentage of nonlinear load compared to the total load. Guidelines like IEEE 519 provide limits for current and voltage harmonic levels.
This document provides an overview of electric motors, including different types of motors, their basic principles and components. It discusses induction motors, synchronous motors, and single phase motors. It also covers motor specifications, testing, storage, lubrication, and maintenance practices. The presentation was prepared by Kapil Singh for Thermax Ltd and includes topics like classification of motors, laws of electromagnetism, rotating magnetic fields, and motor applications.
This document discusses the testing and maintenance of power transformers. It outlines the various routine tests performed on transformers according to standards, including winding resistance measurement, insulation resistance measurement, high voltage tests, no load and load loss measurements. It also describes type tests such as lightning impulse and short circuit tests. Finally, it discusses the importance of preventive maintenance through regular checks of oil levels, insulation resistance, bushings, connections and other components.
This document discusses different types of directional over current relays. It explains that directional over current relays operate when fault current flows in a particular direction and will not operate if power flows in the opposite direction. It provides details on 30 and 90 degree connections for directional relays and describes the construction and operation of non-directional over current relays and shaded pole type directional over current relays.
This document discusses factors to consider when selecting a servo motor and drive for an application. It outlines key sizing factors like inertia ratio, speed, maximum torque at speed, and RMS torque at speed. An inertia ratio between 2:1 and 5:1 is typical, with higher ratios requiring a motor with more inertia or changes to reduce load inertia. It also provides information on synchronous vs induction servo motors and their relative advantages. In general, a modest motor oversizing of up to 20% is acceptable.
The document discusses motor protection and motor control centers. It provides details on sizing conductors that supply single and multiple motors, sizing overload protection devices based on motor nameplate ratings, and protecting motors from short circuits and ground faults. It also describes the components, construction, and wiring classifications of motor control centers, which are used to control and provide protection for motors and connecting cables.
This document discusses a presentation on variable frequency drives (VFDs). It includes sections on load profiles, motor and load torques, control methods for drives, VFD components and working principles, advantages of VFDs, and a case study on potential energy savings from installing VFDs at a power plant. The case study estimates total annual energy savings of 2,350,000 kWh and payback period of 41 months for a VFD installation project with a total investment of 1,758.6 lakhs.
A variable frequency drive (VFD) converts incoming 60 Hz power to DC then converts it back to a variable voltage and frequency output to control the speed of an AC motor. It is composed of a rectifier that converts AC to DC, a DC bus, and an inverter that converts the DC back to AC. The rectifier causes harmonic distortion but devices like reactors and filters can mitigate this. While individual nonlinear loads may have high harmonic distortion, the total harmonic distortion on a system depends on the percentage of nonlinear load compared to the total load. Guidelines like IEEE 519 provide limits for current and voltage harmonic levels.
This document provides an overview of electric motors, including different types of motors, their basic principles and components. It discusses induction motors, synchronous motors, and single phase motors. It also covers motor specifications, testing, storage, lubrication, and maintenance practices. The presentation was prepared by Kapil Singh for Thermax Ltd and includes topics like classification of motors, laws of electromagnetism, rotating magnetic fields, and motor applications.
This document discusses the testing and maintenance of power transformers. It outlines the various routine tests performed on transformers according to standards, including winding resistance measurement, insulation resistance measurement, high voltage tests, no load and load loss measurements. It also describes type tests such as lightning impulse and short circuit tests. Finally, it discusses the importance of preventive maintenance through regular checks of oil levels, insulation resistance, bushings, connections and other components.
This document discusses different types of directional over current relays. It explains that directional over current relays operate when fault current flows in a particular direction and will not operate if power flows in the opposite direction. It provides details on 30 and 90 degree connections for directional relays and describes the construction and operation of non-directional over current relays and shaded pole type directional over current relays.
star delta auto starter with forward reverse and motor protectionBHUPATI PRADHAN
It is a project on pure electrical engineering. Here three phase motor is starting from star to delta automatically by using some components.In other hand it also provide protection to the motor.
1. The document discusses different types of transformers used in power plants including power transformers, service transformers, and measuring transformers.
2. It describes key components of transformers like the core, windings, cooling systems, and protections devices. Transformer connections, vector groups, and voltage classifications are also covered.
3. Various transformers used in thermal power plants are discussed including generator transformers, station transformers, unit auxiliary transformers, and those used for distribution within the plant.
The document discusses transformer protection. It describes various failures that can occur in transformers such as winding failures, bushing failures, and tap changer failures. It provides statistics on historical transformer failures. It also discusses different types of protection for transformers including electrical protection methods like differential protection, overcurrent protection, overexcitation protection and thermal protection. Internal short circuits, system short circuits, and abnormal conditions are some of the issues addressed by transformer protection schemes.
This presentation provides an overview of power transformers. It discusses that power transformers are static machines that transform power from one circuit to another without changing frequency, and are used between generators and distribution circuits. It then describes the typical power ratings of small, medium, and large power transformers. The main components of power transformers are then outlined, including bushings, the core and winding, conservator tank, breather and silica gel, cooling tubes, tap changer, transformer oil, and Buchholz relay. The functions of these key components are explained at a high level.
This document summarizes a research paper on implementing smooth transitions between optimal control modes in a switched reluctance motor (SRM). It begins with introductions to SRM technology and an overview of the paper contents. It then covers the operating principles, characteristics, control strategies, and modes of operation of SRMs. The document describes the development of a Simulink model for a proposed optimal controller, including subsystems for pulse width modulation and single pulse control. Simulation results are presented and analyzed for no-load operation, with load, and under speed and torque dynamics. The analysis shows the controller varies turn-on and turn-off angles optimally under different operating conditions to reduce ripple and enable smooth transitions between control modes. The conclusion
ABB ACS 800 SERIES VFD TRAINNING GUIDE BY DEEPAK GORAIDEEPAK GORAI
ABB ACS 800 SERIES VFD TRAINNING GUIDE BY DEEPAK GORAI.IN THIS GUIDE IO CONNECTION,CONFIGURATION,LAPTOP CONNECTIVITY WITH VFD DRIVE,PROFUSE COMMUNICATION AND SETTINGS
This document discusses different types of motor starters used for AC and DC motors. It describes the necessity of starters to limit inrush current and protect motors. The main types covered are DOL, star-delta, and autotransformer starters. It provides information on their wiring diagrams, motor starting characteristics, advantages and disadvantages, suitable motor sizes and applications. Current ratings for motors used with different starters are also included.
