What are power cables? Explain about them?

What are power cables? Explain about them?
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1 Answer

Answer :

TYPES AND APPLICATIONS
Presently PVC and XLPE cables are being used in electrical installations. The discussion is
restricted to these two types only. The voltage ratings covered are up to and including 33 KV.
a) PVC INSULATED CABLES
PVC insulated cables, covered by IS 1554 are used where combination of ambient
temperature and temperature rise due to load results in conductor temperature not exceeding 70°C
under normal operation and 160°C under short circuit conditions.
b)XLPE INSULATED CABLES
XLPE insulated cables, covered by IS 7098 are used where combination of ambient
temperature and temperature rise due to load results in conductor temperature not exceeding 90°C
under normal operation and 250°C under short circuit conditions.
XLPE cables are particularly suitable in following situations.
• On vertical runs of unlimited difference in level,.
• At locations having severe vibration problems,
• At locations having higher ambient temperatures up to 70°C,
• At conditions demanding short time overload up to 120°C and,
• In systems having higher short circuit levels.
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What is the type cable used in radiation areas?

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Why bimetallic washers provided in aluminium copper transition joints?

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

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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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What is the specified cable life?

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Last Answer : 50 years.  

What are the advantages of XLPE?

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What are the disadvantages of paper insulation?

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

What are the purposes of cable trays?

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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

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

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

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

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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

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