Q.326 Calculate torque developed by the 3-phase, 5 H.P, 4-pole induction motor runs at 1500 rpm
A. 23.5 N-m
B. 22 N-m
C. 0 N-m
D. 10 N-m
Ans.: C
Q.327 Which of the following breaking method save energy?
A. regenerative breaking
B. plugging
C. dynamic breaking
D. resistor breaking
Ans.: A
Q.328 For eliminating 7th harmonics from generated EMF in alternator the fractional pitch must be
A. 2/3
B. 5/6
C. 7/8
D. 6/7
Ans.: D
Q.329 A transformer has negative voltage regulation when its load PF is
A. zero
B. leading
C. unity
D. lagging
Ans.: B
Q.330 In synchronous motor, V-curve is a graph of
A. Armature current Vs Field current
B. Armature current Vs power factor
C. Armature current Vs active power
D. Armature current Vs reactive power
Ans.: A
Q. 331 Stray loss is equal to____
A. frictional loss and copper loss
B. mechanical loss and iron loss
C. copper loss and iron loss
D. field copper loss and iron loss
Ans.: B
Q.332 In a DC motor, back EMF value becomes maximum at___
A. full load
B. ½ load
C. no load
D. ¾ load
Ans.: B
Q.333 Hopkinson’s test is the test to be carried out on
A. induction motor with any DC motor
B. two identical induction motors
C. two identical DC motor
D. induction motor with synchronous motor
Ans.: C
Q.334 In differential protection scheme, a stability resistance connected to
A. block harmonics
B. increase the relay sensitivity
C. increase the current limit
D. reduce the effect of non identical CTs
Ans.: D
Q.335 An over current relay of current rating 5 A and setting 150% is connected to a 200/5A CT. Then the relay to pickup, the line current required is
A. 500
B. 200
C. 100
D. 150
Ans.: A
Q.336 The fault occurring in transmission actually are mostly
A. L-L
B. L-G
C. L-L-L
D. L-L-G
Ans.: B
Q.337 The value of holding ratio of relay is always
A. less than 1
B. greater than 1
C. infinite
D. zero
Ans.: A
Q.338 What is the surge impedance loading of 400Kv line with surge impedance given as 160ohms.
A. 1000 KW
B. 400 MW
C. 250 MW
D. 1000 MW
Ans.: D
Q.339 The power factor of the arc in circuit breaker is
A. always zero
B. always lagging
C. always unity
D. always leading
Ans.: C
Q.340 The relay which is most sensitive to power swings (mal operation) is
A. Mho relay
B. Reactance Relay
C. Impedance relay
D. over current relay
Ans.: B