In-Country Training
On
Operation, Maintenance, Protection & Control of 33/11 kV Substation
Project Name: Design, Supply, Installation, Testing & Commissioning of 33/11 kV sub-stations with source end feeder bays.
Contract No: BREB/UREDS/W-01A-001/02/2016-2017
BREB/UREDS/W-01A-002/03/2016-2017
BREB/UREDS/W-01A-004/04/2016-2017
This document discusses relays, including their basic components, design, operation, applications, advantages, and disadvantages. Relays are electrical devices that use electromagnets to open or close circuits. They have a coil, armature, contacts, and frame. When voltage is applied to the coil, it creates a magnetic field that moves the armature to open or close the contacts. Relays allow low power circuits to control high power circuits and are used for protection, regulation, and auxiliary functions in power systems.
Automatic voltaer regulator and it's modellingrajani51
in power supply system we have to keep the voltage constant.but when load is connected to the generator voltage difference will occur. to tackle this closed loop control of generator voltage is required. this can be achieved by AUTOMATIC VOLTAGE REGULATOR
Energy Savings with Variable Frequency DrivesAzizah Kassim
To understand what is VFD / VSD / ASD / Inverter and what does it do.
To understand what is System Curve, Pump & Fan Curve and also Affinity Law
To understand how VFD saves AC motor ‘s energy
To estimate energy savings by using VFD to control speed of motor driving pumps / fans
To demonstrate few VFD’s applications in building and how it can save the energy
This document provides information on a Power System Protection course taught at Vivekanandha College of Engineering for Women. The syllabus covers 5 units: introduction to protection schemes, relay operating principles and characteristics, apparatus protection, theory of circuit interruption, and circuit breakers. It lists textbooks and presents details on each unit, including topics like relay types, transformer/generator/motor protection, arc phenomena, and different circuit breaker types. The last section provides references for textbooks, websites, and presentations on related topics.
Tap changers are devices fitted to power transformers that regulate output voltage levels by altering the transformer turn ratios (paragraph 1). On-load tap-changers (OLTCs) are commonly used in power grids and industries to continuously regulate voltage during operation (paragraph 2). OLTCs offer variable control to maintain supply voltage within specified limits by selecting different transformer taps, which correspond to different turn ratios and voltage outputs (paragraphs 3-5). Modern OLTCs are designed to change taps while energized since off-load tap changers interrupt power supply (paragraph 6).
The RTCC (Remote Tap Changer Control) panel controls the output voltage of a transformer through an OLTC (On Load Tap Changer) unit using control cables. The RTCC contains an AVR (Automatic Voltage Regulator) that maintains the output voltage at a set reference level by signaling the OLTC to adjust its tap position accordingly. The RTCC can operate in automatic mode, where the AVR controls the voltage, or manual mode, where an operator can raise or lower the voltage using buttons. The OLTC itself is located inside the transformer and changes tap positions to adjust the output voltage through a motorized mechanism that is controlled by the RTCC.
This document contains drawings for an electrical cabinet including a single line diagram, component details, general arrangements, and bill of quantities. Key details include:
- Panel name is Panel No. 1, type is Motor Control Center, with 500A incomer and 415V power/240V control voltage.
- Drawings include details for 6 feeders ranging from 5KW to 63A, using DOL and star-delta motor connections.
- Components shown include contactors, overload relays, push buttons, indicating lights and current transformers.
Operation and maintenance of transformerKapil Singh
The document provides information on operation and maintenance of distribution transformers. It defines transformers and describes their working principle of mutual electromagnetic induction. It then discusses transformation ratios, the purposes of transformers, their advantages, types, parts, insulation, testing, and maintenance procedures. Key points covered include daily, quarterly and yearly maintenance checks, oil testing parameters, and common transformer tests like ratio, no load, short circuit and insulation tests.
This document discusses different types of starters used for three phase induction motors. It describes stator resistance, auto transformer, star-delta, rotor resistance, direct online (DOL), and soft starters. Stator resistance and auto transformer starters limit starting current by adding resistance or reducing voltage. Star-delta starters initially connect the motor in star configuration and then switch to delta. Rotor resistance starters add external resistance to the rotor circuit. DOL starters connect the motor directly to full supply voltage. Soft starters use SCRs to gradually increase voltage during starting.
Safe Operation and Maintenance of Circuit Breakers and SwitchgearLiving Online
Switchgear plays an important role in electricity distribution and its performance significantly affects the overall performance of the system. Failure to efficiently disconnect faults elsewhere in the network or failure in switchgear itself is costly, resulting in additional loss of supply, damage to equipment and possibly fatal injury to personnel. It is therefore critically important that switchgear is operated and maintained correctly, within an overall asset management regime that is both economic and effective in securing a high level of system reliability.
This comprehensive workshop focuses on medium voltage switchgear, which comprises by far the bulk of switchgear on most electricity distribution systems. The emphasis is primarily on oil, air blast, SF6 and vacuum circuit breakers, but other forms of MV switchgear, for example ring main units and auto-reclosers will also be described.
MORE INFORMATION: http://www.idc-online.com/content/safe-operation-and-maintenance-circuit-breakers-and-switchgear-3
This document provides an overview of energy efficient motors. It defines an energy efficient motor as one that uses less power to produce the same output as a standard motor. It notes that energy efficient motors have higher efficiencies of 2-6% compared to standard motors due to features like more copper in the windings and reduced fan losses. The document discusses the need for and advantages of energy efficient motors, including energy and cost savings. It also notes some potential disadvantages like higher initial cost and issues with speed control. Applications mentioned include various industrial uses.
