13 ELECTRIC MOTORS Basic Relations

Save this PDF as:

Size: px
Start display at page:

Download "13 ELECTRIC MOTORS. 13.1 Basic Relations"

Transcription

1 13 ELECTRIC MOTORS Modern underwater vehicles and surface vessels are making increased use of electrical actuators, for all range of tasks including weaponry, control surfaces, and main propulsion. This section gives a very brief introduction to the most prevalent electrical actuators: The DC motor, the AC induction motor, and the AC synchronous motor. For the latter two technologies, we consider the case of three-phase power, which is generally preferred over single-phase because of much higher power density; three-phase motors also have simpler starting conditions. AC motors are generally simpler in construction and more robust than DC motors, but at the cost of increased control complexity. This section provides working parametric models of these three motor types. As with gas turbines and diesel engines, the dynamic response of the actuator is quite fast compared to that of the system being controlled, say a submarine or surface vessel. Thus, we concentrate on portraying the quasi-static properties of the actuator in particular, the torque/speed characteristics as a function of the control settings and electrical power applied. The discussion below on these various motors is generally invertible (at least for DC and AC synchronous devices) to cover both motors (electrical power in, mechanical power out) and generators (mechanical power in, electrical power out). We will only cover motors in this section, however; a thorough treatment of generators can be found in the references listed. The book by Bradley (19??) has been drawn on heavily in the following Basic Relations Concepts First we need the notion of a magnetic flux, analagous to an electrical current, denoted ; a common unit is the Weber or Volt-second. The flux density B = /A (167) is simply the flux per unit area, given in Teslas such that 1T = 1W/m 2. Correponding to electrical field (Volts/m) is the magnetic field intensity H, in Amperes/meter: B H = = ; (168) µ o µ r Aµ o µ r

2 58 13 ELECTRIC MOTORS µ o 4β 10 7Henries/meter is the permeability of free space, and µ r is a (dimensionless) relative permeability. The product µ o µ r represents the real permeability of the material, and is thus the analog of electrical conductivity. A small area A or low relative permeability drives up the field intensity for a given flux Faraday s Law The voltage generated in a conductor experiencing a time rate of change in magnetic flux is given as d e = (169) dt This voltage is commonly called the back-electromotive force or back-e.m.f., since it typically opposes the driving current; it is in fact a limiting factor in DC motors Ampere s Law Current passing through a conductor in a closed loop generates a perpendicular magnetic field intensity given by I = Hdl. (170) An important point is that N circular wraps of the same conductor carrying current I induce the field H = βdn I, where D is the diameter of the circle Force Forces are generated from the orthogonal components of magnetic flux density B and current I: F = I B. (171) The units of this force is N/m, and so represents a distributed force on the conductor DC Motors The DC motor in its simplest form can be described by three relations: e a = K V = e a + R a i a T = K i a, where

3 13.2 DC Motors 59 K is a constant of the motor is the airgap magnetic flux per pole (Webers) is the rotational speed of the motor (rad/s) e a is the back-e.m.f. V is the applied voltage R a is the armature resistance on the rotor i a is the current delivered to the armature on the rotor T is developed torque The magnetic field in a typical motor is stationary (on the stator) and is created by permanent magnets or by coils, i.e., Faraday s law. Current is applied to the rotor armature through slip rings, and thus the force on each conductor in the armature is given by F γ = iγ a B. γ Back-e.m.f. is created because the conductors in the rotor rotate through the stationary field, causing a relative rate of change of flux. The armature voltage loop contains the backe.m.f. plus the resistive losses in the windings. As expected, torque scales with the product of magnetic flux and current. There are three main varieties of DC motors, all of which make use of the relations above. Speed control of the DC motor is primarily through the voltage V, either directly or through pulse-width modulation, but the stator flux could also be controlled in the shunt/independent configurations Permanent Field Magnets Here, the magnetic field is created by permanent magnets arranged in the stator, imposing a steady. The product K is generally written as k t, the torque constant of a DC motor, and has units of N m/a. When SI units are used, k t also describes back-e.m.f.. The three basic relations are thus rewritten e a = k t V = e a + R a i a T = k t i a, which leads via substitution to 1 R a T = V, or k t k t k t T = [V k t ]. R a

