Patent ID: 6279115
Filing Date: 2001-08-21
Classification: H02H

Abstract:
A circuit arrangement for monitoring an electronic tripping device for a low-voltage switch, the electronic tripping device protecting a line from a power supply via a line tripping contact, comprising:a microprocessor device of the electronic tripping device including a zero crossing comparator, the zero crossing comparator generating an enable signal at zero crossings of alternating current on the lines to be protected; anda switchable constant current source receiving the enable signal and generating a constant current pulse in response to receiving the enable signal, the constant current pulse inducing an evaluatable test current in the electronic tripping device via a current transformer winding, an analog to digital converter converting the evaluatable test current for amplitude measurement;wherein the microprocessor device is configured to calibrate the electronic tripping device when the evaluatable test current deviates from a predetermined level within a predetermined tolerance, and the microprocessor device is configured to generate an alarm signal to actuate the line tripping contact when the evaluatable test current deviates from the predetermined level by more than the predetermined tolerance.