Method and device for testing electrical apparatus with or without protective earth

摘要

The method for testing electrical equipment, constructed to prevent shock-risk in the event of insulation breakdown between the equipment housing or other exposed parts, has a connection to an earthed safely conductor (PE) of the mains network (L,N). The system employs a clip-on ammeter (5,6) and in normal circumstances with power on and all three connections (2,3,4) surrounded by the ammeter's current transformer core the resultant current should not differ from zero by more than a defined tolerance. An insulation breakdown is revealed by a resultant current and alternative procedures are also shown which provide similar information for equipment with no safety connection.