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

The minimum dielectric stress in a cable is at (a) armour (b) bedding (c) conductor surface (d) lead sheath
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(d) lead sheath
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Last Answer : (c) provide proper stress distribution

Due to which of the following reasons the cables should not be operated too hot ? (a) The oil may loose its viscosity and it may start drawing off from higher levels (b) Expansion of the oil may cause the sheath to burst (c) Unequal expansion may create voids in the insulation which will lead to ionization (d) The thermal instability may rise due to the rapid increase of dielectric losses with temperature (e) All of the above

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Last Answer : (e) All of the above

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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?

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Why armouring done?

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

How armours /sheaths grounded?

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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 are the advantages of XLPE?

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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. 

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

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

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Last Answer : (a) Yes

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

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Last Answer : (a) Yes

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