This document provides an overview of DC machines, including DC motors and DC generators. It discusses:
- The basic components and construction of DC machines, including the stator, rotor, field winding, armature winding, commutator, and brushes.
- The fundamentals of how DC machines operate based on electromagnetic induction principles of generator and motor action.
- The equivalent circuits used to model DC machines, representing the armature and field circuits.
- Different types of DC motors like separately excited, shunt, series, and compound motors.
- Factors that determine the speed of DC motors like armature voltage, current, and magnetic flux.
- Examples calculating voltages,
DC Machines with explanation in detail of everythingOmer292805
A DC motor chapter is summarized in 3 sentences:
DC machines can operate as motors or generators and include DC motors which use a DC power source and have a stationary field coil and rotating armature. The speed of a DC motor is proportional to its back EMF and inversely proportional to the armature current. Examples show how to calculate the speed of DC motors under different load conditions by determining the back EMF using the motor's equivalent circuit.
- DC machines can operate as either generators or motors. A generator produces voltage when its coil rotates through a magnetic field, while a motor produces torque on its coil when current passes through it in a magnetic field.
- The simplest DC machine is a single loop of wire rotating through magnetic poles. Induced voltage and torque depend on flux, speed/current, and construction constants.
- Real DC machines use commutators and brushes to produce DC output from the AC voltage induced in the rotor coils. Problems during commutation like sparking are reduced by techniques like interpoles.
- The internal voltage and torque equations account for flux, speed/current, and construction constants. Power losses include copper, brush,
1) DC machines operate based on the principles that voltage is induced in a conductor moving through a magnetic field (generator action) and a force is induced on a conductor with current in a magnetic field (motor action).
2) The simplest DC machine is a single loop of wire rotating through magnetic poles, which induces a voltage that can be extracted using a commutator and brushes.
3) Real DC machines have more complex windings and commutation systems to produce a DC output and overcome issues like armature reaction.
4) The main types of DC generators - separately excited, shunt, and series - have different characteristics based on how their fields are connected that determine how voltage and current vary with load
A DC motor converts electrical energy into mechanical energy by using the interaction between a current-carrying conductor and a magnetic field. There are different types of DC motors including permanent magnet, shunt wound, series wound, and compound wound motors. The speed of a DC motor depends on the back emf generated, which is proportional to the flux and rotational speed. The torque depends on the current and flux. DC motors have characteristic curves showing the relationships between torque and current, speed and current, and speed and torque.
DC motors have excellent speed and torque control characteristics and are often used to drive pumps and in transportation applications. A DC motor operates on the principle that a current-carrying conductor in a magnetic field experiences a force. It consists of a rotor that spins inside a stator. DC motors convert electrical energy into mechanical energy. The types of DC motors include shunt-wound, series-wound, and compound-wound motors, which have different characteristics related to torque, speed, and efficiency. The speed and direction of a DC motor can be controlled by varying the current in the field windings or armature. Losses include copper, iron, friction, and brush contact losses.
Torque produced by a DC motor is proportional to the product of current in the armature winding (Ia) and the magnetic field flux (Φ).
The flux is produced by the current in the field winding (If).
Therefore, Torque (T) ∝ Ia × If
For different types of DC motors, the field current If is related differently to the armature current Ia.
2. Derive the Speed equation for a DC Motor.
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.
This document provides information about direct current (DC) motors, including:
- The three main types of DC motors: shunt wound, series wound, and separately excited and their characteristics.
- The principles of operation, construction, and torque-speed characteristics of DC motors.
- How to calculate torque, speed, induced emf, and other parameters for DC motors.
- Applications of the different DC motor types.
- Circuit diagrams and equations for analyzing DC motor performance.
DC Machines with explanation in detail of everythingOmer292805
A DC motor chapter is summarized in 3 sentences:
DC machines can operate as motors or generators and include DC motors which use a DC power source and have a stationary field coil and rotating armature. The speed of a DC motor is proportional to its back EMF and inversely proportional to the armature current. Examples show how to calculate the speed of DC motors under different load conditions by determining the back EMF using the motor's equivalent circuit.
- DC machines can operate as either generators or motors. A generator produces voltage when its coil rotates through a magnetic field, while a motor produces torque on its coil when current passes through it in a magnetic field.
- The simplest DC machine is a single loop of wire rotating through magnetic poles. Induced voltage and torque depend on flux, speed/current, and construction constants.
- Real DC machines use commutators and brushes to produce DC output from the AC voltage induced in the rotor coils. Problems during commutation like sparking are reduced by techniques like interpoles.
- The internal voltage and torque equations account for flux, speed/current, and construction constants. Power losses include copper, brush,
1) DC machines operate based on the principles that voltage is induced in a conductor moving through a magnetic field (generator action) and a force is induced on a conductor with current in a magnetic field (motor action).
2) The simplest DC machine is a single loop of wire rotating through magnetic poles, which induces a voltage that can be extracted using a commutator and brushes.
3) Real DC machines have more complex windings and commutation systems to produce a DC output and overcome issues like armature reaction.
4) The main types of DC generators - separately excited, shunt, and series - have different characteristics based on how their fields are connected that determine how voltage and current vary with load
A DC motor converts electrical energy into mechanical energy by using the interaction between a current-carrying conductor and a magnetic field. There are different types of DC motors including permanent magnet, shunt wound, series wound, and compound wound motors. The speed of a DC motor depends on the back emf generated, which is proportional to the flux and rotational speed. The torque depends on the current and flux. DC motors have characteristic curves showing the relationships between torque and current, speed and current, and speed and torque.
DC motors have excellent speed and torque control characteristics and are often used to drive pumps and in transportation applications. A DC motor operates on the principle that a current-carrying conductor in a magnetic field experiences a force. It consists of a rotor that spins inside a stator. DC motors convert electrical energy into mechanical energy. The types of DC motors include shunt-wound, series-wound, and compound-wound motors, which have different characteristics related to torque, speed, and efficiency. The speed and direction of a DC motor can be controlled by varying the current in the field windings or armature. Losses include copper, iron, friction, and brush contact losses.
Torque produced by a DC motor is proportional to the product of current in the armature winding (Ia) and the magnetic field flux (Φ).
The flux is produced by the current in the field winding (If).
Therefore, Torque (T) ∝ Ia × If
For different types of DC motors, the field current If is related differently to the armature current Ia.
2. Derive the Speed equation for a DC Motor.
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.
