Transmission and distribution. Part – 4

31. If frequency of transmission system is changed from 50Hz to 100Hz the string efficiency

A. Will increase

B. Will decrease

C. Remain unchanged

D. Depend on line parameter

32. Back to back HVDC is used to

A. Increase the transmission capability

B. Decrease line losses

C. provide stable interconnection

D. Reduce voltage drop

33. If receiving end voltage is more than the sending end voltage, the effect is known as ___

A. Proximity effect

B. Skin effect

C. Ferranti effect

D. Losses

34. Use of synchronous condenser improves

A. Power factor

B. System stability

C. Efficiency

D. All of the above

35. The most commonly used insulating materials for low and medium voltage cables is

A. Polyethylene

B. Porcelain

C. PVC

D. vulcanized rubber

36. Ferranti effect can be compensated by which of the following?

A. shunt capacitor

B. shunt reactor

C. series capacitor

D. both (A) and (B)

37. Under over excitations synchronous phase modifier works as

A. Shunt capacitor

B. Series capacitor

C. Shunt reactor

D. Any of the above

38. Telecommunication lines are transposed to reduce the

A. Efficiency

B. Radio interference in communication lines

C. Voltage level

D. All of the above

39. Which test is / are conducted after completion of erection of 11 KV line but before energisation of lines?

A. conductor continuity tests

B. earth resistance tests

C. insulation resistance tests

D. all of above

40. What is the angle between the pole and stay?

A. 30⁰

B. 45⁰

C. 60⁰

D. 10⁰