Design and implementation of a multi-level safety protection system for elevators based on PLC and star-sealing technology in case of power failure

Abstract

To address the secondary entrapment risk and the single-point protection defect of elevator power-off emergency devices, a multi-level safety protection system was designed based on a Programmable Logic Controller (PLC) and permanent magnet synchronous door machine star-sealing technology. The system is centered on the S7-200smart PLC and integrates the Auto Rescue Device (ARD) for elevator emergency leveling during power outages, establishing an active rescue-passive protection-fail-safe framework. Experimental verification shows that the system can achieve 100% emergency leveling rescue, with a braking torque of 15.2 Nꞏm, far exceeding the door-closing torque of 4.5 Nꞏm, completely eliminating secondary entrapment. The system operates reliably, providing an innovative solution for elevator safety.