This document provides information about direct current (DC) motors, including:
- The three main types of DC motors: shunt wound, series wound, and separately excited and their characteristics.
- The principles of operation, construction, and torque-speed characteristics of DC motors.
- How to calculate torque, speed, induced emf, and other parameters for DC motors.
- Applications of the different DC motor types.
- Circuit diagrams and equations for analyzing DC motor performance.
This document discusses direct current (DC) electrical machines. It covers the equivalent circuit of a DC motor, the magnetization curve of a DC machine, and different types of DC motors including separately excited, shunt, permanent magnet, series, and compounded DC motors. The key characteristics and behaviors of shunt DC motors are analyzed through examples, including the effect of armature reaction and derivation of the torque-speed curve. Nonlinear analysis is also demonstrated for a shunt motor without compensating windings.
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, terminal voltage, and methods of connection for DC motors.
- How to analyze performance and calculate characteristics like torque, speed, current, and voltage for DC motors.
This document provides information about direct current (DC) motors, including:
- The three main types of DC motors: shunt wound, series wound, and separately excited and their characteristics.
- The principles of operation, construction, and torque-speed characteristics of DC motors.
- How to calculate torque, speed, induced emf, and other parameters for DC motors.
- Applications of the different DC motor types.
- Circuit diagrams and equations for analyzing DC motor performance.
This document provides information about direct current (DC) motors, including:
- The three main types of DC motors: shunt wound, series wound, and separately excited and their characteristics.
- The principles of operation, construction, and torque-speed characteristics of DC motors.
- How to calculate torque, speed, induced emf, and other parameters for DC motors.
- Applications of the different DC motor types.
- Circuit diagrams and equations for analyzing DC motor performance.
This document provides information about direct current (DC) motors, including:
- The three main types of DC motors: shunt wound, series wound, and separately excited and their characteristics.
- The principles of operation, construction, and torque-speed characteristics of DC motors.
- How to calculate torque, speed, induced emf, and other parameters for DC motors.
- Applications of the different DC motor types.
- Circuit diagrams and equations for analyzing DC motor performance.
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, terminal voltage, and methods of connection for DC motors.
- How to analyze performance and calculate characteristics like torque, speed, current, and voltage for DC motors.
1. A synchronous generator produces power by inducing a 3-phase voltage in its stator windings via a rotating magnetic field created by its rotor.
2. The rotor contains field windings that are supplied with DC current to produce the magnetic field.
3. When load is applied, armature reaction causes the induced voltage to differ from the output voltage based on the load power factor.
This document discusses direct current (DC) motors, including:
1) It introduces DC motors and explains their advantages over AC motors for certain applications.
2) It describes the basic working principle of DC motors, which involves a current-carrying conductor experiencing a force when placed in a magnetic field.
3) It discusses the different types of DC motors - shunt-wound, series-wound, and compound-wound - and explains their characteristics.
4) It provides equations for the voltage and power of DC motors and uses examples to demonstrate how to solve problems related to back EMF, speed, power input/output, and other motor parameters.
The document describes the key components and operation of an AC generator. It includes:
- The main components are the field, armature, prime mover, rotor, stator, and slip rings. The rotor and stator can each be the field or armature depending on the generator type.
- In operation, the prime mover rotates the rotor through the stationary field, inducing voltage in the armature windings. Slip rings allow a continuous connection to the rotating armature.
- Losses occur from internal resistance, hysteresis in the iron cores, and mechanical factors like bearing friction. Efficiency is the ratio of output to input power. Generators are rated by voltage, current, power
Synchronous machines include synchronous generators and motors. Synchronous generators are the primary source of electrical power and rely on synchronous motors for industrial drives. There are two main types - salient-pole and cylindrical rotor machines. Synchronous generator operation is based on synchronizing the electrical frequency to the mechanical speed of rotation. The parameters of synchronous machines can be determined from open-circuit, short-circuit, and DC tests. Synchronous generators must be synchronized before connecting in parallel by matching their voltages, phase sequences, and frequencies.
DC machines operate on the principles of electromagnetic induction and force. They have commutators, field windings, and armature windings. DC machines can operate as motors or generators depending on the direction of power flow. Speed in DC motors can be controlled through methods like armature voltage control, field control, and armature resistance control. DC generators have open-circuit, load, and external characteristics that define their performance based on variables like terminal voltage, field current, and load current. Efficiency is impacted by losses such as copper losses and mechanical losses.
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.
-
This document provides an overview of synchronous machines and synchronous condensers. It discusses key topics such as:
- The basic components and operating principles of synchronous machines and how they can function as motors or generators.
- Concepts like torque, power, energy and their relationships in synchronous machines.
- How synchronous machines synchronize to the frequency of the power system and their operating speed relationship.
- Power flow, internal and terminal voltages, and torque angle in synchronous machines.
- Losses that occur in synchronous machines and how efficiency is affected.
- The use of synchronous condensers to provide reactive power support through field excitation control while transferring little to no real power.
- Models for analyzing
This document provides an overview of basic electrical concepts including Ohm's Law, voltage, current, resistance, and power. It then discusses different types of drives including AC, DC, and servo drives. Key components of induction motors such as the rotor, stator, and magnetic flux are described. The document also covers Ohm's Law, AC and DC motor speed/torque characteristics, and elements of AC and DC drive systems including rectification, pulse width modulation, and IGBT switches. Application issues for AC drives such as line notching and switching noise are also summarized.
The document provides information about DC motors and generators, including:
1) It describes the main construction parts of DC motors/generators including the armature, stator, poles, field windings, and commutator.
2) It explains the characteristics of shunt, series, and compound wound DC motors/generators including their circuit diagrams and load/speed-torque curves.
3) It discusses starting methods for DC motors including the use of a starter resistance to limit starting current.
The document discusses the principles of operation of synchronous machines, which can operate as either motors or generators. It describes their construction, including salient pole and cylindrical rotors. It also covers single phase and three phase alternators, explaining how their windings produce phase-displaced voltages. Additional topics covered include open and short circuit characteristics, load conditions, equivalent circuits, and power flow calculations.
This document describes the principles of operation of a 3-phase alternator. It discusses how a synchronous generator works using Faraday's law of electromagnetic induction. It also describes the different components of a 3-phase alternator including the stator, rotor, and different winding configurations. The document also discusses how varying the field current can control the output voltage of the alternator and how the number of poles and rotor speed determine the output frequency. Open and short circuit testing characteristics are also summarized.
