Dead Tank Circuit Breakers
Circuit breakers are available as live-tank or dead-tank
designs. Dead-tank designs put the interrupter in a grounded metal enclosure.
Interrupter maintenance is at ground level and seismic
withstand is improved vs. the live-tank designs. Bushings are used for line and
load connections which permit installation of bushing current transformers for
relaying and metering at a nominal cost.
The dead-tank breaker does require additional insulating oil
or gas to provide the insulation between the interrupter and the grounded tank
enclosure.
Live Tank Circuit Breakers
Live-tank circuit breakers consist of an interrupter chamber
that is mounted on insulators and is at line potential. This approach allows a
modular design as interrupters can be connected in series to operate at higher
voltage levels.
Operation of the contacts is usually through an insulated
operating rod or rotation of a porcelain insulator assembly by an operator at
ground level. This design minimizes the quantity of oil or gas used for
interrupting the arc as no additional quantity is required for insulation of a
dead-tank enclosure.
The design also readily adapts to the addition of
pre-insertion resistors or grading capacitors when they are required. Seismic
capability requires special consideration due to the high center of gravity of
the interrupting chamber assembly.
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