4 60 13 ELECTRIC MOTORS This result indicates that the torque developed scales linearly with the applied voltage, but that it also scales negatively with the motor speed. Hence, at the speed = V/K t, no torque is created. Additionally, the maximum torque is created at zero speed. Control of these motors is through the voltage V, or, more commonly, directly through current i a, which gives torque directly Shunt or Independent Field Windings The field created by the stator can be strengthened by replacing the permanent magnets with electromagnets. The field windings are commonly placed in series with the rotor circuit, in parallel with it (shunt connection), or, they may be powered from a completely separate circuit. The latter two cases are effectively equivalent, in the sense that current and hence the field strength can be modulated easily, through a variable resistance in the shunt case. We have 1 R a T = V, K K with the important property that the second term in brackets is small due to the increased field strength, compared with the permanent magnet case above. Thus, the motor speed is effectively independent of torque, which makes these motor types ideal for self-regulation applications. At very high torques and currents, however, the total available flux will be reduced because of field armature reactance; the speed starts to degrade as shown in the figure Series Windings When the field windings are arranged in series with the rotor circuit, the flux is = K s i a, where K s is a constant of the field winding. This additional connection requires V = e a + (R a + R s )i a ; the field winding brings a new resistance R s into the voltage loop. It follows through the substitutions that T = KK s i 2 a T I a = KK s V R a + R = s. KKs T KK s

5 13.3 Three-Phase Synchronous Motor 61 The effects of resistance are usually quite small, so that the first term dominates, leading to a nonlinear torque/speed characteristic. The starting torque from this kind of motor is exceptionally high, and the series field winding finds wide application in railway locomotives. At the same time, it should be observed that under light loading, the series motor may well self-destruct since there is no intrinsic upper limit to speed! T V T T V V a) ω b) ω c) ω Figure 6: Torque-speed characteristics of three types of DC motors: a) permanent field magnets, b) shunt or independent field winding, c) series field winding. Some variations on the series and shunt connections are common, and referred to as compound DC motors. These achieve other torque/speed curves, including increasing torque with increasing speed, which can offset the speed droop due to field armature reaction effects in the shunt motor Three-Phase Synchronous Motor The rotor is either fitted with permanent magnets or supplied with DC current to create a static field on the rotor. The stator field windings are driven with three (balanced) phases of an AC supply, such that a moving field is created which rotates around the stator. The torque exerted on the rotor tries to align the two fields, and so the rotor follows the rotating stator field at the same speed. Note that if the rotor speed lags that of the stator field, there is no net torque; hence the name synchronous motor. A simple model of the synchronous motor is straightforward. As with the DC motors, the voltage loop equation for a single phase on the stator gives V = e a + ji a X, where V, e a, and i a are now phasors (magnitude of V and e a measured with respect to ground), j = 1, and X is the reactance (armature and stator leakage) of the machine. Then, let δ denote the angle between i a and V. Equating the electrical (all three phases) and mechanical power gives

6 62 13 ELECTRIC MOTORS 3V i a cos δ = T. Next, let ζ denote the angle between the phasors e a and V. It follows from the voltage loop equation that where i a cos δx = e a sin ζ T = p 3V e a sin ζ, or 2 X T = p V ab e a,ab sin ζ 2 X p is the number of poles on the rotor; two poles means one north pole and one south pole, etc. is both the rotational speed of the rotor, and the rotational speed of the stator field V ab is the line-to-line voltage, equal to 3V e a,ab is the line-to-line back-e.m.f., equal to 3ea delta is the angle by which the rotor field lags the stator field (rad) X is the synchronous reactance The torque scales with sin ζ, and thus the rotor lags the stator field when the motor is powering; in a generator, the stator field lags the rotor. If the load torque exceeds the available torque, the synchronous motor can slip one or more poles, causing a large transient disturbance. Speed control of the three-phase synchronous machine is generally through the frequency of the three-phase power supply,, with the assumption that adequate voltage and current are available Three-Phase Induction Motor Like the synchronous machine, the induction machine has windings on the stator to create a rotating magnetic field at frequency. Letting the rotor speed be r, we see immediately that if = r, a potential field will be induced on any conductor on the rotor. In the case of a squirrel-cage rotor design, the rotor is made of conductor bars which are shorted out through rings at the ends, and hence the potential field will cause a real current flow. Torque is then generated through the familiar F = I B relation. The fact of unequal field and rotor speeds in the induction motor is related to several unique effects, leading to torque-speed characteristic which differs significantly from both the DC the AC synchronous machines.

7 13.4 Three-Phase Induction Motor 63 First we define the slip ratio r s = ; (172) a slip ratio of zero means = r (and hence zero torque because the magnetic field seen by the rotor is constant) while a slip ratio of one implies the rotor is stopped. Most induction motors are designed to operate at a small positive slip ratio, say , for reasons described below. Next, since the magnetic flux lines pass through the rotor, the number of ampere-turns on stator and rotor is equivalent, that is, they form an ideal inductor: N r I r = N s I s. (173) We consider per-unit quantities from here on, for which we set N = N r = N s and hence Ir = I s. If the stator flux at a particular location is s = o sin t, the associated voltage is es = N d /dt = N o s cos t. On the rotor, the same flux applies, but it rotates more slowly: r = o sin r t = o sin s t. Hence the rotor voltage is e r = N d r /dt = N o s cos s t. Then the RMS voltage of the stator and rotor sides of the inductive coupling are related by E s 1 =. (174) s E r The voltage seen at the stator scales inversely with the slip ratio, for a constant voltage at the rotor. In per-unit terms, the current in the rotor and stator are equivalent, and this then indicates that the rotor impedance, seen from the stator, also scales inversely with the slip ratio: 1 Z rs = [R r + jsx r ] s 1 = R r + jx r. s The factor of s in the rotor inductance occurs because the field seen by the rotor is actually rotating at s. Next, we construct the (one phase) Thevenin equivalent circuit of the stator: it has a voltage source V t, and equivalent resistance R and inductance X. This is to be paired with the rotor resistance and inductance, reflected to the stator, giving the following current V t I =. (R r /s + R) 2 + (X r + X) 2 Finally, we need to express the torque/speed characteristic of the machine. The mechanical power is P m = (1 s) T, while the power delivered across the airgap is P gap = I 2 R r /s. The

