Reduction methods of armature reaction in DC machines
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Armature reaction is the effect of the magnetic field produced by current in the armature conductors on the main field produced by the generator's poles. This distorts the main field in two ways: by weakening it (demagnetization) and shifting it (cross-magnetization). Several methods are used to reduce the effects of armature reaction, including using laminated pole shoes, compensating windings, and ensuring a strong main field compared to the armature field.
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Armature reaction
Armature reaction is the distortion of the magnetic field in a DC generator caused by the magnetic field produced by current in the armature. This reaction shifts the neutral plane and affects commutation. It can reduce the induced EMF and torque. Methods to reduce armature reaction include using poles with high reluctance at the tips, laminated pole shoes, reducing armature flux through field pole laminations, having a strong main magnetic field, using interpoles, and adding compensating windings.
Armature Reaction
Armature reaction in a DC machine is the effect of armature flux on the main field flux. It has two undesirable effects - it demagnetizes the main flux and distorts the main flux. This reduces generated voltage and torque and influences commutation limits. Methods to reduce armature reaction include compensating windings and interpoles, which produce fields opposing the armature flux effects.
Armature reaction
Armature reaction is the effect of current flowing in the armature windings on the main field flux in a DC machine. It causes two undesirable effects: 1) a reduction in the main field flux per pole, and 2) distortion of the main field flux wave along the air gap. Armature current produces cross-flux that either aids or weakens the main flux depending on its location. This results in a non-uniform flux distribution and a shift in the magnetic neutral axis in the direction of rotation for a generator and against rotation for a motor. It also causes demagnetization due to magnetic saturation, further reducing the main field flux from its no-load value.
Dc motor
1. A DC motor runs on direct current electricity. It has a field winding that produces a magnetic field when energized, and an armature winding that rotates when placed in this magnetic field.
2. The key parts of a DC motor include the yoke, poles, field winding, armature core, armature winding, commutator, and brushes. The field winding produces flux, and the rotation of the armature winding within this flux induces voltage that is used to power the load.
3. DC motors can be shunt wound, series wound, or compound wound depending on how the field and armature windings are connected. Shunt and series motors have different torque-speed characteristics due
Chapter 2
The document discusses transformers and their operation. It begins by introducing transformers and their basic components. There are two main types of construction: core type and shell type. An ideal transformer is then described as having no losses, infinite core permeability, and zero resistance windings. The document explains how an ideal transformer works based on Faraday's law of induction. It also discusses voltage and current ratios, impedance transformation, and power relationships for an ideal transformer. Real transformers are then discussed, including voltage ratios, magnetizing current, and equivalent circuits.
Testing of dc machines_I
This document discusses different methods for testing DC machines. It describes the objectives of testing as determining if a machine's performance matches its design specifications and investigating any variations. Three main testing methods are outlined: direct, indirect, and regenerative. The direct method involves directly loading the machine and measuring efficiency. The indirect method determines performance characteristics from no-load test data using methods like Swinburne's test. Swinburne's test involves running the machine at no-load and recording parameters to calculate constant and stray losses. Examples of calculations for torque, output, and efficiency using data from brake tests are also provided.
Electrical machines lecture notes
These notes gives the introduction to electrical machines in general and prepare the students to learn other advanced electrical machines as a course
Universal motor
The universal motor can operate on either AC or DC power sources. It is modified slightly from a DC series motor to allow proper operation on AC, such as adding a compensating winding and using laminated pole pieces. Universal motors are commonly used in appliances and power tools where high speed and torque are needed. They have advantages of simple construction and cost effectiveness.
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Armature reaction
Armature reaction is the distortion of the magnetic field in a DC generator caused by the magnetic field produced by current in the armature. This reaction shifts the neutral plane and affects commutation. It can reduce the induced EMF and torque. Methods to reduce armature reaction include using poles with high reluctance at the tips, laminated pole shoes, reducing armature flux through field pole laminations, having a strong main magnetic field, using interpoles, and adding compensating windings.
Armature Reaction
Armature reaction in a DC machine is the effect of armature flux on the main field flux. It has two undesirable effects - it demagnetizes the main flux and distorts the main flux. This reduces generated voltage and torque and influences commutation limits. Methods to reduce armature reaction include compensating windings and interpoles, which produce fields opposing the armature flux effects.
Armature reaction
Armature reaction is the effect of current flowing in the armature windings on the main field flux in a DC machine. It causes two undesirable effects: 1) a reduction in the main field flux per pole, and 2) distortion of the main field flux wave along the air gap. Armature current produces cross-flux that either aids or weakens the main flux depending on its location. This results in a non-uniform flux distribution and a shift in the magnetic neutral axis in the direction of rotation for a generator and against rotation for a motor. It also causes demagnetization due to magnetic saturation, further reducing the main field flux from its no-load value.
