TRANSFORMERS MCQs SET 16

TRANSFORMERS MCQs SET 16

1. When secondaries are connected in phase opposition, power drawn by the circuit is equal to ___________
a) 2*Pi
b) Pi2
c) Pi
d) 2*Pc
 

Answer: a

2. When the AC supply at the primary side of a transformer are shorted, power drawn by the circuit is equal to ___________
a) 2*PC
b) 2*Pi
c) 2*PC + 2*Pi
d) Can’t be determined
 

Answer: a

3.Total power required for Sumpner’s test is given by ________
a) PC + Pi
b) PC + 2Pi
c) 2PC + Pi
d) 2(PC + Pi)
 

Answer: d

4. When will be the efficiency of a transformer maximum?
a) Copper losses = hysteresis losses
b) Hysteresis losses = eddy current losses
c) Eddy current losses = copper losses
d) Copper losses = iron losses
 

Answer: d

5. Efficiency of a power transformer is near to the ___________
a) 100 per cent
b) 98 per cent
c) 50 per cent
d) 25 per cent
 

Answer: b

6. On which factors transformer routine efficiency depends upon?
a) Supply frequency
b) Load current
c) Power factor of load
d) Load current and power factor of load
 

Answer: d

7. Normal transformers are designed to have maximum efficiency at ___________
a) Nearly full load
b) 70% full load
c) 50% full load
d) No load
 

Answer: a

8. At which load condition maximum efficiency of a distribution transformer will be achieved?
a) At no load
b) At 60% full load
c) At 80% full load
d) At full load
 

Answer: b

9. Power transformers other than distribution transformers are generally designed to have maximum efficiency around ______
a) No-load
b) Half-load
c) Near full-load
d) 10% overload
 

Answer: c

10. For a transformer given, operating at constant load current, maximum efficiency will occur at ______
a) 0.8 leading power factor
b) 0.8 lagging power factor
c) Zero power factor
d) Unity power factor
 

Answer: d