8 64 14 TOWING OF VEHICLES actual power dissipated in the copper is related to the real rotor resistance: P loss = I 2 R r, and hence the mechanical power is P m = 3(P gap P loss ) = 3P gap (1 s). It follows that the efficiency of the motor is simply = 1 s. Combining the mechanical power with the torque equation gives P m 3P gap T = = (1 s) 3V t 2 R r =. s [(R r /s + R) 2 + (X r + X) 2 ] Maximum torque is developed at a slight slippage, with decreased values at lower speeds. s = 1 s = 0 Torque ω /ω m Figure 7: Torque-speed characteristics of a typical three-phase induction motor.

Induction Motor (No-Load Test) Induction Motor (Blocked Rotor Test) Example (No-Load/Blocked Rotor Tests) The results of the no-load and blocked rotor tests on a three-phase, 60 hp, 2200 V, six-pole, 60

2. A conductor of length 2m moves at 4m/s at 30 to a uniform magnetic field of 0.1T. Which one of the following gives the e.m.f. generated?

Extra Questions - 2 1. A straight length of wire moves through a uniform magnetic field. The e.m.f. produced across the ends of the wire will be maximum if it moves: a) along the lines of magnetic flux

SYNCHRONOUS MACHINES

SYNCHRONOUS MACHINES The geometry of a synchronous machine is quite similar to that of the induction machine. The stator core and windings of a three-phase synchronous machine are practically identical

Lab 14: 3-phase alternator.

Lab 14: 3-phase alternator. Objective: to obtain the no-load saturation curve of the alternator; to determine the voltage regulation characteristic of the alternator with resistive, capacitive, and inductive

8 Speed control of Induction Machines

8 Speed control of Induction Machines We have seen the speed torque characteristic of the machine. In the stable region of operation in the motoring mode, the curve is rather steep and goes from zero torque

Motor Fundamentals. DC Motor

Motor Fundamentals Before we can examine the function of a drive, we must understand the basic operation of the motor. It is used to convert the electrical energy, supplied by the controller, to mechanical

CHAPTER 3 INDUCTION MOTOR AND DIFFERENT SPEED CONTROL METHODS

CHAPTER 3 INDUCTION MOTOR AND DIFFERENT SPEED CONTROL METHODS Page No 3.1 Introduction 58 3.2 Three Phase Induction Motor 58 3.2.1 Stator 60 3.2.2 Rotor 60 3.2.3 Working principle of three phase induction

Basics of Electricity

Basics of Electricity Generator Theory PJM State & Member Training Dept. PJM 2014 8/6/2013 Objectives The student will be able to: Describe the process of electromagnetic induction Identify the major components

DHANALAKSHMI COLLEGE OF ENGINEERING DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING EE2302 - ELECTRICAL MACHINES II UNIT-I SYNCHRONOUS GENERATOR

1 DHANALAKSHMI COLLEGE OF ENGINEERING DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING Constructional details Types of rotors EE2302 - ELECTRICAL MACHINES II UNIT-I SYNCHRONOUS GENERATOR PART A 1.

Linear DC Motors. 15.1 Magnetic Flux. 15.1.1 Permanent Bar Magnets

Linear DC Motors The purpose of this supplement is to present the basic material needed to understand the operation of simple DC motors. This is intended to be used as the reference material for the linear

Chapter 5 TRANSFORMERS

Chapter 5 TRANSFORMERS Objective Understand the transformer nameplate Describe the basic construction features of a transformer. Explain the relationship between voltage, current, impedance, and power

Induction Motor Theory

PDHonline Course E176 (3 PDH) Induction Motor Theory Instructor: Jerry R. Bednarczyk, P.E. 2012 PDH Online PDH Center 5272 Meadow Estates Drive Fairfax, VA 22030-6658 Phone & Fax: 703-988-0088 www.pdhonline.org

The Synchronous Machine

Experiment No. 5 The Synchronous Machine Synchronous ac machines find application as motors in constant speed applications and, when interfaced to the power source with a variable-frequency converter system,