Electrical Power Systems Synchronous GeneratorMubarek Kurt
Here are the steps to solve this problem:
a) Given: Generator is 6 pole, 50 Hz
Using the synchronous speed formula: nm = 120f/P
nm = 120*50/6 = 1000 RPM
b) Terminal voltage at different power factors:
1) Given load: Ia = 60 A, PF = 0.8 lagging
Using phasor diagram: Vt = Ea - IaXs
Ea = Vt + IaXs = 480 + 60*1 = 540 V
Vt = 540*cos(cos-1(0.8)) = 480 V
2) PF = 1.0
Vt = Ea = 540 V
3) PF
The document describes different types of circuit breakers including air blast circuit breakers, oil circuit breakers, SF6 circuit breakers, and vacuum circuit breakers. It provides details on their construction, working principles, advantages, and disadvantages. Air blast circuit breakers use compressed air to extinguish arcs, while oil circuit breakers absorb arc energy through oil decomposition. SF6 circuit breakers have very short arcing times due to SF6's arc quenching properties. Vacuum circuit breakers interrupt current at the first current zero using a vacuum as the arc quenching medium.
This document discusses direct current (DC) electrical machines. It covers the equivalent circuit of a DC motor, the magnetization curve of a DC machine, and different types of DC motors including separately excited, shunt, permanent magnet, series, and compounded DC motors. The key characteristics and behaviors of shunt DC motors are analyzed through examples, including the effect of armature reaction and derivation of the torque-speed curve. Nonlinear analysis is also demonstrated for a shunt motor without compensating windings.
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, terminal voltage, and methods of connection for DC motors.
- How to analyze performance and calculate characteristics like torque, speed, current, and voltage for DC motors.
This document provides information about direct current (DC) motors, including:
- The three main types of DC motors: shunt wound, series wound, and separately excited and their characteristics.
- The principles of operation, construction, and torque-speed characteristics of DC motors.
- How to calculate torque, speed, induced emf, and other parameters for DC motors.
- Applications of the different DC motor types.
- Circuit diagrams and equations for analyzing DC motor performance.
This document provides information about direct current (DC) motors, including:
- The three main types of DC motors: shunt wound, series wound, and separately excited and their characteristics.
- The principles of operation, construction, and torque-speed characteristics of DC motors.
- How to calculate torque, speed, induced emf, and other parameters for DC motors.
- Applications of the different DC motor types.
- Circuit diagrams and equations for analyzing DC motor performance.
This document provides information about direct current (DC) motors, including:
- The three main types of DC motors: shunt wound, series wound, and separately excited and their characteristics.
- The principles of operation, construction, and torque-speed characteristics of DC motors.
- How to calculate torque, speed, induced emf, and other parameters for DC motors.
- Applications of the different DC motor types.
- Circuit diagrams and equations for analyzing DC motor performance.
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, terminal voltage, and methods of connection for DC motors.
- How to analyze performance and calculate characteristics like torque, speed, current, and voltage for DC motors.
1. A synchronous generator produces power by inducing a 3-phase voltage in its stator windings via a rotating magnetic field created by its rotor.
2. The rotor contains field windings that are supplied with DC current to produce the magnetic field.
3. When load is applied, armature reaction causes the induced voltage to differ from the output voltage based on the load power factor.
This document discusses direct current (DC) motors, including:
1) It introduces DC motors and explains their advantages over AC motors for certain applications.
2) It describes the basic working principle of DC motors, which involves a current-carrying conductor experiencing a force when placed in a magnetic field.
3) It discusses the different types of DC motors - shunt-wound, series-wound, and compound-wound - and explains their characteristics.
4) It provides equations for the voltage and power of DC motors and uses examples to demonstrate how to solve problems related to back EMF, speed, power input/output, and other motor parameters.
The document describes the key components and operation of an AC generator. It includes:
- The main components are the field, armature, prime mover, rotor, stator, and slip rings. The rotor and stator can each be the field or armature depending on the generator type.
- In operation, the prime mover rotates the rotor through the stationary field, inducing voltage in the armature windings. Slip rings allow a continuous connection to the rotating armature.
- Losses occur from internal resistance, hysteresis in the iron cores, and mechanical factors like bearing friction. Efficiency is the ratio of output to input power. Generators are rated by voltage, current, power
Synchronous machines include synchronous generators and motors. Synchronous generators are the primary source of electrical power and rely on synchronous motors for industrial drives. There are two main types - salient-pole and cylindrical rotor machines. Synchronous generator operation is based on synchronizing the electrical frequency to the mechanical speed of rotation. The parameters of synchronous machines can be determined from open-circuit, short-circuit, and DC tests. Synchronous generators must be synchronized before connecting in parallel by matching their voltages, phase sequences, and frequencies.
DC machines operate on the principles of electromagnetic induction and force. They have commutators, field windings, and armature windings. DC machines can operate as motors or generators depending on the direction of power flow. Speed in DC motors can be controlled through methods like armature voltage control, field control, and armature resistance control. DC generators have open-circuit, load, and external characteristics that define their performance based on variables like terminal voltage, field current, and load current. Efficiency is impacted by losses such as copper losses and mechanical losses.
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.
-
This document provides an overview of synchronous machines and synchronous condensers. It discusses key topics such as:
- The basic components and operating principles of synchronous machines and how they can function as motors or generators.
- Concepts like torque, power, energy and their relationships in synchronous machines.
- How synchronous machines synchronize to the frequency of the power system and their operating speed relationship.
- Power flow, internal and terminal voltages, and torque angle in synchronous machines.
- Losses that occur in synchronous machines and how efficiency is affected.
- The use of synchronous condensers to provide reactive power support through field excitation control while transferring little to no real power.
- Models for analyzing
This document provides an overview of basic electrical concepts including Ohm's Law, voltage, current, resistance, and power. It then discusses different types of drives including AC, DC, and servo drives. Key components of induction motors such as the rotor, stator, and magnetic flux are described. The document also covers Ohm's Law, AC and DC motor speed/torque characteristics, and elements of AC and DC drive systems including rectification, pulse width modulation, and IGBT switches. Application issues for AC drives such as line notching and switching noise are also summarized.
The document provides information about DC motors and generators, including:
1) It describes the main construction parts of DC motors/generators including the armature, stator, poles, field windings, and commutator.
