The centre break disconnector is the most widely used disconnector type in the industry. With the centre break disconnector design, the live current path open along the horizontal plane away from the centre point where they connect (similar to how two doors installed next to each other open).
Centre Break Disconnector Components
The centre break design provides a low profile in the open and closed position, but it is wider compared to disconnectors which open along a longitudinal or vertical plane.
A centre break disconnector’s live arms are manufactured from drawn aluminium and the contacts (pads) are manufactured from silver plated electrolytic copper; this provides good conductivity and prevents oxidation. The contact system is bolted to the aluminium arms, usually as a fist/block (male) and finger (female) pair. Sometimes, the contact system contains stainless steel springs, these springs help maintain adequate contact pressure and minimise contact resistance.
Manual or motorised actuators transfer rotational power to a disconnector’s rotary base unit (the entire base rotates) via a series of gears and shafts. A diagonal rod is used to mechanically connect a disconnector’s two rotary base units together to ensure simultaneous operation of both columns. Each rotating base unit utilises high-quality ball bearings and is designed for high mechanical loads. The supporting insulators mounted on top of the rotating base units, transfer the rotational motion from the actuator, to the rotary contact head at the top end of the disconnector.
Centre Break Disconnector Switches in Substation Switchyard
At the rotary contact head, load current is transferred from the connection terminal to the current carrying arms by flexible copper leads. Alternatively, ball bearings in the contact head can form part of current path in a tulip type silver faced contact arrangement.