Fundamentals of Electric Motors and Transformers
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Stepping Motors Fundamentals
AN907 Stepping Motors Fundamentals Author: Reston Condit TYPES OF STEPPING MOTORS Microchip Technology Inc. There are three basic types of stepping motors: Dr. Douglas W. Jones permanent magnet, variable reluctance and hybrid. University of Iowa This application note covers all three types. Permanent magnet motors have a magnetized rotor, while variable reluctance motors have toothed soft-iron rotors. Hybrid INTRODUCTION stepping motors combine aspects of both permanent Stepping motors fill a unique niche in the motor control magnet and variable reluctance technology. world. These motors are commonly used in measure- The stator, or stationary part of the stepping motor ment and control applications. Sample applications holds multiple windings. The arrangement of these include ink jet printers, CNC machines and volumetric windings is the primary factor that distinguishes pumps. Several features common to all stepper motors different types of stepping motors from an electrical make them ideally suited for these types of point of view. From the electrical and control system applications. These features are as follows: perspective, variable reluctance motors are distant 1. Brushless – Stepper motors are brushless. The from the other types. Both permanent magnet and commutator and brushes of conventional hybrid motors may be wound using either unipolar motors are some of the most failure-prone windings, bipolar windings or bifilar windings. Each of components, and they create electrical arcs that these is described in the sections below. are undesirable or dangerous in some environments. Variable Reluctance Motors 2. Load Independent – Stepper motors will turn at Variable Reluctance Motors (also called variable a set speed regardless of load as long as the switched reluctance motors) have three to five load does not exceed the torque rating for the windings connected to a common terminal. -
Difference Between Bipolar Drives and Unipolar Drives for Stepper Motors
WHITE PAPER DIFFERENCE BETWEEN BIPOLAR DRIVES AND UNIPOLAR DRIVES FOR STEPPER MOTORS orking on a motorized development requires some knowledge about motors and controllers. This article Wis focused on the stepper motors which is a type of brushless DC motor with a high number of poles. This technology is generally driven in open loop without any feedback sensor, meaning the current is typically applied on the phases without knowing the rotor position. The rotor moves to be aligned with the stator magnetic flux, then the current can be supplied to the next phase. We will consider two ways to supply current in the coil: bipolar way and unipolar way. In this article, we will explain the differences of bipolar and unipolar motors and driving methods. We will show the advantages and limits of both technologies. Let’s take an example of a four step, permanent magnet stepper motor (see figure 1). The rotor is made with a one pole pair magnet, and the stator is composed of two phases, Phase A and Phase B. • In unipolar: the current always flows in the same direction. Each coil is dedicated to one current direction, meaning either the coil A+ or the coil A- is powered. The coils A+ and A- are never powered together. • In bipolar: the current can flow in both directions in all coils. The phases A+ and A- are powered together. A bipolar motor requires one coil minimum per phase and unipolar motor Figure 1. 4-Step Stepper Motor requires two coils minimum per phase. Let’s review both options in more detail. -
Motor Actuators Basics
Motor Actuators Basics - 1 - Note: All specifications and other information are not guaranteed and are subject to change without notice. Prior to any new usage of JE motor actuators it is recommended to contact Johnson Electric. All information below and content of links are subject to the disclaimer of the Johnson Electric website - 2 - Contents Overview ....................................................................................................................................................................... 4 Classification ............................................................................................................................................................. 5 DC Motors ................................................................................................................................................................. 6 Universal Motors ....................................................................................................................................................... 7 BLDC Motors ............................................................................................................................................................. 8 Synchronous Motors ................................................................................................................................................. 9 Stepper Motors ........................................................................................................................................................ 10 Shaded -
The Performance of a Special Repulsion Motor in A
