This document contains notes from a class on basic electrical and instrumentation engineering. It covers topics like Faraday's law of electromagnetic induction, Lenz's law, three-phase circuits, construction and operation of DC machines including generators and motors. It defines key concepts such as back EMF, torque equation, speed regulation and characteristics of different types of DC motors like shunt, series and compound motors. Methods for controlling speed in DC motors like flux control, armature control and voltage control are also discussed.
- DC generators and motors operate using the principle of electromagnetic induction. When a conductor moves through a magnetic field, an electromotive force (emf) is induced in the conductor.
- The basic components of a DC generator are a magnetic field (produced by poles and field windings) and a conductor (armature) that rotates within the magnetic field. This motion induces an emf in the armature.
- A commutator is used to convert the alternating current from the armature into direct current that can be supplied to a load. Brushes make contact with the commutator segments to carry the output current.
DC generators convert mechanical energy to electrical energy using electromagnetic induction. They have a stationary part that produces a magnetic field and a rotating part called the armature. As the armature rotates in the magnetic field, a current is induced based on Faraday's law of induction. The commutator ensures the current flows in one direction to the load. The main parts are the magnetic frame, field coils, armature core and windings, commutator and brushes. The types of DC generators are separately excited, shunt, series and compound wound which differ in how the field and armature windings are connected. They have various applications including battery charging, motor operation, and power distribution.
The document provides details about the syllabus of an Electrical Machines course. It covers 5 units:
1) Construction and operation of DC machines including generators and motors.
2) Performance characteristics of DC machines like torque equations and efficiency.
3) Starting, speed control and testing methods for DC machines.
4) Construction, operation and testing of single phase transformers.
5) Three phase transformer connections and testing.
The summary covers the main topics covered in each unit at a high level.
1) A DC generator produces direct current through electromagnetic induction. When a conductor moves through a magnetic field, an electromotive force (EMF) is induced in the conductor.
2) The basic components of a DC generator are magnetic poles and conductors that rotate within the magnetic field.
3) In a single loop DC generator, an EMF is induced in the sides of a rotating rectangular conductor loop as it cuts through the magnetic flux lines. The loop is connected to brushes to output a direct current.
The document discusses direct current (DC) generators, including their construction, operation, and applications. It describes how a DC generator works by converting mechanical energy to electrical energy using electromagnetic induction. The key components of a DC generator are identified as the yoke, rotor, stator, field electromagnets, armature, commutator, and brushes. Equations for calculating the generated electromotive force (EMF) are also provided. Finally, common applications of DC generators are listed, such as using separately excited generators for speed control and self-excited shunt generators for battery charging.
The document discusses direct current (DC) generators, including:
1. DC generators operate by converting mechanical energy to electrical energy as conductors move through a magnetic field, inducing an electromotive force (EMF) based on Faraday's law of induction.
2. The construction of DC generators includes a yoke, rotor, stator, field electromagnets, pole cores, brushes, shaft, armature coils, commutator, and bearings. The commutator is needed to produce steady DC output from the pulsating current induced in the armature coils.
3. There are different types of DC generators including separately excited, self-excited (shunt-wound,
The document provides an outline and introduction to DC machines. It discusses the construction and basic parts of DC machines including the stator and rotor. It explains the principle of operation for both DC generators and DC motors. It discusses armature reaction, commutation, and characteristics of DC motors. It also covers the equivalent circuits of DC generators and motors and provides examples of calculating speed and induced emf in DC machines operating as generators and motors.
This document provides an overview of DC machines, including their construction, principles of operation, and characteristics. It discusses DC machines functioning as generators and motors. Key points include:
- DC machines can operate as generators, converting mechanical energy to electrical energy, or motors, converting electrical energy to mechanical energy.
- The main components are the stator (stationary part) and rotor (rotating part).
- In generator operation, relative motion between the magnetic field and armature windings induces an electromotive force (emf) based on Faraday's law of induction.
- In motor operation, current passing through the armature windings in a magnetic field experiences an electromagnetic force based on the left-hand
- DC generators and motors operate using the principle of electromagnetic induction. When a conductor moves through a magnetic field, an electromotive force (emf) is induced in the conductor.
- The basic components of a DC generator are a magnetic field (produced by poles and field windings) and a conductor (armature) that rotates within the magnetic field. This motion induces an emf in the armature.
- A commutator is used to convert the alternating current from the armature into direct current that can be supplied to a load. Brushes make contact with the commutator segments to carry the output current.
DC generators convert mechanical energy to electrical energy using electromagnetic induction. They have a stationary part that produces a magnetic field and a rotating part called the armature. As the armature rotates in the magnetic field, a current is induced based on Faraday's law of induction. The commutator ensures the current flows in one direction to the load. The main parts are the magnetic frame, field coils, armature core and windings, commutator and brushes. The types of DC generators are separately excited, shunt, series and compound wound which differ in how the field and armature windings are connected. They have various applications including battery charging, motor operation, and power distribution.
