K.a. Schmersal Gmbh & Co.

Steute Schaltgeräte Gmbh & Co. Kg

Friedhelm Heuer

Thomas Kuhlmann

The invention relates to a contactless safety switch for detecting the shut position of a shutting part in relation to a closeable part, with a switch unit, supplied with current by an electrical supply source on one of the parts and with a trip arranged on the other part and comprising a magnet. In this case, the switch unit comprises a transmission circuit with a clock-signal generator and with a transmission coil, a receiver circuit connected to an evaluation unit and having at least one receiver coil and also a Hall sensor responding to the magnet, and the trip comprises a trip coil which is capable, in the shut position, of being excited inductively by the transmission coil and exciting the receiver coil, while, in the shut position, the evaluation unit triggers a clearance path when the Hall sensor is activated via the magnet.

Contactless safety switch

A method and apparatus for monitoring a three-phase electric motor which has been disconnected from the electrical mains and is running down, one phase of the voltage generated by the motor being checked respectively in each of two channels for zero crossings and, if a zero crossing occurs, a signal being produced which, after DC-decoupling, is used to control the operation of a safety device. The safety devices are mutually interlocked and control signals therefor are produced only when the period between zero-crossings detected in both channels indicates that the motor output shaft has ceased rotation.

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Oldendorf, Germany

Friedhelm Heuer