THE PERFORMANCE OF A SPECIAL REPULSION MOTOR IN A CLOSED-LOOP POSITIONING SYSTEM A THESIS Presented to the Faculty of the Graduate Division by Eugene Dale McCalia In Partial Fulfillment of the Requirements for the Degree Master of Science in Electrical Engineering Georgia Institute of Technology June, 1959 "In presenting the dissertation as a partial fulfillment of the requirements for an advanced degree from the Georgia Institute of Technology, I agree that the Library of the Institution shall make it available for inspection and circulation in accordance with its regulations governing materials of this type. I agree that permission to copy from, or to publish from, this dissertation may be granted by the professor under whose direction it was written, or, in his absence, by the dean of the Graduate Division when such copying or publication is solely for scholarly purposes and does not involve potential financial gain. It is understood that any copying from, or publication of, this dissertation which involves potential financial gain will not be allowed without written permission. THE PERFORMANCE OF A SPECIAL REPULSION MOTOR IN A CLOSED-LOOP POSITIONING SYSTEM Approved: Z2^__ ^ L.J& a M. Date of Approval: )vkv ^-6 ~ l<i^c/ .J- ...... ' •' ' "t' 11 ACKNOWLEDGMENTS The author wishes to acknowledge with appreciation his indebted ness to Dr. F. 0. Nottingham, Jr. who suggested the problem and also for the assistance and encouragement that he so cheerfully contributed throughout the course of this study, To my wife, I express appreciation for her love, patience and understanding and also for her assistance and encouragement in the preparation of the final draft. -
IEEE/PES Transformers Committee Fall 2017 Meeting Minutes
Transformers Committee Chair: Stephen Antosz Vice Chair: Sue McNelly Secretary: Bruce Forsyth Treasurer: Greg Anderson Awards Chair/Past Chair: Don Platts Standards Coordinator: Jim Graham IEEE/PES Transformers Committee Fall 2017 Meeting Minutes Louisville, KY October 30 – November 2, 2017 Unapproved (These minutes are on the agenda to be approved at the next meeting in Spring 2018) TABLE OF CONTENTS GENERAL ADMINISTRATIVE ITEMS 1.0 Agenda 2.0 Attendance OPENING SESSION – MONDAY OCTOBER 30, 2017 3.0 Approval of Agenda and Previous Minutes – Stephen Antosz 4.0 Chair’s Remarks & Report – Stephen Antosz 5.0 Vice Chair’s Report – Susan McNelly 6.0 Secretary’s Report – Bruce Forsyth 7.0 Treasurer’s Report – Gregory Anderson 8.0 Awards Report – Don Platts 9.0 Administrative SC Meeting Report – Stephen Antosz 10.0 Standards Report – Jim Graham 11.0 Liaison Reports 11.1. CIGRE – Raj Ahuja 11.2. IEC TC14 – Phil Hopkinson 11.3. Standards Coordinating Committee, SCC No. 18 (NFPA/NEC) – David Brender 11.4. Standards Coordinating Committee, SCC No. 4 (Electrical Insulation) – Paulette Payne Powell 12.0 Hot Topics for the Upcoming – Subcommittee Chairs 13.0 Opening Session Adjournment CLOSING SESSION – THURSDAY NOVEMBER 2, 2017 14.0 Chair’s Remarks and Announcements – Stephen Antosz 15.0 Meetings Planning SC Minutes & Report – Gregory Anderson 16.0 Reports from Technical Subcommittees (decisions made during the week) 17.0 Report from Standards Subcommittee (issues from the week) 18.0 New Business 19.0 Closing Session Adjournment APPENDIXES – ADDITIONAL DOCUMENTATION Appendix 1 – Meeting Schedule Appendix 2 – Semi-Annual Standards Report Appendix 3 – IEC TC14 Liaison Report Appendix 4 – CIGRE Report Page 2 of 55 ANNEXES – UNAPPROVED MINUTES OF TECHNICAL SUBCOMMITTEES NOTE: The Annexes included in these minutes are unapproved by the respective subcommittees and are accurate as of the date the Transformers Committee meeting minutes were published. -
IEEE Grounding Transformers
Grounding Transformers John S. Levine, P.E. Levine Lectronics and Lectric, Inc. [email protected] 1 • It is used to provide a ground path on either an ungrounded Wye or a Delta connected system • The relatively low impedance path to ground maintains the system neutral at ground potential • On Ungrounded systems you can have overvoltages of 6 to 8 times normal with arcing faults Arcing Ground Faults Intermittent or Re-strike •Plot of transient over-voltage for an arcing ground fault Arcing Ground Faults Intermittent or Re-strike •Intermittent ground fault: A re-striking ground fault can create a high frequency oscillator (RLC circuit), independent of L and C values, causing high transient over- voltages. – i.e. re-striking due to ac voltage waveform or loose wire caused by vibration 480V Delta Source 3Ø Load Rfe V V Cb Cb S fa THE HIGH RESISTANCE GROUNDED POWER SYSTEM CONTROL OF TRANSIENT OVERVOLTAGE • It supports the voltage on a faulted phase – If a single line-to-ground fault occurs on an ungrounded or isolated system, no return path exists and no current flows – The system will continue to operate but the other two un- faulted lines will rise in in voltage by the square root of 3, possibly overstressing the transformer insulation, and other components, by 173% UNGROUNDED SYSTEM NORMAL CONDITIONS UNGROUNDED SYSTEM GROUND FAULT ON PHASE A • Provides a metering point to measure faults A typical example is a Wind Farm. They utilize grounding transformers for fault protection on ungrounded lines When a ground fault occurs on a collector cable causes the substation circuit breaker to open, the wind turbine string becomes isolated Turbines do not always detect the fault and the generators continue to energize the cable. -
