TRANSFORMERS MCQs SET 14

TRANSFORMERS MCQs SET 14

1. Which of the following is the correct formula for Bm?
a) Bm= (Yo2-Gi2)(1/2)
b) Bm= (Yo2+Gi2)(1/2)
c) Bm= (Yo2-Gi2)(2)
d) Bm= (Yo2+Gi2)(1/2)
 
Answer: a

2. How shunt branch component Y0 is calculated?
a) I0/V1
b) V1/I0
c) P0/V12
d) Cannot be determined
 
Answer: a

3. While conducting short-circuit test on a transformer which side is short circuited?
a) High voltage side
b) Low voltage side
c) Primary side
d) Secondary side
 
Answer: b

4. During short circuit test why iron losses are negligible?
a) The current on secondary side is negligible
b) The voltage on secondary side does not vary
c) The voltage applied on primary side is low
d) Full-load current is not supplied to the transformer
 
Answer: c

5. Short circuit test on transformers is conducted to determine ______
a) Core losses
b) Copper losses
c) Hysteresis losses
d) Eddy current losses
 
Answer: b

6. When a short circuit test on a transformer is performed at 25 V, 50 Hz, the drawn current is I1. If the test is performed by 25 V and 25 Hz and power drawn current is I2, then
a) I1 > I2
b) I1 < I2
c) I1 = I2
d) Can’t be defined
 
Answer: b

7. Why SC test is not conducted on LV side?
a) Difficult to arrange low voltage supply
b) Difficult to arrange high current supply
c) Difficult to arrange low voltage and high current supply to the LV
d) SC test on LV does not give correct results
 
Answer: c

8. SC test gives ______________
a) Series parameters of equivalent circuit
b) Parallel parameters of equivalent circuit
c) Both parameters of equivalent circuit
d) Neither series nor parallel parameter of equivalent circuit
 
Answer: a

9. For 200 kVA, 440/6600-V transformer, short circuit test on the LV side would require ______
a) 22V
b) 330V
c) 44V
d) Can’t be calculated
 
Answer: a

10. For a transformer given of 100 kVA, 220/6000-V transformer, short circuit test is performed. What current rating is needed?
a) 30A
b) 445A
c) 60A
d) Can’t be calculated
 
Answer: b