Explanation of the Perepiteia rotating machine and the accompanying theory concerning "Back EMF"

Size: px
Start display at page:

Download "Explanation of the Perepiteia rotating machine and the accompanying theory concerning "Back EMF""

Transcription

1 Explanation of the Perepiteia rotating machine and the accompanying theory concerning "Back EMF" By Natan Weissman Abstract The "Perepiteia" generator is demonstrated in a test setup driven by a motor taken from a Ryobi bench grinder. The acceleration behaviour of the system as a whole can be explained entirely by the behaviour of the grinder's induction motor. Meanwhile the hypothesis that back-emf is being managed in a novel way is disproved. Introduction In the demonstration videos for the Perepiteia, the audience's attention is directed to the Perepiteia generator, which causes even knowledgeable people to not pay attention to the grinder motor's contribution to the observed phenomena. This focus is a problem. A bench grinder is a load that requires very little starting torque, which leads to Ryobi's selection of a single-phase induction motor with characteristics appropriate to that application. In order to explain the behaviour of the joined induction motor - Perepiteia machine "system", it is essential to pay attention to the grinder motor. The first requirement is an understanding of the behaviour of induction motors in general. What follows is material excerpted verbatim from a white paper on induction motor behaviour on the website of a very reputable established motor manufacturer, Reliance. The paper is not biased. Reliance should have absolutely no vested interest for or against the Perepiteia, indeed, Reliance is probably unaware of the Perepiteia (whereas Ryobi might be) and the white paper probably predates the Perepiteia, since induction motor theory has been well known for decades, albeit by a very narrow circle of specialists. The average reader may find the jargon and mathematics of the paper somewhat daunting, since the webpage assumes a background in general motor theory, and circuit analysis using complex numbers. However, this page does nicely distill the math to a minimum, and presents correct conclusions about generic single phase induction motor behaviour. Below the material has been edited for brevity, but not in a way that distorts its message. The reader is of course strongly encouraged to visit the original page at Reliance's website. [begin excerpt from Reliance white paper] Induction Motors

2 AC Induction Motor Equivalent Circuits Figure 2 The equivalent circuit for an AC induction motor can help visualize some of the motor characteristics. Figure 2a shows separate circuits for the stator and rotor, with the interaction between them modeled as a "transformer." This transformer has the unique characteristic of also changing the frequency of the signal! While the current in the stator is at the applied frequency of the motor power source, the rotor current flows at a frequency based on the slip of the motor. Rather than work with such a two part equivalent circuit having currents at different frequencies, the circuits of Figure 2a are typically modified to come up with a single circuit as shown in Figure 2b. Speed / Torque Curves As an AC induction motor is started, the values of resistance and reactance offered by the motor (or seen by the power source) will vary. At the instant of applying power to a stopped motor, the magnetic field is rotating much faster than the (stationary) rotor. This implies 100% slip, so r2/s is minimized. As a result, the current drawn at starting (locked rotor) conditions is quite high. Also it is common to design rotor slots which have dramatically different impedance at high slip (say 60 Hz for starting) versus at typically less than I2 Hz slip (normal running). This changes the values of both x2 and r2 from starting to running conditions. As a motor accelerates to speed from a standstill, the changing impedances result in a unique characteristic developed torque and current drawn during the time of acceleration. Depending on the design of the motor, a torque / current characteristic such as one of those shown in Figure 3 would typically result. The NEMA Design B motor is considered the most "general purpose" of these characteristic shapes, with Design C and D typically used for more "difficult to start" loads. Table 2 gives some ranges of characteristics for integral HP, 1200 and 1800 RPM motors.

3 Typical AC Induction Motor Speed / Torque / Current Curves Figure 3 As can be seen from all of these speed/torque curves, the current drawn by an AC motor in accelerating a load up to speed can be dramatically higher than the nominal running current. At the same time, the developed torque (during acceleration) may in some cases be less than the rated full load torque. Various methods exist to control the starting current drawn by an AC motor but the torque per amp seen during starting is always much lower than at running conditions. The nature of an AC induction motors acceleration to running speed is such that it can impose high stresses on the stator end turns and the rotor. The high current draw also stresses the upstream power system, including cabling, transformers, switchgear, etc. For this reason, there is often significant effort made to "control" AC motor starting and acceleration - both in terms of motor design as well as application. Efficiency and Losses Returning to the AC motor equivalent circuit of Figure 2b, we can identify three of the five basic component losses which exist in AC induction motors. The losses dissipated in the resistance of the stator and rotor windings, plus the core loss (eddy current and hysteresis losses in lamination steel) are modeled in the equivalent circuit. A fourth component loss is the friction and windage of the rotor, fan, bearings, etc. Finally, there is the "leftover category of stray load losses. These are losses which are a compilation of various less easily modeled losses, but are often a significant loss in highly efficient machines. The stray load losses include eddy current losses in the conductors, core losses due to flux distortion with load, etc. AC Induction Motor Efficiency vs. Load Figure 4

4 Since the friction and windage and core losses are essentially independent of load, while the other losses vary as the square of load (current), the efficiency of an AC induction motor falls off precipitously at light loads (see Figure 4). Adjustable Frequency, Variable Speed Operation For steady-state (as opposed to starting) operation, AC induction motors offer a reasonably linear torque per amp and high power factor characteristic. This is seen in Figure 5 as the part of the speed torque curve between "breakdown RPM" and "synchronous (no load) RPM." It is this portion of the AC induction motor range of operation within which adjustable frequency drives function. AC Induction Motor Speed Torque Curve Figure 5 [end excerpt from Reliance white paper] Explaining the Perepiteia demonstrations Behaviour of the Induction Motor Technical support staff at the Ryobi company in Anderson, South Carolina indicate that Ryobi is not a member of NEMA, and their motor assembly for small grinders is manufactured privately for them, so that it does not carry a formal NEMA classification. However, simple observation of the machine in action distinguishes it as having a Class A or B motor and definitely not class D. To demonstrate the Perepiteia machine in the University of Ottawa laboratory, a reduced AC voltage is applied using a variable autotransformer (variac). The voltage selected is barely enough to get the single-phase induction motor turning. Otherwise it is normal North American 60 Hz AC. Pause to study the speed-torque curve of Class A & B motors in Figure 3part2. Here there is no external mechanical load applied to that induction motor other than the Perepiteia generator. These initial conditions place the induction motor at or close to the torque minimum near 20% of synchronous speed (Figures 3part2 or 5). A typical demonstration has the Perepiteia generator's coils either open or shorted. If they are open, then the Perepiteia's contribution to the load is only due to its mechanical losses, which are small. If the Perepiteia's coils are shorted, there is a speed-dependent drag as well, but it isn't as great as one might think, because the gap between the Perepiteia's rotating magnets and its stator coils is fairly large (which contributes to the Perepiteia being a relatively inefficient, but otherwise conventional permanent magnet alternator). Either way, the load on the induction motor is not great while the machine is in operation at this low speed. This is also a very low efficiency regime for the induction motor. Consider Figure 4. Note that the x-axis here is load, not speed, so the operating point is near 0% load even if the speed is near 20%. The efficiency is also near 0%.

