Testing of synchronous machines induction motors - Electrical Engineering (MCQ) questions and answers

1)   What is the value of no load current at normal voltage?

a. I0 is between 0.2 and 0.5 pu of full load current
b. I0 is between 0.1 and 0.2 pu of full load current
c. I0 is between 0.4 and 0.9 pu of full load current
d. I0 is between 1 and 1.5 pu of full load current
Answer  Explanation 

ANSWER: I0 is between 0.2 and 0.5 pu of full load current

Explanation:
No explanation is available for this question!
2)   What is / are the main causes for the noise in the machine?

a. Magnetostriction
b. Aerodynamics
c. Bearing noise of rotating shaft
d. Only b and c
e. All of these
Answer  Explanation 

ANSWER: All of these

Explanation:
No explanation is available for this question!
3)   What data is provided from the no load test on induction motors?

a. Core loss only
b. Magnetising current
c. No load power factor
d. All of these
e. None of these
Answer  Explanation 

ANSWER: All of these

Explanation:
No explanation is available for this question!
4)   Which among these is a commissioning check during site testing for an induction motor?

a. Insulation resistance
b. Terminal shrouds
c. Heater supply
d. All of these
Answer  Explanation 

ANSWER: Insulation resistance

Explanation:
No explanation is available for this question!
5)   What is the permitted noise level in db for a 500 kW motor running at a speed of 1500 rpm?

a. 60 db
b. 75 db
c. 90 db
d. 55 db
Answer  Explanation 

ANSWER: 90 db

Explanation:
No explanation is available for this question!
6)   Above what ratings is it necessary to fix separate heat exchangers on the machines?

a. Above 500 kW
b. Above 300 kW
c. Above 100 kW
d. Above 1000 kW
Answer  Explanation 

ANSWER: Above 300 kW

Explanation:
No explanation is available for this question!
7)   How many sets of orthogonal accelerometer are fixed on each bearing for performing vibration tests on induction motors?

a. Five
b. Four
c. Three
d. Two
Answer  Explanation 

ANSWER: Three

Explanation:
No explanation is available for this question!
8)   What is the slip equation using stroboscopic method?

a. Slip = (apparent rpm / 120 ) * pair of poles
b. Slip = (apparent rpm / 60 ) * pair of poles
c. Slip = (apparent rpm / 150 ) * pair of poles
d. Slip = (apparent rpm / 30 ) * pair of poles
Answer  Explanation 

ANSWER: Slip = (apparent rpm / 60 ) * pair of poles

Explanation:
No explanation is available for this question!
9)   Which method is used to measure the speed of a synchronous machine?

a. Stroboscopic method
b. By tachometer
c. By measuring the frequency by means of frequency meter
d. Only a and b
e. All of these
Answer  Explanation 

ANSWER: All of these

Explanation:
No explanation is available for this question!
10)   What test is conducted on the synchronous motor before completely assembling the whole machine?

a. Speed torque curves
b. Bearing insulation
c. Dielectric tests on the armature windings
d. Measurement of DC resistance of armature winding
Answer  Explanation 

ANSWER: Bearing insulation

Explanation:
No explanation is available for this question!

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