The document provides details about the syllabus of an Electrical Machines course. It covers 5 units:
1) Construction and operation of DC machines including generators and motors.
2) Performance characteristics of DC machines like torque equations and efficiency.
3) Starting, speed control and testing methods for DC machines.
4) Construction, operation and testing of single phase transformers.
5) Three phase transformer connections and testing.
The summary covers the main topics covered in each unit at a high level.
1) A DC generator produces direct current through electromagnetic induction. When a conductor moves through a magnetic field, an electromotive force (EMF) is induced in the conductor.
2) The basic components of a DC generator are magnetic poles and conductors that rotate within the magnetic field.
3) In a single loop DC generator, an EMF is induced in the sides of a rotating rectangular conductor loop as it cuts through the magnetic flux lines. The loop is connected to brushes to output a direct current.
The document discusses direct current (DC) generators, including their construction, operation, and applications. It describes how a DC generator works by converting mechanical energy to electrical energy using electromagnetic induction. The key components of a DC generator are identified as the yoke, rotor, stator, field electromagnets, armature, commutator, and brushes. Equations for calculating the generated electromotive force (EMF) are also provided. Finally, common applications of DC generators are listed, such as using separately excited generators for speed control and self-excited shunt generators for battery charging.
The document discusses direct current (DC) generators, including:
1. DC generators operate by converting mechanical energy to electrical energy as conductors move through a magnetic field, inducing an electromotive force (EMF) based on Faraday's law of induction.
2. The construction of DC generators includes a yoke, rotor, stator, field electromagnets, pole cores, brushes, shaft, armature coils, commutator, and bearings. The commutator is needed to produce steady DC output from the pulsating current induced in the armature coils.
3. There are different types of DC generators including separately excited, self-excited (shunt-wound,
The document provides an outline and introduction to DC machines. It discusses the construction and basic parts of DC machines including the stator and rotor. It explains the principle of operation for both DC generators and DC motors. It discusses armature reaction, commutation, and characteristics of DC motors. It also covers the equivalent circuits of DC generators and motors and provides examples of calculating speed and induced emf in DC machines operating as generators and motors.
This document provides an overview of DC machines, including their construction, principles of operation, and characteristics. It discusses DC machines functioning as generators and motors. Key points include:
- DC machines can operate as generators, converting mechanical energy to electrical energy, or motors, converting electrical energy to mechanical energy.
- The main components are the stator (stationary part) and rotor (rotating part).
- In generator operation, relative motion between the magnetic field and armature windings induces an electromotive force (emf) based on Faraday's law of induction.
- In motor operation, current passing through the armature windings in a magnetic field experiences an electromagnetic force based on the left-hand
- A DC motor converts electrical energy into mechanical energy through electromagnetic principles. It has a rotor that rotates when current passes through the motor's armature winding within a magnetic field.
- The key components of a DC motor are the armature winding, field winding, commutator, and brushes. The field winding generates a magnetic field and the armature winding cuts this field to produce torque when powered.
- DC motors can be shunt wound, series wound, or compound wound depending on how the field winding is connected in relation to the armature winding. This determines the speed and torque characteristics of the motor.
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
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
It the ppt on Dc machines. Dc machines is. A very good ppt. You can learn more about dc machines. Dc machines are important for science dc are machines are also important for science The DC machine can be classified into two types namely DC motors as well as DC generators. Most of the DC machines are equivalent to AC machines because they include AC currents as well as AC voltages in them. The output of the DC machine is DC output because they convert AC voltage to DC voltage. The conversion of this mechanism is known as the commutator, thus these machines are also named as commutating machines. DC machine is most frequently used for a motor. The main benefits of this machine include torque regulation as well as easy speed. The applications of the DC machine is limited to trains, mills, and mines. For example, underground subway cars, as well as trolleys, may utilize DC motors. In the past, automobiles were designed with DC dynamos for charging their batteries.
What is a DC Machine?
A DC machine is an electromechanical energy alteration device. The working principle of a DC machine is when electric current flows through a coil within a magnetic field, and then the magnetic force generates a torque that rotates the dc motor. The DC machines are classified into two types such as DC generator as well as DC motor.
DC Machine
DC Machine
The main function of the DC generator is to convert mechanical power to DC electrical power, whereas a DC motor converts DC power to mechanical power. The AC motor is frequently used in industrial applications for altering electrical energy to mechanical energy. However, a DC motor is applicable where good speed regulation & an ample range of speeds are necessary like in electric-transaction systems.
Construction of DC Machine
The construction of the DC machine can be done using some of the essential parts like Yoke, Pole core & pole shoes, Pole coil & field coil, Armature core, Armature winding otherwise conductor, commutator, brushes & bearings. Some of the parts of the DC machine is discussed below.
