Switching equipment
AssigneeABB Research Ltd.
InventorsClaude Henrion, Gunnar Johansson, Paul Stephansson, Harald Vefling
Life of this patent
Estimating the term…
Abstract
Switching equipment with a contactor (CE) and a circuit breaker (BR) located ahead of the contactor. For detection of welded-together contacts of the contactor, this is provided with means (SC) adapted, a certain time after an opening order to the contactor, to apply a voltage pulse to the operating coil (12) of the contactor and to compare the current response of the operating coil with a comparison level for forming a detection signal (s.sub.d), which is supplied to the circuit breaker. Upon detection of welded-together contacts, the detection signal triggers an opening of the circuit breaker for disconnection of the contactor.
Claims7
Switching equipment with an electromagnetic contactor and a circuit breaker located ahead of the contactor, the contactor having an operating magnetic circuit with a magnetic core, an operating coil, an armature which moves in dependence on the current through the operating coil, and a number of contacts which are influenced by the armature, the switching equipment further comprising detection circuits for sensing the reluctance of the operating magnetic circuit and, in dependence on the measured reluctance, generating a signal which indicates an incomplete opening of the contactor caused by welded-together contacts, said signal being supplied to the circuit breaker so that, upon detection of welded-together contacts, the contactor is disconnected by opening of the circuit breaker, wherein the detection circuits measure the reluctance of the operating magnetic circuit by sensing the inductance of an inductance measuring coil surrounding the magnetic core, and wherein the detection circuits apply to the inductance measuring coil a voltage pulse and detect the inductance of the coil on the basis of the current response of the coil.
Dependencies are inferred from the claim text.