Patent ID: 8358187

Claim:
An electrical overcurrent tripping device for a circuit breaker, comprising: an actuating member which in case of an overcurrent is driven to interact directly or indirectly with a movable contact piece of the circuit breaker to open a contact point in the circuit breaker if said overcurrent exceeds a preset tripping threshold for a predetermined tripping delay time, wherein said actuating member is coupled to a magnetic circuit whereby the driving force acting on the actuating member is created by the magnetic field of the magnetic circuit, said magnetic field being induced by the overcurrent, that said actuating member is coupled to an electromagnetic damping arrangement to set the tripping delay time, and that said actuating member is connected to a coupling spring for adjusting the overcurrent tripping threshold, wherein said actuating member is an electromagnetically damped rotor in a magnetic circuit where the driving magnetic field is created by the load current, wherein said magnetic circuit includes a tubular stator as part of the magnetic core of the magnetic circuit with at least one winding of a conductor embracing the magnetic core and carrying at least partly the load current, and wherein said stator at least partially embraces the rotor and the rotor is rotatably mounted within said stator.