wound rotor induction motor pdf

Assume a Y-connection for both the stator and rotor, and a turns ratio of 1:1. Wound-Rotor Induction Motors Soft Start, Adjustable Speed Horizontal 100 - 15,000 hp, Up to 16,000 Volts The wound-rotor induction motor, although more expensive than the squirrel cage motor, has some distinct application advantages. The inverter recovers slip power from rotor of induction motor when /2 << and can 1. The benefit of a wound rotor motor is that the resistance of the rotor circuit can be externally varied, to provide either variable resis- tance (in the case of a liquid rheostat) or steps (when a series of external resistors of fixed resistance are used), to maximize the torque to suit a particular application. However, if the rotor stopped or even if it slowed significantly, an EMF Starting methods of Induction motor include: Direct On line (DOL) starters for less than 10 Kw motors. StarDelta starters for large motors. The stator winding is initially connected in a star configuration and later on changed over to a Delta connection, when the motor reaches rated speed. Auto transformer. Students then examine the effects which varying the rotor resistor has on the starting current and torque of the machine. Lab 13: Wound rotor induction motor. Rotor: The slip ring induction motors usually have a Phase-Wound rotor. The rotor is a rotating part of induction motor. TECO-Westinghouse Motor Company Wound Rotor Induction Motors combine outstanding performance with an advanced long-life design. When starting the wound rotor motor, the generator should be unloaded and the generator field rheostat should be in the fully clockwise (most resistance) position.

They are commonly used on fans, pumps, conveyors and crane systems. External resistance connected to slip-ring and 1. The bars are slanted on a small rotor to reduce audible noise. Terms used in Wound R oStliop.r. Inductions Motors Overview of history, physical design, basic theory, and performance with emphasis on aircraft applications Typical large induction motor circa 1894 100 HP 8 pole 600 RPM must be 40 hertz Dripproof, selfvent Formed coil / chain wound / single coil per slot (consequent pole) Wound rotor with spider construction The wound-rotor induction motor has a rotor similar to that of the squirrel-cage machine except that the short-circuited squirrel-cage winding is replaced by a three-phase insulated winding similar to that on the stator. In order to induce an EMF in the rotor, the rotor must move slower than the SS. 28 Figure 6-53 The no-load test of an induction motor. The problem with the capacitive reactance control is the demand of high capacitance requirement and high torque ripples during motor operation. They consist of two main components, the outside stator, and the inside rotor, which are separated by a small air gap. Couple the motor to the electrodynamometer with the timing belt. The rotor core is made up of steel laminations which have slots to accommodate formed 3-single phase windings. Both the motor and the controller are more complex and Induction Motor Testing The No-Load Test: to obtain the rotational losses and information leading to magnetizing reactance. Ch. It also improves the starting power factor. Historically it has been used for hard-to-start, high inertia fans, or where power system These fins work as a fan and improve cooling. There are basic four methods of starting the squirrel cage induction motor using (a) Direct online starters (b) Stator Resistor (or reactor) Starters (c) Auto-transformer Starters (d) Star-Delta Starters Fig: Direct online starters www.getmyuni.com Page 133 Methods of Starting Slip-Ring (Wound Rotor) I.M. They can be produced in horizontal and vertical configurations, with all types of enclo- sures. If the rotor were to somehow turn at SS, the EMF could not be induced in the rotor and therefore the rotor would stop. 3 stator windings (uniformly distributed as in a synchronous generator) Two types of rotor: Squirrel cage Wound rotor (with slip rings) The rotating magnetic field. CONDITION MONITORING OF WOUND-ROTOR INDUCTION MACHINES iv wound motor. 3.1 INDUCTION MOTOR Wound Rotor Induction Motor: What is it? These windings are placed 120 Set the electrodynamometer control knob at 395,622 Wound rotor are known to be more expensive due to its maintenance cost to upkeep the slip rings, carbon brushes and also rotor windings. The K.Ranjith kumar Senior Lecturer 11. Squirrel-cage rotor This rotor has a laminated iron core with slots, and is mounted on a shaft. This paper proposes a novel technique of using a VSI with a H-bridge dynamic capacitor in the rotor circuit in order to improve the performance of the wound rotor induction motor. Decreases the starting current 3. Example 1: A 460 -V, 25-hp, 60-Hz, four-pole, Y-connected wound-rotor induction motor has the following impedances in ohms per phase referred to the stator circuit: Definition of Wound Rotor.. A type of three phase rotor that contains windings and slip rings. A new method for starting of a three-phase motor by using a parallel combination of resistors, self-inductors and capacitors in rotor circuit is proposed in this paper. Aluminum bars are molded in the slots and the bars are short circuited with two end rings. SECONDARY CONTROL CIRCUIT FOR A WOUND ROTOR INDUCTION MOTOR 2 Sheets-Sheet 2 ATTORNEYS United States Patent 3,217,222 SECONDARY CONTROL CIRCUIT FOR A WOUND ROTOR INDUCTION MOTOR William H. Lee, Lakewood, Ohio, assignor to Harris- Intertype Corporation, Cleveland, Ohio, a corporation of Delaware Filed Sept. 10, 1964, Ser. Therefore, in this paper, the optimization of the design of a wound rotor induction motor using a genetic algorithm with objective function including power losses and motor weight is proposed. Initially, after Magnetic Equivalent Circuit (MEC) modeling, different parameters are This paper investigates the enhancement in the performances of a three phase wound rotor induction motor by rotor capacitive reactance control using Fuzzy Logic Controller (FLC). Induction Motors Rotor Slip The difference between the synchronous speed (the speed of the magnetic fields) in an induction motor and the rotor speed is known as theknown as the slip speedslip speed n slip. The efficiency optimization of wound rotor induction motor using soft computing techniques has been presented in [14]. The Wound-Rotor Induction Motor Part III Figure 5-1. Frames with separately enclosed slip-rings can also be The rotor receives its power from an induction process and uses some form of variable external resistance to adjust start-up current and speed. In the case of a squirrel cage induction motor, the rotor is inaccessible and rotor circuit resistance is xed, whereas the wound-rotor machines are provided with slip-rings by which additional resistance can be connected in series with the machine rotor. 2 Since the performance of an induction motor can be varied by altering the rotor parameters, a slip-ring motor, through its rotor circuit, can be made to suit any specific torque and speed requirement. Tel: 713.944.6900 Fax: 713.947.4453 www.powellind.com info@powellind.com page 2 Wound rotor motors have some drawbacks. n=0, s=1), it acts exactly like a conventional transformer. (Diagram & Speed Contro Wound rotor motors, as opposed to AC induction motors, generate the same torque in both forward and reverse. The rotor frequency given by fr = sfs is high at starting in-stant, therefore, the maximum current ows through ca- The windings are geometrically spaced 120 degrees apart. pole, three-phase, squirrel-cage induction motor is diagrammed in Fig.

The rotor cor is laminated t avoid power Ioss from eddy currnts and hysteresis.It is caIled a squirrel cag motor because th rotor inside f it known s a squirrel cag rotor looks Iike a squirrel cag.This rotor is a cylinder of steel laminations, with highly conductive metal (typically aluminum or copper) embedded into its surface. (b) the resulting equivalent circuit. The rotor in an induction motor can not turn at the synchronous speed. Note that at no load the motors impedance is essentially R 1 + j (X 1 +X Wound rotor induction motors have been underestimated for specific applications and high power. The difference between a motor's synchronous speed and its speed at full load.

2. In order to improve the wound-rotor induction motor con-ditions and overcome the above-mentioned problems, us-ing a parallel combination of resistors, self-inductors and capacitors in rotor circuit is proposed in this paper. SPEED CONTROL OF INDUCTION MOTORS The speed of an induction motor is given as N = 120f/p (1-S). The 3-Phase Wound Rotor Induction Motor will be used to drive a self-excited DC generator/dynamometer. No. Wound Rotor Induction Motors and Starters Powell Industries, Inc. PO Box 12818 Houston, TX 77217 2005 Powell Industries, Inc. All rights reserved. 1. They are equal to the voltages injected by the rotor-side converter. The rheostat which is used to vary the resistance per phase causes unbalancing in rotor.The resistances generate huge losses and generate heat in the system.In case of a large machine the size of the rheostat will be large and in such case it is not easily portable.It requires more maintenance, hence the cost associated with it is more.More items HOW DOES A WOUND ROTOR MOTOR WORK? However, there is an important exception; the dq rotor voltages e dr and e qr given in Equation (5.88b) are not equal to zero. Sajan, EEE, JITS Polyphase Motors(Continued..) Three-phase wound-rotor induction machine starting current and torque versus the rotor resistance 7KUHH SKDVH ZRXQG URWRU LQGXFWLRQ PDFKLQHV KDYH DQ LPSRUWDQW DGYDQWDJH RYHU The circuit connections for this configuration are shown in circuit A. The rotor is connected to the mechanical load through the shaft. Experimental results (torque and current characteristic) are compared with computer predictions for the test machine.

The rotor of the three phase induction motor are further classified as Squirrel cage rotor Slip ring rotor or wound rotor or phase wound rotor.

A squirrel-cage rotor consists of thick conducting bars embedded in parallel slots. Equivalent circuits: wound-rotor induction motor 1. Available in ratings from 5 HP up to 15,000 HP, these rugged workhorses are ideal for many demanding applications including: Ball and Sag Mills Cranes Hoists Pumps Fans and Blowers Chippers Conveyors 3-Phase induction machine construction. ELEN 3441 Fundamentals of Power Engineering Lab # 13 Spring 2008 Page 1. So obviously the speed of an induction motor can be controlled by varying any of three factors namely supply frequency f, number of pole P or slip S. The main methods employed for speed control of induction motors are as follows: 1.

wound rotor induction motor pdf