Moulded Case Circuit Breaker (Mccb) & air circuit breaker (acb)Hazem El-Henawy
This document discusses Merlin Gerin's offerings of MCCBs and ACBs. For MCCBs, it introduces the Easypact range up to 100A and the Compact NS range from 100A to 3200A. For ACBs, it presents the Masterpact NT up to 1600A and Masterpact NW up to 6300A. It describes the performance, components, accessories, and control options of these circuit breaker families. It emphasizes innovations like current sensors, connectors, and Micrologic control units that provide flexibility, discrimination, and intelligence across the product lines.
SURVEY OF CONVENTIONAL &NEW GENERATION ADVANCED D.C.BRAKING SYSTEM OF 3-PHASE...IJCI JOURNAL
Any variable frequency drive requires an efficient and controlled braking system. Therefore, different braking techniques have been the subject area of researchers to enhance the performance as well as overall life of the drives. In this paper, a literature study is made of various existing braking methods, focused on induction motor (IM) drive performance. The braking methods are compared and summarized based on speed range, braking time and efficiency of 3-phase squirrel cage IM drive. Finally, an advancedD.C. braking technique is presented where braking torque in terms of varyingD.C.signal is injected into the stator windings using fully controlled Space Vector Pulse Width Modulation pulses (SVPWM). A method has been described for providing occasional fast, smooth and controlled braking torque from a non-regenerative VFD, without additional power circuits. Simulations are performed in MATLAB/Simulink, tested and validated on Digital signal processor (DSP) based drive. Test results are presented in this paper.
When discussing energy savings and variable frequency drives (VFD) the attention often focuses on a centrifugal fan or pump application. However, you should not overlook other applications which also have large potential energy savings and energy recovery. Applications involving regeneration, power factor correction, common bus applications or a combination of the three can also quickly achieve a signi cant reduction in energy use.
star delta auto starter with forward reverse and motor protectionBHUPATI PRADHAN
It is a project on pure electrical engineering. Here three phase motor is starting from star to delta automatically by using some components.In other hand it also provide protection to the motor.
1. The document discusses different types of transformers used in power plants including power transformers, service transformers, and measuring transformers.
2. It describes key components of transformers like the core, windings, cooling systems, and protections devices. Transformer connections, vector groups, and voltage classifications are also covered.
3. Various transformers used in thermal power plants are discussed including generator transformers, station transformers, unit auxiliary transformers, and those used for distribution within the plant.
The document discusses transformer protection. It describes various failures that can occur in transformers such as winding failures, bushing failures, and tap changer failures. It provides statistics on historical transformer failures. It also discusses different types of protection for transformers including electrical protection methods like differential protection, overcurrent protection, overexcitation protection and thermal protection. Internal short circuits, system short circuits, and abnormal conditions are some of the issues addressed by transformer protection schemes.
This presentation provides an overview of power transformers. It discusses that power transformers are static machines that transform power from one circuit to another without changing frequency, and are used between generators and distribution circuits. It then describes the typical power ratings of small, medium, and large power transformers. The main components of power transformers are then outlined, including bushings, the core and winding, conservator tank, breather and silica gel, cooling tubes, tap changer, transformer oil, and Buchholz relay. The functions of these key components are explained at a high level.
This document summarizes a research paper on implementing smooth transitions between optimal control modes in a switched reluctance motor (SRM). It begins with introductions to SRM technology and an overview of the paper contents. It then covers the operating principles, characteristics, control strategies, and modes of operation of SRMs. The document describes the development of a Simulink model for a proposed optimal controller, including subsystems for pulse width modulation and single pulse control. Simulation results are presented and analyzed for no-load operation, with load, and under speed and torque dynamics. The analysis shows the controller varies turn-on and turn-off angles optimally under different operating conditions to reduce ripple and enable smooth transitions between control modes. The conclusion
ABB ACS 800 SERIES VFD TRAINNING GUIDE BY DEEPAK GORAIDEEPAK GORAI
ABB ACS 800 SERIES VFD TRAINNING GUIDE BY DEEPAK GORAI.IN THIS GUIDE IO CONNECTION,CONFIGURATION,LAPTOP CONNECTIVITY WITH VFD DRIVE,PROFUSE COMMUNICATION AND SETTINGS
This document discusses different types of motor starters used for AC and DC motors. It describes the necessity of starters to limit inrush current and protect motors. The main types covered are DOL, star-delta, and autotransformer starters. It provides information on their wiring diagrams, motor starting characteristics, advantages and disadvantages, suitable motor sizes and applications. Current ratings for motors used with different starters are also included.
In-Country Training
On
Operation, Maintenance, Protection & Control of 33/11 kV Substation
Project Name: Design, Supply, Installation, Testing & Commissioning of 33/11 kV sub-stations with source end feeder bays.
Contract No: BREB/UREDS/W-01A-001/02/2016-2017
BREB/UREDS/W-01A-002/03/2016-2017
BREB/UREDS/W-01A-004/04/2016-2017
This document discusses relays, including their basic components, design, operation, applications, advantages, and disadvantages. Relays are electrical devices that use electromagnets to open or close circuits. They have a coil, armature, contacts, and frame. When voltage is applied to the coil, it creates a magnetic field that moves the armature to open or close the contacts. Relays allow low power circuits to control high power circuits and are used for protection, regulation, and auxiliary functions in power systems.
Automatic voltaer regulator and it's modellingrajani51
in power supply system we have to keep the voltage constant.but when load is connected to the generator voltage difference will occur. to tackle this closed loop control of generator voltage is required. this can be achieved by AUTOMATIC VOLTAGE REGULATOR
Energy Savings with Variable Frequency DrivesAzizah Kassim
To understand what is VFD / VSD / ASD / Inverter and what does it do.
To understand what is System Curve, Pump & Fan Curve and also Affinity Law
To understand how VFD saves AC motor ‘s energy
To estimate energy savings by using VFD to control speed of motor driving pumps / fans
To demonstrate few VFD’s applications in building and how it can save the energy
This document provides information on a Power System Protection course taught at Vivekanandha College of Engineering for Women. The syllabus covers 5 units: introduction to protection schemes, relay operating principles and characteristics, apparatus protection, theory of circuit interruption, and circuit breakers. It lists textbooks and presents details on each unit, including topics like relay types, transformer/generator/motor protection, arc phenomena, and different circuit breaker types. The last section provides references for textbooks, websites, and presentations on related topics.