Experiment 1 The DC Machine

Experiment 1 The DC Machine ECEN 4517 R. W. Erickson and D. Maksimovic The purpose of this experiment is to become familiar with operating principles, equivalent circuit models, and basic characteristics

Chap 21. Electromagnetic Induction

Chap 21. Electromagnetic Induction Sec. 1 - Magnetic field Magnetic fields are produced by electric currents: They can be macroscopic currents in wires. They can be microscopic currents ex: with electrons

Power Quality Paper #3

The Effect of Voltage Dips On Induction Motors by: M D McCulloch 1. INTRODUCTION Voltage depressions caused by faults on the system affect the performance of induction motors, in terms of the production

AP Physics C Chapter 23 Notes Yockers Faraday s Law, Inductance, and Maxwell s Equations

AP Physics C Chapter 3 Notes Yockers Faraday s aw, Inductance, and Maxwell s Equations Faraday s aw of Induction - induced current a metal wire moved in a uniform magnetic field - the charges (electrons)

Synchronous motor. Type. Non-excited motors

Synchronous motor A synchronous electric motor is an AC motor in which the rotation rate of the shaft is synchronized with the frequency of the AC supply current; the rotation period is exactly equal to

2. TRANSFORMERS. The main learning objectives for this chapter are listed below. Use equivalent circuits to determine voltages and currents.

. TRANSFORMERS Transformers are commonly used in applications which require the conversion of AC voltage from one voltage level to another. There are two broad categories of transformers: electronic transformers,

DIRECT CURRENT GENERATORS

DIRECT CURRENT GENERATORS Revision 12:50 14 Nov 05 INTRODUCTION A generator is a machine that converts mechanical energy into electrical energy by using the principle of magnetic induction. This principle

Synchronous generators are built in large units, their rating ranging from tens to hundreds of megawatts.

II. Synchronous Generators Synchronous machines are principally used as alternating current (AC) generators. They supply the electric power used by all sectors of modern societies: industrial, commercial,

EDEXCEL NATIONAL CERTIFICATE/DIPLOMA UNIT 5 - ELECTRICAL AND ELECTRONIC PRINCIPLES NQF LEVEL 3. OUTCOME 3 - MAGNETISM and INDUCTION

EDEXCEL NATIONAL CERTIFICATE/DIPLOMA UNIT 5 - ELECTRICAL AND ELECTRONIC PRINCIPLES NQF LEVEL 3 OUTCOME 3 - MAGNETISM and INDUCTION 3 Understand the principles and properties of magnetism Magnetic field:

Keywords: synchronous generator, synchronous motor, automatic voltage regulator, V- curves, synchronizing power, hunting, excitation system

SYNCHRONOUS MACHINES Tze-Fun Chan Hong Kong Polytechnic University, Hong Kong, China Keywords: synchronous generator, synchronous motor, automatic voltage regulator, V- curves, synchronizing power, hunting,

EEE1001/PHY1002. Magnetic Circuits. The circuit is of length l=2πr. B andφ circulate

1 Magnetic Circuits Just as we view electric circuits as related to the flow of charge, we can also view magnetic flux flowing around a magnetic circuit. The sum of fluxes entering a point must sum to

Revision Calcs. 1. The flux produced by a magnet is 10mWb. Determine the flux density if the area of the pole is 250 mm 2

EMA Revision Calcs Miller College Revision Calcs Revision Calcs 1. The flux produced by a magnet is 10mWb. Determine the flux density if the area of the pole is 250 mm 2 2. For the magnet in the previous

Principles and Working of DC and AC machines

BITS Pilani Dubai Campus Principles and Working of DC and AC machines Dr Jagadish Nayak Constructional features BITS Pilani Dubai Campus DC Generator A generator consists of a stationary portion called

IV. Three-Phase Induction Machines. Induction Machines

IV. Three-Phase Induction Machines Induction Machines 1 2 3 4 5 6 7 8 9 10 11 12 13 Example 1: A 480V, 60 Hz, 6-pole, three-phase, delta-connected induction motor has the following parameters: R 1 =0.461

Synchronous Generator Line Synchronization

Synchronous Generator Line Synchronization 1 Synchronous Generator Line Synchronization Introduction One issue in power generation is synchronous generator starting. Typically, a synchronous generator

Applying Faraday s law to both the primary and the secondary (noting the possibility of sources applied to either winding), yields

TRANSFORMERS Transformers are key elements in power systems. In order to effectively transmit power over long distances without prohibitive line losses, the voltage from the generator (a maximum of output

Chapter 11. Inductors. Objectives

Chapter 11 Inductors Objectives Describe the basic structure and characteristics of an inductor Discuss various types of inductors Analyze series inductors Analyze parallel inductors Analyze inductive

