Draw-out vs Fixed Vacuum Circuit Breaker (10/5/2026)

A fixed vacuum circuit breaker is permanently mounted within the switchgear enclosure. A draw-out vacuum circuit breaker is mounted on a movable chassis or truck that allows the complete breaker assembly to be mechanically positioned within the switchgear.

Article - October 5, 2026 By LarsonElectronics.com

Vacuum Circuit Breaker, Drawout, 3-Phase 3-Wire, 15kV Class, Generator Breaker Application, 2000A, 40kA

Draw-out vs Fixed Vacuum Circuit Breaker

Vacuum circuit breakers (VCBs) use a sealed vacuum interrupter to interrupt medium-voltage current and extinguish the arc when the contacts separate.

Two common mechanical configurations are draw-out and fixed vacuum circuit breakers. Both use the same fundamental vacuum-interruption technology, but their mechanical construction, installation method, maintenance requirements and applications differ significantly.

Fixed Vacuum Circuit Breaker

A fixed vacuum circuit breaker is permanently mounted within the switchgear enclosure. The vacuum interrupter, operating mechanism, conductors and insulation system are installed in a fixed position, with the incoming and outgoing power connections made directly to the breaker terminals or bus connections. The breaker itself does not move between connected, test and disconnected positions.

Fixed VCBs have a simple mechanical arrangement because they do not require a carriage, racking mechanism, shutters or position interlocks associated with a draw-out design. This type of VCB is often appropriate for simple distribution systems where breaker removal is infrequent and the installation does not require rapid breaker replacement.

Draw-out Vacuum Circuit Breaker

A draw-out vacuum circuit breaker is mounted on a movable chassis or truck that allows the complete breaker assembly to be mechanically positioned within the switchgear. The draw-out design incorporates additional mechanical and safety components. These can include a racking mechanism, position indicators, disconnect contacts, control plugs, shutters, mechanical interlocks and grounding provisions.

The shutters cover energized stationary primary contacts when the breaker is withdrawn, reducing the possibility of accidental contact. Interlocking systems are used to prevent improper operations, such as attempting to rack a closed breaker into or out of the connected position. A draw-out VCB can be disconnected and removed from the switchgear without dismantling the entire lineup or disturbing permanent bus connections.