Tap changers are devices fitted to power transformers that regulate output voltage levels by altering the transformer turn ratios (paragraph 1). On-load tap-changers (OLTCs) are commonly used in power grids and industries to continuously regulate voltage during operation (paragraph 2). OLTCs offer variable control to maintain supply voltage within specified limits by selecting different transformer taps, which correspond to different turn ratios and voltage outputs (paragraphs 3-5). Modern OLTCs are designed to change taps while energized since off-load tap changers interrupt power supply (paragraph 6).
The RTCC (Remote Tap Changer Control) panel controls the output voltage of a transformer through an OLTC (On Load Tap Changer) unit using control cables. The RTCC contains an AVR (Automatic Voltage Regulator) that maintains the output voltage at a set reference level by signaling the OLTC to adjust its tap position accordingly. The RTCC can operate in automatic mode, where the AVR controls the voltage, or manual mode, where an operator can raise or lower the voltage using buttons. The OLTC itself is located inside the transformer and changes tap positions to adjust the output voltage through a motorized mechanism that is controlled by the RTCC.
This document contains drawings for an electrical cabinet including a single line diagram, component details, general arrangements, and bill of quantities. Key details include:
- Panel name is Panel No. 1, type is Motor Control Center, with 500A incomer and 415V power/240V control voltage.
- Drawings include details for 6 feeders ranging from 5KW to 63A, using DOL and star-delta motor connections.
- Components shown include contactors, overload relays, push buttons, indicating lights and current transformers.
Operation and maintenance of transformerKapil Singh
The document provides information on operation and maintenance of distribution transformers. It defines transformers and describes their working principle of mutual electromagnetic induction. It then discusses transformation ratios, the purposes of transformers, their advantages, types, parts, insulation, testing, and maintenance procedures. Key points covered include daily, quarterly and yearly maintenance checks, oil testing parameters, and common transformer tests like ratio, no load, short circuit and insulation tests.
This document discusses different types of starters used for three phase induction motors. It describes stator resistance, auto transformer, star-delta, rotor resistance, direct online (DOL), and soft starters. Stator resistance and auto transformer starters limit starting current by adding resistance or reducing voltage. Star-delta starters initially connect the motor in star configuration and then switch to delta. Rotor resistance starters add external resistance to the rotor circuit. DOL starters connect the motor directly to full supply voltage. Soft starters use SCRs to gradually increase voltage during starting.
Safe Operation and Maintenance of Circuit Breakers and SwitchgearLiving Online
Switchgear plays an important role in electricity distribution and its performance significantly affects the overall performance of the system. Failure to efficiently disconnect faults elsewhere in the network or failure in switchgear itself is costly, resulting in additional loss of supply, damage to equipment and possibly fatal injury to personnel. It is therefore critically important that switchgear is operated and maintained correctly, within an overall asset management regime that is both economic and effective in securing a high level of system reliability.
This comprehensive workshop focuses on medium voltage switchgear, which comprises by far the bulk of switchgear on most electricity distribution systems. The emphasis is primarily on oil, air blast, SF6 and vacuum circuit breakers, but other forms of MV switchgear, for example ring main units and auto-reclosers will also be described.
MORE INFORMATION: http://www.idc-online.com/content/safe-operation-and-maintenance-circuit-breakers-and-switchgear-3
This document provides an overview of energy efficient motors. It defines an energy efficient motor as one that uses less power to produce the same output as a standard motor. It notes that energy efficient motors have higher efficiencies of 2-6% compared to standard motors due to features like more copper in the windings and reduced fan losses. The document discusses the need for and advantages of energy efficient motors, including energy and cost savings. It also notes some potential disadvantages like higher initial cost and issues with speed control. Applications mentioned include various industrial uses.
Moulded Case Circuit Breaker (Mccb) & air circuit breaker (acb)Hazem El-Henawy
This document discusses Merlin Gerin's offerings of MCCBs and ACBs. For MCCBs, it introduces the Easypact range up to 100A and the Compact NS range from 100A to 3200A. For ACBs, it presents the Masterpact NT up to 1600A and Masterpact NW up to 6300A. It describes the performance, components, accessories, and control options of these circuit breaker families. It emphasizes innovations like current sensors, connectors, and Micrologic control units that provide flexibility, discrimination, and intelligence across the product lines.
SURVEY OF CONVENTIONAL &NEW GENERATION ADVANCED D.C.BRAKING SYSTEM OF 3-PHASE...IJCI JOURNAL
Any variable frequency drive requires an efficient and controlled braking system. Therefore, different braking techniques have been the subject area of researchers to enhance the performance as well as overall life of the drives. In this paper, a literature study is made of various existing braking methods, focused on induction motor (IM) drive performance. The braking methods are compared and summarized based on speed range, braking time and efficiency of 3-phase squirrel cage IM drive. Finally, an advancedD.C. braking technique is presented where braking torque in terms of varyingD.C.signal is injected into the stator windings using fully controlled Space Vector Pulse Width Modulation pulses (SVPWM). A method has been described for providing occasional fast, smooth and controlled braking torque from a non-regenerative VFD, without additional power circuits. Simulations are performed in MATLAB/Simulink, tested and validated on Digital signal processor (DSP) based drive. Test results are presented in this paper.