Dc motor
1. A DC motor runs on direct current electricity. It has a field winding that produces a magnetic field when energized, and an armature winding that rotates when placed in this magnetic field.
2. The key parts of a DC motor include the yoke, poles, field winding, armature core, armature winding, commutator, and brushes. The field winding produces flux, and the rotation of the armature winding within this flux induces voltage that is used to power the load.
3. DC motors can be shunt wound, series wound, or compound wound depending on how the field and armature windings are connected. Shunt and series motors have different torque-speed characteristics due
Chapter 2
The document discusses transformers and their operation. It begins by introducing transformers and their basic components. There are two main types of construction: core type and shell type. An ideal transformer is then described as having no losses, infinite core permeability, and zero resistance windings. The document explains how an ideal transformer works based on Faraday's law of induction. It also discusses voltage and current ratios, impedance transformation, and power relationships for an ideal transformer. Real transformers are then discussed, including voltage ratios, magnetizing current, and equivalent circuits.
Testing of dc machines_I
This document discusses different methods for testing DC machines. It describes the objectives of testing as determining if a machine's performance matches its design specifications and investigating any variations. Three main testing methods are outlined: direct, indirect, and regenerative. The direct method involves directly loading the machine and measuring efficiency. The indirect method determines performance characteristics from no-load test data using methods like Swinburne's test. Swinburne's test involves running the machine at no-load and recording parameters to calculate constant and stray losses. Examples of calculations for torque, output, and efficiency using data from brake tests are also provided.
Electrical machines lecture notes
These notes gives the introduction to electrical machines in general and prepare the students to learn other advanced electrical machines as a course
Universal motor
The universal motor can operate on either AC or DC power sources. It is modified slightly from a DC series motor to allow proper operation on AC, such as adding a compensating winding and using laminated pole pieces. Universal motors are commonly used in appliances and power tools where high speed and torque are needed. They have advantages of simple construction and cost effectiveness.
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3. The case study involves simulating a step-up transformer in MATLAB, obtaining the simulation results, and analyzing the technical specifications and applications of step-up transformers.
electrical machines
This document provides information about various types of electrical machines and transformers. It discusses direct current machines and alternating current machines. It also describes different types of motors like induction motors, synchronous motors, and transformers. Key components of these machines like the rotor, stator, windings and magnetic core are explained. Different speed control methods for induction motors are also summarized.
DC GENERATORS
A DC generator converts mechanical energy to DC electrical energy using electromagnetic induction. It has two main parts - a rotor that rotates within a stator. As the rotor cuts the magnetic field in the stator, an alternating voltage is induced in the rotor windings. A commutator is used to convert the alternating voltage to direct voltage that can be used to power loads. The characteristics of a DC generator include its open circuit characteristic showing the relationship between generated voltage and field current, and its external characteristic showing the relationship between terminal voltage and load current.
Synchronous machines
Synchronous machines include generators and motors. Synchronous generators are the primary source of electrical energy and convert mechanical power to AC power. They rely on synchronous motors which are used for constant speed industrial drives. Synchronous generators have a rotor with DC excitation and a stator with a 3-phase winding. They come in salient-pole or cylindrical rotor types. Synchronous motors operate by synchronizing their rotor field to the rotating stator field to convert electric power to mechanical power. They are often used for large, low speed, high power applications like pumps and compressors.
Losses dc machines
1) There are several types of losses that reduce the efficiency of DC machines, including electrical or copper losses, core losses, brush losses, mechanical losses, and stray load losses.
2) Electrical losses include losses from the armature winding resistance, shunt field winding resistance, series field winding resistance, and interpole winding resistance.
3) Core losses are hysteresis and eddy current losses and account for around 20% of full load losses.
4) Brush losses are due to the voltage drop and current at the brush contact with the commutator.
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In this video you will learn about,derivation of dc machine emf equation,back emf,torque equation of dc motor,dc generated,dc motor.To understand electrical machine with trick watch all videos,
MUST UPGRADE YOUR KNOWLEDGE BY FLIPPED LEARNING
#Topic - ELECTRICAL TRANSFORMER
~ Link of all sessions are.