2) It explains the characteristics of shunt, series, and compound wound DC motors/generators including their circuit diagrams and load/speed-torque curves.
3) It discusses starting methods for DC motors including the use of a starter resistance to limit starting current.
The document discusses the principles of operation of synchronous machines, which can operate as either motors or generators. It describes their construction, including salient pole and cylindrical rotors. It also covers single phase and three phase alternators, explaining how their windings produce phase-displaced voltages. Additional topics covered include open and short circuit characteristics, load conditions, equivalent circuits, and power flow calculations.
This document describes the principles of operation of a 3-phase alternator. It discusses how a synchronous generator works using Faraday's law of electromagnetic induction. It also describes the different components of a 3-phase alternator including the stator, rotor, and different winding configurations. The document also discusses how varying the field current can control the output voltage of the alternator and how the number of poles and rotor speed determine the output frequency. Open and short circuit testing characteristics are also summarized.
Electrical Power Systems Synchronous GeneratorMubarek Kurt
Here are the steps to solve this problem:
a) Given: Generator is 6 pole, 50 Hz
Using the synchronous speed formula: nm = 120f/P
nm = 120*50/6 = 1000 RPM
b) Terminal voltage at different power factors:
1) Given load: Ia = 60 A, PF = 0.8 lagging
Using phasor diagram: Vt = Ea - IaXs
Ea = Vt + IaXs = 480 + 60*1 = 540 V
Vt = 540*cos(cos-1(0.8)) = 480 V
2) PF = 1.0
Vt = Ea = 540 V
3) PF
The document describes different types of circuit breakers including air blast circuit breakers, oil circuit breakers, SF6 circuit breakers, and vacuum circuit breakers. It provides details on their construction, working principles, advantages, and disadvantages. Air blast circuit breakers use compressed air to extinguish arcs, while oil circuit breakers absorb arc energy through oil decomposition. SF6 circuit breakers have very short arcing times due to SF6's arc quenching properties. Vacuum circuit breakers interrupt current at the first current zero using a vacuum as the arc quenching medium.
This document outlines a technical seminar presentation on the effect of new Internet of Things (IoT) features on security and privacy. It discusses various IoT features like interdependence, constrained resources, unattended operation, mobility, ubiquity, intimacy with devices, and the myriad of devices and data. It analyzes research on security threats in different IoT application scenarios and years. The document also covers advantages and disadvantages of IoT, examples applications, and concludes by summarizing threats, challenges and opportunities of each discussed IoT feature.
1) Synchronous machines are AC rotating machines whose speed is proportional to the frequency of the current in the armature. They are commonly used as generators in power grids.
2) A synchronous generator has a rotor that is excited by DC current to produce a rotating magnetic field. The rotation of this field induces AC voltage in the stationary stator windings.
3) Synchronous machines have high operating efficiency, reliability, and allow control of power factor, making them well-suited for large power generation applications like power plants.
This document provides an overview of occupational health and safety topics including hazards, safe working practices, emergencies, first aid procedures, and documentation. It covers various types of hazards like physical, chemical, mechanical, electrical hazards. It describes safe working practices, use of personal protective equipment, safe material handling, classification of fires and use of fire extinguishers. The document demonstrates how to deal with emergency situations, provide first aid for bleeding, wounds, burns, choking, and perform CPR. It also shows how to move injured people correctly during an emergency.
This document provides information about different types of electric motors, including:
- AC induction motors, which are the most common type used in industry. They have a simple design and are inexpensive to maintain.
- AC synchronous motors, which run at a constant speed determined by the frequency of the power supply. They are used where power factor improvement is needed.
- Single phase AC motors like shaded-pole, split-phase, and capacitor-start motors, which are used in household appliances. These motors require additional components to generate a rotating magnetic field for starting.
- DC motors that have different winding configurations determining their speed and torque characteristics, like series-wound, shunt-wound,
The document discusses the key concepts of induction motors. It explains that an induction motor operates by using a rotating magnetic field in the stator to induce currents in the rotor that generate torque. It describes the different components of an induction motor including the squirrel cage and wound rotors. It also discusses important concepts like slip speed, synchronous speed, rotor frequency, equivalent circuits, power flow, and how torque is developed based on the interaction between stator and rotor magnetic fields.
This document describes the components and working principle of a DC generator. It contains the following key points:
1. A DC generator converts mechanical energy to electrical energy through electromagnetic induction. It consists of a magnetic field and a conductor that can move to cut the magnetic flux.
2. The basic components are a magnetic frame, field coils, armature shaft, armature core and windings, commutator, and brushes. The rotating armature windings cut the magnetic flux from the stationary field coils to induce an alternating current.
3. The commutator rectifies the alternating current from the armature to produce a unidirectional current that is collected by the brushes and supplied to the external
The document discusses various topics related to DC machines including Maxwell's corkscrew rule, Fleming's left-hand and right-hand rules, Lenz's law, the construction and working principles of DC generators and motors. It describes the field system, armature, commutator, brushes, and winding types. It also covers EMF equations, characteristics, speed control methods, losses, testing, and applications of DC generators and motors.
The document summarizes new challenges facing electricity distribution and regulation in India. Key challenges include high costs from past capacity additions, financial losses for distribution companies, high transmission and distribution losses, poor supply quality, grid integration of renewables, and safety issues. Suggested solutions discussed include avoiding long-term coal contracts, encouraging large consumer migration to open access, promoting efficiency, deploying agricultural solar feeders, rationalizing tariffs, and increasing professional participation in policy processes.
Rainfall intensity duration frequency curve statistical analysis and modeling...bijceesjournal
Using data from 41 years in Patna’ India’ the study’s goal is to analyze the trends of how often it rains on a weekly, seasonal, and annual basis (1981−2020). First, utilizing the intensity-duration-frequency (IDF) curve and the relationship by statistically analyzing rainfall’ the historical rainfall data set for Patna’ India’ during a 41 year period (1981−2020), was evaluated for its quality. Changes in the hydrologic cycle as a result of increased greenhouse gas emissions are expected to induce variations in the intensity, length, and frequency of precipitation events. One strategy to lessen vulnerability is to quantify probable changes and adapt to them. Techniques such as log-normal, normal, and Gumbel are used (EV-I). Distributions were created with durations of 1, 2, 3, 6, and 24 h and return times of 2, 5, 10, 25, and 100 years. There were also mathematical correlations discovered between rainfall and recurrence interval.
