Method and apparatus for the measurement of a resistance of a switching contact of an electrical circuit breaker

摘要

An apparatus and method for the measurement of a resistance of a switching contact of an electrical circuit breaker. A first resistance value across the circuit breaker is determined while the circuit breaker is grounded at both sides and the switching contact is closed. Further, a second resistance value across the circuit breaker is determined while the circuit breaker is grounded at both sides and the switching contact is open. The resistance of the closed switching contact is then determined based on the first resistance value and the second resistance value.

主权项

1. A method for the measurement of resistances of switching contacts arranged in a series connection of an electrical circuit breaker, comprising the steps:
feeding a first measurement current in a first direction through a first switching contact of the switching contacts arranged in the series connection, wherein the first measurement current is fed in a first terminal of the first switching contact and drawn at a second terminal of the first switching contact; feeding a second measurement current in a second direction through a second switching contact of the switching contacts arranged in the series connection, wherein the second measurement current is fed in a first terminal of the second switching contact and drawn at a second terminal of the second switching contact, the first direction and the second direction being opposite to one another with respect to the series connection of the switching contacts, and the first measurement current and the second measurement current being fed while the series connection is grounded at both sides resulting in a grounding loop; adjusting the first measurement current and the second measurement current such that a voltage drop across the first switching contact equals a voltage drop across the second switching contact, resulting in a voltage drop across the grounding loop being zero; and determining a resistance value of the first switching contact on the basis of the first measurement current while the first switching contact and the second switching contact are closed.