Pilz Gmbh & Co Kg.

Pilz Gmbh & Co.

Guenter Hornung

Thomas Nitsche

Christoph Zinser

Juergen Pullmann

Ralf Bauer

A safety switching apparatus for failsafe disconnection of an electrical load has a first and a second connecting terminal for connecting a first signaling switch and a third and a fourth connecting terminal for connecting a second signaling switch. It also has a first and a second output switching element, which are designed to produce a redundant output switching signal. The first connecting terminal is connected to a first potential and the third connecting terminal is connected to a second potential. The potentials differ from one another. In addition, the second connecting terminal is coupled to the first switching element in such a way that the first switching element receives the first potential via the first signaling switch. Likewise, the fourth connecting terminal is coupled to the second switching element in such a way that the second switching element receives the second potential via the second signaling switch. According to one aspect of the invention, a circuit arrangement is provided for determining at least one further potential at the second and/or fourth connecting terminal, and said circuit arrangement is designed to control the redundant output switching signal as a function of the further potential.

Safety switching apparatus for a failsafe disconnection of an electrical load

A safety switching device comprises a position encoder, such as a potentiometer, for user selection of an operational quantity, such as an operating mode. The position encoder has a first terminal, a second terminal, and a tap moveable through a plurality of positions. A total impedance is defined between the first terminal and the second terminal. A first partial impedance is defined between the first terminal and the tap, and a second partial impedance is defined between the tap and the second terminal. An arrangement for determining an instantaneous position of the tap comprises a first evaluation circuit designed to determine a first measurement value representative of the first partial impedance, and a second evaluation circuit designed to determine a second measurement value representative of the second partial impedance. At least one from the first and second evaluation circuits is designed to determine the instantaneous position of the tap by means of the first and second measurement values.

Arrangement for failsafe evaluation of a position encoder

The invention relates to a safety switching device for the failsafe shutdown of an electric load, such as an electrically driven machine. The safety switching device has a signal processing part for receiving and evaluating an input-side switching signal, which, for example, originates from an emergency stop switch. It also has at least one switching element which, controlled by the signal processing part, provides an output-side switching signal for shutting down the load. An anti-surge element is provided for canceling reaction voltage spikes when the load is shut down. The anti-surge element has at least a first and a second anti-surge operating mode, which can be activated as an alternative to one another.

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Leinfelden-Echterdingen, Germany

Guenter Hornung