# A large-size alternator is protected against overloads by providing

1.  Over current relays

2.  Temperature sensitive relays

3.  Thermal relays

4.  A combination of (a) and (b)

4

Temperature sensitive relays

Explanation :
No Explanation available for this question

# The insulation of the modern EHV lines is designed based on

1.  The lighting voltage

2.  The switching voltage

3.  Corona

4.  RI

4

The switching voltage

Explanation :
No Explanation available for this question

# The rate of rise of restricting voltage depends upon the

1.  Type of circuit breaker

2.  Inductance of the system only

3.  Capacitance of the system only

4.  Inductance and capacitance of the system

4

Inductance and capacitance of the system

Explanation :
No Explanation available for this question

# A 3-phase breaker is rated at 2000 MVA, 33 kV, its making current will be

1.  35 kA

2.  49 kA

3.  70 kA

4.  89 kA

4

89 kA

Explanation :
No Explanation available for this question

# If the inductance and capacitance of a system are 1.0 H and 0.01 µF respectively and the instantaneous value of current interrupted is 10 amp, the voltage across the breaker contacts will be

1.  50 kV

2.  100 kV

3.  60 kV

4.  89 kA

4

100 kV

Explanation :
No Explanation available for this question

# For protection of rotating machines against lighting surges a combination of

1.  Lighting conductor and capacitance are used

2.  Lighting conductor and lighting arrester are used

3.  Lighting arrester and capacitance are used

4.  Lighting arrester alone is used

4

Lighting arrester and capacitance are used

Explanation :
No Explanation available for this question

# If the inductance and capacitance of a system are 1 H and 0.01 µF respectively and the instantaneous value of current interrupted is 10 amps. The value of shunt resistance across the breaker for critical damping is

1.  100 k

2.  10 k?

3.  5 k?

4.  1 k?

4

5 k?

Explanation :
No Explanation available for this question

# An IDMT over current relay has a current setting of 15% and has a time multiplier setting of 0.5. The relay is connected in the circuit through a CT having 500 : 5. What is the time of operation of the relay if the circuit carries a fault current of 6000 A

1.  2.5 sec

2.  1.25 sec

3.  1.575 sec

4.  3.2 sec

4

1.575 sec

Explanation :
No Explanation available for this question

# For a 132 kV system, the reactance and capacitance upto the location of the circuit breaker is 3 and 0.015 µF respectively. The frequency of transient oscillation will be

1.  14.2 kHz

2.  13.29 kHz

3.  10 kHz

4.  none of these

4

13.29 kHz

Explanation :
No Explanation available for this question

# Resistance switching is normally employed in

1.  All breakers

2.  Bulk oil breakers

3.  Minimum oil breakers

4.  Air blast circuit breaker

4