Patent ID: 7898118
Filing Date: 2011-03-01
Classification: H01H

Abstract:
1. A safety switching apparatus for safely switching on and off an electrical load, in particular an automated installation, comprising: a first port connected to a first manually-actuable signaling element; a second port connected to a second manually-actuable signaling element; a first power switching device comprising a first switching activator operatively coupled to first switching contacts for controlling the opening and closing of said first switching contacts; a second power switching device comprising a second switching activator operatively coupled to second switching contacts for controlling the opening and closing of said second switching contacts; said first and second switching contacts being connected in series for controlling the application of power to the automated installation; and a timing control circuit connected to said first and second manually-actuable signaling elements and to said first and second switching activators for energizing said first and second switching activators if the time between the actuation of said first and second manually-actuable signaling elements is less than a predetermined maximum duration; wherein said timing control circuit includes a first solid-state switching element connected in series with said first switching activator for controlling the energization of said first switching activator, a second solid-state switching element connected in series with said second switching activator for controlling the energization of said second switching activator, and a first microcontroller connected to said first and second ports and to said first and second solid-state switching elements and configured to detect said actuations of said first and second manually-actuable signaling elements and enable said first and second solid-state switching elements when the time between said actuations is less than said predetermined maximum duration.