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.Management Sciences
Category: Rectifiers and Converters
The internal efficiency of a mercury arc rectifier depends on___________?
A. voltage only
B. current only
C. voltage and current
D. r.m.s. value of current
E. none of the above
A synchronous converter can be started______________?
A. by means of a small auxiliary motor
B. from AC. side as induction motor
C. from D.C. side as D.C. motor
D. any of the above methods
E. none of the above methods
In which of the following equipment direct current is needed ?
A. Telephones
B. Relays
C. Time switches
D. All of the above
The applications of selenium rectifiers are usually limited to potential of_____________?
A. 10 V
B. 30 V
C. 60 V
D. 100 V
E. 200 V
Which of the following mercury arc rectifier will deliver least undulating current?
A. Six-phase
B. Three-phase
C. Two-phase
D. Single-phase
In selenium rectifiers efficiencies ranging from _______ to _______ percent are attainable?
A. 25, 35
B. 40, 50
C. 60, 70
D. 75, 85
Selenium rectifier can be operated at temperatures as high as____________?
A. 25°C
B. 40°C
C. 60°C
D. 75°C
In phase-shift control method the control is carried out by varying the of grid voltage
A. magnitude
B. polarity
C. phase
D. any of the above
E. none of the above
The voltage drop between the anode and cathode, of a mercury arc rectifier comprises of the following_____________?
A. anode drop and cathode drop
B. anode drop and arc drop
C. cathode drop and arc drop
D. anode drop, cathode drop and arc drop
When a rectifier is loaded which of the following voltage drops take place ?
A. Voltage drop in transformer reactance
B. Voltage drop in resistance of transformer and smoothing chokes
C. Arc voltage drop
D. All of the above
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