DAY 1 (Need/Definition)
https://youtu.be/BvaykFJ_NoE
DAY 2 (Working principle and Construction)
https://youtu.be/06rgxocihaM
DAY 3 (EMF equation and Turns Ratio)
https://youtu.be/g7e5xBPmv3Y
DAY 4 (Classification of Transformer)
https://youtu.be/6NP5L4MlvY4
DAY 5 ( Ideal and practical transformer on no load)
(Equivalent Transformer)
https://youtu.be/6LCLQC1p3lg
DAY 6 ( Losses in Transformer)
https://youtu.be/ObYNiGgd3hA
DAY 7 (O.C. and S.C. test)
https://youtu.be/8WiJRawHiTce/6LCLQC1p3lg
DAY 8 (Voltage Regulation & Efficiency)
https://youtu.be/6LCLQC1p3lg
DAY 9 (Zero Lecture)
https://youtu.be/N4xWOwgi8I4
DAY 10 (Classification of machine)
https://youtu.be/bmxnU5rC5m4
Construction of Machine
https://youtu.be/34mpphDk3gg
Working Principle of Synchronous Generator & Synchronous Motor
https://youtu.be/bkgf72M8BCY
Working Principle of Induction Motor
https://youtu.be/Lj_iQBoRiK0
armature Winding
Winding
What is Armature winding?
Terms related to armature winding.
Single layer and double layer windings.
Comparison between closed and open windings.
Types of DC armature winding.
Types of AC armature winding.
Single phase induction motor
This document discusses the construction and working principle of single phase induction motors. It explains that single phase induction motors have a stationary stator and a rotating rotor. The stator is wound to produce a pulsating magnetic field when powered by single phase AC supply. This pulsating field can be resolved into two counter-rotating revolving fields of equal magnitude. However, at startup the torque produced by each field cancels out, preventing self-starting. Therefore, single phase induction motors require auxiliary starting mechanisms to produce a rotational torque. The document also covers torque-speed characteristics and how starting mechanisms make the forward field torque dominant to enable motor rotation.
Induction machines
An induction motor is described with the following specifications:
- 480-V, 60 Hz, 50-hp, 3-phase
- Drawing 60A at 0.85 PF lagging
- Stator copper losses of 2 kW
- Rotor copper losses of 700 W
To determine the rotor frequency at full load, the slip is calculated using the given power rating, current, and power factor. The slip is then used to calculate the rotor frequency.
Three phase transformer
Three Phase Transformer
Presented by:
Rizwan Yaseen 2017-EE-432
Zeeshan Saeed 2017-EE-414
Muhammad Hamad 2017-EE-404
Muhammad Zeeshan 2017-EE-402
A three phase transformer is made of three sets of primary and secondary windings wound around the legs of a common iron core. It allows for higher transmission voltages using lower amperage wiring. The core can be constructed as either a core type or shell type configuration. A three phase transformer works by inducing secondary voltages from the three phase primary voltages to maintain the proper phase relationships for power distribution.
Dc machines
This document provides an overview of DC machines and motors. It discusses:
1) The fundamentals of DC generators and motors, including how voltage is induced in a conductor moving through a magnetic field and how a force is induced on a current-carrying conductor in a magnetic field.
2) The construction of DC machines, including the stationary stator with field poles and rotating armature/rotor with windings.
3) Different types of DC motors like shunt, series, and compound motors and how their field and armature windings are connected. Speed control methods for DC motors are also discussed.
4) Workings of DC motors are explained through equivalent circuits and equations for induced voltage
testing of dc machine
The document describes different testing methods for DC machines. It discusses the simple/direct test method, Swinburne's indirect test method, and Hopkinson's regenerative test method. The simple/direct test method calculates efficiency by directly loading the DC machine, but it is only suitable for small machines. Swinburne's method measures no-load losses to determine efficiency indirectly. Hopkinson's method couples two identical DC machines together to test them simultaneously, with one acting as a motor and the other as a generator.
IGBT
The document discusses insulated gate bipolar transistors (IGBTs). It describes IGBTs as having MOSFET-like input characteristics and bipolar junction transistor-like output characteristics. The document summarizes IGBT structure, working principles, characteristics including transfer and switching characteristics, and methods of connecting IGBTs in series and parallel. It also discusses protection of IGBTs from overvoltage, overcurrent, high dv/dt, and overheating.
DC motors characteristics, Torque & Speed Equations, Torque -Armature current...
DC motors
Torque & Speed Equations
Torque -Armature current Characteristics
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Torque-speed characteristics
Applications
Speed Control
Protection of alternator
This document discusses various protections provided for alternators, including mechanical protections from prime mover failure, field failure, overcurrent, overspeed, and overvoltage, as well as electrical protections from unbalanced loading and stator winding faults. It describes different protection mechanisms like differential protection, balanced earth fault protection, and inter-turn fault protection that are used to protect against faults in the alternator windings or unbalanced loading. The document emphasizes the importance of alternator protection given their high individual cost and importance in power generation.
Electrical ac & dc drives ppt
This document discusses electric drives and AC motor drives. It defines electric drives as systems that use 50% of electrical energy produced and can operate equipment at constant or variable speeds. The main components of electric drives are motors, including DC and AC types, and power sources like batteries or utilities. It also summarizes different types of single-phase and three-phase DC drives classified by their converter configurations. For AC drives, it explains that speed and torque can be controlled through stator voltage, rotor voltage or frequency control. It concludes that variable speed AC drives can increase system efficiency from 15-27% compared to constant speed operation.
Power factor presentation
This document discusses AC power, power factor, and power factor correction. It defines active power, reactive power, and apparent power. It explains that power factor is the cosine of the angle between the voltage and current waveforms, and that most loads have a lagging power factor less than 1 due to their inductive nature. This causes issues like increased conductor size and utility charges. Power factor can be corrected by using static capacitors or a synchronous condenser to supply leading reactive current to balance the load's lagging current.
synchronous motor for presentation
The document summarizes the key aspects of synchronous motors. It describes how synchronous motors synchronize the rotation of their shaft to the frequency of the AC power supply. There are two main types: non-excited motors which use the stator magnetic field to induce poles on the steel rotor, and DC-excited motors which require a separate DC source to excite the rotor. Synchronous motors have advantages over other motors like constant speed operation and unity power factor, and they are commonly used where precise constant speed is required, like in power generation and precision machinery.
dc Generator Ppt
1) DC generators convert mechanical energy to electrical energy through Faraday's law of electromagnetic induction. When a conductor moves through a magnetic field, an EMF is induced in the conductor.
2) The main components of a DC generator are the yoke, field electromagnets, armature, commutator, and brushes. The armature is wound with coils and rotates within the magnetic field produced by the field electromagnets to generate an EMF.
3) As the armature rotates, the commutator and brushes are used to periodically reverse the direction of current in the external circuit, thereby producing direct current. Losses in the generator arise from copper, iron, and mechanical components
Armature reaction
1) Armature reaction is the effect of the magnetic field produced by current in the armature conductors on the main field produced by the poles of a DC machine.
2) This causes distortion and weakening of the main field flux along the air gap, reducing the overall main field flux in each pole.
3) Compensating windings and interpoles are used to reduce the demagnetizing effect of armature reaction and produce a more uniform main flux distribution in the air gap.
Armature Reaction
This presentation contains animative understanding of Armature reaction,compensating winding and interpoles
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ELECTRICAL MACHINES 1
1. The document discusses a case study on simulating a step-up transformer in MATLAB.
2. A step-up transformer increases voltage by having more turns in the secondary coil than the primary coil, inducing a higher voltage on the secondary side.
3. The case study involves simulating a step-up transformer in MATLAB, obtaining the simulation results, and analyzing the technical specifications and applications of step-up transformers.
electrical machines
This document provides information about various types of electrical machines and transformers. It discusses direct current machines and alternating current machines. It also describes different types of motors like induction motors, synchronous motors, and transformers. Key components of these machines like the rotor, stator, windings and magnetic core are explained. Different speed control methods for induction motors are also summarized.
DC GENERATORS
A DC generator converts mechanical energy to DC electrical energy using electromagnetic induction. It has two main parts - a rotor that rotates within a stator. As the rotor cuts the magnetic field in the stator, an alternating voltage is induced in the rotor windings. A commutator is used to convert the alternating voltage to direct voltage that can be used to power loads. The characteristics of a DC generator include its open circuit characteristic showing the relationship between generated voltage and field current, and its external characteristic showing the relationship between terminal voltage and load current.
Synchronous machines
Synchronous machines include generators and motors. Synchronous generators are the primary source of electrical energy and convert mechanical power to AC power. They rely on synchronous motors which are used for constant speed industrial drives. Synchronous generators have a rotor with DC excitation and a stator with a 3-phase winding. They come in salient-pole or cylindrical rotor types. Synchronous motors operate by synchronizing their rotor field to the rotating stator field to convert electric power to mechanical power. They are often used for large, low speed, high power applications like pumps and compressors.
Losses dc machines
1) There are several types of losses that reduce the efficiency of DC machines, including electrical or copper losses, core losses, brush losses, mechanical losses, and stray load losses.
2) Electrical losses include losses from the armature winding resistance, shunt field winding resistance, series field winding resistance, and interpole winding resistance.
3) Core losses are hysteresis and eddy current losses and account for around 20% of full load losses.
4) Brush losses are due to the voltage drop and current at the brush contact with the commutator.
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#DERIVATION OF DC MOTOR EMF EQUATION
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#back emf in dc motor
#back emf in dc motor in hindi
In this video you will learn about,derivation of dc machine emf equation,back emf,torque equation of dc motor,dc generated,dc motor.To understand electrical machine with trick watch all videos,
MUST UPGRADE YOUR KNOWLEDGE BY FLIPPED LEARNING
#Topic - ELECTRICAL TRANSFORMER
~ Link of all sessions are.