Findings: Based on findings, the Gumbel approach produced the highest intensity values, whereas the other approaches produced values that were close to each other. The data indicates that 461.9 mm of rain fell during the monsoon season’s 301st week. However, it was found that the 29th week had the greatest average rainfall, 92.6 mm. With 952.6 mm on average, the monsoon season saw the highest rainfall. Calculations revealed that the yearly rainfall averaged 1171.1 mm. Using Weibull’s method, the study was subsequently expanded to examine rainfall distribution at different recurrence intervals of 2, 5, 10, and 25 years. Rainfall and recurrence interval mathematical correlations were also developed. Further regression analysis revealed that short wave irrigation, wind direction, wind speed, pressure, relative humidity, and temperature all had a substantial influence on rainfall.
Originality and value: The results of the rainfall IDF curves can provide useful information to policymakers in making appropriate decisions in managing and minimizing floods in the study area.
Introduction- e - waste – definition - sources of e-waste– hazardous substances in e-waste - effects of e-waste on environment and human health- need for e-waste management– e-waste handling rules - waste minimization techniques for managing e-waste – recycling of e-waste - disposal treatment methods of e- waste – mechanism of extraction of precious metal from leaching solution-global Scenario of E-waste – E-waste in India- case studies.
Optimizing Gradle Builds - Gradle DPE Tour Berlin 2024Sinan KOZAK
Sinan from the Delivery Hero mobile infrastructure engineering team shares a deep dive into performance acceleration with Gradle build cache optimizations. Sinan shares their journey into solving complex build-cache problems that affect Gradle builds. By understanding the challenges and solutions found in our journey, we aim to demonstrate the possibilities for faster builds. The case study reveals how overlapping outputs and cache misconfigurations led to significant increases in build times, especially as the project scaled up with numerous modules using Paparazzi tests. The journey from diagnosing to defeating cache issues offers invaluable lessons on maintaining cache integrity without sacrificing functionality.
Design and optimization of ion propulsion dronebjmsejournal
Electric propulsion technology is widely used in many kinds of vehicles in recent years, and aircrafts are no exception. Technically, UAVs are electrically propelled but tend to produce a significant amount of noise and vibrations. Ion propulsion technology for drones is a potential solution to this problem. Ion propulsion technology is proven to be feasible in the earth’s atmosphere. The study presented in this article shows the design of EHD thrusters and power supply for ion propulsion drones along with performance optimization of high-voltage power supply for endurance in earth’s atmosphere.
AI for Legal Research with applications, toolsmahaffeycheryld
AI applications in legal research include rapid document analysis, case law review, and statute interpretation. AI-powered tools can sift through vast legal databases to find relevant precedents and citations, enhancing research accuracy and speed. They assist in legal writing by drafting and proofreading documents. Predictive analytics help foresee case outcomes based on historical data, aiding in strategic decision-making. AI also automates routine tasks like contract review and due diligence, freeing up lawyers to focus on complex legal issues. These applications make legal research more efficient, cost-effective, and accessible.
Use PyCharm for remote debugging of WSL on a Windo cf5c162d672e4e58b4dde5d797...shadow0702a
This document serves as a comprehensive step-by-step guide on how to effectively use PyCharm for remote debugging of the Windows Subsystem for Linux (WSL) on a local Windows machine. It meticulously outlines several critical steps in the process, starting with the crucial task of enabling permissions, followed by the installation and configuration of WSL.
The guide then proceeds to explain how to set up the SSH service within the WSL environment, an integral part of the process. Alongside this, it also provides detailed instructions on how to modify the inbound rules of the Windows firewall to facilitate the process, ensuring that there are no connectivity issues that could potentially hinder the debugging process.
The document further emphasizes on the importance of checking the connection between the Windows and WSL environments, providing instructions on how to ensure that the connection is optimal and ready for remote debugging.
It also offers an in-depth guide on how to configure the WSL interpreter and files within the PyCharm environment. This is essential for ensuring that the debugging process is set up correctly and that the program can be run effectively within the WSL terminal.
Additionally, the document provides guidance on how to set up breakpoints for debugging, a fundamental aspect of the debugging process which allows the developer to stop the execution of their code at certain points and inspect their program at those stages.
Finally, the document concludes by providing a link to a reference blog. This blog offers additional information and guidance on configuring the remote Python interpreter in PyCharm, providing the reader with a well-rounded understanding of the process.
Build the Next Generation of Apps with the Einstein 1 Platform.
Rejoignez Philippe Ozil pour une session de workshops qui vous guidera à travers les détails de la plateforme Einstein 1, l'importance des données pour la création d'applications d'intelligence artificielle et les différents outils et technologies que Salesforce propose pour vous apporter tous les bénéfices de l'IA.
DEEP LEARNING FOR SMART GRID INTRUSION DETECTION: A HYBRID CNN-LSTM-BASED MODELijaia
As digital technology becomes more deeply embedded in power systems, protecting the communication
networks of Smart Grids (SG) has emerged as a critical concern. Distributed Network Protocol 3 (DNP3)
represents a multi-tiered application layer protocol extensively utilized in Supervisory Control and Data
Acquisition (SCADA)-based smart grids to facilitate real-time data gathering and control functionalities.
Robust Intrusion Detection Systems (IDS) are necessary for early threat detection and mitigation because
of the interconnection of these networks, which makes them vulnerable to a variety of cyberattacks. To
solve this issue, this paper develops a hybrid Deep Learning (DL) model specifically designed for intrusion
detection in smart grids. The proposed approach is a combination of the Convolutional Neural Network
(CNN) and the Long-Short-Term Memory algorithms (LSTM). We employed a recent intrusion detection
dataset (DNP3), which focuses on unauthorized commands and Denial of Service (DoS) cyberattacks, to
train and test our model. The results of our experiments show that our CNN-LSTM method is much better
at finding smart grid intrusions than other deep learning algorithms used for classification. In addition,
our proposed approach improves accuracy, precision, recall, and F1 score, achieving a high detection
accuracy rate of 99.50%.
Applications of artificial Intelligence in Mechanical Engineering.pdfAtif Razi
Historically, mechanical engineering has relied heavily on human expertise and empirical methods to solve complex problems. With the introduction of computer-aided design (CAD) and finite element analysis (FEA), the field took its first steps towards digitization. These tools allowed engineers to simulate and analyze mechanical systems with greater accuracy and efficiency. However, the sheer volume of data generated by modern engineering systems and the increasing complexity of these systems have necessitated more advanced analytical tools, paving the way for AI.