Construction of DC Machine
Construction of DC Machine
Yoke
Another name of a yoke is the frame. The main function of the yoke in the machine is to offer mechanical support intended for poles and protects the entire machine from moisture, dust, etc. The materials used in the yoke are designed with cast iron, cast steel otherwise rolled steel.
Pole and Pole Core
The pole of the DC machine is an electromagnet and the field winding is winding among pole. Whenever field winding is energized then the pole gives magnetic flux. The materials used for this are cast steel, cast iron otherwise pole core. It can be built with the annealed steel laminations for reducing the power drop because of the eddy currents.
PCBWay
Pole Shoe
Pole shoe in the DC machine is an extensive part as well as to enlarge the region of the pole. Because of this region, flux can be spread out within the air-gap as well as extra flux can be passed
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
The document discusses direct current (DC) machines and their operation. It provides details on:
1) The basic components and construction of a DC machine including its armature winding, commutator, and field poles.
2) How an alternating current induced in the armature coils is converted to direct current via the commutator and brush assembly.
3) Different types of armature windings including lap and wave windings.
4) Factors that affect the performance of DC machines such as armature reaction and how it can be mitigated through techniques like using interpoles.
5) Equations for calculating the generated electromotive force (EMF) in a DC generator.
BEE - DC Machines basic of electronic and electrical enginnerringkavi7010764469
The document discusses the construction and working principles of DC machines. It describes how DC machines can operate as either generators or motors. As a generator, a DC machine converts mechanical energy into electrical energy via electromagnetic induction. As a motor, it converts electrical energy into mechanical torque by applying a current-carrying conductor in a magnetic field. The key components of a DC machine include an armature, commutator, field coils, and poles which allow it to generate or be driven by a DC current based on Faraday's law of induction.
- Electromagnetic induction is the process of generating current through a wire in a changing magnetic field. When a wire moves perpendicular to a magnetic field, charges in the wire move and create an induced electromotive force (EMF).
- Transformers use electromagnetic induction to increase or decrease alternating current voltages. They have primary and secondary coils wound around an iron core. The ratio of turns determines the ratio of voltages.
- Lenz's law states that the direction of the induced current is such that the magnetic field it creates opposes the original change in magnetic flux that caused it. This induced magnetic field allows transformers, motors, and generators to function.
1) A transformer is a static electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. It works on the principle that a changing magnetic field in one coil induces a voltage in a nearby coil.
2) A DC machine can operate as a motor or generator. As a motor, it converts electrical energy into mechanical energy. As a generator, it converts mechanical energy into electrical energy.
3) The key components of a DC machine are the stator, rotor, commutator, and brushes. The stator contains field windings that generate a magnetic field. The rotor contains armature windings. The commutator and brushes convert alternating current from the rotor into direct current.
DC machines can operate as motors or generators. They have a commutator that converts the internal alternating current to direct current at the terminals. This allows for easy speed and torque control of DC motors. While DC is no longer widely used by consumers, DC machines were commonly used in industry and transportation due to their versatility and controllability. Advances in solid-state AC drive systems have replaced DC machines in many applications. However, DC machines remain useful due to their simple drive systems and versatility in operating characteristics.
DC machines can operate as motors or generators. They have a commutator that converts the internal alternating current to direct current at the terminals. This allows for easy speed and torque control of DC motors. While DC is no longer widely used by consumers, DC machines were commonly used in industry and transportation due to their versatility and controllability. Advances in solid-state AC drive systems have replaced DC machines in many applications.
Slides of DC Machines with detailed explanationOmer292805
This document provides an overview of DC machines, including DC motors and generators. It discusses the basic components and principles of operation for DC machines. Some key points:
- DC machines convert mechanical energy to electrical energy (generators) or vice versa (motors). They are commonly used to drive industrial loads.
- The main parts are the stator, rotor/armature, commutator, and brushes. The commutator converts the AC voltage in the rotor to DC.
- DC motors operate by applying a DC current to the armature in a magnetic field, producing a torque via the Lorentz force. Speed and torque can be regulated by controlling field and armature circuits.
-
The document discusses the working principle and construction of a DC generator. It describes how a DC generator works by cutting magnetic flux with a conductor to induce an EMF. It explains the key components of a generator including the magnetic field, conductor/armature, and motion of the armature with respect to the magnetic field. The document also provides details on the construction of DC generators, including the field system, armature core, armature winding, commutator, and brushes. It discusses how the commutator and brushes are used to produce a steady DC voltage from the pulsating voltage induced in the armature coils.
The document outlines the course content for EECE-259, which covers electrical and electronics technology. The course covers principles and characteristics of DC generators, DC motors, AC generators/alternators, induction motors, synchronous motors, and transformers. It also discusses losses in generators and motor characteristics. Key references on electrical machinery fundamentals and AC/DC machines are provided.