When discussing energy savings and variable frequency drives (VFD) the attention often focuses on a centrifugal fan or pump application. However, you should not overlook other applications which also have large potential energy savings and energy recovery. Applications involving regeneration, power factor correction, common bus applications or a combination of the three can also quickly achieve a signi cant reduction in energy use.
motor drive trouble shooting and diagnosis with Fluke ScopeMeter by checking unbalance of voltage and current, overvoltage and undervoltage, variable torque and constant torque, motor shaft voltage and bearing voltage
This document discusses various types of faults that can occur in alternators, including internal faults like stator winding faults and excitation circuit faults, and external faults like prime mover failure. It provides details on specific faults such as stator winding faults, prime mover failure, overcurrent faults, overvoltage faults, unbalanced loading, stator interturn faults, loss of synchronism, and over/under frequency faults. Protection methods are discussed for each fault type, such as differential protection for stator faults, reverse power protection for prime mover failure, time-delayed overcurrent protection, and frequency-based protection for over/under frequency operation.
The document provides information on assessing the energy performance of motors and variable speed drives. It discusses methods for determining motor efficiency through no-load, locked rotor, and full load tests. It also covers factors that affect motor efficiency like loading, temperature, and stray losses. The document then discusses applications of variable speed drives and factors for successful implementation like torque requirements, efficiency, and power factor. Key points on evaluating energy savings with variable speed applications are also summarized.
This technical guide discusses electrical braking solutions for AC drives. It begins by evaluating braking power needs based on load characteristics such as constant versus quadratic torque. It then describes various electrical braking methods available in drives, including motor flux braking, braking choppers with resistors, and IGBT regeneration units. The guide concludes by comparing the life cycle costs of different braking solutions.
This document discusses electrical energy conservation in electric motors. It begins by explaining that induction motors are widely used in industry due to their simplicity, reliability and efficiency. It then describes the various types of losses that occur in electric motors, such as copper, iron and stray load losses. It provides examples of how improving motor efficiency from 85% to 90% can significantly reduce energy losses and costs. Finally, it discusses various methods for improving motor efficiency, such as using energy efficient motors, variable speed drives and power factor correction.
This document discusses speed control methods for three-phase induction motors. It describes various speed control techniques including stator voltage control, stator frequency control, V/F control, and static rotor resistance control. It explains the advantages of speed control, such as energy savings and meeting different process requirements. Industrial applications of induction motor drives are also mentioned, such as in fans, compressors, pumps and machine tools.
Nidec asi electric power solutions for pipeline applicationsNidec Corporation
Nidec ASI provides electric power solutions for pumps and compressors used in oil and gas pipelines. They have over 40 years of experience designing customized solutions that meet clients' needs in terms of power quality, network connection flexibility, maintenance costs, machine durability, and capital expenditures. Nidec ASI works closely with end users, engineers, and OEMs to develop optimal global solutions for pipeline operations. Their solutions include soft starters, variable frequency drives, and fully integrated packages for applications up to 30 MW. Nidec takes an integrated engineering approach considering mechanical, electrical, and site factors to optimize performance, reliability, and costs.
IRJET- Adaptive Observer-Based Fault Estimation for DFIG based Wind Turbine S...IRJET Journal
This document proposes an adaptive observer-based fault estimation method for a doubly fed induction generator (DFIG) wind turbine system to improve fault estimation accuracy and speed. It considers a DFIG winding short circuit fault scenario due to its high occurrence rate. The proposed method uses a fault estimator and compensator based on fault information to guarantee system stability while providing online fault compensation. Simulation results using MATLAB/Simulink demonstrate the effectiveness of the proposed approach for fault estimation in a DFIG wind turbine system.
Braking of Three Phase Induction Motorsby Controlling Applied Voltage and Fre...IJPEDS-IAES
Braking of three phase induction motors is required in many industrial applications. This paper introduces braking of three phase induction motors using particle swarm optimization (PSO) technique. The objective is to determine the optimum values of the applied voltage and frequency during braking to stop the motor in a certain time with minimum braking energy losses to limit any excessive thermal heating. The proposed technique is important and more useful in applications of repeated braking cycles. The results are compared with that obtained using plugging braking method and it's found that the proposed technique gives lower braking energy and shorter braking time. The braking energy losses with the proposed method are about 20% of the plugging braking energy losses with the same braking time. The proposed method determines the variation of optimal values of applied voltage and frequency to have a certain braking time of three phase induction motor at a certain load torque with minimum braking energy losses. The characteristics of the motor are simulated using SIMULINK/MATLAB.
- Motor winding insulation experiences higher voltage stresses when used with an inverter compared to direct mains supply, due to fast rising voltage pulses from the inverter interacting with cable capacitance.
- For supply voltages less than or equal to 500V AC, most standard motors are immune to the higher stresses. For voltages over 500V AC, an enhanced winding insulation system or additional components to limit voltage are required.
- The report provides guidance on motor selection, insulation requirements, and alternative preventative methods to limit voltage stresses when using PWM inverters.
This paper presents a design and development of 8/6 switched reluctance motor for small electric vehicle using analytical method. The absent of permanent magnet, inherent fault tolerance capabilities, simple and robust construction make this motor become more attractive for small electric vehicle application such as electric scooter and go-kart. The switched reluctance motor is modelled using analytical formula in designing process. Later, the designed model is analyzed using ANSYS RMxprt software. In order to achieve 5kW power rating and to match with the design requirement, the switched reluctance motor model has been analyzed using RMxprt tools for the preliminary parameters design process. This tools is able to predict the output performance of motor in term of speed, flux linkage characteristic, output torque and efficiency.
The document describes Thor Power Corporation's Trezium power system. The system consists of a patented microelectronic power converter and permanent magnet power unit called Grismir. The power converter uses vector control for high efficiency and torque control. Grismir is a brushless, slotless, sensorless AC motor that can operate as a motor, generator, or alternator with over 90% efficiency. The Trezium system provides benefits like universality, high efficiency, compact size, and wide input voltage range.
Elspec Equalizer ST - The Ultimate Motor Start-Up Solution
Designed to limit voltage drop motor startup to local standards.
A more cost effective solution than Variable Speed Drives or Variable Frequency Drives.
EQUALIZER-ST can be used as a considerably less expensive substitute than VSD.
