Practice Test: Question Set - 06
1. Which of the following is reversible in action?
- (A) Motor generator set
- (B) Motor converter
- (C) Rotary converter
- (D) Any of the above
2. Normally, which of the following is used, when a large-scale conversion from AC. to D.C. power is required?
- (A) Motor-generator set
- (B) Motor converter
- (C) Rotary converter
- (D) Mercury arc rectifier
3. In which of the following amputations, direct current is absolutely essential?
- (A) Illumination
- (B) Electrolysis
- (C) Variable speed operation
- (D) Traction
4. In which of the following equipment direct current is needed?
- (A) Telephones
- (B) Relays
- (C) Time switches
- (D) All of the above
5. The potential drop in the arc, in a mercury arc rectifier, varies
- (A) 0.05 V to 0.2 V per cm length of the arc
- (B) 0.5 V to 1.5 V per cm length of the arc
- (C) 2 V to 3.5 V per cm length of the arc
- (D) None of the above
6. In a mercury arc rectifier________ flow from anode to cathode
- (A) Ions
- (B) Electrons
- (C) Ions and electrons
- (D) Any of the above
7. A mercury arc rectifier possesses __________ regulation characteristics
- (A) Straight line
- (B) Curved line
- (C) Exponential
- (D) None of the above
8. In a grid control of mercury arc rectifiers when the grid is made positive relative to cathode, then it the electrons on their way __________ to anode.
- (A) Accelerates
- (B) Decelerates
- (C) Any of the above
- (D) None of the above
9. Ageing of a selenium rectifier may change the output voltage by
- (A) 5 to 10 per cent
- (B) 15 to 20 per cent
- (C) 25 to 30 per cent
- (D) None of the above
10. The efficiency of an electrolytic rectifier is nearly
- (A) 80 %
- (B) 70 %
- (C) 60 %
- (D) 40 %