Practice Test: Question Set - 12
1. The size of a transformer core will depend on
- (A) Frequency
- (B) Area of the core
- (C) Flux density of the core material
- (D) Both (A) and (B)
2. The full-load copper loss of a transformer is 1600 W. At half-load, the copper loss will be
- (A) 6400 W
- (B) 1600 W
- (C) 800 W
- (D) 400 W
3. The changes in volume of transformer cooling oil due to variation of atmospheric temperature during day and night is taken care of by which part of transformer
- (A) Conservator
- (B) Breather
- (C) Bushings
- (D) Buchholz relay
4. The efficiency of two identical transformers under load conditions can be determined by
- (A) Short-circuit test
- (B) Back-to-back test
- (C) Open circuit test
- (D) Any of the above
5. The voltage transformation ratio of a transformer is equal to the ratio of
- (A) Primary turns to secondary turns
- (B) Secondary current to primary current
- (C) Secondary induced e.m.f. to primary induced
e.m.f.
- (D) Secondary terminal voltage to primary
applied voltage
6. The permissible flux density in case of cold rolled grain oriented steel is around
- (A) 1.7 Wb/m2
- (B) 2.7 Wb/m2
- (C) 3.7 Wb/m2
- (D) 4.7 Wb/m2
7. Natural oil cooling is used for transformers up to a rating of
- (A) 3000 kVA
- (B) 1000 kVA
- (C) 500 kVA
- (D) 250 kVA
8. The use of higher flux density in the transformer design
- (A) Reduces weight per kVA
- (B) Reduces iron losses
- (C) Reduces copper losses
- (D) Increases part load efficiency
9. Delta/star transformer works satisfactorily when
- (A) Load is balanced only
- (B) Load is unbalanced only
- (C) On balanced as well as unbalanced loads
- (D) None of the above
10. Noise level test in a transformer is a
- (A) Special test
- (B) Routine test
- (C) Type test
- (D) None of the above
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