Available for sales, rentals, hire and sales @ http://www.supremetechnology.com.au/product/elspec-equalizer-st-the-ultimate-motor-start-up-solution.aspx?Id=346&ProductType=Regular
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dynamic braking resistor selection calculation
1. CTAN291 V1.1 Page 1 of 10 12/8/2010
Application Note
CTAN #291
The Application Note All AC Drives
A Guide to Sizing and Protecting
Dynamic Braking Resistors for AC Drives
The intention of this application note is to provide some basic guidance in applying, sizing and
protecting dynamic braking resistors applied to Control Techniques Drives.
Dynamic braking is a very common option used with both AC and DC drives. Calculating the wattage
for both type drives can sometimes be difficult and to some degree may require a bit of guesswork.
This is because in many cases there is not enough information about the machine inertia and frictional
load. In general, for most applications (barring indexing and press drives) an “e-stop” duty rated
braking resistor is sufficient for applications requiring occasional stops and some regeneration. In dc
drive applications, resistor protection is not needed since once the motor is stopped, there is no longer
a source of energy to the resistor. In ac drives on the other hand, even though the motor is stopped,
the resistor is still connected across the dc bus of the drive through the braking transistor and the bus
is powered directly across the ac line. If for some reason the braking transistor fails (which can be a
short); the resistor will be tied directly across the dc bus and thus will continuously dissipate energy.
This can equate to 3 -20 times the rated wattage of the resistor depending upon the particular kit.
Thus the reason for providing some form of overload protection.
Dynamic Braking Resistor Selection
In order to properly apply dynamic braking resistors three items must be determined:
1. Resistance
2. Wattage
3. Protection Scheme
1. Resistance Value
The value of the resistor sets the maximum value of braking torque. Once this value is chosen, it must
be compared to “minimum” allowable resistance for the particular drive model. If it works out to be a
value below the “minimum” allowable resistance a decision must be made. The first step is to
calculate what torque you can get and determine if that value is sufficient for the application.
Remember, if you are close, these calculations do not include the motor and drive losses which can
easily be 10% of the motor horsepower. If the resistance works out to be greater than the minimum
value, use the value calculated. Using the minimum value can unnecessarily increases the peak
power requirements of the resistor which in turn can decrease the maximum allowable “on” time. An
example will be used to show the “mechanics” of a typical calculation. This example will be used
throughout this document.
Motor Data: 5 HP, 460 vac, 6.8 amps, 1760 rpm, 0.857 pf, 0.90 eff,
rotor inertia = 0.74 lb-ft2
(TEFC frame vector duty)
Braking Requirements: 150 % of motor rated torque
2. CTAN291 V1.1 Page 2 of 10 12/8/2010
The drive we will use is the SP1405 which is rated at 7.6 amps continuous (Heavy Duty). The basic
equation for calculating the braking resistor value is:
Power, P = Bus Voltage squared (V2
) R = (Vb)2
Resistance (R) P
The Power, P is the braking power of the motor in watts times the percent braking torque required (in
per unit)
P = 5 HP X 746 (watts / Hp) X 1.5 (percent torque in per unit, i.e. 150%)
For this example: Power, P = 5595 watts
The voltage used is the DC Bus voltage at which the braking transistor turns on. The table below gives
the voltage levels for the various drive ratings
Drive Voltage Rating Nominal Bus Voltage Brake Turn On Voltage
240 340vdc 390vdc
480 680vdc 780vdc
575 813vdc 930vdc
690 976vdc 1120vdc
For a 480vac drive the voltage is 780vdc therefore:
5595 watts = 7802
/ R R = 7802
/ 5595 = 108.7 ohms
The minimum resistance allowable for the SP1405 is 58 ohms, therefore 108.7 ohms is ok. In this
case a standard 100 ohm resistor would be fine instead of ordering a custom value. In the case of a
Vector or Servo drive, the drive allows 175% peak torque. A resistance value of 93.2 ohms would be
required.
2. Wattage Value
This is the tricky part because the wattage required will be based on the application. A few basic
questions need to be answered as a minimum in order to make an educated guess.
1. What kind of machine is it?
Extruder, conveyor, fan, pump, press drive, rewind, unwind, pull roll, feed roll,
dynamometer ….
The answer to this question can make a tremendous difference on the required wattage.
An Extruder has a heavy frictional load and pretty much stops very rapidly where as a
Press drive is a large “fly-wheel” having very little frictional load and a very high inertial
(mass) component which may take 30 minutes or more to coast to a stop. Of course the
Press drive would require a good sized braking resistor while the extruder does not require
any.
Fans and pumps in general do not require dynamic braking unless they can be “over
hauled or driven” by an external force or for some reason the process they are involved in
requires rapid changes in speed. Fans and pumps (variable torque) exhibit heavy frictional
loads at high speeds and high inertial characteristics at low speeds.
3. CTAN291 V1.1 Page 3 of 10 12/8/2010
2. How often is the machine stopped?
Again, the size of the braking resistor can be greatly affected by frequency of stopping.
For applications requiring an occasional stop, a resistor rated at 5-10% of the drive rating is
adequate where as an indexing application, may require as much as a 50% to 75% of the
drive rating.
3. a) How long does it take the machine to coast from full speed to zero?
b) How long does it take the machine to accelerate from one speed to another speed at a
specific torque level?
c) How much motor load is there when the machine is running?
Knowing these Items help characterize the machine, i.e. frictional load and inertia.
4. Is the braking used to absorb energy during a speed change?
In this application you might want to know how often the speed is changed and what the
speed change is. This would be very similar to an indexing application.
5. Is the motor being used to provide hold back torque or to prevent the motor from being
overhauled?
This would typically be a continuous duty application where the wattage would be directly
proportional to the required “hold-back” torque.
6. What is the machine Inertia?
Knowing this allows you to calculate the stored energy of the machine and thus more easily
determine the required wattage of the brake resistor. This is commonly the case with
indexing applications.
In many applications, all the information you’re given is;
I have an SP1405, what DB resistor do I need?
