Commutating circuit breaker

Abstract

A commutating circuit breaker that works by progressively inserting increasing resistance into a circuit. This is done via physical motion of a shuttle that is linked into the circuit by at least one set of sliding electrical contacts on the shuttle ('shuttle electrodes') that connect the power through the moving shuttle to a sequence of different resistive paths with increasing resistance; the motion of the shuttle can be either linear or rotary. A feature of the commutating circuit breaker is that at no point are the shuttle electrodes separated from the matching stationary stator electrodes so as to generate a powerful arc, which minimizes damage to the electrodes. Instead, the current is commutated from one resistive path to the next with small enough changes in resistance at each step that arcing can be suppressed. The variable resistance can either be within the moving shuttle, or the shuttle can comprise a commutating shuttle that moves the current over a series of stationary resistors. In either case, a 'soft' opening of the circuit can be accomplished, with low switching transients, provided that the maximum step change of resistance is limited until the current is nearly extinguished. Commutating circuit breakers work equally well for DC or AC power.