CHAPTER 5 SYNCHRONOUS GENERATOR

CHPTER 5 SYNCHRONOUS GENERTOR Summary: 1. Synchronous Generator Construction 2. The Speed of Rotation of a Synchronous Generator 3. The Internal Generated Voltage of a Synchronous Generator 4. The Equivalent

Chapter 11. Inductors ISU EE. C.Y. Lee

Chapter 11 Inductors Objectives Describe the basic structure and characteristics of an inductor Discuss various types of inductors Analyze series inductors Analyze parallel inductors Analyze inductive

MAGNETISM MAGNETISM. Principles of Imaging Science II (120)

Principles of Imaging Science II (120) Magnetism & Electromagnetism MAGNETISM Magnetism is a property in nature that is present when charged particles are in motion. Any charged particle in motion creates

Chapter 9: Ideal Transformer. 10/9/2003 Electromechanical Dynamics 1

Chapter 9: Ideal Transformer 10/9/003 Electromechanical Dynamics 1 Introduction Transformers are one of the most useful electrical devices provides a change in voltage and current levels provides galvanic

Chapter 4: DC Generators

Chapter 4: DC Generators Creating an AC Voltage The voltage produced in a DC generator is inherently AC and only becomes DC after rectification Consider an AC generator, consisting of a coil on the rotor

1. The diagram below represents magnetic lines of force within a region of space.

1. The diagram below represents magnetic lines of force within a region of space. 4. In which diagram below is the magnetic flux density at point P greatest? (1) (3) (2) (4) The magnetic field is strongest

Extra Questions - 1. 1. What current will flow in a 20Ω resistor when it is connected to a 50V supply? a) 0.4A b) 1.6A c) 2.5A

Extra Questions - 1 1. What current will flow in a 20Ω resistor when it is connected to a 50V supply? a) 0.4A b) 1.6A c) 2.5A 2. A current of 500mA flows in a resistance of 12Ω. What power is dissipated

Characteristics and Benefits

Defining Quality. Building Comfort. Characteristics and Benefits Characteristics and Benefits The two most common electronic devices to vary fan speed in HVAC equipment are the variable frequency drive

AC Induction Motor Slip What It Is And How To Minimize It

AC Induction Motor Slip What It Is And How To Minimize It Mauri Peltola, ABB Oy, Helsinki, Finland The alternating current (AC) induction motor is often referred to as the workhorse of the industry because

Prof. Krishna Vasudevan, Prof. G. Sridhara Rao, Prof. P. Sasidhara Rao

6 Synchronous motor 6.1 Principle of operation In order to understand the principle of operation of a synchronous motor, let us examine what happens if we connect the armature winding (laid out in the

Unit 33 Three-Phase Motors

Unit 33 Three-Phase Motors Objectives: Discuss the operation of wound rotor motors. Discuss the operation of selsyn motors. Discuss the operation of synchronous motors. Determine the direction of rotation

Introduction. Three-phase induction motors are the most common and frequently encountered machines in industry

Induction Motors Introduction Three-phase induction motors are the most common and frequently encountered machines in industry - simple design, rugged, low-price, easy maintenance - wide range of power

Lab 8: DC generators: shunt, series, and compounded.

Lab 8: DC generators: shunt, series, and compounded. Objective: to study the properties of DC generators under no-load and full-load conditions; to learn how to connect these generators; to obtain their

Direct Current Motors

Direct Current Motors DC MOTORS The DC machine can operate as a generator and as a motor. Chap 5. Electrical Machines by Wildi, 6 e Lecturer: R. Alba-Flores Alfred State College Spring 2008 When a DC machine

CHAPTER 4 DESIGN OF INTEGRAL SLOT AND FRACTIONAL SLOT BRUSHLESS DC MOTOR

47 CHAPTER 4 DESIGN OF INTEGRAL SLOT AND FRACTIONAL SLOT BRUSHLESS DC MOTOR 4.1 INTRODUCTION This chapter deals with the design of 24 slots 8 poles, 48 slots 16 poles and 60 slots 16 poles brushless dc

AC generator theory. Resources and methods for learning about these subjects (list a few here, in preparation for your research):

AC generator theory This worksheet and all related files are licensed under the Creative Commons Attribution License, version 1.0. To view a copy of this license, visit http://creativecommons.org/licenses/by/1.0/,

NO LOAD & BLOCK ROTOR TEST ON THREE PHASE INDUCTION MOTOR

INDEX NO. : M-142 TECHNICAL MANUAL FOR NO LOAD & BLOCK ROTOR TEST ON THREE PHASE INDUCTION MOTOR Manufactured by : PREMIER TRADING CORPORATION (An ISO 9001:2000 Certified Company) 212/1, Mansarover Civil

* Self-inductance * Mutual inductance * Transformers. PPT No. 32

* Self-inductance * Mutual inductance * Transformers PPT No. 32 Inductance According to Faraday s Electromagnetic Induction law, induction of an electromotive force occurs in a circuit by varying the magnetic

