AP ECET EEE 2017-6

1. A Buchholz relay is used for

A. protection of transformer against all internal faults
B. protection of transformer against external faults
C. protection of transformer against both internal and external faults
D. protection of induction motors

Answer : protection of transformer against all internal faults
Explain:-

2. Which one of the following grounding methods is used to reduce the tower footing resistance where an earth resistance is low

A. Single driven rod
B. Multiple rods
C. counterpoises
D. Plates

Answer : Single driven rod
Explain:-

3. A lightning arrestor connected the line and earth in Power system

A. Protects the terminal equipment against travelling surges
B. Protects the transmission line against direct lighting stroke
C. Suppresses high frequency oscillations in the line
D. Reflects back the traveling wave approaching it

Answer : Protects the terminal equipment against travelling surges
Explain:-

4. For a transmission line with resistance R, reactance X, and negligible capacitance the transmission line parameter A is

A. 0
B. 1
C. R+jX
D. R+X

Answer : 1
Explain:-

5. The insulation resistance of a single core cable is 200Mohm/km. The insulation resistance for 5km length is

A. 40Mohm
B. 1000Mohm
C. 200Mohm
D. 8Mohm

Answer : 40Mohm
Explain:-

6. Which of the following equation is correct

A. -AB+CB=-1
B. AD+CB=1
C. AB-CD=-1
D. -AD+BC=-1

Answer : -AD+BC=-1
Explain:-

7. When is the ferranti effect on long overhead lines experienced

A. The line is lightly loaded
B. The line is heavily loaded
C. The line is fully loaded
D. The power factor is unity

Answer : The line is lightly loaded
Explain:-

8. Whenever the conductors are dead ended or there is a change in the direction of transmission line, the insulators used are of the

A. Pin type
B. Suspension type
C. Strain type
D. Shackle type

Answer : Strain type
Explain:-

9. In a three unit insulator string, voltage across the lowest unit is 17.5KV and string efficiency is 84.28%. The total voltage across the string will be equal to

A. 8.825 KV
B. 44.248 KV
C. 88.25 KV
D. 442.5 KV

Answer : 44.248 KV
Explain:-

10. In the case of a HVDC system, there is

A. Charging current but no skin effect
B. No charging current but skin effect
C. Neither charging current nor skin effect
D. both charging current and skin effect

Answer : Neither charging current nor skin effect
Explain:-