This document provides information about direct current (DC) motors, including:
- The three main types of DC motors: shunt wound, series wound, and separately excited.
- How to calculate torque-speed characteristics for each type.
- The construction, principle of operation, induced electromotive force (emf), torque, and terminal voltage of DC motors.
- How shunt wound, series wound, and separately excited motors differ in their field and armature windings connections.
- Formulas for calculating speed, torque, induced emf, and armature current as a function of motor parameters like resistance, flux, and supply voltage.
1. The document discusses the syllabus and basics of synchronous generators or alternators.
2. Synchronous generators convert mechanical power into electrical power through electromagnetic induction. They are used as the primary source of electrical energy in large power grids.
3. The basic parts are the rotor with field windings, and the stator with 3-phase armature windings. The frequency of the induced EMF depends on the rotor speed and number of poles.
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).
1. A DC machine can operate as either a generator or motor. It converts mechanical power to electrical power as a generator and converts electrical power to mechanical power as a motor.
2. The main components of a DC machine are the stator, rotor, field windings, armature windings, commutator, and brushes. The field windings produce flux and the armature windings, which rotate, cut this flux to generate voltage or consume current depending on if it is operating as a generator or motor.
3. Armature reaction causes the magnetic neutral axis to shift from its ideal position, requiring careful brush placement. Commutation is the process that converts the alternating currents induced in the armature to
DC Machines can be either generators or motors. A DC generator converts mechanical power into electrical power, while a DC motor converts electrical power into mechanical power. Both have similar constructions with a stator and rotor separated by an air gap. The rotor contains field windings to produce a magnetic field, while the stator contains armature windings. A commutator and brushes allow current to flow in one direction from the armature to an external circuit. The direction of current induced in the armature windings changes as it rotates, but the commutator switches the connections to maintain unidirectional current output.
William Sydney Porter, better known by his pen name O. Henry, was an American writer known for his short stories. The story "The Cop and the Anthem" follows a homeless man named Soapy who wants to get arrested and sent to jail for the winter. Soapy tries various methods to get arrested like loitering, stealing, and causing disturbances but fails each time. Frustrated by his failed plans, Soapy decides to make an honest life for himself instead of continuing to try to get arrested.
This document provides an overview of high speed packet-switching networks and frame relay networks. It discusses the basics of packet-switching technology, including datagram and virtual circuit approaches. Frame relay networks are described as being designed to eliminate much of the overhead of X.25 networks by separating call control signaling from user data transfer and implementing multiplexing at layer 2. Key aspects of frame relay like virtual connections, architecture, and call control messaging are summarized.
- A DC motor converts electrical energy into mechanical energy through electromagnetic principles. It has a rotor that rotates when current passes through the motor's armature winding within a magnetic field.
- The key components of a DC motor are the armature winding, field winding, commutator, and brushes. The field winding generates a magnetic field and the armature winding cuts this field to produce torque when powered.
- DC motors can be shunt wound, series wound, or compound wound depending on how the field winding is connected in relation to the armature winding. This determines the speed and torque characteristics of the motor.
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
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
It the ppt on Dc machines. Dc machines is. A very good ppt. You can learn more about dc machines. Dc machines are important for science dc are machines are also important for science The DC machine can be classified into two types namely DC motors as well as DC generators. Most of the DC machines are equivalent to AC machines because they include AC currents as well as AC voltages in them. The output of the DC machine is DC output because they convert AC voltage to DC voltage. The conversion of this mechanism is known as the commutator, thus these machines are also named as commutating machines. DC machine is most frequently used for a motor. The main benefits of this machine include torque regulation as well as easy speed. The applications of the DC machine is limited to trains, mills, and mines. For example, underground subway cars, as well as trolleys, may utilize DC motors. In the past, automobiles were designed with DC dynamos for charging their batteries.
What is a DC Machine?
A DC machine is an electromechanical energy alteration device. The working principle of a DC machine is when electric current flows through a coil within a magnetic field, and then the magnetic force generates a torque that rotates the dc motor. The DC machines are classified into two types such as DC generator as well as DC motor.
DC Machine
DC Machine
The main function of the DC generator is to convert mechanical power to DC electrical power, whereas a DC motor converts DC power to mechanical power. The AC motor is frequently used in industrial applications for altering electrical energy to mechanical energy. However, a DC motor is applicable where good speed regulation & an ample range of speeds are necessary like in electric-transaction systems.
Construction of DC Machine
The construction of the DC machine can be done using some of the essential parts like Yoke, Pole core & pole shoes, Pole coil & field coil, Armature core, Armature winding otherwise conductor, commutator, brushes & bearings. Some of the parts of the DC machine is discussed below.
Construction of DC Machine
Construction of DC Machine
Yoke
Another name of a yoke is the frame. The main function of the yoke in the machine is to offer mechanical support intended for poles and protects the entire machine from moisture, dust, etc. The materials used in the yoke are designed with cast iron, cast steel otherwise rolled steel.
