Practice Test: Question Set - 10
1. A certain transformer has a turns ratio of 1 and a 0.85 coefficient of coupling. When 2 V ac is applied to the primary, the secondary voltage is
- (A) 1.7 V
- (B) 0.85 V
- (C) 1 V
- (D) 0 V
2. Sumpner's test is conducted on transformers to determine
- (A) Temperature
- (B) Stray losses
- (C) All-day efficiency
- (D) None of the above
3. Which winding in a transformer has more number of turns?
- (A) Low voltage winding
- (B) High voltage winding
- (C) Primary winding
- (D) Secondary winding
4. Power transformers are designed to have maximum efficiency at
- (A) Nearly full load
- (B) 70% full load
- (C) 50% full load
- (D) No load
5. What will happen if the transformers working in parallel are not connected with regard to polarity?
- (A) The power factor of the two transformers will
be different from the power factor of common load
- (B) Incorrect polarity will result in dead short
circuit
- (C) The transformers will not share load in
proportion to their kVA ratings
- (D) None of the above
6. To step 110 V ac down to 20 V ac, the turns ratio must be
- (A) 5.5
- (B) 18
- (C) 0.18
- (D) 0.018
7. An ideal transformer has infinite values of primary and secondary inductances. The statement is
- (A) True
- (B) False
8. A Buchholz relay can be installed on
- (A) Auto-transformers
- (B) Air-cooled transformers
- (C) Welding transformers
- (D) Oil cooled transformers
9. The core used in high frequency transformer is usually
- (A) Copper core
- (B) Cast iron core
- (C) Air core
- (D) Mild steel core
10. An ideal transformer is one which has
- (A) No losses and magnetic leakage
- (B) Interleaved primary and secondary windings
- (C) A common core for its primary and secondary
windings
- (D) Core of stainless steel and winding of pure
copper metal
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