Short-circuit protection for current-source inverters

摘要

Electrical equipment, particularly also in underground mining, must be protected against the effects of short circuit currents by means of short-circuit protection elements in accordance with VDE 0118/part 2/draft 1/82. This short-circuit protection cannot be achieved by using currently conventional short-circuit protection elements in current-source inverters. Together with commercially available voltage and current transformers, an electronic module which is installed into a plug-in housing is provided as short-circuit protection for current-source inverters. The electronic module consists of the respective adapter in accordance with the delta circuit, followed by a fast RMS-forming circuit for the voltages and currents and analog IC dividers for the determining the respective conductances. The currents and conductances are evaluated by means of comparators and processed further in the subsequent logic which then drives a relay. This relay switches a latching relay which can only be energised when the inverter is ready for operation. The latching relay indicates the short circuit and triggers the disconnection via the main contactor.