Dielectric strength of rubber is around (a) 5 kV/mm (b) 15 kV/mm (c) 30 kV/mm (d) 200 kV/mm

Dielectric strength of rubber is around (a) 5 kV/mm (b) 15 kV/mm (c) 30 kV/mm (d) 200 kV/mm
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(c) 30 kV/mm
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If a cable of homogeneous insulation has a maximum stress of 10 kV/mm, then the dielectric strength of insulation should be (a) 5 kV/mm (b) 10 kV/mm (a) 15 kV/mm (d) 30 kV/mm

Description : If a cable of homogeneous insulation has a maximum stress of 10 kV/mm, then the dielectric strength of insulation should be (a) 5 kV/mm (b) 10 kV/mm (a) 15 kV/mm (d) 30 kV/mm

Last Answer : (b) 10 kV/mm

Is a cable is to be designed for use on 1000 kV, which insulation would you prefer ? (a) Polyvinyle chloride (b) Vulcanised rubber (c) Impregnated paper (d) Compressed SFe gas (e) none of the above

Description : Is a cable is to be designed for use on 1000 kV, which insulation would you prefer ? (a) Polyvinyle chloride (b) Vulcanised rubber (c) Impregnated paper (d) Compressed SFe gas (e) none of the above

Last Answer : (d) Compressed SFe gas

Cables for 220 kV lines are invariably (a) mica insulated (b) paper insulated (c) compressed oil or compressed gas insulated (d) rubber insulated (e) none of the above

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Last Answer : (c) compressed oil or compressed gas insulated

The insulating material should have (a) low permittivity (b) high resistivity (c) high dielectric strength (d) all of the above

Description : The insulating material should have (a) low permittivity (b) high resistivity (c) high dielectric strength (d) all of the above

Last Answer : (d) all of the above

The insulating material for a cable should have (a) low cost (b) high dielectric strength (c) high mechanical strength (d) all of the above

Description : The insulating material for a cable should have (a) low cost (b) high dielectric strength (c) high mechanical strength (d) all of the above

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Why 1.1 kV grade cables used for 415V?

Description : Why 1.1 kV grade cables used for 415V?

Last Answer : To take care of the both earthed / unearthed systems.  

What are the types of cables used in 6.6 kV and 415 V system voltages?

Description : What are the types of cables used in 6.6 kV and 415 V system voltages? 

Last Answer : In 6.6 kV system AC (unearthed) grade having stranded aluminium conductors cables are used. Their insulation's are as follows. 1. XLPE - Crossed linked polyethylene insulation. 2. FRLS PVC - Fire ... V grade copper or aluminium stranded cables are used. Their insulations are HR PVC and FS type. 

Solid type cables are considered unreliable beyond 66 kV because (a) insulation may melt due to higher temperature (b) skin effect dominates on the conductor (c) of corona loss between conductor and sheath material (d) there is a danger of breakdown of insulation due to the presence of voids

Description : Solid type cables are considered unreliable beyond 66 kV because (a) insulation may melt due to higher temperature (b) skin effect dominates on the conductor (c) of corona loss between conductor and sheath material (d) there is a danger of breakdown of insulation due to the presence of voids

Last Answer : (d) there is a danger of breakdown of insulation due to the presence of voids

Cables, generally used beyond 66 kV are (a) oil filled (b) S.L. type (c) belted (d) armoured

Description : Cables, generally used beyond 66 kV are (a) oil filled (b) S.L. type (c) belted (d) armoured

Last Answer : (a) oil filled

Pressure cables are generally not used beyond (a) 11 kV (b) 33 kV (c) 66 kV (d) 132 kV

Description : Pressure cables are generally not used beyond (a) 11 kV (b) 33 kV (c) 66 kV (d) 132 kV

Last Answer : (c) 66 kV

High tension cables are generally used up to (a) 11kV (b) 33kV (c) 66 kV (d) 132 kV

Description : High tension cables are generally used up to (a) 11kV (b) 33kV (c) 66 kV (d) 132 kV

Last Answer : (a) 11kV

cables are used for 132 kV lines. (a) High tension (b) Super tension (c) Extra high tension (d) Extra super voltage

Description : cables are used for 132 kV lines. (a) High tension (b) Super tension (c) Extra high tension (d) Extra super voltage

Last Answer : (d) Extra super voltage

Polyethylene has very poor dielectric and ageing properties. (a) Yes (b) No

Description : Polyethylene has very poor dielectric and ageing properties. (a) Yes (b) No

Last Answer : (b) No

In capacitance grading a homogeneous dielectric is used. (a) Yes (b) No

Description : In capacitance grading a homogeneous dielectric is used. (a) Yes (b) No

Last Answer : (b) No

Capacitance grading of cable implies (a) use of dielectrics of different permeabilities (b) grading according to capacitance of cables per km length (c) cables using single dielectric in different concentrations (d) capacitance required to be introduced at different lengths to counter the effect of inductance (e) none of the above

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Last Answer : (a) use of dielectrics of different permeabilities

