A/C ELECTRICAL SYSTEM
1. Suppose you suddenly come across a colleague who is stuck to live bus-bars in a sub-station. Your first action
would be to: (Ref. BL Theraja)
a. switch off the supply b. put him away from the bus-bars
c. immediately call for medical assistance d. start artificial breathing straightaway
2. The centripetal force necessary to keep electrons rotating the elliptical orbits round the nucleus is supplied by the
force of attraction between their charges are given by (Ref. BL Theraja)
a. coulomb‟s laws b. faraday‟s laws
c. Fleming‟s law d. none of the above
3. The purpose of carbon contact in attracted-core, heavy duty relay: (Ref. EHJ Pallet, 108)
a. to limit the current in relay coil
b. to absorb initial heavy current and thereby reduce arcing to a minimum before positive connection with
main contacts is made
c. to compensate for loss of spring
d. all the above are correct
4. The RMS value of alternating current is: (Ref. EHJ Pallet, 33)
a. sum of square of individual component of currents
b. sum of square of individual components of currents divided by no. of individual components
c. during a half cycle, squaring the value and taking their mean value and then taking the square root
d. none of the above
5. A tumbler switch is also called: (Ref. AC 65 – 9A)
a. micro switch b. toggle switch
c. push switch d. none of the above
b. toggle switch
d. none of the above
6. The performance of rectifier depend on: (Ref. Grob., 812)
a. maximum temperature of plate b. maximum reverse voltage
c. minimum voltage d. both a & c are correct
7. Which switch is not having moving parts: (Ref. TK Eismin, 259)
a. mercury b. thermal
c. proximity d. rotary
8. Which is not thermally affected by temperature: (Ref. AC 65 – 9A)
a. fuse b. CB c. limiting resistor d. thermistor
9. The effect of change in frequency will change: (Ref. BL Theraja – Ed 1991, 578)
a. hysteresis loss b. eddy current loss
c. both a & b d. none of the above
b. eddy current lossd.
d. none of the above