# If pu impedance value of an alternator corresponding to base values 13.2 kV and 30 MVA is 0.2 p.u., then p.u. value for, the base value 13.8 kV and 50MVAwill be

1.  0.306 p.u.

2.  0.33 p.u.

3.  0.318 p.u

4.  0:328 p.u.

4

0.306 p.u.

Explanation :
No Explanation available for this question

# A lightning arrester connected the line and earth in a power system

1.  protects terminal equipment against travelling surges

2.  protects transmission line against direct lightning stroke

3.  suppresses high frequency oscillations in the line

4.  reflects back travelling wave aproaching

4

protects terminal equipment against travelling surges

Explanation :
No Explanation available for this question

# While using air-blast circuit breaker current, chopping is a phenomenon often observed when a

1.   long overhead line is switched off

2.  bank of capacitors is switched off

3.  transformer on no load is Switched off

4.  heavy load, is switched off

4

transformer on no load is Switched off

Explanation :
No Explanation available for this question

# Lightning arresters amused in power systems to protect electrical equipments against

1.  direct strokes of lightning

2.  power frequency of over voltages

3.  over voltages due to indirect lightning stroke

4.  over currents due to lightning stroke

4

over voltages due to indirect lightning stroke

Explanation :
No Explanation available for this question

# To prevent maloperation of differentially connected relay while energising a transformer, the relay restraining coil is biased with

1.  second harmonic current

2.  third harmonic current

3.  fifth harmonic current

4.  seventh harmonic current

4

fifth harmonic current

Explanation :
No Explanation available for this question

# Rated breaking capacity (MVA) Of a circuit breaker is equal to

1.  produce of rated breaking current (kA) and rated voltage (kV)

2.  product of rated symmetrical breaking current (kA) and rated voltage (kV)

3.  product of breaking current (kA) and fault voltage (kV)

4.  twice the value of rated current (kA) and rated voltage (kV)

4

produce of rated breaking current (kA) and rated voltage (kV)

Explanation :
No Explanation available for this question

# The transient stability of the power system can be effectively improve by

1.  excitation control

2.  phase shifting transformer

3.  single pole switching of circuit breakers

4.  increasing the turbine valve opening

4

excitation control

Explanation :
No Explanation available for this question

# During a disturbance on a synchronous machine, the rotor swings from A to B before finally settling down to a steady state at point C on the power angle curve. The speed of the machine during oscillation is synchronous at point(s)

1.  A and B

2.  A and C

3.  B and C

4.  only at C

4

A and B

Explanation :
No Explanation available for this question

# A 100 MVA, 11 kV 3-phase, 50 Hz, 8-pole synchronous generator has an inetria constant H equal to 4 seconds. The stored energy in the rotor of the generator at synchronous speed will be

1.  100MJ

2.  400JM

3.  800MJ

4.  12.5MJ

4

800MJ

Explanation :
No Explanation available for this question

# Steady state. stability. a power system is the. ability of the power system to

1.  maintain voltage- at the rated voltage level

2.  maintain frequency exactly at 50 Hz

3.  maintain a spinning reserve margin at

4.  maintain synchronous between machines and on external tie lines

4