STUDY OF IDEAL TRANSFORMER AND PRACTICAL TRANSFORMER

STUDY OF IDEAL TRANSFORMER AND PRACTICAL TRANSFORMER RUBY DHANKAR, SAPNA KAMRA,VISHAL JANGRA Abstract- This paper proposes the study of real and ideal transformer. It also explains load, no-load conditions

INSTRUMENTATION AND CONTROL TUTORIAL 2 ELECTRIC ACTUATORS

INSTRUMENTATION AND CONTROL TUTORIAL 2 ELECTRIC ACTUATORS This is a stand alone tutorial on electric motors and actuators. The tutorial is of interest to any student studying control systems and in particular

With Zero Emission and Human Powered Vehicles

Powering the Future With Zero Emission and Human Powered Vehicles Antoni Garcia Espinosa UPC CONTROL OF BRUSHLESS PERMANENT MAGNET MACHINES (BLDC) Powering the Future With Zero Emission and Human Powered

DC motors: dynamic model and control techniques

DC motors: dynamic model and control techniques Luca Zaccarian Contents 1 Magnetic considerations on rotating coils 1 1.1 Magnetic field and conductors.......................... 1 1.2 The magneto-motive

The Polyphase Induction Motor

Experiment No. 4 The Polyphase Induction Motor The polyphase induction motor is the most commonly used industrial motor, finding application in many situations where speed regulation is not essential.

Copyright 2014 Edmentum - All rights reserved. Science Physics Electromagnetic Blizzard Bag 2014-2015 1. Two coils of insulated wire are placed side by side, as shown in the illustration. The blue lines

Electrical Power & Machines

d.c. Machines a.c. Single & Three Phase Machines Dissectible Machines Single & Three phase Transformers Measurement & Control Power Electronics Conventional & Virtual (PC based) Instrumentation Renewable

Einstein Classes, Unit No. 102, 103, Vardhman Ring Road Plaza, Vikas Puri Extn., Outer Ring Road, New Delhi , Ph. : ,

1 EMI & AC 1. Derive an expression for the impendance of a coil in AC ciruit. A current of 1.1 A flows through a coil when connected to a 110 V DC. When 110 V AC of 50 Hz is applied to the same coil, only

Single-Phase AC Induction Squirrel Cage Motors. Permanent Magnet Series Wound Shunt Wound Compound Wound Squirrel Cage. Induction.

FAN ENGINEERING Information and Recommendations for the Engineer FE-1100 Single-Phase AC Induction Squirrel Cage Motors Introduction It is with the electric motor where a method of converting electrical

Control circuit. gathering and reporting fault messages. carrying out of protective functions for the frequency converter and motor.

Control circuit The control circuit, or control card, is the fourth main component of the frequency converter and has four essential tasks: control of the frequency converter semi-conductors. data exchange

Chapter 20. Magnetic Induction Changing Magnetic Fields yield Changing Electric Fields

Chapter 20 Magnetic Induction Changing Magnetic Fields yield Changing Electric Fields Introduction The motion of a magnet can induce current in practical ways. If a credit card has a magnet strip on its

Equipment: Power Supply, DAI, Synchronous motor (8241), Electrodynamometer (8960), Tachometer, Timing belt.

Lab 9: Synchronous motor. Objective: to examine the design of a 3-phase synchronous motor; to learn how to connect it; to obtain its starting characteristic; to determine the full-load characteristic of

Figure Notional Portion of a Shipboard Electric Power Generation System

AC SYCHROOUS GEERATORS Why do we study AC synchronous generators? The short answer is that 3-phase AC generators are the workhorse of the power generation arena. Why? They are not as power limited as DC

Chapt ha e pt r e r 12 RL Circuits

Chapter 12 RL Circuits Sinusoidal Response of RL Circuits The inductor voltage leads the source voltage Inductance causes a phase shift between voltage and current that depends on the relative values of

Inductance. Motors. Generators

Inductance Motors Generators Self-inductance Self-inductance occurs when the changing flux through a circuit arises from the circuit itself. As the current increases, the magnetic flux through a loop due

AC Generators. Basic Generator

AC Generators Basic Generator A basic generator consists of a magnetic field, an armature, slip rings, brushes and a resistive load. The magnetic field is usually an electromagnet. An armature is any number

Electrical impedance - Wikipedia, the free encyclopedia

Electrical impedance From Wikipedia, the free encyclopedia Electrical impedance, or simply impedance, describes a measure of opposition to a sinusoidal alternating current (AC). Electrical impedance extends

The Basics of Permanent Magnet Motor Operations

COURSE# - 1 The Basics of Permanent Magnet Motor Operations By George Holling COURSE# - 2 Introduction Introduction The physics of permanent magnets Basic PM motor operating principles Basic motor parameters

