Device for preventative detection of faults with recognition of the load type

摘要

The preventative detection operates with an electrical load (5) connected to an alternating supply through a first switch (6). The switch is controlled by a circuit (7) that detects the nature of the load and detects a fault in the load. The circuit also includes a facility to temporarily connect the load to the supply. The current flowing in the load during this temporary connection is measured. The test potential is applied for one cycle of the alternating supply, and the potential and current measured to determine the instantaneous impedance of the load. Changes in impedance during the test period are computed and the impedance curve compared to predetermined impedance curves.