591. An inductance of one H carrying a current of two amperes will store the energy of
A. 2 watts
B. 2 joules
C. 4 watts
D. 4 joules
Ans.: B
592. The square waveform of current has following relation between r.m.s value and
average value
A. r.m.s. value of current is greater than the average value
B. r.m.s. value of current is less than the average value
C. r.m.s. value of current is equal to the average value
D. There is no definite relation between the r.m.s. value and average value for a
square wave
Ans.: C
593. Two numbers of 500 ohms one watt resistors are connected in parallel. Their combined resistance and wattage rating will be
A. 250 ohms, 1 watt
B. 250 ohms, 2 watts
C. 1000 ohms, 2 watts
D. 500 ohms, 2 watts
Ans.: B
594. For transfer function of a physical two-port network
A. All zeros must lie only in the left half of the s-plane
B. All poles may lie anywhere in the s-plane
C. The poles lying on the imaginary axis must be simple
D. All the above
Ans.: D
595. The starting torque of a three phase induction motor can be increased by
A. Increasing rotor reactance
B. Increasing rotor resistance
C. Increasing stator resistance
D. None of the above
Ans.: B
596. The capacitor start-capacitor run single phase induction motor is operationally a
A. Single phase motor
B. Two phase motor
C. Three phase motor
D. A.C. series motor
Ans.: B
597. What would happen if the field of a D.C. shunt motor is opened?
A. Speed will be reduced
B. Continue to run normally
C. Speed will enormously increase damaging the motor
D. None of the above
Ans.: C
598. Equalizer rings in D.C. generator with lap winding are used for
A. Equal distribution of current at brush for sparkles commutation
B. Prevention of harmonics
C. Reduction of noise and vibration
D. Avoiding overhang
Ans.: A
599. The Buchholz relay is normally used to protect the
A. Alternators against all internal faults
B. Oil immersed transformers against all internal faults
C. Synchronous motors against all internal faults
D. Transmission lines against all short circuit faults
Ans.: B
600. The power transformer is a
A. Constant current device
B. Constant voltage device
C. Constant power device
D. Pulsating main flux device
Ans.: D
601. A change of 5% in supply voltage to an induction motor will produce a change of
approximately
A. 5% in the rotor torque
B. 7.5% in the rotor torque
C. 10% in the rotor torque
D. 25% in the rotor torque
Ans.: C
602. If the supply frequency to the transformer is increased, the iron loss
A. Will increase
B. Will decrease
C. Will not change
D. May reach zero
Ans.: A
603. The maximum temperature permitted for class A insulation is
A. 180 degree centigrade
B. 105 degree centigrade
C. 120 degree centigrade
D. None of the above
Ans.: B
604. Two transformers connected in parallel share load in the ratio of their KVA ratings, provided their ohmic impedance are
A. Equal
B. In direct ratio of their ratings
C. In inverse ratio of their ratings
D. Purely reactive
Ans.: C
605. The high frequency hum in the transformers is mainly due to
A. Loose laminations
B. Magnetostriction
C. Impurity in oil
D. Weakness of tank wall
Ans.: B