1. Title Electrical fundamentals II (Mechanics Repair and Maintenance)

1. Title Electrical fundamentals II (Mechanics Repair and Maintenance) 2. Code EMAMBG429A 3. Range The knowledge is needed for a wide range of aircraft repair and maintenance works,e.g. applicable to aircrafts,

Motors and Generators

Motors and Generators Electro-mechanical devices: convert electrical energy to mechanical motion/work and vice versa Operate on the coupling between currentcarrying conductors and magnetic fields Governed

USE OF ARNO CONVERTER AND MOTOR-GENERATOR SET TO CONVERT A SINGLE-PHASE AC SUPPLY TO A THREE-PHASE AC FOR CONTROLLING THE SPEED OF A THREE-PHASE INDUCTION MOTOR BY USING A THREE-PHASE TO THREE-PHASE CYCLOCONVERTER

International Journal of Electrical Engineering & Technology (IJEET) Volume 7, Issue 2, March-April, 2016, pp.19-28, Article ID: IJEET_07_02_003 Available online at http:// http://www.iaeme.com/ijeet/issues.asp?jtype=ijeet&vtype=7&itype=2

POWER ELECTRONICS PAGE 2-1 CHAPTER 4 AC MOTORS REV:A MOTORS MOTORS 2 2 REFERENCE LIST 14. Motors. 2 units Motors (3 phase and DC inc.

POWER ELECTRONICS PAGE 2- MOTORS MOTORS 2. BASIC CONCEPT 2.2 ROTATING FIELD 2.3 INDUCTION MOTORS 4.3. CONCEPT 4.3.2 INDUCTION MOTOR EQUIVALENT CIRCUIT 5.3.3 INDUCTION MOTOR TORQUE 5.3.4 EFFECT OF VARYING

Three-Phase Induction Motor

EXPERIMENT Induction motor Three-Phase Induction Motors 208V LL OBJECTIVE This experiment demonstrates the performance of squirrel-cage induction motors and the method for deriving electrical equivalent

How to Turn an AC Induction Motor Into a DC Motor (A Matter of Perspective) Steve Bowling Application Segments Engineer Microchip Technology, Inc.

1 How to Turn an AC Induction Motor Into a DC Motor (A Matter of Perspective) Steve Bowling Application Segments Engineer Microchip Technology, Inc. The territory of high-performance motor control has

FREQUENCY CONTROLLED AC MOTOR DRIVE

FREQUENCY CONTROLLED AC MOTOR DRIVE 1.0 Features of Standard AC Motors The squirrel cage induction motor is the electrical motor motor type most widely used in industry. This leading position results mainly

Open circuit and short circuit tests on single phase transformer

1 Aim Experiment No: 2 Open circuit and short circuit tests on single phase transformer To understand the basic working principle of a transformer. To obtain the equivalent circuit parameters from OC and

Inductive and Magnetic Sensors

Chapter 12 Inductive and Magnetic Sensors 12.1 Inductive Sensors A number of the actuators developed in previous chapters depend on the variation of reluctance with changes in angle or displacement. Since

Physics 12 Study Guide: Electromagnetism Magnetic Forces & Induction. Text References. 5 th Ed. Giancolli Pg

Objectives: Text References 5 th Ed. Giancolli Pg. 588-96 ELECTROMAGNETISM MAGNETIC FORCE AND FIELDS state the rules of magnetic interaction determine the direction of magnetic field lines use the right

April 8. Physics 272. Spring Prof. Philip von Doetinchem

Physics 272 April 8 Spring 2014 http://www.phys.hawaii.edu/~philipvd/pvd_14_spring_272_uhm.html Prof. Philip von Doetinchem philipvd@hawaii.edu Phys272 - Spring 14 - von Doetinchem - 218 L-C in parallel

Chapter 3 AUTOMATIC VOLTAGE CONTROL

Chapter 3 AUTOMATIC VOLTAGE CONTROL . INTRODUCTION TO EXCITATION SYSTEM The basic function of an excitation system is to provide necessary direct current to the field winding of the synchronous generator.

Simple Analysis for Brushless DC Motors Case Study: Razor Scooter Wheel Motor

Simple Analysis for Brushless DC Motors Case Study: Razor Scooter Wheel Motor At first glance, a brushless direct-current (BLDC) motor might seem more complicated than a permanent magnet brushed DC motor,

Coupled Inductors. Introducing Coupled Inductors

Coupled Inductors From power distribution across large distances to radio transmissions, coupled inductors are used extensively in electrical applications. Their properties allow for increasing or decreasing

Electric Engineering II EE 326 Lecture 4 & 5

Electric Engineering II EE 326 Lecture 4 & 5 Transformers ١ Transformers Electrical transformers have many applications: Step up voltages (for electrical energy transmission with

