1. ........ relay is preferred for phase fault on short transmission line ?

Reactance

Impedence

Induction type

None of the above

Answer: Reactance

Explanation:


2. The single phasing relays are used for the protection of ?

single phase motors only

two single phase motors running in parallel

three phase motors

two phase motors only

Answer: three phase motors

Explanation:


3. Wave trap is used to trap waves of ?

power frequencies

either of the above

higher frequencies entering generator or transformer units

none of the above

Answer: higher frequencies entering generator or transformer units

Explanation:


4. The delay fuses are used for the protection of ?

light circuits

motors

fluorescent lamps

power outlet circuits

Answer: motors

Explanation:


5. Overheating of relay contacts or contact born out is due to ?

foreign matter on the contact surface

slow making and breaking of load circuit contacts

too low contact pressure

all of the above

Answer: all of the above

Explanation:


6. Directional relays are based on flow of ?

voltage wave

power

current

all of the above

Answer: power

Explanation:


7. Resistance grounding is used for voltage between ?

11 kV to 33 kV

3.3 KV and 11kV

33 kV to 66 kV

none of the above

Answer: 3.3 KV and 11kV

Explanation:


8. Discrimination between main and back up protection is provided by the use of relays which are ?

fact

sensitive

slow

none of the above

Answer: slow

Explanation:


9. Which of the following statements is incorrect ?

The peak short current is (1.8 x root2) times the A.C. component

Lightning arrestors are used before the switchgear

The MVA at fault is equal to base MVA divided by per unit equivalent fault reactance

Shunt reactors are used as compensation reactors

Answer: Lightning arrestors are used before the switchgear

Explanation:


10. ........ transmission line has reflection coefficient as one ?

Long

Short-circuit

Open circuit

None of the above

Answer: Open circuit

Explanation: