Siemens Aktiengesellschaft

Bernd Josef Siepmann

Peer Thilo

A fault current protection switch detects fault currents from conductors of a supply means to ground. The system uses at least one difference transformer connected to the conductors of the supply mains. An oscillation generator circuit is connected to the difference transformer through feedback windings. The oscillation generator circuit checks the magnetization of a core of the difference transformer, and, in the event of a change in the transforming properties of the core due to 'mis' magnetization caused by a fault current, the oscillation generator circuit triggers a control and switching member connected in the supply mains to disconnect the same.

Fault current protection switch

A circuit arrangement for a DC to DC converter has at least one switching transistor and one transformer. The transformer includes a primary winding which is connected in the collector circuit of the transistor and a secondary winding from which at least one stabilized DC voltage may be tapped by way of rectifiers. The switching transistor is actuated and blocked by way of a control component in dependence upon load. A voltage comparison device is provided for comparing the collector-emitted voltage of the switching transistor with a predetermined reference value, and upon overshoot of the reference voltage the collector-emitter voltage is analyzed for disconnection of the base current of the switching transistor.

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Geretsried, Germany

Bernd Josef Siepmann