AI offers the capability to process vast amounts of data, identify patterns, and make predictions with a level of speed and accuracy unattainable by traditional methods. This has profound implications for mechanical engineering, enabling more efficient design processes, predictive maintenance strategies, and optimized manufacturing operations. AI-driven tools can learn from historical data, adapt to new information, and continuously improve their performance, making them invaluable in tackling the multifaceted challenges of modern mechanical engineering.
2. Introduction
• An electrical machine is link between an electrical
system and a mechanical system.
• Conversion from mechanical to electrical: generator
• Conversion from electrical to mechanical: motor
3. Introduction
Machines are called
• AC machines (generators or motors) if the electrical
system is AC.
• DC machines (generators or motors) if the electrical
system is DC.
4. DC machines can be divide by:
DC Machines
DC Motor DC Generator
9. DC Machines Fundamentals
• Stator: is the stationary part of the machine. The
stator carries a field winding that is used to
produce the required magnetic field by DC
excitation.
• Rotor (Armature): is the rotating part of the
machine. The rotor carries a distributed winding,
and is the winding where the e.m.f. is induced.
• Field winding: Is wound on the stator poles to
produce magnetic field (flux) in the air gap.
• Armature winding: Is composed of coils placed in
the armature slots.
• Commutator: Is composed of copper bars,
insulated from each other. The armature winding is
connected to the commutator.
• Brush: Is placed against the commutator surface.
Brush is used to connect the armature winding to
external circuit through commutator
10. DC Machines Fundamentals
In DC machines, conversion of energy from
electrical to mechanical form or vice versa results
from the following two electromagnetic phenomena
Generator action:
An e.m.f. (voltage) is induced in a conductor if it
moves through a magnetic field.
Motor action:
A force is induced in a conductor that has a current
going through it and placed in a magnetic field
•Any DC machine can act either as a generator or
as a motor.
11. DC Machines Equivalent Circuit
The equivalent/modelling circuit of DC machine
has two components:
Armature circuit:
• It can be represented by a voltage source and a
resistance connected in series (the armature
resistance). The armature winding has a
resistance, RA.
The field circuit:
• It is represented by a winding that generates the
magnetic field and a resistance connected in
series. The field winding has resistance RF.
14. Classification of DC Motor
1. Separately Excited DC Motor
• Field and armature windings are either connected
separate.
2. Shunt DC Motor
• Field and armature windings are either connected in
parallel.
3. Series DC Motor
• Field and armature windings are connected in series.
4. Compound DC Motor
• Has both shunt and series field so it combines features
of series and shunt motors.
15. Equivalent Circuit of a DC Motor
Armature circuit - voltage source, EA and a resistor, RA.
The field coils, which produce the magnetic flux are
represented by inductor, LF and resistor, RF.
The separate resistor, Radj represents an external variable
resistor used to control the amount of current in the field
circuit. Basically it lumped together with Rf and called Rf
16. Equivalent Circuit of DC Motor
F
T
F
R
V
I
A
A
A
T R
I
E
V
F
F
F
R
V
I
A
A
A
T R
I
E
V
A
L I
I
1. Separately Excited DC Motor
2. Shunt DC Motor
F
A
L I
I
I
17. )
( S
A
A
A
T R
R
I
E
V
L
S
A I
I
I
3. Series DC Motor
)
( S
A
A
A
T R
R
I
E
V
F
T
F
R
V
I F
L
A I
I
I
4. Compound DC Motor
18. Important terms in DC motor
equivalent circuit
• VT – supply voltage
• EA – internal generated voltage/back e.m.f.
• RA – armature resistance
• RF – field/shunt resistance
• RS – series resistance
• IL – load current
• IF – field current
• IA – armature current
• IL – load current
• n – speed
19. Speed of a DC Motor
• For shunt motor • For series motor
1
2
1
2
1
2
2
1
1
2
1
2
,
A
A
A
A
E
E
n
n
then
If
E
E
n
n
2
1
1
2
1
2
2
1
1
2
1
2
A
A
A
A
A
A
I
I
E
E
n
n
E
E
n
n
If Constant field excitation,
means; if1 = if2 or constant
flux; 1 = 2
Flux, ϕ produce proportional
to the current produce
20. Example 1
A 250 V, DC shunt motor takes a line
current of 20 A. Resistance of shunt field
winding is 200 Ω and resistance of the
armature is 0.3 Ω. Find the armature
current, IA and the back e.m.f., EA.
21. Solution
Given parameters:
• Terminal voltage, VT = 250 V
• Field resistance, RF = 200 Ω
• Armature resistance, RA = 0.3 Ω
• Line current, IL = 20 A
Figure 1
22. Solution (cont..)
the field current,
the armature current,
VT = EA + IARA
the back e.m.f.,
EA = VT – IARA = 250 V – (18.75)(0.3) = 244.375 V
A
25
.
1
200
V
250
F
T
F
F
A
L
R
V
I
I
I
I
18.75A
A
25
.
1
A
20
F
L
A I
I
I
23. Example 2
A 50hp, 250 V, 1200 rpm DC shunt motor
with compensating windings has an
armature resistance (including the brushes,
compensating windings, and interpoles) of
0.06 Ω. Its field circuit has a total resistance
Radj + RF of 50 Ω, which produces a no-load
speed of 1200 rpm. There are 1200 turns
per pole on the shunt field winding.
24. Example 2 (cont..)
a) Find the speed of this motor when its
input current is 100 A.
b) Find the speed of this motor when its
input current is 200 A.
c) Find the speed of this motor when its
input current is 300 A.
25. Solution
Given quantities:
• Terminal voltage, VT = 250 V
• Field resistance, RF = 50 Ω
• Armature resistance, RA = 0.06 Ω
• Initial speed, n1 = 1200 r/min
Figure 2
26. Solution (cont..)
(a) When the input current is 100A, the armature
current in the motor is
Therefore, EA at the load will be
A
95
A
5
A
100
50
V
250
A
100
F
T
L
F
L
A
R
V
I
I
I
I
V
3
.
244
V
7
.
5
V
250
)
06
.
0
)(
A
95
(
V
250
A
A
T
A R
I
V
E
27. Solution (cont..)
• The resulting speed of this motor is
min
/
r
1173
min
/
r
1200
250
3
.