5 It bears emphasizing that this initial extremely inefficient operating point for the induction motor is nowhere close to a normal operating condition. It is also unstable. If the motor speed increases an infinitessimal bit, then it increases in torque (Figures 3part2 or 5), and decreases in its current consumption (Figure 3part1), which in turn implies an improving efficiency (Figure 4). The improving efficiency permits further acceleration while drawing less power, until the induction motor approaches the breakdown RPM. At or near this point, the acceleration ceases, and the induction motor establishes a steady-state mode of operation, often beyond the breakdown RPM but necessarily below the synchronous RPM. Note that just because the induction motor does accelerate over some range of operation - while drawing less power as it speeds up - one cannot extrapolate and conclude that it will keep speeding up forever (it doesn't), nor that its efficiency will keep increasing forever (that doesn't happen either). It can at most approach synchronous speed, and reach an efficiency of perhaps 90%. Behaviour of the Perepiteia Generator What about the Perepiteia generator's contribution to the above picture? True, the load represented by the Perepiteia generator increases as the motor speed increases, however, so long as that load doesn't fully consume the available torque from the motor, the motor can continue accelerating towards a stable operating point at a faster speed. Thus the acceleration is governed by the induction motor, not by the Perepiteia generator. Changes in Coupling between Motor and Generator What about the demonstrated differences between the ferromagnetic (iron or steel) shaft coupling vs. the non-ferromagnetic coupling (brass, plastic, etc)? Or what about the application of an external permanent magnet to the induction motor in the demo video that doesn't involve the Perepiteia at all? These phenomena are also explained by the nature of single-phase induction motors. One must remember that an induction motor is a rotating transformer. Its core is built of magnetically "soft" material, "soft" in the sense that it allows the direction of magnetization to change very easily and with minimal hysteresis losses. Nonetheless, a magnetic hysteresis curve is traced out with every reversal of the magnetization direction. Changing the externally applied magnetic field "biases" the magnetization in the induction motor's core, placing it in a slightly different efficiency regime. That shift can result in greater or lesser efficiency. The videos demonstrate some cases where the efficiency happens to improve at least marginally thanks to the magnetic bias. When the opposite happens, the result isn't very interesting: the motor simply stops. Thus, the acceleration behaviour of the Perepiteia in the demonstration videos can be explained entirely by the behaviour of the induction motor. No unconventional manipulation of "back EMF" is required to explain this. None. Visitors have gone to the laboratory at the University of Ottawa, and have seen the setup operating. Their observations are consistent with the present hypothesis. The inventor Mr. Heins and his colleagues have been asked whether they have attempted the same experiment with a DC motor. Visitors were told that this has indeed been tried, and that the Perepiteia didn't work when driven by a DC motor. This reinforces the hypothesis that the induction motor was solely responsible for the acceleration phenomenon, since if unconventional "back EMF" manipulation in the generator were responsible, it would have worked with a DC motor as well. Apparently the Perepiteia has not been tested using a dynamometer instead of a single phase induction motor, a test that would further confirm the present result. The Back-EMF Theory A separate issue is Mr. Heins' "back EMF" hypothesis, which claims that the direction of the magnetic flux in a transformer or rotating machine can be manipulated to reinforce rather than oppose the applied current and flux. The conventional result is predicted by Lenz's law and

