Electrical protective equipment switch with overcurrent and undervoltage function and overcurrent sensor for it

Abstract

The protective equipment switch comprises a mechanical switching contact (,) for a conductor (S,-S,), a latchable switch latch (,) for the switching contact (,), an overcurrent sensor (,) associated with the conductor, and an electromechanical undervoltage relay (,) whose exciting voltage is derived from the conductor voltage and which in its excited state latches the switch latch (,). In the case of overcurrent, the overcurrent sensor (,) causes the separation of the undervoltage relay (,) from its exciting voltage which also drops in the case of undervoltage. Thus both in the case of overcurrent and in the case of undervoltage, unlatching of the switch latch (,) is caused by the same component, namely by the undervoltage relay (,). Preferably the overcurrent sensor (,) is formed by the combination of a current transformer signal with an electronic circuit which itself is preferably an integrated circuit. A particularly simple current transformer for acquiring the current flowing in the current conductor (S,-S,) results from a pair of inductive loops on both sides of a section of the conductor on a printed circuit board, with, for the purpose of forming an iron core for the current transformer, a pair of iron core halves (K,-K,) facing each other can be provided, one half on each side of the printed circuit board.