AP ECET EEE 2016-1

1. The losses are measured in auto transformer, when it is operating at no load are 150W. Iron losses of this transformer at full load operation are

A. 150w
B. 180w
C. 120w
D. 220w

Answer : 150w
Explain:-

2. During the SC test, power drawn by the primary winding is predominantly observed by

A. Copper loss
B. Core loss
C. Copper loss plus core loss
D. Eddy current, and hysteresis loss

Answer : Copper loss
Explain:-

3. In parallel operation load sharing by transformers is according to

A. Pu impedance
B. kVA rating
C. kW rating
D. Efficiency

Answer : Pu impedance
Explain:-

4. When speed of alternator is changed from 3600 rpm to 1800 rpm, the generated emf per phase will become

A. Twice
B. Four times
C. 1/4
D. 1/2

Answer : 1/2
Explain:- EMF generated ∝ Speed of Alternator
N1=3600rpm;N2=1800rpm
N1/N2=E1/E2
3600/1800=E1/E2
E1/E2=2
E2=E1/2
Generated EMF Will become half

5. The regulation of an alternator is

A. The reduction in terminal voltage when alternator is Loaded
B. The variation of terminal voltage under the conditions of maximum and minimum excitation
C. The increase in voltage when load is thrown off
D. The change in terminal voltage from lagging pf to leading pf

Answer : The increase in voltage when load is thrown off
Explain:-

6. In case of turbo-alternators, rotor is made of

A. Forged steel
B. Cast iron
C. Stainless steel
D. Laminated silicon steel

Answer : Forged steel
Explain:-

7. A synchronous motor is supplied a load at unity p.f. If the load on the motor is increased keeping its excitation and terminal voltage\nconstant, then the p.f

A. Will remain the same
B. Will become leading
C. Will become lagging
D. Will become zero

Answer : Will become lagging
Explain:-

8. When synchronous motor is running at synchronous speed, the damper winding produces

A. Damping torque
B. Eddy current torque
C. Torque aiding the developed torque
D. No torque

Answer : No torque
Explain:-

9. While starting a synchronous motor by induction motor action its field winding should be

A. Kept open
B. Short circuited
C. Connected to DC source
D. Connected to AC source

Answer : Short circuited
Explain:-

10. The stator core of a three phase inductionmotor is laminated in order to reduce the

A. Eddy current loss
B. Hysteresis loss
C. Winding and frictional loss
D. Copper loss

Answer : Eddy current loss
Explain:-