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.Management Sciences
Category: Switchgear and Protection
Bus coupler is very essential in arrangement______________?
A. single bus
B. double bus, double breaker
C. main and transfer bus
D. all of the above
Shunt capacitance is neglected while considering______________?
A. short transmission line
B. medium transmission line
C. long transmission line
D. medium and long transmission lines
In order that current should flow without causing excessive heating or voltage drop, the relay contacts should_________________?
A. have low contact resistance
B. be clean and smooth
C. be of sufficient size and proper shape
D. have all above properties
Thermal overload relays are used to protect the motor against over current due to____________?
A. short-circuits
B. heavy loads
C. grounds
D. all of the above
Short-circuit currents are due to_______________?
A. single phase to ground faults
B. phase to phase faults
C. two phase to ground faults
D. three phase faults
E. any of these
The short circuit in any winding of the transformer is the result of______________?
A. mechanical vibration
B. insulation failure
C. loose connection
D. impulse voltage
Induction cup relay is operated due to changes in________________?
A. current
B. voltage
C. impedance
D. all of the above
Circuit breakers are essentially______________?
A. current carrying contacts called electrodes
B. arc extinguishers
C. circuits to break the system
D. transformers to isolate the two systems
E. any of the above
On which of the following routine tests are conducted ?
A. Oil circuit breakers
B. Air blast circuit breakers
C. Minimum oil circuit breakers
D. All of the above
The contacts of high voltage switches used in power system are submerged in oil. The main purpose of the oil is to______________?
A. lubricate the contacts
B. insulate the contacts from switch body
C. extinguish the arc
D. all of the above
E. none of the above
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