In this case to be on the safe side you would need to use a 4KW resistor since it is a 4KW drive, this is
clearly not enough information. In almost all cases this resistor is overkill unless the application
happens to be a dynamometer. Many applications only require the motor to stop a few times a day
and have low inertia (i.e., not a fly-wheel). In these cases a much smaller resistor may be used. As a
rule of thumb, a wire wound power resistor can handle about 20 times rated power for 3 seconds (then
allowed to cool back down to ambient temperature) while an vitreous enamel (ceramic) power resistor
is typically good for about 10 times rated power for 6 seconds. This equates to an energy rating of 60
times the wattage rating of both resistors, the difference being that the wire wound resistor can handle
a greater “thermal shock” ( i.e. higher peak current) than a ceramic resistor and thus the peak
allowable rated wattage is greater than that of the ceramic. The other difference would be the longer
cool down period on the ceramic resistor due to its greater mass. Based on this assumption, the
lowest useable wattage could be calculated based on the peak power dissipated in the brake resistor
divided by 20 (we will use wire wound resistors as standard). This of course refers to E-Stop duty (or
limited duty) rated resistors as opposed to repetitive applications (indexers for example) or
dynamometer based applications (load stands or applications requiring hold back torque).
P (peak) = 7802
/ 108.7 = 5597 watts
Pdb (min) = P(peak) / 20 = 279.8 watts minimum
E (max) = 279.8 * 60 = 16788 joules
4. CTAN291 V1.1 Page 4 of 10 12/8/2010
Note that I mentioned previously that the minimum allowable resistance typically should not be used if
the calculated resistance is higher. In this case if we had used the 58 ohm minimum allowable
resistance for an SP1405, the wattage, based on our “rule of thumb; 20 times rated power for 3
seconds, would be almost twice the value required for the 108.7 ohm resistor.
P (peak) = 7802
/ 58 = 10489 watts
Pdb (min) = P (peak) / 20 = 524.45 watts minimum
E (max) = 524.45 * 60 = 31467 joules
A few other ill effects of using the minimum resistance are, an increase in ripple current and voltage in
the bus capacitors, decrease in max on time , lack of brake current sharing in common bus
applications and motor overload protection sizing.
In our example of the 5 HP drive, the motor has an inertia (j) of 0.74 lb-ft2
(or 0.031 KgM2
), lets
calculate just how much inertia we can couple to the motor and stop it from full speed within the
constraints of the resistor we selected above.
First of all, what are the equations we need to use? We will use the MKS system since calculations
are more direct.
The inertia of the motor ( j ) as shown above is 0.031 KgM2
(nothing more that 0.04214 times the lb-
ft2
value).
The motor speed now needs to be expressed in radians / second (w).
w = rpm x 2Pi = 1800 x 6.28 = 188.5
60 60
The stored energy is (e):
e = ½ j w2
= 0.5 x .031 x 188.52
= 570 joules for the motor alone
The equation for deceleration time is:
td = (j x w) / (tm + tf)
where tm is the motor braking torque and tf is the frictional load torque
Since the resistor can handle full power (20 times rated wattage) for 3 seconds and the power from
the motor linearly decreases with motor speed (a triangular shape) the maximum allowable
deceleration time would actually be 6 seconds (2 times the 3 seconds since the area of a triangle is
equal to ½ base times height). Therefore:
6 seconds = (j x 188.5) / tm (assuming no frictional load tf = 0)
The motor torque would be:
P = (1.5 x 5 x 746) = tm x w, => tm = 29.76 nm
j = 6 seconds x tm = 6 x 29.76 = .947KgM2
=> 22.47 Lb-ft2
w 188.5
5. CTAN291 V1.1 Page 5 of 10 12/8/2010
This is equal to 30 times the motor inertia. A flywheel made of steel with a 1 inch thickness and 20
inch diameter would have about this amount of inertia compared to a motor rotor size of 6.3 inches
thick and 5 inches in diameter.
As a comparison, the motor by itself could be stopped in less than 0.2 seconds @ 150% braking
torque.
A system with this amount of inertia would take about 3 minutes to ramp down to zero speed with 5%
braking torque (frictional and drive losses) as opposed to 6 seconds when 150% braking torque is
available.
Let’s now check the amount of energy stored in the system. The total inertia is 0.947KgM2
, the speed
is 188.5 radians / second, therefore:
e = 0.947 x (188.5) 2
= 16824 joules
2
Very close to the energy rating of the resistor we selected (see page 3).
3. Resistor Protection
As mentioned above, dynamic braking resistors are designed to dissipate energy for a specific period
of time and then be allowed to cool back down to “room” temperature or on a continuous basis. The
protection device must allow this current to flow during normal operation without tripping. If this time is
exceeded, it must open, protecting the resistor. To perform this protective function, a few options exist.
These options are shown in figures 1 thru 3 in the pages to follow.
Figure 1
The simplest method, a manual motor circuit protector will be used. The overload current for the
device for a particular resistor will be selected based on the trip curves, the dynamic braking current
and a trip time adequate to protect the resistor. Below are the values we calculated for our example,
the first using a resistance value based on motor horsepower, the other using the minimum allowable
resistance for the drive size.
P (peak) = 7802
/ 108.7 = 5597 watts (Rdb = 108.7)
Pdb (min) = P(peak) / 20 = 279.8 watts minimum
E (max) = 279.8 * 60 = 16788 joules
I (peak) = 780 / 108.7 = 7.71 amps
P (peak) = 7802
/ 58 = 10489 watts (Rdb = 58)
Pdb (min) = P (peak) / 20 = 524.45 watts minimum
E (max) = 524.45 * 60 = 31467 joules
I (peak) = 780 / 58 = 13.45 amps
The above data shows the peak current that will flow in the resistor when the brake transistor turns on.
The recommended protection scheme is two-fold; first and foremost, we need to stop the current flow
in the resistor if the brake transistor fails to prevent heat related damage in the control enclosure,
secondly, set the Full Power Braking Time (#10.30) and the Full Power Braking Period (#10.31) to
protect the resistor from “over-use” under normal operating conditions.
6. CTAN291 V1.1 Page 6 of 10 12/8/2010
Overload Sizing
The overload current setting should be based on the average current, I(ave) , that would flow through
the resistor if it was connected directly across the dc bus of the drive. The following equation should
be used:
I(overload) = 1.35 X Nominal Line voltage = I(ave)
6 X Resistance 6
In our example the nominal line voltage was 480vac and the resistor was 100 ohms (108.7
calculated).
