Modified Part 2 Tender Document - Naya Raipur

NRDA F-1- Schedule-D- Section III- Technical Specification of Works
Construction of Forest and Water Resources department buildings, North Block at Naya Raipur
NRDA
D. HIGH TENSION CIRCUIT BREAKER
1. Circuit Breaker
The circuit breaker panel shall be complete with the following:
i. Raising and lowering mechanism.
ii.
iii.
iv.
Isolation plugs and sockets.
Mechanical inter-locks and safety shutters with pad locking facility.
Mechanical ON/OFF indicator.
v. 6 No. and 6 NC Auxiliary contacts rated at 10 amps and 30 V DC directly operated by the
circuit breaker.
vi. First filling filtered and tested oil .
vii.
viii.
Anti-condensation space heaters suitable for operation on 240 V single phase, 50 Hz AC
for each panel where specified.
Tripping Arrangement : As specified in schedule.
. Type
The circuit breaker shall be oil type with cross jet arc control devices, for the rating specified. The
circuit breaker shall be of vertical isolation horizontal draw out pattern.
. Breaker Truck
The breaker carriage shall be fabricated from steel, providing a sturdy vehicle for the circuit
breaker and its operating and tripping mechanisms. The carriage shall be mounted on wheels,
moving on guides, designed to align correctly and allow easy movement of the circuit breaker and
for removing the carriage for inspection and maintenance purposes. The carriage shall have the
winding mechanism for isolating the breaker from the bus bars and cable spouts.
The raising and lowering mechanism shall be provided with facility for pad locking at any
position namely "Service","Test" and "Fully Isolated". It shall be possible for testing the circuit
breaker for its operation without energising the power circuit in the "Testing" position.
. Breaker Tank
The circuit breaker tank shall be fabricated of steel plate designed to withstand internal
pressures resulting from fault clearance and shall be suitably vented at the top. The joint between
the tank and the top plate shall be grooved and tongued to be oil and gas light and shall be
secured by short high tensile steel bolts.
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