6 Maxwell's theory. One may argue that just because the back-emf hypothesis isn't applicable to explaining the Perepiteia experimental results, that this doesn't mean that the back-emf hypothesis isn't correct in its own right. Fortunately the back-emf hypothesis can be subjected to a very simple test. Anybody who has tried to turn a conventional generator by hand while it is under load will have noticed that the torque required to turn it isn't uniform. The torque you have to apply increases and decreases periodically. This variation in the drag load is called "cogging torque". Try it sometime with a bicycle generator for example. If you can observe what happens inside the generator, you will notice that the number of "bumps" in the torque per rotation is equal to the number of poles. On the Perepiteia machine, the rotor poles are conveniently visible. They are the disk magnets on the rotor, and their path takes them past coils on the stator that are also perfectly visible. Concerning the cogging torque, the "back EMF" hypothesis makes a radically different prediction than James Clerk Maxwell's theory of electromagnetics. The Back EMF hypothesis claims that when a rotor magnet on the Perepiteia approaches a stator coil, it is drawn towards that coil, and when the magnet recedes from a stator coil, it pushes away from that coil. This is the exact opposite of the behaviour predicted by Maxwell's theory (more specifically, by Lenz' law) for all generators, which predicts the cogging drag described in the previous paragraph: When the magnet approaches a coil, it opposes the motion, and when it receeds from the coil, it also opposes the motion, but that opposition is nonuniform and is strongest when the magnet is closest to the coil. So, who is right in the case of the Perepiteia? Resolving this question is very easy to test by hand-cranking the Perepiteia, with it either decoupled from the induction motor, or with the motor simply not powered. Visitors to the lab at the University of Ottawa have performed this simple experiment. The answer is simple and unequivocal: the cogging behaviour of the Perepiteia is normal, exactly as predicted by Maxwell. Another telltale sign of whether "back EMF" was being manipulated would be to observe the phase of the flux in the cores beneath the Perepiteia's coils. This is not at all easy to do except perhaps with a Kerr effect microscope, however, observing the magnitude and phase of the current in the stator coils (which results from the flux) is very easy by means of an oscilloscope. This test has not been applied to the Perepiteia machine, but has been tried independently with a Perepiteia transformer, which is claimed to use the same anomalous back-emf mechanism to obtain perpetuum mobile levels of efficiency in excess of 100% (sometimes as high as several thousand %). A transformer was tested carefully by an engineer with a Ph.D. under various operating conditions recommended by the inventor himself, conditions under which the inventor reported efficiencies between one hundred and several thousand percent, and it was found that: (1) the magnitude and phase of the current in its coils was consistent with Lenz's Law and Maxwell's theory in general. (2) the efficiency of the transformer was poor, between 12% and 75% (vs. over 90% for typical conventional transformers). The poor efficiency was due in part to poor design, and in part to the fact that the specified operating conditions were beyond the unit's flux handling capacity, so the core was in saturation. (3) the saturation flux handling was poor for a transformer of its size, such that it wasn't able to carry anywhere near the currents that it should be able to handle. Conclusions The acceleration of the Perepiteia generator in all the configurations shown in the demonstration videos can be explained by the behaviour of the induction motor driving the Perepiteia. The acceleration phenomena cannot be observed when a DC/universal motor is used. There is no evidence that anomalous manipulation of Back-EMF takes place within the Perepiteia generator or the Perepiteia transformer. The behaviour of both Perepiteia devices is consistent with Maxwell's theory.

Single Phase Induction Motor. Dr. Sanjay Jain Department Of EE/EX

Single Phase Induction Motor. Dr. Sanjay Jain Department Of EE/EX Single Phase Induction Motor Dr. Sanjay Jain Department Of EE/EX Application :- The single-phase induction machine is the most frequently used motor for refrigerators, washing machines, clocks, drills,

More information

CHAPTER 6 INTRODUCTION TO MOTORS AND GENERATORS

CHAPTER 6 INTRODUCTION TO MOTORS AND GENERATORS CHAPTER 6 INTRODUCTION TO MOTORS AND GENERATORS Objective Describe the necessary conditions for motor and generator operation. Calculate the force on a conductor carrying current in the presence of the

More information

CHAPTER THREE DC MOTOR OVERVIEW AND MATHEMATICAL MODEL

CHAPTER THREE DC MOTOR OVERVIEW AND MATHEMATICAL MODEL CHAPTER THREE DC MOTOR OVERVIEW AND MATHEMATICAL MODEL 3.1 Introduction Almost every mechanical movement that we see around us is accomplished by an electric motor. Electric machines are a means of converting

More information

PI Electrical Equipment - Course PI 30.2 MOTORS

PI Electrical Equipment - Course PI 30.2 MOTORS Electrical Equipment - Course PI 30.2 MOTORS OBJECTIVES On completion of this module the student will be able to: 1. Briefly explain, in writing, "shaft rotation" as an interaction of stator and rotor

More information

Pre-lab Questions: Please review chapters 19 and 20 of your textbook

Pre-lab Questions: Please review chapters 19 and 20 of your textbook Introduction Magnetism and electricity are closely related. Moving charges make magnetic fields. Wires carrying electrical current in a part of space where there is a magnetic field experience a force.

More information

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

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

More information

A Practical Guide to Free Energy Devices

A Practical Guide to Free Energy Devices A Practical Guide to Free Energy Devices Part PatD20: Last updated: 26th September 2006 Author: Patrick J. Kelly This patent covers a device which is claimed to have a greater output power than the input

More information

VIII. Three-phase Induction Machines (Asynchronous Machines) Induction Machines

VIII. Three-phase Induction Machines (Asynchronous Machines) Induction Machines VIII. Three-phase Induction Machines (Asynchronous Machines) Induction Machines 1 Introduction Three-phase induction motors are the most common and frequently encountered machines in industry simple design,

More information

DEPARTMENT OF EI ELECTRICAL MACHINE ASSIGNMENT 1

DEPARTMENT OF EI ELECTRICAL MACHINE ASSIGNMENT 1 It is the mark of an educated mind to be able to entertain a thought without accepting it. DEPARTMENT OF EI ELECTRICAL MACHINE ASSIGNMENT 1 1. Explain the Basic concepts of rotating machine. 2. With help

More information

DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING

DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING QUESTION BANK 16EET41 SYNCHRONOUS AND INDUCTION MACHINES UNIT I SYNCHRONOUS GENERATOR 1. Why the stator core is laminated? 2. Define voltage regulation

More information

BELT-DRIVEN ALTERNATORS

BELT-DRIVEN ALTERNATORS CHAPTER 13 BELT-DRIVEN ALTERNATORS INTRODUCTION A generator is a machine that converts mechanical energy into electrical energy using the principle of magnetic induction. This principle is based on the

More information

AP Physics B: Ch 20 Magnetism and Ch 21 EM Induction

AP Physics B: Ch 20 Magnetism and Ch 21 EM Induction Name: Period: Date: AP Physics B: Ch 20 Magnetism and Ch 21 EM Induction MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) If the north poles of

More information

Pre-lab Questions: Please review chapters 19 and 20 of your textbook

Pre-lab Questions: Please review chapters 19 and 20 of your textbook Introduction Magnetism and electricity are closely related. Moving charges make magnetic fields. Wires carrying electrical current in a part of space where there is a magnetic field experience a force.