DAY 1 (Need/Definition)
https://youtu.be/BvaykFJ_NoE
DAY 2 (Working principle and Construction)
https://youtu.be/06rgxocihaM
DAY 3 (EMF equation and Turns Ratio)
https://youtu.be/g7e5xBPmv3Y
DAY 4 (Classification of Transformer)
https://youtu.be/6NP5L4MlvY4
DAY 5 ( Ideal and practical transformer on no load)
(Equivalent Transformer)
https://youtu.be/6LCLQC1p3lg
DAY 6 ( Losses in Transformer)
https://youtu.be/ObYNiGgd3hA
DAY 7 (O.C. and S.C. test)
https://youtu.be/8WiJRawHiTce/6LCLQC1p3lg
DAY 8 (Voltage Regulation & Efficiency)
https://youtu.be/6LCLQC1p3lg
DAY 9 (Zero Lecture)
https://youtu.be/N4xWOwgi8I4
DAY 10 (Classification of machine)
https://youtu.be/bmxnU5rC5m4
Construction of Machine
https://youtu.be/34mpphDk3gg
Working Principle of Synchronous Generator & Synchronous Motor
https://youtu.be/bkgf72M8BCY
Working Principle of Induction Motor
https://youtu.be/Lj_iQBoRiK0
armature Winding
Winding
What is Armature winding?
Terms related to armature winding.
Single layer and double layer windings.
Comparison between closed and open windings.
Types of DC armature winding.
Types of AC armature winding.
Single phase induction motor
This document discusses the construction and working principle of single phase induction motors. It explains that single phase induction motors have a stationary stator and a rotating rotor. The stator is wound to produce a pulsating magnetic field when powered by single phase AC supply. This pulsating field can be resolved into two counter-rotating revolving fields of equal magnitude. However, at startup the torque produced by each field cancels out, preventing self-starting. Therefore, single phase induction motors require auxiliary starting mechanisms to produce a rotational torque. The document also covers torque-speed characteristics and how starting mechanisms make the forward field torque dominant to enable motor rotation.
Induction machines
An induction motor is described with the following specifications:
- 480-V, 60 Hz, 50-hp, 3-phase
- Drawing 60A at 0.85 PF lagging
- Stator copper losses of 2 kW
- Rotor copper losses of 700 W
To determine the rotor frequency at full load, the slip is calculated using the given power rating, current, and power factor. The slip is then used to calculate the rotor frequency.
Three phase transformer
Three Phase Transformer
Presented by:
Rizwan Yaseen 2017-EE-432
Zeeshan Saeed 2017-EE-414
Muhammad Hamad 2017-EE-404
Muhammad Zeeshan 2017-EE-402
A three phase transformer is made of three sets of primary and secondary windings wound around the legs of a common iron core. It allows for higher transmission voltages using lower amperage wiring. The core can be constructed as either a core type or shell type configuration. A three phase transformer works by inducing secondary voltages from the three phase primary voltages to maintain the proper phase relationships for power distribution.
Dc machines
This document provides an overview of DC machines and motors. It discusses:
1) The fundamentals of DC generators and motors, including how voltage is induced in a conductor moving through a magnetic field and how a force is induced on a current-carrying conductor in a magnetic field.
2) The construction of DC machines, including the stationary stator with field poles and rotating armature/rotor with windings.
3) Different types of DC motors like shunt, series, and compound motors and how their field and armature windings are connected. Speed control methods for DC motors are also discussed.
4) Workings of DC motors are explained through equivalent circuits and equations for induced voltage
testing of dc machine
The document describes different testing methods for DC machines. It discusses the simple/direct test method, Swinburne's indirect test method, and Hopkinson's regenerative test method. The simple/direct test method calculates efficiency by directly loading the DC machine, but it is only suitable for small machines. Swinburne's method measures no-load losses to determine efficiency indirectly. Hopkinson's method couples two identical DC machines together to test them simultaneously, with one acting as a motor and the other as a generator.
IGBT
The document discusses insulated gate bipolar transistors (IGBTs). It describes IGBTs as having MOSFET-like input characteristics and bipolar junction transistor-like output characteristics. The document summarizes IGBT structure, working principles, characteristics including transfer and switching characteristics, and methods of connecting IGBTs in series and parallel. It also discusses protection of IGBTs from overvoltage, overcurrent, high dv/dt, and overheating.
DC motors characteristics, Torque & Speed Equations, Torque -Armature current...
DC motors
Torque & Speed Equations
Torque -Armature current Characteristics
Speed - Armature current Characteristics
Torque-speed characteristics
Applications
Speed Control
Protection of alternator
This document discusses various protections provided for alternators, including mechanical protections from prime mover failure, field failure, overcurrent, overspeed, and overvoltage, as well as electrical protections from unbalanced loading and stator winding faults. It describes different protection mechanisms like differential protection, balanced earth fault protection, and inter-turn fault protection that are used to protect against faults in the alternator windings or unbalanced loading. The document emphasizes the importance of alternator protection given their high individual cost and importance in power generation.
