Chose the correct answer: 1- The resultant flux in stator winding of three-phase induction motor is equal to (A) Maximum value of flux due to any phase (B) Twice of the maximum value of flux due to any phase. (C) 0.5 times the maximum value of flux due to any phase (D) 1.5 times the maximum value of flux due to any phase 2- Which one of the following starters cannot be used for 3-phase, star - connected, slip-ring induction motor? (A) Auto-transformer starter (B) Star-delta starter (C) Direct-on-line starter 3- The crawling in the induction motor is caused by. (D) Rotor resistance starter (C) harmonics developed in the motor (A) low voltage supply (B) high loads (D) improper design of the machine 4- The 'cogging' of an induction motor can be avoided by.......... (A) good ventilation (B) using DOL starter (C) star-connecting of stator winding (D) having number of rotor slots more or less than the number of stator slots 5- The method which can be used for the speed control of induction motor from stator side is. (A) V/f control. (B) Controlling number of stator poles (C) Adding rheostats in stator circuit 6-21- Synchronous motors are .......... (A) not self-starting (B) self-starting (D) All of these choices (C) single excited 7- The plot of armature current verses excitation is known as (D) none of above .... for synchronous motor. (A) V-curves (B) inverted V-curves (C) load characteristics (D) magnetization curves B-Which of the following conditions is not to be satisfied for proper synchronization of alternators? A) Equal terminal voltage (B) Same phase sequence (C) Same frequency (D) Same kVA rating - For synchronous generator operated with resistive load, the armature reaction has field flux. .......... on the main (A) Demagnetizing effect (B) Magnetizing effect (C) cross magnetizing effect (D) No effect 10- The synchronous reactance of synchronous machine is www. (A) reactance due to armature reaction of the machine (B) reactance due to leakage flux (C) combined reactance due to leakage flux and armature reaction (D) reactance either due to armature reaction or leakage flux

Chose the correct answer: 1- The resultant flux in stator winding of three-phase induction motor is equal to (A) Maximum value of flux due to any phase (B) Twice of the maximum value of flux due to any phase. (C) 0.5 times the maximum value of flux due to any phase (D) 1.5 times the maximum value of flux due to any phase 2- Which one of the following starters cannot be used for 3-phase, star - connected, slip-ring induction motor? (A) Auto-transformer starter (B) Star-delta starter (C) Direct-on-line starter 3- The crawling in the induction motor is caused by. (D) Rotor resistance starter (C) harmonics developed in the motor (A) low voltage supply (B) high loads (D) improper design of the machine 4- The 'cogging' of an induction motor can be avoided by.......... (A) good ventilation (B) using DOL starter (C) star-connecting of stator winding (D) having number of rotor slots more or less than the number of stator slots 5- The method which can be used for the speed control of induction motor from stator side is. (A) V/f control. (B) Controlling number of stator poles (C) Adding rheostats in stator circuit 6-21- Synchronous motors are .......... (A) not self-starting (B) self-starting (D) All of these choices (C) single excited 7- The plot of armature current verses excitation is known as (D) none of above .... for synchronous motor. (A) V-curves (B) inverted V-curves (C) load characteristics (D) magnetization curves B-Which of the following conditions is not to be satisfied for proper synchronization of alternators? A) Equal terminal voltage (B) Same phase sequence (C) Same frequency (D) Same kVA rating - For synchronous generator operated with resistive load, the armature reaction has field flux. .......... on the main (A) Demagnetizing effect (B) Magnetizing effect (C) cross magnetizing effect (D) No effect 10- The synchronous reactance of synchronous machine is www. (A) reactance due to armature reaction of the machine (B) reactance due to leakage flux (C) combined reactance due to leakage flux and armature reaction (D) reactance either due to armature reaction or leakage flux

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...

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