I(overload) = 1.35 X Nominal Line voltage = 1.35 X 480 = 1.08 amps ( ie 1 amp)
6 X Resistance 6 X 100
We would therefore use a 1 amp overload device. Looking at the trip curves below you would see the
trip time with a class 10 overload would be 10 seconds, a class 20 overload would be 20 seconds and
a class 30 overload would be 30 seconds for a current of 6 times the rated overload current. The
actual trip time based on the peak current during normal braking would be somewhat less since it is
7.7 times the rated overload current (~ 7 seconds for the class 10 and 14 seconds for the class 20). In
our application we would be using the class 10 overload since the max on time (Full Power Braking
Time, #10.30) was 3 seconds.
Drive Overload Parameter Setting
The drive software would be used to protect the resistor from being used too much, which if it was
selected properly, would only be due to some abnormal condition. We know we need to set parameter
#10.30 to 3 seconds, but what about #10.31? #10.31 can be determined from the formula below;
#10.31 = #10.30 X P(peak) = 3 X 5597 = 60 seconds
Rated Wattage 279.8
This limits the rms power dissipation in the resistor to its rated value.
In Summary: For our 5 HP example we would need:
300 Watt (279.8 is not a standard value) 100 Ohm Resistor (108.7 is not a standard value)
(- note you could use the exact values but it would be a custom value and probably cost much more
than the standard value)
A 1 amp class 10 manual motor circuit protector
Set parameter #10.30 = 3 and #10.31 = 60 --- a 5% duty cycle
If the 58 Ohm resistor was used instead of the 108.7, the only difference is that a 2 amp manual motor
circuit protector would be required since the overload current would be twice that of the 108.7 ohm
resistor. The drive settings would be slightly different since the resistor wattage is twice that of the
108.7 ohm resistor and the energy stored in the system (in our example) is the same for both cases,
the value in #10.31 could be 30.
Remember, this is a protection device and therefore will only need to open under a transistor
failure. Since the device was designed for ac and not dc current, each time the device opens
there will be some arcing in the contacts which will decrease the life of the device.
7. CTAN291 V1.1 Page 7 of 10 12/8/2010
DB
Connections
On Drive
Manual Motor
Circuit Protector
Figure 1
OL
Current
Setting
8. CTAN291 V1.1 Page 8 of 10 12/8/2010
DB
Connections
On Drive
Motor
Thermal
Overload
Figure 2
Figure 2
This set up is exactly the same as Figure 1 as far as sizing the overload device is concerned. The
thermal switch contact is then used to control a motor contactor supplying power the drive. This circuit
also has the advantage of dropping out power to the drive during a momentary power loss; preventing
damage to drive’s capacitor pre-charging circuit. An IEC AC-1 rating may be used in the input of AC
Drives. In applications requiring some form of agency approval, method #2 or method #3
would probably be required.
Thermal
Switch
Input Line
Voltage
L1
L2
L3
1L1
1L2
1L3
Line Voltage
to Drive
Power
ON
C
C
115
VAC
Thermal Switch
Power
Off
9. CTAN291 V1.1 Page 9 of 10 12/8/2010
DB
Connections
On Drive
Thermal
Switch
Figure 3
Figure 3
This set up should be used for any applications having very large inertia loads or indexers
with high indexing rates where high wattage resistors are used. The thermal switch contact is
then used to control a motor contactor supplying power the drive. This circuit also has the advantage
of dropping out power to the drive during a momentary power loss; preventing damage to drive’s
capacitor pre-charging circuit. In some applications, a class 30 overload may be useable but
one needs to be careful that the rms current flowing through the overload does not exceed
the continuous current rating of the overload. All of our enclosed dynamic braking kits are
provided with an internal thermal switch for resistor protection. In applications requiring some
form of agency approval, method #2 or method #3 would probably be required.
Input Line
Voltage
L1
L2
L3
1L1
1L2
1L3
Line Voltage
to Drive
C
C
115
VAC
Thermal Switch
Power
Off
Power
ON
10. CTAN291 V1.1 Page 10 of 10 12/8/2010
4. Overload / Braking Resistor Wiring Guide
In order to determine the appropriate wire size to connect a dynamic braking resistor to an AC
Drive, you need to know the resistance value and voltage class of the drive. The resistance can
either be measured with a digital multi-meter or if it was obtained from Control Techniques, the
part number of the kit contains the resistance value.
DBR-0100-03000-enc This would be a 10 Ohm , 3000 Watt resistor
DBR-XXX.X (ohms) – XXXXX (watts)- enc (enclosed unit)
The current through the resistor can then be calculated based on the resistance value and the
“Nominal Bus Voltage” in the table below.
For a 480vac drive with the 10 Ohm resistor, the current would be 680/10 = 68 amps. The wire
gauge would be based on this current, the maximum ambient temperature whether the wires
are run in “free air” or conduit. This info can be found in the National Electrical Code handbook
and or Local electrical codes.
Drive Voltage Rating Nominal Bus Voltage Brake Turn On Voltage
240 340vdc 390vdc
480 680vdc 780vdc
575 813vdc 930vdc
690 976vdc 1120vdc
When referring to wiring within the resistor enclosure (not exiting the enclosure) the following
applies (note that this wire is still useable to wire to the drive as well, its advantage is the
smaller gauge size) ;
Internal wiring connecting to heating circuits shall have a temperature rating of 200°C per
UL508A 2005 Edition, 26.4.4.
Wire Gage / Current Rating* HP @ 240 VAC HP @ 480 VAC
14 awg / 54 1 - 15 1 - 30
12 awg / 68 20 - 60 40 - 125
10 awg / 90 75 150
Table based on highest HP in column and the drives minimum allowable resistance
Based on single conductor in free air
Questions: Ask the author??
Steve Zaleski Email: mailto:steve.zaleski@emerson.com Tel: 800-367-8067