Choose the correct answer: 1- In a 3-phase squirrel cage induction motor--------- (A) Rotor conductors are short circuited through end rings (B) Rotor conductor ends are short circuited through slip rings (C) Rotor conductors are kept open (D)None of the above 2- A smaller air gap in a poly phase induction motor helps to ----- (A) Reduce the chance of crawling (B) Increase the starting torque (C) Reduce the chance of cogging (D) Reduce the magnetizing current 3- The efficiency of a three-phase induction motor can be expected to be nearly. (A)60 to 90% (B) 80 to 90% (C) 95 to 98 % (D) 99% 4-The skin effect in a deep bar induction motor is maximum when rotor is (A) At standstill (C) Running at no load 5-Deep bar or double cage (B) Running at its maximum speed (D) Running at half load O ----- rotors are used in squirrel cage induction motor to obtain (A) High starting current (B) High starting torque (C) Moderate starting current (D) Reduced rotor resistance --- 6- Which of the following are used in preventing the hunting phenomenon in synchronous motors? (A) Damper bars (B) Short pitch winding (C) Distributed winding (D) Full pitch winding 7-Oscillations of the rotor about its new equilibrium position, due to sudden application or removal of load in synchronous motor is called (A) Phasing out (B) Damping (C) Hunting (D) None of these 8- The method used to determine X and X, the direct and quadrature axis reactance is called ------- (A) Reactance test (B) Blondel's two reaction theory (C) Slip test (D) All of these 9- Consider a purely inductive load connected to the alternator having zero lagging power factor. In this case the effect of armature reaction will be (A) Demagnetizing effect (B) Cross magnetizing effect (C) Magnetizing effect (D) None of these 10- The synchronous reactance of an alternator is equal to ___ (A) Leakage reactance of armature (B) Armature reaction reactance (C) Sum of leakage reactance and armature reaction reactance (D) Difference of leakage reactance and armature reaction reactance
Choose the correct answer: 1- In a 3-phase squirrel cage induction motor--------- (A) Rotor conductors are short circuited through end rings (B) Rotor conductor ends are short circuited through slip rings (C) Rotor conductors are kept open (D)None of the above 2- A smaller air gap in a poly phase induction motor helps to ----- (A) Reduce the chance of crawling (B) Increase the starting torque (C) Reduce the chance of cogging (D) Reduce the magnetizing current 3- The efficiency of a three-phase induction motor can be expected to be nearly. (A)60 to 90% (B) 80 to 90% (C) 95 to 98 % (D) 99% 4-The skin effect in a deep bar induction motor is maximum when rotor is (A) At standstill (C) Running at no load 5-Deep bar or double cage (B) Running at its maximum speed (D) Running at half load O ----- rotors are used in squirrel cage induction motor to obtain (A) High starting current (B) High starting torque (C) Moderate starting current (D) Reduced rotor resistance --- 6- Which of the following are used in preventing the hunting phenomenon in synchronous motors? (A) Damper bars (B) Short pitch winding (C) Distributed winding (D) Full pitch winding 7-Oscillations of the rotor about its new equilibrium position, due to sudden application or removal of load in synchronous motor is called (A) Phasing out (B) Damping (C) Hunting (D) None of these 8- The method used to determine X and X, the direct and quadrature axis reactance is called ------- (A) Reactance test (B) Blondel's two reaction theory (C) Slip test (D) All of these 9- Consider a purely inductive load connected to the alternator having zero lagging power factor. In this case the effect of armature reaction will be (A) Demagnetizing effect (B) Cross magnetizing effect (C) Magnetizing effect (D) None of these 10- The synchronous reactance of an alternator is equal to ___ (A) Leakage reactance of armature (B) Armature reaction reactance (C) Sum of leakage reactance and armature reaction reactance (D) Difference of leakage reactance and armature reaction reactance
Introductory Circuit Analysis (13th Edition)
13th Edition
ISBN:9780133923605
Author:Robert L. Boylestad
Publisher:Robert L. Boylestad
Chapter1: Introduction
Section: Chapter Questions
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Transcribed Image Text:Choose the correct answer:
1- In a 3-phase squirrel cage induction motor---------
(A) Rotor conductors are short circuited through end rings
(B) Rotor conductor ends are short circuited through slip rings
(C) Rotor conductors are kept open (D)None of the above
2- A smaller air gap in a poly phase induction motor helps to -----
(A) Reduce the chance of crawling (B) Increase the starting torque
(C) Reduce the chance of cogging (D) Reduce the magnetizing current
3- The efficiency of a three-phase induction motor can be expected to be nearly.
(A)60 to 90% (B) 80 to 90% (C) 95 to 98 % (D) 99%
4-The skin effect in a deep bar induction motor is maximum when rotor is
(A) At standstill
(C) Running at no load
5-Deep bar or double cage
(B) Running at its maximum speed
(D) Running at half load
O
-----
rotors are used in squirrel cage induction motor to obtain
(A) High starting current (B) High starting torque (C) Moderate starting current
(D) Reduced rotor resistance
---
6- Which of the following are used in preventing the hunting phenomenon in synchronous motors?
(A) Damper bars (B) Short pitch winding (C) Distributed winding (D) Full pitch winding
7-Oscillations of the rotor about its new equilibrium position, due to sudden application or removal of
load in synchronous motor is called
(A) Phasing out (B) Damping (C) Hunting (D) None of these
8- The method used to determine X and X, the direct and quadrature axis reactance is called -------
(A) Reactance test (B) Blondel's two reaction theory (C) Slip test (D) All of these
9- Consider a purely inductive load connected to the alternator having zero lagging power factor. In this
case the effect of armature reaction will be
(A) Demagnetizing effect (B) Cross magnetizing effect (C) Magnetizing effect (D) None of these
10- The synchronous reactance of an alternator is equal to
___
(A) Leakage reactance of armature (B) Armature reaction reactance
(C) Sum of leakage reactance and armature reaction reactance
(D) Difference of leakage reactance and armature reaction reactance
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