Pole and Pole Core
The pole of the DC machine is an electromagnet and the field winding is winding among pole. Whenever field winding is energized then the pole gives magnetic flux. The materials used for this are cast steel, cast iron otherwise pole core. It can be built with the annealed steel laminations for reducing the power drop because of the eddy currents.
PCBWay
Pole Shoe
Pole shoe in the DC machine is an extensive part as well as to enlarge the region of the pole. Because of this region, flux can be spread out within the air-gap as well as extra flux can be passed
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
The document discusses direct current (DC) machines and their operation. It provides details on:
1) The basic components and construction of a DC machine including its armature winding, commutator, and field poles.
2) How an alternating current induced in the armature coils is converted to direct current via the commutator and brush assembly.
3) Different types of armature windings including lap and wave windings.
4) Factors that affect the performance of DC machines such as armature reaction and how it can be mitigated through techniques like using interpoles.
5) Equations for calculating the generated electromotive force (EMF) in a DC generator.
BEE - DC Machines basic of electronic and electrical enginnerringkavi7010764469
The document discusses the construction and working principles of DC machines. It describes how DC machines can operate as either generators or motors. As a generator, a DC machine converts mechanical energy into electrical energy via electromagnetic induction. As a motor, it converts electrical energy into mechanical torque by applying a current-carrying conductor in a magnetic field. The key components of a DC machine include an armature, commutator, field coils, and poles which allow it to generate or be driven by a DC current based on Faraday's law of induction.
- Electromagnetic induction is the process of generating current through a wire in a changing magnetic field. When a wire moves perpendicular to a magnetic field, charges in the wire move and create an induced electromotive force (EMF).
- Transformers use electromagnetic induction to increase or decrease alternating current voltages. They have primary and secondary coils wound around an iron core. The ratio of turns determines the ratio of voltages.
- Lenz's law states that the direction of the induced current is such that the magnetic field it creates opposes the original change in magnetic flux that caused it. This induced magnetic field allows transformers, motors, and generators to function.
1) A transformer is a static electrical device that transfers electrical energy between two or more circuits through electromagnetic induction. It works on the principle that a changing magnetic field in one coil induces a voltage in a nearby coil.
2) A DC machine can operate as a motor or generator. As a motor, it converts electrical energy into mechanical energy. As a generator, it converts mechanical energy into electrical energy.
3) The key components of a DC machine are the stator, rotor, commutator, and brushes. The stator contains field windings that generate a magnetic field. The rotor contains armature windings. The commutator and brushes convert alternating current from the rotor into direct current.
DC machines can operate as motors or generators. They have a commutator that converts the internal alternating current to direct current at the terminals. This allows for easy speed and torque control of DC motors. While DC is no longer widely used by consumers, DC machines were commonly used in industry and transportation due to their versatility and controllability. Advances in solid-state AC drive systems have replaced DC machines in many applications. However, DC machines remain useful due to their simple drive systems and versatility in operating characteristics.
DC machines can operate as motors or generators. They have a commutator that converts the internal alternating current to direct current at the terminals. This allows for easy speed and torque control of DC motors. While DC is no longer widely used by consumers, DC machines were commonly used in industry and transportation due to their versatility and controllability. Advances in solid-state AC drive systems have replaced DC machines in many applications.
Slides of DC Machines with detailed explanationOmer292805
This document provides an overview of DC machines, including DC motors and generators. It discusses the basic components and principles of operation for DC machines. Some key points:
- DC machines convert mechanical energy to electrical energy (generators) or vice versa (motors). They are commonly used to drive industrial loads.
- The main parts are the stator, rotor/armature, commutator, and brushes. The commutator converts the AC voltage in the rotor to DC.
- DC motors operate by applying a DC current to the armature in a magnetic field, producing a torque via the Lorentz force. Speed and torque can be regulated by controlling field and armature circuits.
-
The document discusses the working principle and construction of a DC generator. It describes how a DC generator works by cutting magnetic flux with a conductor to induce an EMF. It explains the key components of a generator including the magnetic field, conductor/armature, and motion of the armature with respect to the magnetic field. The document also provides details on the construction of DC generators, including the field system, armature core, armature winding, commutator, and brushes. It discusses how the commutator and brushes are used to produce a steady DC voltage from the pulsating voltage induced in the armature coils.
The document outlines the course content for EECE-259, which covers electrical and electronics technology. The course covers principles and characteristics of DC generators, DC motors, AC generators/alternators, induction motors, synchronous motors, and transformers. It also discusses losses in generators and motor characteristics. Key references on electrical machinery fundamentals and AC/DC machines are provided.
This document provides information about direct current (DC) motors, including:
- The three main types of DC motors: shunt wound, series wound, and separately excited.
- How to calculate torque-speed characteristics for each type.