Neutral Current Problem and Mitigation Techniques: an Overview
IOSR Journal of Engineering (IOSR JEN) www.iosrjen.org ISSN (e): 2250-3021, ISSN (p): 2278-8719 PP 62-68 Neutral Current Problem and Mitigation Techniques: An Overview Karuna Nikum1, Rakesh Saxena2, Abhay Wagh3 1(Department of Electrical Engineering, ACE, Mumbai University, India) 2(SGSITS, RGPV University, Indore, India) 3(Directorate of Technical Education, Mumbai, India ) Abstract: In this paper, an attempt to overview a various number of mitigation techniques and power quality problems associated with neutral current for commercial loads are discussed. The load connected to three phase four wire system are generally single-phase loads and generate triplen harmonic currents due to unbalancing in phases at neutral. There are various neutral current mitigation techniques including active and passive has been discussed. The existing approach and a framework of references for researchers in this field are provided. I. ‘Introduction The ample use of electronic devices in all types of loads i.e. residential, commercial and industrial is adversely affecting the power quality (PQ) of the system[1]-[10]. When three-phase four-wire distribution (3P4W) systems are used to supply single-phase low voltage loads such as lighting ballasts (electronic type), light emitting diodes (LED), compact fluorescent lighting (CFL), personal computers, monitors, laser printers, variable speed drives, adjustable speeds drives (ASD) in air conditioner, UPS systems and other electronic equipment. These loads produces harmonics especially 3rd harmonics in the neutral. In general, the distribution systems designed for linear load type and no longer suitable for delivering large number of non-linear and harmonic generating loads [11]-[15]. The concern PQ issues are high reactive power requirement, harmonic current, low power factor and increased losses[16], [17]. -
Brushless DC Electric Motor
Please read: A personal appeal from Wikipedia author Dr. Sengai Podhuvan We now accept ₹ (INR) Brushless DC electric motor From Wikipedia, the free encyclopedia Jump to: navigation, search A microprocessor-controlled BLDC motor powering a micro remote-controlled airplane. This external rotor motor weighs 5 grams, consumes approximately 11 watts (15 millihorsepower) and produces thrust of more than twice the weight of the plane. Contents [hide] 1 Brushless versus Brushed motor 2 Controller implementations 3 Variations in construction 4 AC and DC power supplies 5 KM rating 6 Kv rating 7 Applications o 7.1 Transport o 7.2 Heating and ventilation o 7.3 Industrial Engineering . 7.3.1 Motion Control Systems . 7.3.2 Positioning and Actuation Systems o 7.4 Stepper motor o 7.5 Model engineering 8 See also 9 References 10 External links Brushless DC motors (BLDC motors, BL motors) also known as electronically commutated motors (ECMs, EC motors) are electric motors powered by direct-current (DC) electricity and having electronic commutation systems, rather than mechanical commutators and brushes. The current-to-torque and frequency-to-speed relationships of BLDC motors are linear. BLDC motors may be described as stepper motors, with fixed permanent magnets and possibly more poles on the rotor than the stator, or reluctance motors. The latter may be without permanent magnets, just poles that are induced on the rotor then pulled into alignment by timed stator windings. However, the term stepper motor tends to be used for motors that are designed specifically to be operated in a mode where they are frequently stopped with the rotor in a defined angular position; this page describes more general BLDC motor principles, though there is overlap. -
Stepper Motor Basics
Industrial Circuits Application Note Stepper Motor Basics A stepper motor is an electromechanical Disadvantages device which converts electrical pulses into 15° discrete mechanical movements. The shaft 1. Resonances can occur if not A or spindle of a stepper motor rotates in properly controlled. D' discrete step increments when electrical 2. Not easy to operate at extremely B command pulses are applied to it in the high speeds. 1 proper sequence. The motors rotation has 6 several direct relationships to these applied 2 C' C input pulses. The sequence of the applied Open Loop Operation 5 pulses is directly related to the direction of One of the most significant advantages 3 motor shafts rotation. The speed of the of a stepper motor is its ability to be 4 B' motor shafts rotation is directly related to accurately controlled in an open loop D the frequency of the input pulses and the system. Open loop control means no length of rotation is directly related to the feedback information about position is A' number of input pulses applied. needed. This type of control eliminates the need for expensive Figure 1. Cross-section of a variable- sensing and feedback devices such as reluctance (VR) motor. Stepper Motor Advantages optical encoders. Your position is and Disadvantages known simply by keeping track of the input step pulses. Advantages 1. The rotation angle of the motor is Stepper Motor Types proportional to the input pulse. There are three basic stepper motor types. They are : 2. The motor has full torque at stand- N N S N S N still (if the windings are energized) • Variable-reluctance 3. -
