| 摘要 |
<p>An arc crowbar with electrodes (34A, 34B, 34C) separated by a gap (35) in a protective case. Each electrode is connected to an electrically different conductor of a circuit. A sensor (42, 44) detects an arc flash condition on the circuit and signals a trigger circuit (52) to send an electrical pulse to an arc-triggering device (36) in the arc crowbar gap. The triggering device ionizes a portion of the gas between the electrodes, initiating a protective arc between the electrodes that absorbs energy from the power circuit and trips a breaker, eliminating the arc flash condition. The triggering device may be a plasma gun, especially one that injects plasma of an ablated material into the gap. The sensor may signal a circuit breaker (26) to open in the power circuit. Arc flash sensor types may include a differential current sensor and/or an optical sensor.</p> |