Electrical ac & dc drives ppt
This document discusses electric drives and AC motor drives. It defines electric drives as systems that use 50% of electrical energy produced and can operate equipment at constant or variable speeds. The main components of electric drives are motors, including DC and AC types, and power sources like batteries or utilities. It also summarizes different types of single-phase and three-phase DC drives classified by their converter configurations. For AC drives, it explains that speed and torque can be controlled through stator voltage, rotor voltage or frequency control. It concludes that variable speed AC drives can increase system efficiency from 15-27% compared to constant speed operation.
Power factor presentation
This document discusses AC power, power factor, and power factor correction. It defines active power, reactive power, and apparent power. It explains that power factor is the cosine of the angle between the voltage and current waveforms, and that most loads have a lagging power factor less than 1 due to their inductive nature. This causes issues like increased conductor size and utility charges. Power factor can be corrected by using static capacitors or a synchronous condenser to supply leading reactive current to balance the load's lagging current.
synchronous motor for presentation
The document summarizes the key aspects of synchronous motors. It describes how synchronous motors synchronize the rotation of their shaft to the frequency of the AC power supply. There are two main types: non-excited motors which use the stator magnetic field to induce poles on the steel rotor, and DC-excited motors which require a separate DC source to excite the rotor. Synchronous motors have advantages over other motors like constant speed operation and unity power factor, and they are commonly used where precise constant speed is required, like in power generation and precision machinery.
dc Generator Ppt
1) DC generators convert mechanical energy to electrical energy through Faraday's law of electromagnetic induction. When a conductor moves through a magnetic field, an EMF is induced in the conductor.
2) The main components of a DC generator are the yoke, field electromagnets, armature, commutator, and brushes. The armature is wound with coils and rotates within the magnetic field produced by the field electromagnets to generate an EMF.
3) As the armature rotates, the commutator and brushes are used to periodically reverse the direction of current in the external circuit, thereby producing direct current. Losses in the generator arise from copper, iron, and mechanical components
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Similar to Reduction methods of armature reaction in DC machines
Armature reaction
1) Armature reaction is the effect of the magnetic field produced by current in the armature conductors on the main field produced by the poles of a DC machine.
2) This causes distortion and weakening of the main field flux along the air gap, reducing the overall main field flux in each pole.
3) Compensating windings and interpoles are used to reduce the demagnetizing effect of armature reaction and produce a more uniform main flux distribution in the air gap.
Armature Reaction
This presentation contains animative understanding of Armature reaction,compensating winding and interpoles
Armature reaction
This document discusses armature reaction in DC generators and motors. It explains that armature reaction is caused by the magnetic field produced by current flowing through the armature windings, which distorts the main magnetic field produced by the poles. This shifts the magnetically neutral axis and causes brush shift. Compensating windings and interpoles are used to counteract the cross-magnetizing effect of armature reaction and make commutation sparkless. Compensating windings carry current in the opposite direction of the armature below the poles, while interpoles have the same polarity as the leading pole and induce a reversing e.m.f. to help current reversal during commutation.
Armature reaction
This document discusses armature reaction and commutation in DC machines. It defines armature reaction as the effect of armature magnetic flux on the main field flux produced by the stator poles. This causes the magnetic neutral axis to shift and the main flux to weaken. Commutation is defined as the process of reversing the current direction in armature coils as they pass from one pole to the next. Methods to improve commutation include using interpoles and adjusting brush position.
Design of inter poles
Interpoles are used in DC motors and generators to reduce the effects of armature reaction. They are small poles placed between the main poles that are wound with turns carrying the full armature current. This helps neutralize the cross-magnetizing effect of armature reaction and improves commutation. The interpole windings produce a commutating EMF that aids in reversing the current in the armature coils during commutation. Together, this allows for sparkless commutation even at higher loads and currents. The design of interpoles involves determining the required mmf to overcome armature reaction effects and provide the desired flux density in the interpole gaps.
LOW CONVERSION LOSS DUAL GENERATOR
This paper explains losses associated with conventional generators due to armature reaction and self-induced emf and introduces a new design, dual generators, to scale down these losses. In the following paper, it will be shown how dual generators can offer better conversion of energy from mechanical to electrical and also reduce the above mentioned losses.