Single-Phase Motors
mywbut.com Chapter (9) Single-Phase Motors Introduction As the name suggests, these motors are used on single-phase supply. Single- phase motors are the most familiar of all electric motors because they are extensively used in home appliances, shops, offices etc. It is true that single- phase motors are less efficient substitute for 3-phase motors but 3-phase power is normally not available except in large commercial and industrial establishments. Since electric power was originally generated and distributed for lighting only, millions of homes were given single-phase supply. This led to the development of single-phase motors. Even where 3-phase mains are present, the single-phase supply may be obtained by using one of the three lines and the neutral. In this chapter, we shall focus our attention on the construction, working and characteristics of commonly used single-phase motors. 9.1 Types of Single-Phase Motors Single-phase motors are generally built in the fractional-horsepower range and may be classified into the following four basic types: 1. Single-phase induction motors (i) split-phase type (ii) capacitor type (iii) shaded-pole type 2. A.C. series motor or universal motor 3. Repulsion motors (i) Repulsion-start induction-run motor (ii) Repulsion-induction motor 4. Synchronous motors (i) Reluctance motor (ii) Hysteresis motor 9.2 Single-Phase Induction Motors A single phase induction motor is very similar to a 3-phase squirrel cage induction motor. It has (i) a squirrel-cage rotor identical to a 3-phase motor and (ii) a single-phase winding on the stator. -
Compensated Repulsion Motor Repulsion-Start Induction-Run Motor Repulsion Induction Motor Types of Repulsion Motor
Introduction Construction of Repulsion Motor Types of Repulsion Motor Advantage of Repulsion Motor Disadvantage of Repulsion Motor Application of Repulsion motors Repulsion motors are classified under single phase motors. In magnetic repulsion motors the stator windings are connected directly to the ac power supply and the rotor is connected to commutator and brush assembly, very similar to that of DC armature. Repulsion Motor Construction of Repulsion Motor: Repulsion motors are based on the principle of repulsion between two magnetic fields. Consider a 2-pole motor with a vertical magnetic axis. The armature is connected to a commutator and brushes. The brushes are short circuited using a low-resistance jumper. When alternating current is supplied to the field (stator) winding, it induces an electromotive force (emf) in the armature. Construction of Repulsion Motor: The direction of alternating current is such that it creates a north pole at the top and a south pole at the bottom. The direction of induced emf is given by Lenz's law, according to which the direction of induced emf opposes the cause producing it. The induced emf induces current in the armature conductors and the direction of the induced current depends on the position of the brushes. Circuit-diagram of Repulsion motor Types of Repulsion Motor The various types of motors which works under the repulsion principle are : Compensated repulsion motor Repulsion-start Induction-run motor Repulsion Induction motor Types of Repulsion Motor Compensated repulsion motor : • It carries an additional winding, called compensating winding. • There is another set of two brushes which are placed midway between the usual short circuit brush set. -
Motor Actuators Basics
Motor Actuators Basics - 1 - Note: All specifications and other information are not guaranteed and are subject to change without notice. Prior to any new usage of JE motor actuators it is recommended to contact Johnson Electric. All information below and content of links are subject to the disclaimer of the Johnson Electric website - 2 - Contents Overview ....................................................................................................................................................................... 4 Classification ............................................................................................................................................................. 5 DC Motors ................................................................................................................................................................. 6 Universal Motors ....................................................................................................................................................... 7 BLDC Motors ............................................................................................................................................................. 8 Synchronous Motors ................................................................................................................................................. 9 Stepper Motors ........................................................................................................................................................ 10 Shaded