The breakdown of insulation of the cable can be avoided economically by the use of (a) inter-sheaths (b) insulating materials with different dielectric constants (c) both (a) and (b) (d) none of the above

Description : The breakdown of insulation of the cable can be avoided economically by the use of (a) inter-sheaths (b) insulating materials with different dielectric constants (c) both (a) and (b) (d) none of the above

Last Answer : (c) both (a) and (b)

In capacitance grading of cables we use a ______ dielectric. (a) composite (b) porous (c) homogeneous (d) hygroscopic

Description : In capacitance grading of cables we use a ______ dielectric. (a) composite (b) porous (c) homogeneous (d) hygroscopic

Last Answer : (a) composite

The minimum dielectric stress in a cable is at (a) armour (b) bedding (c) conductor surface (d) lead sheath

Description : The minimum dielectric stress in a cable is at (a) armour (b) bedding (c) conductor surface (d) lead sheath

Last Answer : (d) lead sheath

The current carrying capacity of cables in D.C. is more that in A.C. mainly due to (a) absence of harmonics (b) non-existence of any stability limit (c) smaller dielectric loss (d) absence of ripples (e) none of the above

Description : The current carrying capacity of cables in D.C. is more that in A.C. mainly due to (a) absence of harmonics (b) non-existence of any stability limit (c) smaller dielectric loss (d) absence of ripples (e) none of the above

Last Answer : (c) smaller dielectric loss

The relative permittivity of rubber is (a) between 2 and 3 (b) between 5 and 6 (c) between 8 and 10 (d) between 12 and 14

Description : The relative permittivity of rubber is (a) between 2 and 3 (b) between 5 and 6 (c) between 8 and 10 (d) between 12 and 14

Last Answer : (a) between 2 and 3

Rubber is most commonly used insulation in cables. (a) Yes (b) No

Description : Rubber is most commonly used insulation in cables. (a) Yes (b) No

Last Answer : (a) Yes

Natural rubber is obtained from milky sap of tropical trees. (a) Yes (b) No

Description : Natural rubber is obtained from milky sap of tropical trees. (a) Yes (b) No

Last Answer : (a) Yes

Empire tape is (a) varnished cambric (b) vulcanized rubber (c) impregnated paper (d) none of the above

Description : Empire tape is (a) varnished cambric (b) vulcanized rubber (c) impregnated paper (d) none of the above

Last Answer : (a) varnished cambric

Which of the following insulation is used in cables? (a) Varnished cambric (b) Rubber (c) Paper (d) Any of the above

Description : Which of the following insulation is used in cables? (a) Varnished cambric (b) Rubber (c) Paper (d) Any of the above

Last Answer : (d) Any of the above

The thickness of metallic shielding on cables is usually (a) 0.04 mm (b) 0.2 to 0.4 mm (e) 3 to 5 mm (d) 40 to 60 mm

Description : The thickness of metallic shielding on cables is usually (a) 0.04 mm (b) 0.2 to 0.4 mm (e) 3 to 5 mm (d) 40 to 60 mm

Last Answer : (a) 0.04 mm

The dielectric strength of transformer oil should be (A) 100 V. (B) 5 KV. (C) 30 KV. (D) 132 KV.

Description : The dielectric strength of transformer oil should be (A) 100 V. (B) 5 KV. (C) 30 KV. (D) 132 KV.

Last Answer : (C) 30 KV.

Low tension cables are generally used up to (a) 200 V (b) 500 V (c) 700 V (d) 1000 V

Description : Low tension cables are generally used up to (a) 200 V (b) 500 V (c) 700 V (d) 1000 V

Last Answer : (d) 1000 V

In the cables, sheaths are used to (a) prevent the moisture from entering the cable (b) provide enough strength (e) provide proper insulation (d) none of the above

Description : In the cables, sheaths are used to (a) prevent the moisture from entering the cable (b) provide enough strength (e) provide proper insulation (d) none of the above

Last Answer : (a) prevent the moisture from entering the cable

The dielectric strength of a vacuum or dry air is approximately ________________. A. 450 volts/inch B. 1000 volts/inch C. 20-kv/inch D. 50-kv/inch

Description : The dielectric strength of a vacuum or dry air is approximately ________________. A. 450 volts/inch B. 1000 volts/inch C. 20-kv/inch D. 50-kv/inch

Last Answer : Answer: C

63 The dielectric strength of transformer oil is expected to be A. 1kV B. 33kV C. 100kV D. 330 kV

Description : 63 The dielectric strength of transformer oil is expected to be A. 1kV B. 33kV C. 100kV D. 330 kV

Last Answer : B. 33kv

The surge resistance of cable is (a) 5 ohms (b) 20 ohms (c) 50 ohms (d) 100 ohms

Description : The surge resistance of cable is (a) 5 ohms (b) 20 ohms (c) 50 ohms (d) 100 ohms

Last Answer : (c) 50 ohms

What is the type cable used in radiation areas?

Description : What is the type cable used in radiation areas?