RGPV Unit i ex503 - copy
This document provides reading material for electrical and electronics engineering students studying electrical machines II at RGPV affiliated colleges. It covers the syllabus for the unit on DC machines, including the basic construction of DC machines, types of excitation, armature and field windings, EMF equations, armature reaction and methods to limit it, commutation processes, performance of DC generators, and different types of DC motors like metadyne, amplidyne, permanent magnet, and brushless motors. The topics are explained over several pages with diagrams and examples. Key concepts covered are the magnetic circuits, armature and commutator construction, separately excited and self-excited machines, wave and lap windings, EMF equations, ar
DC-Machine-Armature Reaction.pptx
In a DC machine, armature reaction occurs due to the interaction between the main field flux and armature flux. This distorts the main flux and shifts the magnetic neutral axis from the geometric neutral axis. To address this, methods like brush shift, interpoles, and compensating windings are used. Interpoles are commonly used as they can neutralize the armature reaction mmf in the interpolar axis irrespective of load or operating conditions. Compensating windings are concentric windings that produce a flux opposite to the armature flux under the pole shoes to counteract the cross-magnetizing effect.
Armaturereaction&commutation
The document discusses armature reaction and commutation in DC machines. It describes how armature reaction demagnetizes and distorts the main magnetic field, requiring brush shift. Commutation involves the reversal of current in armature coils as they pass between poles. Sparking can occur due to reactance voltage impeding quick current reversal. Methods to improve commutation include resistance commutation using carbon brushes and EMF commutation using interpoles to neutralize reactance voltage.
UNIT 1.pptx
The document discusses various methods to determine the voltage regulation of a synchronous generator or alternator. It describes the synchronous impedance method, MMF (ampere-turns) method, and zero power factor (Potier) method. The synchronous impedance method calculates regulation using synchronous reactance Xs obtained from open-circuit and short-circuit tests. The MMF method considers the field mmf required for open-circuit voltage and to cancel armature reaction mmf. The zero power factor method separates armature leakage reactance from armature reaction effects using open-circuit and zero power factor tests.
Dc generator
This document discusses DC generators and their components and operation. It describes:
1) The basic components of a DC generator including the armature, electromagnet, slip rings, and brushes.
2) How a DC generator works by inducing an electromotive force (emf) in the armature coils as they cut through the magnetic field.
3) Issues that can occur with commutation in DC generators and different methods to improve commutation such as using resistance or interpole commutation.
AC GENERATOR.pptx
The document summarizes the key components and working principle of an AC generator. The AC generator converts mechanical energy to electrical energy through electromagnetic induction. It has a field magnet that produces a magnetic field, an armature coil that rotates in this field, slip rings to carry the alternating current produced, and brushes to transfer the current to an external circuit. As the coil rotates, the changing magnetic flux induces an alternating current whose frequency depends on the rotation speed.
UNIT-5.pptx
The document discusses synchronous generators. It begins by listing various topics related to synchronous generators including constructional details, types of rotors, the EMF equation, synchronous reactance, armature reaction, voltage regulation methods, synchronization, and operating characteristics. It then provides more details on synchronous generators, describing their construction, types including salient pole and cylindrical rotors, EMF equation derivation, armature windings, and causes of voltage drops. Finally, it discusses various methods for determining voltage regulation including the direct loading method, synchronous impedance method, MMF method, zero power factor method, and two reaction theory.
Unit 1
The document discusses synchronous generators and provides details about:
1. The types of synchronous generators based on the arrangement of field and armature windings.
2. The construction and components of a synchronous generator including the stationary armature and rotating field.
3. The different tests conducted on synchronous generators like open circuit, short circuit, and zero power factor tests to determine parameters like synchronous reactance.
4. Methods to calculate the voltage regulation of a synchronous generator like the EMF method, MMF method, and zero power factor method.
Dc machiness
DC machines can be generators or motors. DC generators convert mechanical energy to DC voltage and current using magnetic induction. They have an armature that rotates inside magnetic fields produced by poles. The armature is connected to a commutator that changes the alternating voltage induced in the armature to pulsating DC voltage. DC motors convert electrical energy to mechanical energy by supplying DC power to an armature within magnetic fields, and are used widely in applications. Major parts include the rotor (armature) and stator (field coils).
Notes on armature reaction in dc machines
Part of a lecture series delivered by me on DC machines to BE Third Year Students, Z. H. College of Engg. & Technology, AMU, Aligarh, 2012-13.
Please comment and feel free to ask anything related. Thanks!
ROTATING MACHINES via magnetic field
Fleming's left hand rule is used to determine the direction of force acting on a current carrying conductor placed in a magnetic field. The middle finger represents the direction of current, the forefinger represents the direction of the magnetic field, and the thumb indicates the direction of the force acting on the conductor. This rule is used in motors. DC motors are used in applications requiring constant torque, rapid acceleration/deceleration, and responsiveness to feedback signals, such as electric vehicles, steel/aluminum mills, trains, cranes, and controls. DC motors consist of a commutator, armature, and field windings that generate a magnetic field to cause rotation.