More information

Iowa State University Electrical and Computer Engineering. E E 452. Electric Machines and Power Electronic Drives

Iowa State University Electrical and Computer Engineering. E E 452. Electric Machines and Power Electronic Drives Electrical and Computer Engineering E E 452. Electric Machines and Power Electronic Drives Laboratory #12 Induction Machine Parameter Identification Summary The squirrel-cage induction machine equivalent

More information

Motor Basics AGSM 325 Motors vs Engines

Motor Basics AGSM 325 Motors vs Engines Motor Basics AGSM 325 Motors vs Engines Motors convert electrical energy to mechanical energy. Engines convert chemical energy to mechanical energy. 1 Motors Advantages Low Initial Cost - $/Hp Simple &

More information

Fachpraktikum Elektrische Maschinen. Theory of Induction Machines

Fachpraktikum Elektrische Maschinen. Theory of Induction Machines Fachpraktikum Elektrische Maschinen Theory of Induction Machines Prepared by Arda Tüysüz January 2013 Fundamentals Induction machines (also known as asynchronous machines) are by far the most common type

More information

Figure 1: Relative Directions as Defined for Faraday s Law

Figure 1: Relative Directions as Defined for Faraday s Law Faraday s Law INTRODUCTION This experiment examines Faraday s law of electromagnetic induction. The phenomenon involves induced voltages and currents due to changing magnetic fields. (Do not confuse this

More information

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

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 Twin City Fan FE-1100 Single-Phase AC Induction Squirrel Cage Motors Introduction It is with the electric motor where a method of converting

More information

Technical Guide No. 7. Dimensioning of a Drive system

Technical Guide No. 7. Dimensioning of a Drive system Technical Guide No. 7 Dimensioning of a Drive system 2 Technical Guide No.7 - Dimensioning of a Drive system Contents 1. Introduction... 5 2. Drive system... 6 3. General description of a dimensioning

More information

Mr. Freeze QUALITATIVE QUESTIONS

Mr. Freeze QUALITATIVE QUESTIONS QUALITATIVE QUESTIONS Many of the questions that follow refer to the graphs of data collected when riding Mr. Freeze with high tech data collection vests. With your I.D., you can borrow a vest without

More information

PHY 152 (ELECTRICITY AND MAGNETISM)

PHY 152 (ELECTRICITY AND MAGNETISM) PHY 152 (ELECTRICITY AND MAGNETISM) ELECTRIC MOTORS (AC & DC) ELECTRIC GENERATORS (AC & DC) AIMS Students should be able to Describe the principle of magnetic induction as it applies to DC and AC generators.

More information

AUCOM WHITE PAPER SERIES GET YOUR MOTOR RUNNING. An introduction to reduced voltage starting of three phase induction motors

AUCOM WHITE PAPER SERIES GET YOUR MOTOR RUNNING. An introduction to reduced voltage starting of three phase induction motors AUCOM WHITE PAPER SERIES GET YOUR MOTOR RUNNING An introduction to reduced voltage starting of three phase induction motors GET YOUR MOTOR RUNNING WHITE PAPER #1 Reduced voltage starting of three phase

More information

EEE3441 Electrical Machines Department of Electrical Engineering. Lecture. Introduction to Electrical Machines

EEE3441 Electrical Machines Department of Electrical Engineering. Lecture. Introduction to Electrical Machines Department of Electrical Engineering Lecture Introduction to Electrical Machines 1 In this Lecture Induction motors and synchronous machines are introduced Production of rotating magnetic field Three-phase

More information

Induction machine characteristics and operation. Induction Machines

Induction machine characteristics and operation. Induction Machines Induction Machines 1.1 Introduction: An essential feature of the operation of the synchronous machine is that the rotor runs at the same speed as the rotating magnetic field produced by the stator winding.

More information

Almost 200 years ago, Faraday looked for evidence that a magnetic field would induce an electric current with this apparatus:

Almost 200 years ago, Faraday looked for evidence that a magnetic field would induce an electric current with this apparatus: Chapter 21 Electromagnetic Induction and Faraday s Law Chapter 21 Induced EMF Faraday s Law of Induction; Lenz s Law EMF Induced in a Moving Conductor Changing Magnetic Flux Produces an E Field Inductance

More information

EXPERIMENT 13 QUALITATIVE STUDY OF INDUCED EMF

EXPERIMENT 13 QUALITATIVE STUDY OF INDUCED EMF 220 13-1 I. THEORY EXPERIMENT 13 QUALITATIVE STUDY OF INDUCED EMF Along the extended central axis of a bar magnet, the magnetic field vector B r, on the side nearer the North pole, points away from this

More information

ALTERNATING CURRENT - PART 1

ALTERNATING CURRENT - PART 1 Reading 9 Ron Bertrand VK2DQ http://www.radioelectronicschool.com ALTERNATING CURRENT - PART 1 This is a very important topic. You may be thinking that when I speak of alternating current (AC), I am talking

More information

UNIT 2. INTRODUCTION TO DC GENERATOR (Part 1) OBJECTIVES. General Objective

UNIT 2. INTRODUCTION TO DC GENERATOR (Part 1) OBJECTIVES. General Objective DC GENERATOR (Part 1) E2063/ Unit 2/ 1 UNIT 2 INTRODUCTION TO DC GENERATOR (Part 1) OBJECTIVES General Objective : To apply the basic principle of DC generator, construction principle and types of DC generator.

More information

IMPROVING MOTOR SYSTEM EFFICIENCY WITH HIGH EFFICIENCY BELT DRIVE SYSTEMS

IMPROVING MOTOR SYSTEM EFFICIENCY WITH HIGH EFFICIENCY BELT DRIVE SYSTEMS IMPROVING MOTOR SYSTEM EFFICIENCY WITH HIGH EFFICIENCY BELT DRIVE SYSTEMS Contents Introduction Where to Find Energy Saving Opportunities Power Transmission System Efficiency Enhancing Motor System Performance

More information

PHYS 2212L - Principles of Physics Laboratory II

PHYS 2212L - Principles of Physics Laboratory II PHYS 2212L - Principles of Physics Laboratory II Laboratory Advanced Sheet Faraday's Law 1. Objectives. The objectives of this laboratory are a. to verify the dependence of the induced emf in a coil on

More information

Basic Motor Theory. Introduction

Basic Motor Theory. Introduction Basic Motor Theory Introduction It has been said that if the Ancient Romans, with their advanced civilization and knowledge of the sciences, had been able to develop a steam motor, the course of history

