CONTROL CABLING IN SUB-STATION.

CONTROL CABLING PHILOSOPHY IN SUB-STATION


a)         Each secondary core of each phase CT/CVT shall be brought to the equipment marshalling box through independent cables.

b)         Each three phase secondary core of each CT/CVT shall be brought to the associated control/relay panel from the equipment marshalling box through independent cables.

c)         Single cores with at least 2.5mm2 equivalent core cross-sectional area per connection shall be used for connection of all CT/CVT circuits.

d)         VT leads used for tariff metering shall have an equivalent core cross-sectional area of at least 2.5 mm2 or equivalent per phase/neutral connection.

e)         Duplicate channels of protection shall have independent cables for tripping, DC supply, etc.

f)          For the following applications multiple cores with at least 2.5 mm2 equivalent core cross - sectional area per connection shall be used:

i)          DC supply to Bay Marshalling box

ii)         DC supply to circuit-breaker cubicle

iii)         DC looping for closing and tripping circuits of circuit-breaker

g)         Spare cores shall be provided as per following norms:

Up to 3-core cable
-
Nil
5 Core Cable
-
Min. 1 core
7 to 14 core cables
-
Min. 2 cores
More than 14 core
-
Min. 3 cores


h)         For various field input from the breaker, transformer etc. for alram, at least 1.5mmsq equivalent cross section area per connection shall be used.


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