A hardwired or electronic relay that monitors the elevator safety circuit and prevents the drive from starting or running if any safety device — door contacts, overspeed governor, safety gear, buffers or limit switches — has opened the circuit.
Full Definition
The elevator safety relay (also called the safety circuit relay or monitoring relay) is the interface between the hard-wired safety circuit and the elevator drive/controller. In traditional relay-logic controllers: (1) Safety circuit relay — a single or dual-channel relay coil energised only when all safety circuit contacts are closed; if any contact opens, the relay de-energises and removes the enable signal from the drive; (2) Direction contactors — reversing contactors (up/down) that are mechanically and electrically interlocked to prevent simultaneous energisation (which would cause a short circuit); (3) Brake release contactor — energises the machine brake coil to release the brake when the drive is running. In modern microprocessor-controlled elevators, safety functions are increasingly implemented via PESSRAL (Programmable Electronic Systems in Safety-Related Applications for Lifts), as permitted by EN 81-20/50. A PESSRAL system replaces hardwired safety relays with safety-rated PLCs or microcontrollers meeting SIL 2 (Safety Integrity Level) per IEC 62061 or IEC 61508. Relay-logic controllers are still common in existing installations and older modernisations.