More information

MOTORS, VOLTAGE, EFFICIENCY AND WIRING. A Deeper Understanding

MOTORS, VOLTAGE, EFFICIENCY AND WIRING. A Deeper Understanding MOTORS, VOLTAGE, EFFICIENCY AND WIRING A Deeper Understanding An understanding of motors, voltage, efficiency, wiring, and how these concepts fit together cohesively is important for several reasons. Greater

More information

Electrical machines - generators and motors

Electrical machines - generators and motors Electrical machines - generators and motors We have seen that when a conductor is moved in a magnetic field or when a magnet is moved near a conductor, a current flows in the conductor. The amount of current

More information

SEMA Technology Redundancy Advantages

SEMA Technology Redundancy Advantages SEMA Technology Redundancy Advantages Authored by Kinetic Art & Technology Revised May 11, 2009 Purpose The purpose of this document is to describe some of the advantages of Kinetic Art & Technology's

More information

INDUCTANCE FM CHAPTER 6

INDUCTANCE FM CHAPTER 6 CHAPTER 6 INDUCTANCE INTRODUCTION The study of inductance is a very challenging but rewarding segment of electricity. It is challenging because at first it seems that new concepts are being introduced.

More information

Electrical Theory. Generator Theory. PJM State & Member Training Dept. PJM /22/2018

Electrical Theory. Generator Theory. PJM State & Member Training Dept. PJM /22/2018 Electrical Theory Generator Theory PJM State & Member Training Dept. PJM 2018 Objectives The student will be able to: Describe the process of electromagnetic induction Identify the major components of

More information

Chapter 22: Electric motors and electromagnetic induction

Chapter 22: Electric motors and electromagnetic induction Chapter 22: Electric motors and electromagnetic induction The motor effect movement from electricity When a current is passed through a wire placed in a magnetic field a force is produced which acts on

More information

14 Single- Phase A.C. Motors I

14 Single- Phase A.C. Motors I Lectures 14-15, Page 1 14 Single- Phase A.C. Motors I There exists a very large market for single-phase, fractional horsepower motors (up to about 1 kw) particularly for domestic use. Like many large volume

More information

(d) None of the above.

(d) None of the above. Dr. Mahalingam College of Engineering and Technology, Pollachi-3 (An Autonomous Institution affiliated to Anna niversity) CCET II (2016 Regulation) Name of Programme: B.E. (EEE) Course Code & Course Title:

More information

Electromagnetic Induction (approx. 1.5 h) (11/9/15)

Electromagnetic Induction (approx. 1.5 h) (11/9/15) (approx. 1.5 h) (11/9/15) Introduction In 1819, during a lecture demonstration, the Danish scientist Hans Christian Oersted noticed that the needle of a compass was deflected when placed near a current-carrying

More information

AGN Unbalanced Loads

AGN Unbalanced Loads Application Guidance Notes: Technical Information from Cummins Generator Technologies AGN 017 - Unbalanced Loads There will inevitably be some applications where a Generating Set is supplying power to

More information

Electrical Machines -II

Electrical Machines -II Objective Type Questions: 1. Basically induction machine was invented by (a) Thomas Alva Edison (b) Fleming (c) Nikola Tesla (d) Michel Faraday Electrical Machines -II 2. What will be the amplitude and

More information

Introduction: Electromagnetism:

Introduction: Electromagnetism: This model of both an AC and DC electric motor is easy to assemble and disassemble. The model can also be used to demonstrate both permanent and electromagnetic motors. Everything comes packed in its own

More information

APGENCO/APTRANSCO Assistant Engineer Electrical Previous Question Papers Q.1 The two windings of a transformer is conductively linked. inductively linked. not linked at all. electrically linked. Q.2 A

More information

ESO 210 Introduction to Electrical Engineering

ESO 210 Introduction to Electrical Engineering ESO 210 Introduction to Electrical Engineering Lectures-37 Polyphase (3-phase) Induction Motor 2 Determination of Induction Machine Parameters Three tests are needed to determine the parameters in an induction

More information

Electromagnetic Induction Chapter Questions. 1. What is the Electromagnetic Force (EMF)? What are the units of EMF?

Electromagnetic Induction Chapter Questions. 1. What is the Electromagnetic Force (EMF)? What are the units of EMF? Electromagnetic Induction Chapter Questions 1. What is the Electromagnetic Force (EMF)? What are the units of EMF? 2. The discovery of electric currents generating an magnetic field led physicists to look

More information

Experiment 6: Induction

Experiment 6: Induction Experiment 6: Induction Part 1. Faraday s Law. You will send a current which changes at a known rate through a solenoid. From this and the solenoid s dimensions you can determine the rate the flux through

More information

694 Electric Machines

694 Electric Machines 694 Electric Machines 9.1 A 4-pole wound-rotor induction motor is used as a frequency changer. The stator is connected to a 50 Hz, 3-phase supply. The load is connected to the rotor slip rings. What are

More information

CHAPTER 4 HARDWARE DEVELOPMENT OF DUAL ROTOR RADIAL FLUX PERMANENT MAGNET GENERATOR FOR STAND-ALONE WIND ENERGY SYSTEMS

CHAPTER 4 HARDWARE DEVELOPMENT OF DUAL ROTOR RADIAL FLUX PERMANENT MAGNET GENERATOR FOR STAND-ALONE WIND ENERGY SYSTEMS 66 CHAPTER 4 HARDWARE DEVELOPMENT OF DUAL ROTOR RADIAL FLUX PERMANENT MAGNET GENERATOR FOR STAND-ALONE WIND ENERGY SYSTEMS 4.1 INTRODUCTION In this chapter, the prototype hardware development of proposed

More information

Motional emf. as long as the velocity, field, and length are mutually perpendicular.

