TWO-CHANNEL FORKED LIGHT BARRIER IN FAIL-SAFE CONSTRUCTION

摘要

- 15 - Two-channel forked light barrier in fail-safe construction IP 1002 / Hergiswil, 31 October 1990 Sg/tb Summary: A two-channel forked light barrier in fail-safe construction for the production of a shaft information in the region of the storeys for the premature opening of the doors on arrival of the cage displays a cyclical dynamic self-monitoring (ZDU, 6), by means of which a prophxlactic.fault recognition.. is possible. The ZDU (6) on arrival and standstill of the cage at a storey periodically simulates genuine operational sequences in that a brief emergence of the switching vane is simulated by optical short- circuit of the FS light barrier. The thereby effected interruption of the relay feed is however shorter than the release time of the relays so that. these do not release when the circuit is intact. A sequential course of timing signals (tA/B1 to 4, tVB) controls the sequence of the self- monitoring functions. In the case of any kind of component faults, this run-down is disturbed and a corresponding reaction in the safety circuits of the lift control takes place by way of relay contacts. A cyclically appearing test signal (TSA, TSB) is the primary control signal for simulated interruptions.