- The construction, principle of operation, induced electromotive force (emf), torque, and terminal voltage of DC motors.
- How shunt wound, series wound, and separately excited motors differ in their field and armature windings connections.
- Formulas for calculating speed, torque, induced emf, and armature current as a function of motor parameters like resistance, flux, and supply voltage.
1. The document discusses the syllabus and basics of synchronous generators or alternators.
2. Synchronous generators convert mechanical power into electrical power through electromagnetic induction. They are used as the primary source of electrical energy in large power grids.
3. The basic parts are the rotor with field windings, and the stator with 3-phase armature windings. The frequency of the induced EMF depends on the rotor speed and number of poles.
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).
1. A DC machine can operate as either a generator or motor. It converts mechanical power to electrical power as a generator and converts electrical power to mechanical power as a motor.
2. The main components of a DC machine are the stator, rotor, field windings, armature windings, commutator, and brushes. The field windings produce flux and the armature windings, which rotate, cut this flux to generate voltage or consume current depending on if it is operating as a generator or motor.
3. Armature reaction causes the magnetic neutral axis to shift from its ideal position, requiring careful brush placement. Commutation is the process that converts the alternating currents induced in the armature to
DC Machines can be either generators or motors. A DC generator converts mechanical power into electrical power, while a DC motor converts electrical power into mechanical power. Both have similar constructions with a stator and rotor separated by an air gap. The rotor contains field windings to produce a magnetic field, while the stator contains armature windings. A commutator and brushes allow current to flow in one direction from the armature to an external circuit. The direction of current induced in the armature windings changes as it rotates, but the commutator switches the connections to maintain unidirectional current output.
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C(s)/R(s) = 4/(s^2 + 2s + 4)
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1. EVEN SEMESTER
2017-2018
P. MARIA SHEEBA
ASSISTANT PROFESSOR /ECE
MOUNT ZION COLLEGE OF ENGINEERING AND TECHNOLOGY
PUDUKKOTTAI
1
BE8254- BASIC ELECTRICAL AND INSTRUMENTATION
ENGINEERING
2. m
d d dx
Blx Bl
dt dt dt
dx
Blv Bl
dt
E
m
Therefore,
d
dt
E
CONCLUSION: to produce emf one should make ANY
change in a magnetic flux with time!
Faraday’s Law
2
3. Changing magnetic flux produces an emf (or changing B-
Field produces E-Field)
The rate of change of magnetic flux is required
Faraday’s Law
3
4. The direction of the emf
induced by changing flux
will produce a current
that generates a
magnetic field opposing
the flux change that
produced it.
Lenz’s Law
4
5. Lenz’s Law: emf appears and current flows that creates a magnetic field that
opposes the change – in this case an decrease – hence the negative sign in
Faraday’s Law.
B, H
N S
V+, V-
Lenz’s Law
5
6. Lenz’s Law: emf appears and current flows that creates a
magnetic field that opposes the change – in this case an
increase – hence the negative sign in Faraday’s Law.
B, H
N S
V-, V+
Lenz’s Law
6
9. Claim: Direction of induced current must be so as to
oppose the change; otherwise conservation of
energy would be violated.
• Why???
– If current reinforced the change, then the
change would get bigger and that would in
turn induce a larger current which would
increase the change, etc..
– No perpetual motion machine!
Conclusion: Lenz’s law results from energy
conservation principle.
Lenz’s Law
9
10. Induced Current – quantitative
Suppose we pull with velocity
v a coil of resistance R through
a region of constant magnetic
field
v
w
x
x x x x x x
x x x x x x
x x x x x x
x x x x x x
We must supply energy to produce the current
and to move the loop (until it is completely out of
the B-field region). The work we do is exactly
equal to the energy dissipated in the resistor, i.e.
W=I2Rt 10
17. • Balanced phase voltages are equal in magnitude and are out of phase
with one another by 120 degrees.
• Phase voltages sum up to zero.
• Two possible combinations:
abc or (+) sequence acb or () sequence
Three phase circuits
17
18. Y-connected Load D-connected Load
A balanced load is one in which the phase impedances are equal
in magnitude and in phase.
Three phase circuits
18
19. Construction of DC machines
An electrical machine deals with the energy transfer either
from mechanical to electrical or electrical to mechanical
form. This process is called electromechanically energy
conversion. The device which is used for electromechanical
energy conversion is known as machine.
Machine
Generator - mechanical to
electrical
Motor- electrical to
mechanical
19
20. Construction of DC machines
• The machine is DC generator or motor the
constructions are remain same.
• The main parts of de machine are:-
Yoke
Pole
Field winding
Armature
Commutator
Brushes
20
23. Yoke
• Functions :-
It serves the purpose of outermost cover
of D.C. machine.
It provide mechanical support to the pole.
It provide low reluctance path.
23
24. Yoke
Choice of material:-
To provide low reluctance path, it must be
made up of some magnetic material.
