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.