ECET EEE 2009-5

1. With sinusoidal excitation, the true power is given by

A. VI Cos∅
B. VI Sin∅
C. VI
D. (VI/2)cos∅

Answer : VI Sin∅
Explanation:-

2. The power in a 3-phase circuit is given by

A. √3VL Cos∅
B. VL I Cos∅
C. √3VL Sin∅
D. VL Sin∅

Answer : √3VL Cos∅
Explanation:-

3. In a low voltage distribution system, the following transformer connection is preferred

A. Delta/Delta
B. Delta/star
C. Star/Star
D. Delta/star with neutral

Answer : Delta/star with neutral
Explanation:-

4. The efficiency of a transformer is high because of

A. Absence of copper loss
B. Absence of core loss
C. Absence of mechanical loss
D. Absence of air gap in magnetic circuit

Answer : Absence of mechanical loss
Explanation:-

5. Breather in a transformer contains

A. Sand
B. Mercury
C. Coal
D. Silica jel

Answer : Silica jel
Explanation:-

6. One of the latest material used for core in a transformer is

A. Iron
B. Steel
C. CRGO
D. Silicon steel

Answer : CRGO
Explanation:-

7. The no - load losses in a transformer comprises of

A. Copper loss
B. Iron loss
C. Eddy loss
D. Hysteresis loss

Answer : Iron loss
Explanation:-

8. Two transformers operating in parallel share the load proportional to their ratings when

A. Voltages are equal
B. Impedances are equal
C. Efficiencies are equal
D. Per unit impedances are equal

Answer : Per unit impedances are equal
Explanation:-

9. An open circuit test on a transformer is performed basically to determine

A. Iron loss
B. Copper loss
C. Regulation
D. Leakage impedance

Answer : Iron loss
Explanation:-

10. A 3 - phase, 440 V, 6 pole induction motor is fed form a 50 Hz supply, and if it runs at 960 r.p.m., then he slip of the motor is

A. 4%
B. 2%
C. 6%
D. 8%

Answer : 4%
Explanation:-