Method and device for switching off an inductive load in a failsafe manner
AssigneePilz GmbH & Co. KG
InventorsHans Schwenkel, Thomas Leitmann, Mark Hufnagel
Life of this patent
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Abstract
A method and a device for switching off an inductive load in a failsafe manner are proposed. According to one aspect of the invention, the method and the device are configured such that a predefined inductive voltage is generated during switch-off. The predefined inductive voltage is monitored by means of a monitoring circuit. In a preferred embodiment, the inductive voltage is set by means of threshold switches and the inductive voltage also is monitored by means of these threshold switches.
Claims14
A safety switching device for switching off an inductive load in a failsafe manner, the device comprising:
- a signal processing section for receiving and evaluating an input-sided switching-off signal,
- at least one first switching element, activated by the signal processing section, for switching off the load,
- a first threshold switch for limiting an inductive voltage to a predefined inductive voltage at the load during the switching-off,
- a monitoring circuit for monitoring the threshold switch,
- wherein the monitoring circuit is configured to generate an error signal when the inductive voltage drops below a threshold value, and
- at least one second threshold switch for limiting the inductive voltage to the predefined inductive voltage, the first and second threshold switches being arranged in such a manner that the magnitude of the inductive voltage is influenced by each of the threshold switches.
A method for switching off an inductive load in a failsafe manner, the method comprising the steps of:
- receiving and evaluating an input-sided switch-off request signal, activating a first switching element for switching off the load, providing a first threshold switch for limiting an inductive voltage to a predefined inductive voltage at the load during activation of the first switching element for switching off the load,
- monitoring the predefined inductive voltage by means of a monitoring circuit,
- wherein an error signal is generated when the inductive voltage drops below a threshold value, and
- further wherein the inductive voltages is divided into at least two inductive partial voltages, wherein a divider ratio of the at least two inductive partial voltages is monitored.
Dependencies are inferred from the claim text.