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.Management Sciences
Category: Electrical Engineering Mcqs
The capacitance of reversed bised junction J2 in a thyristor is CJ2 = 20 pF and can be assumed to be independant of the off state voltage. The limiting value of the charging current to turn on the thyristor is 16 mA. What is the critical value of dv/dt?
0
A. 600 V/µs
B. 800 V/µs
C. 1200 V/µs
D. 1000 V/µs
The power factor of a D.C. circuit is always__________?
A. less than unity
B. unity
C. greater than unity
D. zero
Flame proof motors are used in_________________?
A. paper mills
B. steel mills
C. moist atmospheres
D. explosive atmospheres
Which of the following AC. motors is usually used in large motor-generator sets?
A. Synchronous motor
B. Squirrel cage induction motor
C. Slip ring induction motor
D. Any of the above
Air blast circuit breakers for 400 kV power system are designed to operate in_______________?
A. 100 microsecond
B. 50 millisecond
C. 0.5 sec
D. 0.1 sec
D.C. generators are normally designed for maximum efficiency around_____________?
A. full-load
B. rated r.p.m.
C. rated voltage
D. all of the above
Materials used in heat sink should have_____________?
A. high thermal conductivity
B. large surface area
C. high melting point
D. All of these
The speed of a locomotive is controlled by_______________?
A. flywheel
B. gear box
C. applying brakes 11.
D. regulating steam flow to engine
The draught which a chimney produces is called_____________?
A. induced draught
B. natural draught
C. forced draught
D. balanced draught
The power dissipation in each of four parallel branches is 1.2 W. The total power dissipation is________________?
A. 1.2 W
B. 4.8 W
C. 0.3 W
D. 12 W
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