Motional emf. as long as the velocity, field, and length are mutually perpendicular. Motional emf Motional emf is the voltage induced across a conductor moving through a magnetic field. If a metal rod of length L moves at velocity v through a magnetic field B, the motional emf is: ε =

More information

Unit III-Three Phase Induction Motor:

Unit III-Three Phase Induction Motor: INTRODUCTION Unit III-Three Phase Induction Motor: The three phase induction motor runs on three phase AC supply. It is an ac motor. The power is transferred by means of induction. So it is also called

More information

1. What type of material can be induced to become a temporary magnet? A) diamagnetic B) ferromagnetic C) monomagnetic D) paramagnetic

1. What type of material can be induced to become a temporary magnet? A) diamagnetic B) ferromagnetic C) monomagnetic D) paramagnetic Assignment 1 Magnetism and Electromagnetism Name: Multiple Choice Identify the letter of the choice that best completes the statement or answers the question. Show appropriate workings. 1. What type of

More information

DISSECTIBLE TRANSFORMER - large

DISSECTIBLE TRANSFORMER - large DESCRIPTION: DISSECTIBLE TRANSFORMER - large Cat: EM1660-001 220/240V.AC. 50/60Hz. The IEC Dissectible Transformer is a very useful instrument for the teaching of transformer theory and many other AC phenomena.

More information

A Practical Guide to Free Energy Devices

A Practical Guide to Free Energy Devices A Practical Guide to Free Energy Devices Part PatD11: Last updated: 3rd February 2006 Author: Patrick J. Kelly Electrical power is frequently generated by spinning the shaft of a generator which has some

More information

INSTITUTE OF AERONAUTICAL ENGINEERING Dundigal, Hyderabad

INSTITUTE OF AERONAUTICAL ENGINEERING Dundigal, Hyderabad INSTITUTE OF AERONAUTICAL ENGINEERING Dundigal, Hyderabad - 500 043 MECHANICAL ENGINEERING ASSIGNMENT Name : Electrical and Electronics Engineering Code : A40203 Class : II B. Tech I Semester Branch :

More information

1. This question is about electrical energy and associated phenomena.

1. This question is about electrical energy and associated phenomena. 1. This question is about electrical energy and associated phenomena. Electromagnetism The current in the circuit is switched on. electromagnet State Faraday s law of electromagnetic induction and use

More information

AC MOTOR TYPES. DESCRIBE how torque is produced in a single-phase AC motor. EXPLAIN why an AC synchronous motor does not have starting torque.

AC MOTOR TYPES. DESCRIBE how torque is produced in a single-phase AC motor. EXPLAIN why an AC synchronous motor does not have starting torque. Various types of AC motors are used for specific applications. By matching the type of motor to the appropriate application, increased equipment performance can be obtained. EO 1.5 EO 1.6 EO 1.7 EO 1.8

More information

ECE 325 Electric Energy System Components 6 Three Phase Induction Motors. Instructor: Kai Sun Fall 2016

ECE 325 Electric Energy System Components 6 Three Phase Induction Motors. Instructor: Kai Sun Fall 2016 ECE 325 Electric Energy System Components 6 Three Phase Induction Motors Instructor: Kai Sun Fall 2016 1 Content (Materials are from Chapters 13-15) Components and basic principles Selection and application

More information

General Purpose Permanent Magnet Motor Drive without Speed and Position Sensor

General Purpose Permanent Magnet Motor Drive without Speed and Position Sensor General Purpose Permanent Magnet Motor Drive without Speed and Position Sensor Jun Kang, PhD Yaskawa Electric America, Inc. 1. Power consumption by electric motors Fig.1 Yaskawa V1000 Drive and a PM motor

More information

R07 SET - 1

R07 SET - 1 R07 SET - 1 II B. Tech II Semester Supplementary Examinations April/May 2013 ELECTRICAL MACHINES - II (Electrical and Electronics Engineering) Time: 3 hours Max. Marks: 80 Answer any FIVE Questions All

More information

Historical Development

Historical Development TOPIC 3 DC MACHINES DC Machines 2 Historical Development Direct current (DC) motor is one of the first machines devised to convert electrical power into mechanical power. Its origin can be traced to the

More information

Synchronous Generators I. Spring 2013

Synchronous Generators I. Spring 2013 Synchronous Generators I Spring 2013 Construction of synchronous machines In a synchronous generator, a DC current is applied to the rotor winding producing a rotor magnetic field. The rotor is then turned

More information

Chapter 7: DC Motors and Transmissions. 7.1: Basic Definitions and Concepts

Chapter 7: DC Motors and Transmissions. 7.1: Basic Definitions and Concepts Chapter 7: DC Motors and Transmissions Electric motors are one of the most common types of actuators found in robotics. Using them effectively will allow your robot to take action based on the direction

More information

EXPERIMENT CALIBRATION OF 1PHASE ENERGY METER

EXPERIMENT CALIBRATION OF 1PHASE ENERGY METER EXPERIMENT CALIBRATION OF PHASE ENERGY METER THEORY:- Energy Meters are integrating instruments used to measure the quantity of electrical energy supplied to a circuit in a given time. Single phase energy

More information

Chapter 31. Faraday s Law

Chapter 31. Faraday s Law Chapter 31 Faraday s Law Michael Faraday 1791 1867 British physicist and chemist Great experimental scientist Contributions to early electricity include: Invention of motor, generator, and transformer

More information

Page 1. Design meeting 18/03/2008. By Mohamed KOUJILI

Page 1. Design meeting 18/03/2008. By Mohamed KOUJILI Page 1 Design meeting 18/03/2008 By Mohamed KOUJILI I. INTRODUCTION II. III. IV. CONSTRUCTION AND OPERATING PRINCIPLE 1. Stator 2. Rotor 3. Hall sensor 4. Theory of operation TORQUE/SPEED CHARACTERISTICS

More information

Armature Reaction and Saturation Effect

Armature Reaction and Saturation Effect Exercise 3-1 Armature Reaction and Saturation Effect EXERCISE OBJECTIVE When you have completed this exercise, you will be able to demonstrate some of the effects of armature reaction and saturation in

More information

CHAPTER 8: ELECTROMAGNETISM

CHAPTER 8: ELECTROMAGNETISM CHAPTER 8: ELECTROMAGNETISM 8.1 Effect of a Magnet on a Current-carrying Conductor 8.1.1 Straight Wire Magnetic fields are circular Field is strongest close to the wire Increasing the current increases