It is prepared by cost iron because it is
cheapest.
For large machine rolled steel, cast steel,
silicon steel is used.
24
26. Functions :-
Poles
Choices of material:-
Cost iron.
Pole core basically carries a field
winding.
It directs the flux.
Pole shoe enlarge the area of armature
core to come across the flux.
26
27. • The field winding is wound on the pole core
with a definite direction.
Functions:-
• To carry the current due to pole core, on
which the field winding is placed.
Choice of material:-
• It has carry the current hence its made up of
copper.
Field Winding
27
28. It is further divided in to two parts namely,
1. Armature core
2. Armature winding.
Armature core :
Armature core is cylindrical in shape.
It consists of slots on its periphery.
It has air ducts to permit the air flow through
armature for cooling purpose.
Armature
28
29. Functions:
• Armature core provides house for armature
winding.
Choice of material:
• Cost iron or cost steel.
Armature core
29
30. Functions:
Generation of EMF take place in the armature
winding in case of generator.
To carry the current supply in case of d.c.
motors.
Choice of material:
Copper.
Armature winding
30
32. Brushes
Bearings are stationary and resting on the surface of
the commutator.
Functions:
To collect the current from commutator.
Choice of material:
Carbon.
32
33. Bearing
• Bearing :-
For heavy duty machines roller bearings are
preferred.
• Types of armature winding:-
Lap winding Wave winding
33
34. Mechanical energy is converted to electrical
energy
Three requirements are essential
1. Conductors
2. Magnetic field
3. Mechanical energy
DC Generator
34
35. All generators work on a principle of dynamically induced
EMF, this is also known as Faraday’s law of
electromagnetic induction.
• Whenever the number of flux linked with the coil
changes , an electromotive force is set up in that coil.
Generator action requires following basic components.
The conductor
The flux
The relative motion between conductor and flux.
Theory operation of DC generators
35
36. • Fleming’s right hand rule is also known as
generator rule.
Fleming’s right hand rule
36
42. • In Separately Exited Generator, a separate d.c
supply is used to provide exciting current
through the field winding.
• The d.c generator produces d.c voltage. If this
generated voltage itself is used to excite the
field winding of same d.c generator, it is called
Self Excited Generator.
42
45. Self exited generator
Based on how field winding is connected to the
armature to derive its excitation, this is further
divided in to following three types:
1. Shunt generator.
2. Series generator.
3. Compound generator.
45
46. Shunt Generator
When the field winding is
connected in parallel with
the armature and the
combination across the
load then the generator is
called shunt generator.
46
48. Series generator
• When the field winding
is connected in series
with the armature and
the combination across
the load then the
generator is called
series generator.
48
50. A 250 V, 10 kW, separately exited generator has
an induced e.m.f. of 250 V at full load. If the
brush drop is 2 V per brush, calculate the
armature resistance of the generator.
Example 2
Solution
50
51. Note that 250 V, 10kW generator means the full
load capacity of generator is to supply 10 kW
load at a terminal voltage =250 V.
51
53. • A short shunt compound d.c. generator supplies a current of 75 A at a
voltage of 225 Calculate the generated voltage if the resistance of
armature, shunt field and series field windings are 0.04 ohms , 0.90 ohms
and 0.02 ohms respectively.
Example 3
Solution
Consider a short shunt generator
53
60. Now there are two fluxes present,
1. The flux produced by the permanent magnet
called main flux.
2. The flux produced by the current current
carrying conductor.
60
63. • In the practical d.c. motor
the permanent magnet is
replaced by a field
winding which produces
the required flux called
main flux and all the
armature conductors,
mounted on the
periphery of the armature
drum, get subjected to
the mechanical force.
• Due to this , overall
armature experiences a
twisting, force called
torque and armature of
the motor starts rotating.
63
64. Direction of rotation of motor
• The magnitude of the force experienced by the
conductor in a motor is given by,
B= flux density.
L= length of conductor.
I= Magnitude of current.
64
65. • In the figure it is shown
that, a portion of a
conductor of length L
placed vertically in a
uniform horizontal
magnetic field strength
H, produced by two
magnetic poles N and S.
If i is the current flowing
through this conductor,
Fleming Left Hand Rule
65
68. There are 2 types of winding
- Lap and Wave winding
Lap winding
A = P
The armature windings are divided into
no. of sections equal to the no of poles
Wave winding
A = 2
It is used in low current output and high
voltage.
2 brushes
Armature windings DC motors
68
69. • It is seen in the generating action, that when a conductor cuts
the lines of flux, e.m.f. gets induced in the conductor. After a
motering action, armature starts rotating and armature
conductors cut the main flux. So there is a generation action
existing In a motor, the e.m.f induced due to generating action
is known as back e.m.f
Back EMF
69
72. • A 220 V, d.c. motor has an armature resistance of 0.75 ohms.
