I have a setup with a Bender IRDH375 connected to the DC bus of an IGBT based inverter. If I connect a 50kOhm resistor to earth while running the inverter, it detects it well. That part is reasonably ok to understand. However while not running it still detects about 200-400kOhms to ground. How is this possible?
Schematic of setup illustrated below. Only 1 of 3 phases are illustrated for brevety.
Shouldn't the IGBT be almost fully blocking while "OFF"?
Update: If I take off R2, the earth meter will show almost maximum insulation (10MOhms). Same if the inverter is running or not.