Circuit device for inverter circuit device such as photovoltaic inverter, determines insulation fault from detected potential differences which are caused by change of intermediate circuit voltage and input voltage

摘要

Two DC output terminals (22,24,26) are connected to intermediate circuit (20) and to inverter (28). A measuring device is provided with first measuring unit (36) to detect potential and potential difference between DC input terminals (12,14) and DC output terminals, and second measuring unit (38,39,40) to detect potentials and potential difference of input and output terminals to earth or neutral conductor. The insulation fault is determined from detected potential differences which are caused by change of intermediate circuit voltage (UZK) and input voltage (UIN). Independent claims are included for the following: (1) inverter circuit device; and (2) method for insulation monitoring circuit device.