244
1
1
2
2
1
2
1
2
V
V
n
E
E
n
E
E
n
n
A
A
A
A
28. Solution (cont..)
(b) When the input current is 200A, the armature
current in the motor is
Therefore, EA at the load will be
A
195
A
5
A
200
50
V
250
A
200
F
T
L
F
L
A
R
V
I
I
I
I
V
3
.
238
V
7
.
11
V
250
)
06
.
0
)(
195
(
V
250
A
R
I
V
E A
A
T
A
29. Solution (cont..)
• The resulting speed of this motor is
min
/
r
1144
min
/
r
1200
250
3
.
238
1
1
2
2
1
2
1
2
V
V
n
E
E
n
E
E
n
n
A
A
A
A
30. Solution (cont..)
(c) When the input current is 300A, the armature
current in the motor is
Therefore, EA at the load will be
A
295
A
5
A
300
50
V
250
A
300
F
T
L
F
L
A
R
V
I
I
I
I
V
3
.
232
V
7
.
17
V
250
)
06
.
0
)(
295
(
V
250
A
R
I
V
E A
A
T
A
31. Solution (cont..)
• The resulting speed of this motor is
min
/
r
1115
min
/
r
1200
V
250
V
3
.
232
1
1
2
2
1
2
1
2
n
E
E
n
E
E
n
n
A
A
A
A
32. Example 3
The motor in Example 2 is now connected in
separately excited circuit as shown in Figure 3. The
motor is initially running at speed, n = 1103 r/min
with VA = 250 V and IA = 120 A, while supplying a
constant-torque load. If VA is reduced to 200 V,
determine
i). the internal generated voltage, EA
ii). the final speed of this motor, n2
34. Solution
Given quantities
• Initial line current, IL = IA = 120 A
• Initial armature voltage, VA = 250 V
• Armature resistance, RA = 0.06 Ω
• Initial speed, n1 = 1103 r/min
35. Solution (cont..)
i) The internal generated voltage
EA = VT - IARA
= 250 V – (120 A)(0.06 Ω)
= 250 V – 7.2 V
= 242.8 V
36. Solution (cont..)
ii) Use KVL to find EA2
EA2 = VT - IA2RA
Since the torque and the flux is constant, IA is
constant. This yields a voltage of:
EA2 = 200 V – (120 A)(0.06 Ω)
= 200 V – 7.2 V
= 192.8 V
37. Solution (cont..)
• The final speed of this motor
min
/
r
876
min
/
r
1103
V
8
.
242
V
8
.
192
1
1
2
2
1
2
1
2
n
E
E
n
E
E
n
n
A
A
A
A
38. Example 4
A DC series motor is running with a speed of
800 r/min while taking a current of 20 A from
the supply. If the load is changed such that
the current drawn by the motor is increased
to 55 A, calculate the speed of the motor on
new load. The armature and series field
winding resistances are 0.2 Ω and 0.3 Ω
respectively. Assume the flux produced is
proportional to the current. Assume supply
voltage as 200 V.
39. Solution
Given quantities
• Supply voltage, VT = 200 V
• Armature resistance, RA = 0.2 Ω
• Series resistance, RS = 0.3 Ω
• Initial speed, n1 = 800 r/min
• Initial armature current, Ia1 = IL1 = 20 A
Figure 4
40. Solution (cont..)
When the armature current increased, Ia2 = 55
A, the back emf
EA2 = V – Ia2 (RA + RS)
= 200 – 55(0.2 + 0.3)
= 225 V
min
/
r
300
50
20
240
225
800
2
1
1
2
1
2
2
1
1
2
1
2
2
1
1
2
1
2
I
I
E
E
n
n
I
I
E
E
n
n
E
E
n
n
A
A
A
A
A
A
The speed of the motor on new load
41. Solution (cont..)
For initial load, the armature current, Ia1 = 20 A and
the speed n1 = 800 r/min
V = EA1 + Ia1 (RA + RS)
The back e.m.f. at initial speed
EA1 = V - Ia1 (RA + RS)
= 200 – 20(0.2 + 0.3)
= 190 V
43. Generating of an AC Voltage
• The voltage generated in any DC generator inherently
alternating and only becomes DC after it has been
rectified by the commutator
44. Armature windings
• The armature windings are usually former-
wound. This are first wound in the form of flat
rectangular coils and are then puller.
• Various conductors of the coils are insulated
each other. The conductors are placed in the
armature slots which are lined with tough
insulating material.
• This slot insulation is folded over above the
armature conductors placed in the slot and is
secured in place by special hard wooden or fiber
wedges.
45. Generated or back e.m.f. of DC
Generator
• General form of generated e.m.f.,
Φ = flux/pole (Weber)
Z = total number of armature conductors
= number of slots x number of conductor/slot
P = number of poles
A = number of parallel paths in armature
[A = 2 (for wave winding), A = P (for lap winding)]
N = armature rotation (rpm)
E = e.m.f. induced in any parallel path in armature
A
P
ZN
E
60
46. Classification of DC Generator
1. Separately Excited DC Generator
• Field and armature windings are either connected
separate.
2. Shunt DC Generator
• Field and armature windings are either connected in
parallel.
3. Series DC Generator
• Field and armature windings are connected in
series.
4. Compound DC Generator
• Has both shunt and series field so it combines
features of series and shunt motors.
47. Equivalent circuit of DC generator
F
A
L I
I
I
A
L I
I
Separately excited DC generator
F
F
F
R
V
I
A
A
A
T R
I
E
V
Shunt DC generator
F
T
F
R
V
I
A
A
A
T R
I
E
V
48. F
A
L I
I
I
A
S
L I
I
I
Series DC generator
)
( S
A
A
A
T R
R
I
E
V
Shunt DC generator
F
T
F
R
V
I
A
A
A
T R
I
E
V
49. Example
• A DC shunt generator has shunt field winding
resistance of 100Ω. It is supplying a load of 5kW at
a voltage of 250V. If its armature resistance is
0.02Ω, calculate the induced e.m.f. of the
generator.