Last Answer : Mineral insulated (MI) cables. 

Why bimetallic washers provided in aluminium copper transition joints?

Description : Why bimetallic washers provided in aluminium copper transition joints?

Last Answer : To avoid galvanic corrosion failure.  

How the required conductor size can be reduced by use of HRC fuses?

Description : How the required conductor size can be reduced by use of HRC fuses?

Last Answer : HRC fuse limits the peak amplitude of fault current. HRC fuse melts at prospective current but not allows circuit to pass their high rupturing capacity that is it’s kA. 

Why armouring done?

Description : Why armouring done?

Last Answer : For mechanical strength, protect against damage by impact of an object.  

How armours /sheaths grounded?

Description : How armours /sheaths grounded? 

Last Answer : 1 core cables -- sheaths/shields/armours grounded at one end only, other end insulated to prevent the circulating current through sheaths. 3 core cables -- grounded at both ends but not including core balance CT’s, since even small induced current causes 50N operation. 

What is the specified cable life?

Description : What is the specified cable life? 

Last Answer : 50 years.  

What are the advantages of XLPE?

Description : What are the advantages of XLPE? 

Last Answer : a. Easy routing at heights b. Easy maintenance c. Large current (90 ºC) d. No sheath (no fatigue) e. No paper tape wrapping technique f. High dielectric strength g. Very little deformation ... i. Low tan delta and hence suits long routes j. Very light k. Good mechanical properties. 

What are the disadvantages of paper insulation?

Description : What are the disadvantages of paper insulation? 

Last Answer : a. Absorbs moisture. b. Cable termination/sealing problems. 

What are the purposes of cable trays?

Description : What are the purposes of cable trays? 

Last Answer : a. Avoid sagging of cables b. Give mechanical support 

The metallic sheath may be made of lead or lead alloy or of aluminium. (a) Yes (b) No

Description : The metallic sheath may be made of lead or lead alloy or of aluminium. (a) Yes (b) No

Last Answer : (b) No

In congested areas where excavation is expensive and inconvenient 'draw in system' of laying of underground cables is often adopted. (a) Yes (b) No

Description : In congested areas where excavation is expensive and inconvenient 'draw in system' of laying of underground cables is often adopted. (a) Yes (b) No

Last Answer : (a) Yes

It is difficult to maintain oil filled cables. (a) Yes (b) No

Description : It is difficult to maintain oil filled cables. (a) Yes (b) No

Last Answer : (a) Yes

The breakdown voltage of a cable depends on (a) presence of moisture (b) working temperature (c) time of application of the voltage (d) all of the above

Description : The breakdown voltage of a cable depends on (a) presence of moisture (b) working temperature (c) time of application of the voltage (d) all of the above

Last Answer : (d) all of the above

The disadvantage with paper as insulating material is (a) it is hygroscopic (6) it has high capacitance (c) it is an organic material (d) none of the above

Description : The disadvantage with paper as insulating material is (a) it is hygroscopic (6) it has high capacitance (c) it is an organic material (d) none of the above

Last Answer : (a) it is hygroscopic

The advantage of oil filled cables is (a) more perfect impregnation (b) smaller overall size (c) no ionisation, oxidation and formation of voids (d) all of the above

Description : The advantage of oil filled cables is (a) more perfect impregnation (b) smaller overall size (c) no ionisation, oxidation and formation of voids (d) all of the above

Last Answer : (d) all of the above

Copper as conductor for cables is used as (a) annealed (b) hardened and tempered (c) hard drawn (d) alloy with chromium

Description : Copper as conductor for cables is used as (a) annealed (b) hardened and tempered (c) hard drawn (d) alloy with chromium

Last Answer : (a) annealed

If a power cable and a communication cable are to run parallel the minimum distance between the two, to avoid interference, should be (a) 2 cm (b) 10 cm (c) 50 cm (d) 400 cm

Description : If a power cable and a communication cable are to run parallel the minimum distance between the two, to avoid interference, should be (a) 2 cm (b) 10 cm (c) 50 cm (d) 400 cm

Last Answer : (c) 50 cm

The advantage of cables over overhead transmission lines is (a) easy maintenance (b) low cost (c) can be used in congested areas (d) can be used in high voltage circuits

Description : The advantage of cables over overhead transmission lines is (a) easy maintenance (b) low cost (c) can be used in congested areas (d) can be used in high voltage circuits

Last Answer : (c) can be used in congested areas

Underground cables are laid at sufficient depth (a) to minimise temperature stresses (b) to avoid being unearthed easily due to removal of soil (c) to minimise the effect of shocks and vibrations due to gassing vehicles, etc. (d) for all of the above reasons

Description : Underground cables are laid at sufficient depth (a) to minimise temperature stresses (b) to avoid being unearthed easily due to removal of soil (c) to minimise the effect of shocks and vibrations due to gassing vehicles, etc. (d) for all of the above reasons

Last Answer : (c) to minimise the effect of shocks and vibrations due to gassing vehicles, etc.