Method, circuit breaker and switching unit for switching off high-voltage DC currents

摘要

A high voltage DC circuit breaker comprises a semiconductor switching assembly (3) in series to a mechanical switch (4). When the semiconductor switching assembly (3) is switched off due to a current fault, the residual current (I R ) flowing through the arresters (9) of the assembly (3) is switched off by the mechanical switch (4). A capacitor (12) arranged parallel to mechanical switch (4) leads to passive resonance effects, which in turn induce current zero crossings in its arc. The current zero crossings allow to extinguish the arc reliably. The mechanical switch (4) can be an AC circuit breaker.