32. The star connected rotor of a a 3-phase induction motor has a resistance and standstill reactance of 0.4 ohms/phase and 2.5 ohm/phase respectively. The emf induced between slip rings at stand still is 80 V, the stator being connected to small supply voltage. Find the rotor current and power factor at starting current when the rings are (i) short circuited (ii) joined to a star star-connected resistance of 5 ohm/phase.

32. The star connected rotor of a a 3-phase induction motor has a resistance and standstill reactance of 0.4 ohms/phase and 2.5 ohm/phase respectively. The emf induced between slip rings at stand still is 80 V, the stator being connected to small supply voltage. Find the rotor current and power factor at starting current when the rings are (i) short circuited (ii) joined to a star star-connected resistance of 5 ohm/phase.

Delmar's Standard Textbook Of Electricity

7th Edition

ISBN:9781337900348

Author:Stephen L. Herman

Publisher:Stephen L. Herman

Chapter35: Harmonics 916

Section: Chapter Questions

Problem 3RQ: Would a positive-rotating harmonic or a negative-rotating harmonic be more harmful to an induction...

See similar textbooks

Similar questions

Name three factors that determine the torque produced by an induction motor.
Design and develop equivalent circuit model of a single phase Induction motor with th consideration of core losses present with the parameter consideration of stator resistance R1 and reactance X1 and two rotor parameters which includes r2,x2 and magnetising reactance xm. (Illustration is required) Draw by hand please
A 25 HP, 6 pole, 50 Hz, 3-phase slip ring induction motor runs at 960revolutions per minute on full load with a rotor current per phase of 35 A.Allowing 250 W for the copper loss in the short-circuiting gear, and 1000Wfor mechanical losses, find the resistance per phase of the three-phaserotor winding.
The rotor resistance and standstill reactance of a 3-phase induction motor are respectively 0.015 ohmsand 0.09 ohms / phase. At normal voltage, the full-load torque at the full-load speed. b.) Calculate thepower factor.
A 3-phase induction motor , the impedance of star connected stator winding is 0.2+j 3 ohm per phase. the no load induced EMF between slip ring is 220 V. Find the rotor current and power factor at rated speed of ? 1455 r.p.m
14 P.14 - A three-phase induction motor with 4 magnetic poles, 60 Hz, rotates with a speed of n=1750 rpm In order to achieve a quick stop we can use a proper swap of 2 phases which normally corresponds to an inversion of rotation direction. For fast crossing, the technique of inversion of the direction of rotation by changing 2 phases is used. At the precise moment we swap the 2 phases, what are the slip, s, and the rotor current frequency, fR, like?
A three-phase induction motor used for a commercial application in Oman runs at 586 rpm at no load and at 540 rpm at full load. a) How many poles do this motor have? b) What is the percentage slip at full load? c) The frequency of the rotor currents when slip is 7 % d) The frequency of the rotor currents at standstill.
A three-phase 60 Hz induction motor connected to a three-phase bus at rated voltage isoperating at a low slip condition (i.e s < 20%) resulting in a steady state speed of 1090 rpm.(a) How many poles does the motor have?(b) What is the percentage slip at the operating speed?(c) What is the corresponding frequency, (fr) of the currents and voltages induced in therotor winding?
A three-phase induction motor, operating at rated voltage and frequency, has a startingtorque of 1.35 times and a maximum torque of 2.2 times, both with respect to its rated-loadtorque. Ignoring the effects of the stator resistance and rotational losses and assumingconstant rotor resistance, determine the slip rated load, and the rotor current at starting (as a percentage of the rotor current at rated load). The slip at maximum torque is 0.343 if that helps.
Three-phase induction motor, 460 V 50 Hz, 4 poles, 50 hp with Delta, operating at 3.8% slip rated torque when receives Line Voltage 460 V, 50 Hz The parameters of the equivalent circuit per phase are as follows.R1 = 0.33, X1 = X2 = 0.42 and Xm = 30 Ohm / phase.Answer the following questions by neglecting the mechanical losses, Core losses and Stray load losses.A) Value of the rotor resistance R2 B) Maximum torque and rated speed C) line current and starting torque of motor
A delta connected 1185 V, 50 Hz three phase induction motor has a star-connected slip-ring rotor with a phase transformation ratio of 4. 2. The per phase rotor resistance and standstill leakage reactance are 0.0627 ohm and 0.049 ohm respectively. Assuming the stator impedance and magnetizing current are neglected. Calculate the the following, (i) The rotor current at starting with slip-rings are short circuited. (ii) The rotor power factor at starting with slip-rings are short circuited.
{Q.1} A three-phase induction motor runs at almost 1198 revolutions per minute (rpm) at no load and 1112 rpm at full load when supplied from a 60-Hz, three-phase source. (a) How many poles does this motor have? (b) What is the slip in percent at full load? (C) What is the corresponding frequency of the rotor currents? (D) What is the corresponding speed of the rotor field with respect to the rotor and with respect to the stator?