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.Management Sciences
Category: Switchgear and Protection
The inverse definite mean time relays are used for over current and earth fault protection of transformer against_________________?
A. heavy loads
B. internal short-circuits
C. external short-circuits
D. all of the above
The inductive interference between power and communication line can be minimized by__________?
A. transposition of the power line
B. transposition of the communication line
C. both (A) and (B)
D. increasing the distance between the conductors
Admittance relay is __________ relay?
A. impedance
B. directional
C. non-directional
D. none of the above
A fuse is never inserted in____________?
A. neutral wire
B. negative of D.C. circuit
C. positive of D.C. circuit
D. phase dine
What will be the reflection co-efficient of the wave of load connected to transmission line if surge impedance of the line is equal to load ?
A. Zero
B. Unity
C. Infinity
D. None of the above
The arcing contacts in a circuit breaker are made of______________?
A. copper tungsten alloy
B. porcelain
C. electrolytic copper
D. aluminium alloy
The current zero interruption, in oil and air blast circuit breakers, is achieved by____________?
A. lengthening of the gap
B. cooling and blast effect
C. both (A) and (B)
D. deionizing the oil with forced air
E. none of the above
Large internal faults are protected by_______________?
A. merz price percentage differential protection
B. mho and ohm relays
C. horn gaps and temperature relays
D. earth fault and positive sequence relays
A fuse in a motor circuit provides protection against__________?
A. overload
B. short-circuit and overload
C. open circuit, short-circuit and overload
D. none of the above
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