It is drawing an armature current of 30 A, driving a certain
load. Calculate the induced e.m.f. in the motor under this
condition.
Example 4
Solution
72
73. Power equation of DC motor
• The voltage equation is;
• Multiplying by Ia
• The above equation is called power equation of DC motor
73
76. • N= speed, then angular
speed is
• Work done in one
revolution is
• W= F * distance traveled in
one revelation
• W= F * 2 𝜋R
Torque Equation of DC Motor
76
79. • DC shunt motor
• DC series motor
• DC compound motor
Types of DC Motor
79
80. Shunt Motor
• The parallel
combination of two
windings is connected
across a common dc
power supply.
• The resistance of shunt
field winding is always
higher than the
armature winding.
80
82. Series Motor
• The field winding is
connected in series with
the armature.
• The current passing
through the series
winding is same as the
armature current.
82
85. Long Shunt compound motor
• In this the series
winding in series with
the armature winding
and the shunt winding
is connected in parallel
with the armature
connection.
85
86. Short Shunt compound motor
• In this the series
winding is series with
the parallel
combination of
armature winding and
the shunt winding.
• It has good starting
torque and constant
speed characteristic.
86
87. Cumulative compound DC motors
• If the two field windings i.e. series and shunt
are wounded in such a way that the fluxes
produced by them add each other.
Differential compound DC motors
• If the two field windings i.e. series and shunt
are wounded in such a way that the fluxes
produced by them airways try to cancel each
other.
87
95. • The speed regulation for a d.c. motor is
defined as the ratio of change in speed
corresponding to no load and full load
condition to speed corresponding to full load.
Speed Regulation
95
97. DC Shunt Motor Characteristics
Torque (vs) armature current characteristics
97
98. • From the speed equation we get,
• When the load increases the
armature current increases and
hence drop IR also increases.
DC Shunt Motor Characteristics
Speed – Armature current characteristics
98
99. • This curve shows that
the speed remains
constant when the
torque from no load to
full load.
DC Shunt Motor Characteristics
Speed – torque characteristics
99
102. DC Shunt Motor Characteristics
Speed – torque characteristics
102
103. DC Shunt Motor Characteristics
Speed – torque characteristics
103
104. • Flux Control Method
• Armature Control Method
• Voltage Control Method
Speed DC Motor
104
105. • It is seen that speed of the
motor is inversely
proportional to flux. Thus by
decreasing flux speed can
be increased and vice versa.
• To control the flux, a
rheostat is added in series
with the field winding, as
shown in the circuit
diagram. Adding more
resistance in series with
field winding will increase
the speed, as it will
decrease the flux.
Flux Control Method
105
106. • Field current is relatively
small and hence I2R loss is
small, hence this method is
quiet efficient.
• Though speed can be
increased by reducing flux
with this method, it puts a
limit to maximum speed as
weakening of flux beyond
the limit will adversely
affect the commutation.
Flux Control Method
106
107. • Speed of the motor is
directly proportional to the
back emf Eb and Eb = V-
IaRa.
• That is when supply voltage
V and armature resistance
Ra are kept constant, speed
is directly proportional to
armature current Ia.
• Thus if we add resistance in
series with armature,
Ia decreases and hence
speed decreases.
Armature Control Method
107
108. • A) Multiple voltage control:
• B) Ward-Leonard System
Multiple voltage control:
• In this method the, shunt filed is connected to a fixed exciting voltage, and
armature is supplied with different voltages.
• Voltage across armature is changed with the help of a suitable switchgear.
The speed is approximately proportional to the voltage across the
armature.
Voltage Control Method
108
109. This system is used where very sensitive speed control of motor is required
(e.g electric excavators, elevators etc.) The arrangement of this system is as
required in the figure beside.
Ward-Leonard System
M2 is the motor whose speed control is required.
M1 may be any AC motor or DC motor with constant speed.
G is the generator directly coupled to M1.
109
110. .
Ward-Leonard System
In this method the output from the generator G is fed to
the armature of the motor M2 whose speed is to be
controlled.
The output voltage of the generator G can be varied from
zero to its maximum value, and hence the armature voltage
of the motor M2 is varied very smoothly. Hence very
smooth speed control of motor can be obtained by this
method
110
111. Type of Motor Applications
shunt 1. Blowers
2. Fans
3. Lath machines
4. Drilling machines
series 1. Cranes
2. Trolleys
3. Conveyers
Cumulative compound 1. Rolling mills
2. elevators
Differential compound Not suitable for any
practical applications
Applications of DC Motor
111
112. Type of Generator Applications
Separately exited
Generator
1. Electro plating
2. Electro refining
Shunt Generator 1. Battery charging
2. Ordinary lighting purpose
Series Generator 1. Welding
2. Arc lamp
Cumulative
compound Generator
1. Domestic lamp
Differential
compound Generator
1. Electric arc welding
Applications of Generator
112