Protection switch

Abstract

A low-voltage protection switch has an external conductor section and a neutral conductor section, wherein a mechanical bypass switch is arranged in the external conductor section, and the semiconductor circuit device of the low-voltage protection switch is connected in parallel to the bypass switch. In the external conductor section A current measuring device is provided, which is connected to an electronic control unit of the protective switch, the electronic control unit being designed to actuate the bypass switch and the The semiconductor circuit arrangement provides that the undervoltage circuit breaker has at least one second current measuring device for measuring the first current through the bypass switch or the second current through the semiconductor circuit arrangement.

Description

technical field [0001] The invention relates to a low-voltage protection switch. Background technique [0002] A corresponding protective switch is known from WO 2015 / 028634 A1 of the applicant. When the protective switch is switched off, for example when a circuit break occurs, the bypass switch is first opened, an arc occurs and as a result a current is switched on the semiconductor circuit arrangement. The short-circuit current is then cut off through the IGBT. It is important here that the bypass switch is opened sufficiently before switching off by means of the IGBT in order to avoid re-ignition of the arc at the contacts of the bypass switch or to keep the arc present. [0003] In the known protection switch, the collector-emitter voltage is measured at at least one of the IGBTs in order to infer in this way whether the contacts of the bypass switch have started to open. As soon as this is detected based on a rise in the collector-emitter voltage, a counter is start...

AI Technical Summary

Problems solved by technology

However, in conjunction with a strongly increasing short-circuit current, this time is sufficient to cause a sufficiently high current in the IGBT parallel branch that the control electronics recognizes that the contacts of the bypass switch are open, activates the counter and switches off accordingly. open short circuit early

This results in a damaging arc across the bypass switch, which is significantly loaded

Furthermore, a long wait before opening the short-circuit leads to a high load on the IGBT parallel strings and other existing varistors, since they must be able to draw correspondingly high voltages, even if the configuration systems involved are functioning as specified or intended.