Underground Cable MCQ

31. Property of absorbing moisture from the atmosphere is

1. Solubility
2. Viscosity
3. Porosity
4. Hygroscopicity

32. In terms of cost, the overhead transmission line is better than underground transmission line in the field of

1. Insulation
2. Right of way
3. Visibility
4. None of these

33. The material commonly used for sheaths of underground cable is

1. Lead
2. Steel
3. Rubber
4. Copper

34. The capacitance measured between any two cores of a 3-core cable with sheath earthed is 3 μF. The capacitance per phase will be

1. 1.5 μF
2. 6 μF
3. 1 μF
4. None of the above

35. The small pockets of air in the high voltage cable provide _____ relative permittivity, ______ electric field and at these sites breakdown is likely to be initiated.

1. High, high
2. Low, low
3. Low, high
4. High, low

36. The leakage resistance of a 50 km long cable is 1 Mohm. For a 100 km long cable it will be

1. 0.5 Mohm
2. 2 Mohm
3. 0.66 Mohm
4. None of these

37. Power distribution by cable  is generally adopted for line length

1. Less than 10 km
2. Above 10 km
3. Less than 50 km
4. Above 50 km

38. In a 60 km underground power transmission system, the best transmission system is

1. Single-phase ac system
2. Three-phase ac system
3. High voltage ac voltage system
4. DC transmission system

39. Least number of faults occur in

1. Transmission lines
2. Cables
3. Switchgears
4. Transformers

40. A.C.S.R. conductor having 7 steel strands surrounded by 25 aluminium conductors will be specified as

1. 25/7
2. 7/25
3. 50/15
4. 15/50