Mutual inductance. Resources and methods for learning about these subjects (list a few here, in preparation for your research):

Mutual inductance This worksheet and all related files are licensed under the Creative Commons Attribution License, version 1.0. To view a copy of this license, visit http://creativecommons.org/licenses/by/1.0/,

Chapter 22. Electromagnetic Induction

Chapter 22 Electromagnetic Induction 22.4 Faraday s Law of Electromagnetic Induction FARADAY S LAW OF ELECTROMAGNETIC INDUCTION The average emf induced in a coil of N loops is E E ) = N ' ( Φ Φ t t o o

Magnetic electro-mechanical machines

Magnetic electro-mechanical machines Lorentz Force A magnetic field exerts force on a moving charge. The Lorentz equation: f = q(e + v B) f: force exerted on charge q E: electric field strength v: velocity

AC : PERMANENT MAGNET LINEAR ALTERNATOR MAG- NETIC FIELD ANALYSIS

AC 2011-1731: PERMANENT MAGNET LINEAR ALTERNATOR MAG- NETIC FIELD ANALYSIS Chong Chen, Middle Tennessee State University Dr. Chong Chen is a professor in the Department of Engineering Technology at Middle

Chapter 14 Magnets and

Chapter 14 Magnets and Electromagnetism How do magnets work? What is the Earth s magnetic field? Is the magnetic force similar to the electrostatic force? Magnets and the Magnetic Force! We are generally

Name: Date: Regents Physics Mr. Morgante UNIT 4B Magnetism

Name: Regents Physics Date: Mr. Morgante UNIT 4B Magnetism Magnetism -Magnetic Force exists b/w charges in motion. -Similar to electric fields, an X stands for a magnetic field line going into the page,

Basic Electrical Theory

Basic Electrical Theory Impedance PJM State & Member Training Dept. PJM 2014 10/24/2013 Objectives Identify the components of Impedance in AC Circuits Calculate the total Impedance in AC Circuits Identify

Edmund Li. Where is defined as the mutual inductance between and and has the SI units of Henries (H).

INDUCTANCE MUTUAL INDUCTANCE If we consider two neighbouring closed loops and with bounding surfaces respectively then a current through will create a magnetic field which will link with as the flux passes

Chapter 27 Magnetic Induction. Copyright 2008 Pearson Education Inc., publishing as Pearson Addison-Wesley

Chapter 27 Magnetic Induction Motional EMF Consider a conductor in a B-field moving to the right. In which direction will an electron in the bar experience a magnetic force? V e - V The electrons in the

Chapter 14: Magnets and Electromagnetism

Chapter 14: Magnets and Electromagnetism 1. Electrons flow around a circular wire loop in a horizontal plane, in a direction that is clockwise when viewed from above. This causes a magnetic field. Inside

EFFICIENCY COMPARISON OF MODERN VARIABLE SPEED DRIVE TECHNOLOGIES

EFFICIENCY COMPARISON OF MODERN VARIABLE SPEED DRIVE TECHNOLOGIES JUNE 1993 BY EDWARD C. LEE POWERTEC INDUSTRIAL CORPORATION Abstract: Brushless D.C. technology is new to the general industrial maketplace

Equipment: Power Supply, DAI, Wound rotor induction motor (8231), Electrodynamometer (8960), timing belt.

Lab 13: Wound rotor induction motor. Objective: to examine the construction of a 3-phase wound rotor induction motor; to understand exciting current, synchronous speed and slip in this motor; to determine

Module 7. Transformer. Version 2 EE IIT, Kharagpur

Module 7 Transformer Version EE IIT, Kharagpur Lesson 4 Practical Transformer Version EE IIT, Kharagpur Contents 4 Practical Transformer 4 4. Goals of the lesson. 4 4. Practical transformer. 4 4.. Core

Prof. Krishna Vasudevan, Prof. G. Sridhara Rao, Prof. P. Sasidhara Rao. D.C Machines

D.C Machines 1 Introduction The steam age signalled the beginning of an industrial revolution. The advantages of machines and gadgets in helping mass production and in improving the services spurred the

1 Introduction. 2 The Symmetrical Component Transformation. J.L. Kirtley Jr.

Massachusetts Institute of Technology Department of Electrical Engineering and Computer Science 6.06 Introduction to Power Systems Class Notes Chapter 4 Introduction To Symmetrical Components J.L. Kirtley

ELG4126 Wind Turbine Generators for Wind Power Plants

ELG4126 Wind Turbine Generators for Wind Power Plants The application of WTGs in modern wind power plants (WPPs) requires an understanding of a number of different aspects related to the design and capabilities

Physics 1214 Chapter 21: Electromagnetic Induction 02/15

Physics 1214 Chapter 21: Electromagnetic Induction 02/15 1 Induction Experiments emf or electromotive force: (from Chapter 19) the influence that moves charge from lower to higher potential. induced current: