In a slip power recovery system, 22 V/phase are injected into the rotor circuit of a fourpole, 50 Hz, 380 V, star-connected slip-ring induction motor, reducing its speed to 900 r/min. The stator impedance is (1,2 + j3,8) Ω/phase and the rotor impedance at standstill is (0,4 + j0,8) Ω/phase. The admittance of the shunt magnetising circuit is 0,3∟– 70° S per phase and the effective turns ratio is 2. Use the approximate equivalent circuit and calculate the rotor referred current and power factor and the electromagnetic torque in Nm

In a slip power recovery system, 22 V/phase are injected into the rotor circuit of a fourpole, 50 Hz, 380 V, star-connected slip-ring induction motor, reducing its speed to 900 r/min. The stator impedance is (1,2 + j3,8) Ω/phase and the rotor impedance at standstill is (0,4 + j0,8) Ω/phase. The admittance of the shunt magnetising circuit is 0,3∟– 70° S per phase and the effective turns ratio is 2. Use the approximate equivalent circuit and calculate the rotor referred current and power factor and the electromagnetic torque in Nm

Electric Motor Control

10th Edition

ISBN:9781133702818

Author:Herman

Publisher:Herman

Chapter39: Synchronous Motor Operation

Section: Chapter Questions

Problem 14SQ: Induction motors and welding transformers require magnetizing current, which causes a. lagging power...

See similar textbooks

Similar questions

Permanent-split capacitor motor is in effect a 2-phase motor and at no load could attain the synchronous speed. True False
If two 3-phase induction machines are mechanically coupled with each other. The two machines are supplied by 50 Hz and 60 Hz, respectively. the speed of the combination of both machines will be:
In three-phase induction motor rotor speed is zero at the time of starting the induction motor. Select one: True False
An ideal dc generator has regulation of 40% 20% O 30% Zero
question Oc. 0.08 O d. 0.04 Generators using salient pole structure rotors are called turbo-alternators. Select one: O True O False Skewing of rotor conductors in a squirrel cage induction motor reduces
At rest condition, the slip of induction motor is 1. Select one: O True False
4. An induction motor draws 4.5 A at a 0.75 lagging power factor from a 208V, 60 Hz source. a) What value of capacitance must be connected in parallel with the motor to raise the overall p.f. to 1. b) Calculate the magnitudes of the motor current, capacitor current and source current with the capacitor in place. 5. A 3-phase Y-connected motor is connected to a three phase Y-conected source with 440V line voltage. It draws a line current of 5A from the source. If the power factor of the motor is 0.8, calculate a) Active power and Reactive power absorbed by the load b) Total Apparent power
A 4-pole induction motor, supplied by a slightly unbalanced three-phase 50 Hz source, is rotating at 1440 rpm. The electrical frequency in Hz of the induced negative sequence current in the rotor is A 100 B 98 C 52 D 48
6. Home Works: a) The figure below shows the per-phase equivalent circuit of a two- pole three-phase induction motor operating at 50 Hz. The voltage (E1) across the magnetizing inductance is 210 V, and the slip (s) is 0.05. What is the developed torque produced by the motor ? 0.04 0 jo.22 Q j0.22 0 j6.28 NE E1 0.05 0
A 50 Hz, 3-phase induction motor is working at a full load speed of 1440 r.p.m. The full load slip will be a. 0.12 b. 0.06 c. 0.08 d. 0.04
10- What is the ratio of rotor input power to rotor copper loss in an induction motor? a) 1/(1-S) b) 1 - S c) 1/S d) S 11- If the frequency of 3-phase supply to the stator of a 3-phase induction motor is increased, then synchronous speed a) Increased b) Decreased c) Remain unchanged d) None of the above
The rotor resistance of the three phase induction motor is not affected by of the supply. If a balanced3 phase supply is provided to an inductive load, the phase current lags the phase voltage. Select one: True False