50. Solution
Given quantities
• Terminal voltage, VT = 250V
• Field resistance, RF = 100Ω
• Armature resistance, RA = 0.22Ω
• Power at the load, P = 5kW
52. Power flow and losses in DC machines
DC generators take in mechanical power and
produce electric power while DC motors take in
electric power and produce mechanical power
Efficiency
%
x
P
P
in
out
100
%
x
P
P
P
in
loss
out
100
53. The losses that occur in DC machine can be
divided into 5 categories
1.Copper losses (I2R)
2.Brush losses
3.Core losses
4.Mechanical losses
5.Stray load losses
a
a
a R
I
P 2
f
f
f R
I
P 2
Ia = armature current
If = field current
Ra = armature
resistance
Rf = field resistance
54. Core losses – Hysteresis losses and Eddy current losses
Mechanical losses – The losses that associated with
mechanical effects.
Two basic types of mechanical losses: Friction & Windage.
Friction losses caused by the friction of the bearings in the
machine.
Windage are caused by the friction between the moving parts
of the machine and the air inside the motor casing’s
Stray losses (Miscellaneous losses) – Cannot placed in one
of the previous categories.
Power Losses
57. Example
A short-shunt compound generator delivers 50A at
500V to a resistive load. The armature, series field
and shunt field resistance are 0.16, 0.08 and 200,
respectively.
Calculate the armature current if the rotational
losses are 520W, determine the efficiency of the
generator
58. Solution
W
520
Pu W
25000
A
50
Vx
500
Pout
A
5
2
200
500
If .
A
5
52
A
50
A
5
2
I
I
I L
f
a .
.
Armature Copper
Loss
W
441
16
0
5
52
R
I
P 2
a
2
a
ca
)
.
(
)
.
(
)
(
Series Field
Copper Loss
W
5
220
08
0
5
52
R
I
P 2
2
f
2
a
2
cf .
)
.
(
)
.
(
)
(
Shunt Field
Copper Loss
W
1250
200
5
2
R
I
P 2
1
f
2
f
1
cf
)
(
)
.
(
)
(
Friction + Stray + windage
+ etc:
W
520
Pu
Total Losses = W
5
2431
520
1250
5
220
441 .
)
.
(
61. The induction machine is the most rugged and the most
widely used machine in industry.
Like dc machine, the induction machine has a stator and a
rotor mounted on bearings and separated from the stator
by an air gap.
However, in the induction machine both stator winding and
rotor winding carry alternating currents.
The induction machine can operate both as a motor and as
generator
As motors, they have many advantages.
They are rugged, relatively inexpensive and require very
little maintenance.
They range in size from a few watts to about 10,000 hp.
The speed of an induction motor is nearly but not quite
constant, dropping only a few percent in going from no load
to full load.
INDUCTION MACHINE
62. The main disadvantages of induction motors are
a. The speed is not easily controlled.
b. The starting current may be five to eight times
full-load current.
c. The power factor is low and lagging when the
machine is lightly loaded
63. INDUCTION MOTOR CONSTRUCTION
Two different types of induction motor which can be placed in
stator
a) squirrel cage rotor
b) wound rotor
Squirrel Cage rotor Wound rotor
64. Squirrel cage rotor – consists of conducting bars embedded
in slots in the rotor magnetic core and these bars are short
circuited at each end by conducting end rings. The rotor bars
and the rings are shaped like squirrel cage.
Wound rotor – carries three windings similar to the stator
windings. The terminals of the rotor windings are connected
to the insulated slip rings mounted on the rotor shaft. Carbon
brushes bearing on these rings make the rotor terminals
available to the user of the machine. For steady state
operation, these terminals are short circuited.
Types of rotor
66. Wound Rotor
• Most motors use the squirrel-cage rotor because of the
robust and maintenance-free construction.
• However, large, older motors use a wound rotor with three
phase windings placed in the rotor slots.
• The windings are connected in a three-wire wye.
• The ends of the windings are connected to three slip rings.
• Resistors or power supplies are connected to the slip rings
through brushes for reduction of starting current and
speed control
68. BASIC INDUCTION MOTOR CONCEPT
A single/three phase set of voltages has been applied to
the stator, and single/three phase set of stator currents is
flowing. These produce a magnetic field Bs, which is
rotating in a counterclockwise direction .
The speed of the magnetic field’s rotation is P
f
n e
sync
120
69. THE CONCEPT OF ROTOR SLIP
The voltage induced in a rotor depends on the
speed of the rotor relative to the magnetic field.
Slip speed is defined as the difference between
synchronous speed and rotor speed
m
sync
slip n
-
n
n
where
nslip = slip speed of the machine
nsync = speed of the magnetic fields
nm = mechanical shaft speed of motor
Slip is the relative speed expressed on a per unit or
a percentage basis
100%
x
n
n
s
sync
slip
100%
x
n
n
-
n
s
sync
m
sync
70. In term angular velocity (radians per second, rps)
100%
x
-
s
sync
m
sync
If the rotor turns at synchronous speed, s = 0
while if the rotor is stationary/standstill, s = 1
synx
m s)n
-
(1
n
synx
m s)
-
(1
71. THE ELECTRICAL FREQUENCY CONCEPT
Like a transformer, the primary (stator) induces a
voltage in the secondary (rotor) but unlike a
transformer, the secondary frequency is not
necessary the same as the primary frequency.
If the rotor of a motor is locked, then the rotor will
have same frequency as the stator.
The rotor frequency can be expressed
e
r sf
f )
( m
sync
r n
-
n
120
P
f
72. A 208V, 10hp, 4 pole, 60Hz, Y connected induction
motor has full load slip of 5%.
Calculate,
a. synchronous speed, nsync
(Ans:1800rpm)
b. rotor speed, nm
(Ans: 1710rpm)
c. rotor frequency, fr at the rated load
(Ans: 3 Hz)
d. Shaft torque at the rated load (Ans: 41.7Nm)
Example
73. The derivation of the induction motor induced-
torque equation
m
conv
ind
P
sync
AG
ind
P
The induced torque in induction motor is
s
R
I
PAG
2
2
2
s
R
I
PAG
2
2
2
3
Air gap power
Total Air gap power
74. a) What is the motor’s slip? (Ans:1.67%)
b) What is the induced torque in the motor in Nm
under these conditions? (48.6Nm)
c) What will the operating speed of the motor be if
its torque is doubled? (2900 rpm)
d) How much power will be supplied by the motor
when the torque is doubled? (29.5kW)
A two pole, 50hz induction motor supplies 15kW to
a load at speed 2950 rpm.
Assignment 6.5
75. Speed control of induction motors
i. Induction motor speed control by pole
ii. changing
iii. Speed control by changing the line frequency
iv. Speed control by changing the line voltage
v. Speed control by changing the rotor
vi. resistance