DC-machines (1).ppt
This document discusses DC machines and provides details on various concepts related to DC generators and DC motors. It describes Maxwell's corkscrew rule and Fleming's left-hand and right-hand rules for determining magnetic fields and forces. It also explains Lenz's law, the construction and working principles of DC generators and motors, including their windings, commutation, and speed control methods. Various types of DC generators and motors are defined along with their characteristics and applications. Testing methods for determining efficiency of DC machines are also summarized.
DC-machines (2).pptvnbnbmmvvvmvmvvmvmmmvm
This document discusses DC machines including Maxwell's corkscrew rule, Fleming's left and right hand rules, Lenz's law, the construction and working principles of DC generators and motors. It describes how DC generators convert mechanical energy to electrical energy using electromagnetic induction. It also explains how DC motors convert electrical energy to mechanical energy by producing torque on the armature windings when placed in a magnetic field. Various types of DC motors and methods for controlling motor speed are also summarized.
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Reduction methods of armature reaction in DC machines
- 1. POLE FACE ARMATURE YOKE N S BRUSH Armature Reaction is the effect of “Armature Field” on the “ main Field “. Armature field is the field which is produced by the armature conductorsdue to current flowing through them. Main field is the field which is produced by the poles which is necessary for the operation. DC Generator Armature Reaction
- 2. Motion Magnetic Field Current Fleming’s Right Hand Rule Direction of current running through conductor
- 3. N S q - axis GNA d- axis Current Right Hand Thumb Rule Magnetic Field Magnetic Field Direction of Magnetic Field due to Armature Conductor Current
- 5. (1) De- Magnetisation -It weakens /reduces the main flux. (2)Cross- Magnetisation -It distorts the main flux. Effects Of Armature Reaction
- 6. Terminology Related To Armature Reaction -MNA (Magnetically Neutral Axis) It is the axis along which no E.M.F is produced, hence brushes are kept on this axis. -GNA (Geometrically Neutral Axis) It is the axis which divides the armature core in two equal parts. -Polar Axis It is the imaginary line which joins the center of NS poles.
- 7. Consider a two pole D.C Generator. For the sake of simplicity, the brushes are shown directly touching the armature conductors, but practically they touch commutator segments. Assume that there is no current flowing through armature conductors, Hence.. (1)The flux is distributed symmetrically with respect to polar axis. (2)The M.N.A coincides the G.N.A.
- 8. Field MMF (Fm) A d- axis O Flux due to field current alone GNA MNA (At no load) Main Field Flux produced by field m.m.f at no load d- axis
- 9. N S O d- axis Armature MMF (Fa) q - axis GNA BFlux due to Armature current alone d- axis Armature Field Flux produced by Armature m.m.f with field unexcited q - axis GNA
- 10. d - axis Fa m A d- axis F GNA MNA (At on load ) O FR θ Resultant of Main Field Flux and Armature Field Flux
- 11. Generator Direction x x x x x x N S Polar Axis Interpolar Axis GNA MNA Polar AxisMotor Direction Bm Fa Ba ϕ Flux distribution and Flux waveforms due to Field and Armature currents ϕm ϕa
- 12. Peaky wave Mmf & B Resultant Flux waveform ϕ
- 13. Demagnetizing and Cross-magnetizing Conductors:
- 15. Calculation of Cross-magnetizing Amp-Turns
- 17. Methods to reduce Armature Reaction By high Reluctanceat POLE TIPS: At the time of constructionwe use chamfered poles. These poleshave larger air gap on the tips and smaller air gap at the centre. These polesprovide non-uniformair gap. The effect of armature reaction is more near to edge of poles and negligible near the centre of pole. If air gap is kept non uniform i.e., larger air gap at the edges(Pole Tip) and smaller near the centre of the poleand then armature flux near the pole tip decreases and armature reaction decreases.
- 18. Fig. High reluctance at pole tips
- 19. By Laminated Pole Shoe: We insert Laminated objects in the pole. By having Laminated pole shoe the reluctance in the armature flux path increases. Hence the armature flux gap gets reduced.
- 20. By Reduction in Armature flux: The effect of Armature Reaction is reduced by creating more reluctance in the path of Armature flux. This is achieved by using field Pole Laminations having several Rectangular holes punched in them. It gives high Reluctance in the path of armature flux. Due to this armature cross flux reduces whereas main field remains almost unaffected.
- 21. By having Strong main magnetic field: During the design of DC machine it should be ensured that the main field m.m.f. is sufficiently strong in comparison with full load armature flux. Greater the main field, lesser will be the distortion.
- 22. Compensating Winding: Compensating windings are used to nullify the cross- magnetizing effect. These windings are kept in slots of pole faces. It carries current in opposite direction to the current of armature winding just below the pole faces. It is connected in series with the armature winding.
- 23. N Direction of rotation Assuming this as pole face Main Field Armature Field Field by Comp. winding