Monitoring circuit for computer controlled safety devices

The invention relates to a monitoring circuit for computer-controlled safety devices. The monitoring circuit described here is an arrangement which initially holds safety-relevant loads switched off by means of a safety relay (K) until a self-test of the controlling computer has been completed withi...

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Bibliographic Details
Main Authors HAUG, RUDOLF, SINNER, ALFRED, DUNGS, KARL JUN
Format Patent
LanguageEnglish
French
German
Published 06.11.1996
Edition6
Subjects
BASIC ELECTRIC ELEMENTS
ELECTRIC SWITCHES
ELECTRICITY
EMERGENCY PROTECTIVE DEVICES
RELAYS
SELECTORS
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Summary:The invention relates to a monitoring circuit for computer-controlled safety devices. The monitoring circuit described here is an arrangement which initially holds safety-relevant loads switched off by means of a safety relay (K) until a self-test of the controlling computer has been completed within required time conditions. A holding capacitor (C1) is connected in parallel with the drive path of the safety relay (K), which holding capacitor (C1) can be charged via a charging circuit (R1, V1) when the safety relay (K) is in the quiescent position (Nc), and, after charging has been completed, moves the relay into the operating position, subject to simultaneous application of a drive signal from the microprocessor, only when specified connection conditions for the safety-relevant loads are met. A remanence relay can be used as the safety relay (K) for defect locking. The monitoring circuit according to the invention uses the difference between the pull-in voltage and the tripping voltage of the safety relay (K).
Bibliography:Application Number: EP19930104908