More information

The Wound-Rotor Induction Motor Part I

The Wound-Rotor Induction Motor Part I Experiment 1 The Wound-Rotor Induction Motor Part I OBJECTIVE To examine the construction of the three-phase wound-rotor induction motor. To understand exciting current, synchronous speed and slip in a

More information

Synchronous Generators I. EE 340 Spring 2011

Synchronous Generators I. EE 340 Spring 2011 Synchronous Generators I EE 340 Spring 2011 Construction of synchronous machines In a synchronous generator, a DC current is applied to the rotor winding producing a rotor magnetic field. The rotor is

More information

Regulation: R16 Course & Branch: B.Tech EEE

Regulation: R16 Course & Branch: B.Tech EEE SIDDHARTH GROUP OF INSTITUTIONS :: PUTTUR Siddharth Nagar, Narayanavanam Road 517583 QUESTION BANK (Descriptive) Subject with Code : Electrical Machines-II (16EE215) Regulation: R16 Course & Branch: B.Tech

More information

ELECTROMAGNETISM. 1. the number of turns. 2. An increase in current. Unlike an ordinary magnet, electromagnets can be switched on and off.

ELECTROMAGNETISM. 1. the number of turns. 2. An increase in current. Unlike an ordinary magnet, electromagnets can be switched on and off. ELECTROMAGNETISM Unlike an ordinary magnet, electromagnets can be switched on and off. A simple electromagnet consists of: - a core (usually iron) - several turns of insulated copper wire When current

More information

Richard Hull s Mysterious Motor

Richard Hull s Mysterious Motor Update June 2009: The following is some updated information regarding http://www.mtaonline.net/~hheffner/hullmotor.pdf fig. 3 provided below is an improved version of Fig. 3 in the above original work.

More information

ECE1750, Spring Motor Drives and Other

ECE1750, Spring Motor Drives and Other ECE1750, Spring 2018 Motor Drives and Other Applications 1 Three-Phase Induction Motors Reliable Rugged Long lived Low maintenance Efficient (Source: EPRI Adjustable Speed Drives Application Guide) The

More information

UNIT I D.C. MACHINES PART A. 3. What are factors on which hysteresis loss? It depends on magnetic flux density, frequency & volume of the material.

UNIT I D.C. MACHINES PART A. 3. What are factors on which hysteresis loss? It depends on magnetic flux density, frequency & volume of the material. EE6352-ELECTRICAL ENGINEERING AND INSTRUMENTATION UNIT I D.C. MACHINES PART A 1. What is prime mover? The basic source of mechanical power which drives the armature of the generator is called prime mover.

More information

Single Phase Induction Motors

Single Phase Induction Motors Single Phase Induction Motors Prof. T. H. Panchal Asst. Professor Department of Electrical Engineering Institute of Technology Nirma University, Ahmedabad Introduction As the name suggests, these motors

More information

EXPERIMENTAL VERIFICATION OF INDUCED VOLTAGE SELF- EXCITATION OF A SWITCHED RELUCTANCE GENERATOR

EXPERIMENTAL VERIFICATION OF INDUCED VOLTAGE SELF- EXCITATION OF A SWITCHED RELUCTANCE GENERATOR EXPERIMENTAL VERIFICATION OF INDUCED VOLTAGE SELF- EXCITATION OF A SWITCHED RELUCTANCE GENERATOR Velimir Nedic Thomas A. Lipo Wisconsin Power Electronic Research Center University of Wisconsin Madison

More information

Lab 6: Wind Turbine Generators

Lab 6: Wind Turbine Generators Lab 6: Wind Turbine Generators Name: Pre Lab Tip speed ratio: Tip speed ratio (TSR) is defined as: Ω, where Ω=angular velocity of wind, and R=radius of rotor (blade length). If the rotational speed of

More information

ELECTROMAGNETIC INDUCTION. Faraday s Law Lenz s Law Generators Transformers Cell Phones

ELECTROMAGNETIC INDUCTION. Faraday s Law Lenz s Law Generators Transformers Cell Phones ELECTROMAGNETIC INDUCTION Faraday s Law Lenz s Law Generators Transformers Cell Phones Recall Oersted's principle: when a current passes through a straight conductor there will be a circular magnetic field

More information

3 Electricity from Magnetism

3 Electricity from Magnetism CHAPTER 2 3 Electricity from Magnetism SECTION Electromagnetism BEFORE YOU READ After you read this section, you should be able to answer these questions: How can a magnetic field make an electric current?

More information

IMPACT OF SKIN EFFECT FOR THE DESIGN OF A SQUIRREL CAGE INDUCTION MOTOR ON ITS STARTING PERFORMANCES

IMPACT OF SKIN EFFECT FOR THE DESIGN OF A SQUIRREL CAGE INDUCTION MOTOR ON ITS STARTING PERFORMANCES IMPACT OF SKIN EFFECT FOR THE DESIGN OF A SQUIRREL CAGE INDUCTION MOTOR ON ITS STARTING PERFORMANCES Md. Shamimul Haque Choudhury* 1,2, Muhammad Athar Uddin 1,2, Md. Nazmul Hasan 1,2, M. Shafiul Alam 1,2

More information

Pretest Module 21 Units 1-4 AC Generators & Three-Phase Motors

Pretest Module 21 Units 1-4 AC Generators & Three-Phase Motors Pretest Module 21 Units 1-4 AC Generators & Three-Phase Motors 1. What are the two main parts of a three-phase motor? Stator and Rotor 2. Which part of a three-phase squirrel-cage induction motor is a

More information

Electrical Machines and Energy Systems: Overview SYED A RIZVI

Electrical Machines and Energy Systems: Overview SYED A RIZVI Electrical Machines and Energy Systems: Overview SYED A RIZVI Electrical Machines and Energy Systems Deal with the generation, transmission & distribution, and utilization of electric power. This course

