Power systems miscellaneous
- The ratio of reset to pick up current for an induction cup relay is approximately _________
-
View Hint View Answer Discuss in Forum
The ratio of reset to pick-up is inherently high in case of induction relays as compared to attracted armature relays as their operation does not involve any change in the air gap of the magnetic circuit as it in the case of the latter. Thus this ratio lies between 15% to 100%, not exactly 100% because of friction and imperfect compensation of the control spring torque.
Correct Option: B
The ratio of reset to pick-up is inherently high in case of induction relays as compared to attracted armature relays as their operation does not involve any change in the air gap of the magnetic circuit as it in the case of the latter. Thus this ratio lies between 15% to 100%, not exactly 100% because of friction and imperfect compensation of the control spring torque.
- The impedance value of generator is 0.2 p.u. on a base value of 11 kV, 50 MVA. The impedance value for a base value of 22 kV, 150 MVA is _______ p.u.
-
View Hint View Answer Discuss in Forum
Xnew = 150 × 
11 
² × 0.2 50 22
= 0.15 p.uCorrect Option: C
Xnew = 150 × 11 ² × 0.2 50 22
= 0.15 p.u
- The plug setting of a negative sequence relay is 0.2 A. The current transformer ratio is 5: 1. The minimum value of line to line fault current for the operation of the relay is _______ A
-
View Hint View Answer Discuss in Forum
NA
Correct Option: B
NA
- A 100/5 A bar primary current transformer supplies an O/C relay set at 25% pick up and it has a burden of 5 VA. The secondary voltage i s __________V
-
View Hint View Answer Discuss in Forum
NA
Correct Option: D
NA
- In a 400 kV power network, 360 kV is recorded at 400 kV bus. The reactive power absorbed by a shunt reactor for 50 MVAr, 400 kV connected at the bus is _________ MVAr
-
View Hint View Answer Discuss in Forum
NA
Correct Option: C
NA