More information

Electromagnetic Induction, Faraday s Experiment

Electromagnetic Induction, Faraday s Experiment Electromagnetic Induction, Faraday s Experiment A current can be produced by a changing magnetic field. First shown in an experiment by Michael Faraday A primary coil is connected to a battery. A secondary

More information

Inverter control of low speed Linear Induction Motors

Inverter control of low speed Linear Induction Motors Inverter control of low speed Linear Induction Motors Stephen Colyer, Jeff Proverbs, Alan Foster Force Engineering Ltd, Old Station Close, Shepshed, UK Tel: +44(0)1509 506 025 Fax: +44(0)1509 505 433 e-mail:

More information

DC Series Motors by Thomas E. Kissell Industrial Electronics, Second Edition, Prentice Hall PTR

DC Series Motors by Thomas E. Kissell Industrial Electronics, Second Edition, Prentice Hall PTR Site Help Search NI Developer Zone DC Series Motors by Thomas E. Kissell Industrial Electronics, Second Edition, Prentice Hall PTR Back to Document Table of Contents: Series Motor Diagram Series Motor

More information

Chapter 29 Electromagnetic Induction and Faraday s Law

Chapter 29 Electromagnetic Induction and Faraday s Law Chapter 29 Electromagnetic Induction and Faraday s Law 29.1 Induced EMF Units of Chapter 29 : 1-8 29.3 EMF Induced in a Moving Conductor: 9, 10 29.4 Electric Generators: 11 29.5 Counter EMF and Torque;

More information

CSDA Best Practice. Hi-Cycle Concrete Cutting Equipment. Effective Date: Oct 1, 2010 Revised Date:

CSDA Best Practice. Hi-Cycle Concrete Cutting Equipment. Effective Date: Oct 1, 2010 Revised Date: CSDA Best Practice Title: Hi-Cycle Concrete Cutting Equipment Issue No: CSDA-BP-010 : Oct 1, 2010 Revised : Introduction Hi-cycle/high frequency concrete cutting equipment has become more prevalent in

More information

Step Motor Lower-Loss Technology An Update

Step Motor Lower-Loss Technology An Update Step Motor Lower-Loss Technology An Update Yatsuo Sato, Oriental Motor Management Summary The demand for stepping motors with high efficiency and low losses has been increasing right along with the existing

More information

COMPARING SLOTTED vs. SLOTLESS BRUSHLESS DC MOTORS

COMPARING SLOTTED vs. SLOTLESS BRUSHLESS DC MOTORS COMPARING SLOTTED vs. SLOTLESS Authored By: Engineering Team Members Pittman Motors Slotless brushless DC motors represent a unique and compelling subset of motors within the larger category of brushless

More information

1. Which device creates a current based on the principle of electromagnetic induction?

1. Which device creates a current based on the principle of electromagnetic induction? Assignment 2 Electromagnetism Name: 1. Which device creates a current based on the principle of electromagnetic induction? A) galvanometer B) generator C) motor D) solenoid 2. The bar magnet below enters

More information

ELECTRO MAGNETIC INDUCTION

ELECTRO MAGNETIC INDUCTION 6 ELECTRO MAGNETIC INDUCTION 06.01 Electromagnetic induction When the magnetic flux linked with a coil or conductor changes, an emf is developed in it. This phenomenon is known as electromagnetic induction.

More information

Full Voltage Starting (Number of Starts):

Full Voltage Starting (Number of Starts): Starting Method Full Voltage Starting (Number of Starts): Squirrel cage induction motors are designed to accelerate a NEMA inertia along a NEMA load curve with rated voltage applied to the motor terminals.

More information

Comprehensive Technical Training

Comprehensive Technical Training Comprehensive Technical Training For Sugar Mills Staff on Operation & Maintenance of Baggase Based HP Cogeneration System Schedule: 10 th July to 13 th July, 2017 A.C. GENERATOR Topics Covered. Introduction.

More information

Pump ED 101. Power Factor (Part 2) - - Electricity Behaving Better

Pump ED 101. Power Factor (Part 2) - - Electricity Behaving Better Pump ED 101 Power Factor (Part 2) - - Electricity Behaving Better Joe Evans, Ph.D http://www.pumped101.com Last month we took a close look at the flow of voltage and current in purely resistive and inductive

More information

2014 ELECTRICAL TECHNOLOGY

2014 ELECTRICAL TECHNOLOGY SET - 1 II B. Tech I Semester Regular Examinations, March 2014 ELECTRICAL TECHNOLOGY (Com. to ECE, EIE, BME) Time: 3 hours Max. Marks: 75 Answer any FIVE Questions All Questions carry Equal Marks ~~~~~~~~~~~~~~~~~~~~~~~~~~

More information

DC CIRCUITS ELECTROMAGNETISM

DC CIRCUITS ELECTROMAGNETISM DC CIRCUITS 1. State and Explain Ohm s Law. Write in brief about the limitations of Ohm s Law. 2. State and explain Kirchhoff s laws. 3. Write in brief about disadvantages of series circuit and advantages

More information

Induction Motor Control

Induction Motor Control Induction Motor Control A much misunderstood yet vitally important facet of electrical engineering. The Induction Motor A very major consumer of electrical energy in industry today. The major source of

More information

Date: Name: ID: LABORATORY EXPERIMENT NO. 8 INDUCTION MOTOR/GENERATOR 8-1

Date: Name: ID: LABORATORY EXPERIMENT NO. 8 INDUCTION MOTOR/GENERATOR 8-1 Date: Name: ID: LABORATORY EXPERIMENT NO. 8 INDUCTION MOTOR/GENERATOR 8-1 OBJECT 1. To determine the general performance of a squirrel motors 2. To observe the characteristics of induction generators.

More information

Update. This week A. B. Kaye, Ph.D. Associate Professor of Physics. Michael Faraday

Update. This week A. B. Kaye, Ph.D. Associate Professor of Physics. Michael Faraday 10/26/17 Update Last week Completed Sources of Magnetic Fields (Chapter 30) This week A. B. Kaye, Ph.D. Associate Professor of Physics (Chapter 31) Next week 30 October 3 November 2017 Chapter 32 Induction

More information