A PCB or DIN-rail assembly carrying electromechanical or solid-state relays that interface the low-voltage controller logic with higher-power actuators, safety circuits, and external signals in an elevator control system.
Full Definition
The relay board is the signal-level-to-power-level interface in the elevator controller. Input relays are driven by 24 V DC logic outputs from the microcontroller or PLC and switch 110 or 230 V AC loads such as door operators, motor contactors, and indicator lighting. Safety relays on the relay board are used in monitored dual-channel configurations for safety-critical outputs (e.g., brake release, drive enable) to meet the safety integrity requirements of EN ISO 13849 (PL d or e) or IEC 62061. Relay boards are plugged into the main controller rack or mounted on a DIN rail within the controller cabinet. Maintenance checks include contact resistance measurement, coil voltage verification, and inspection for carbonised contacts. On older installations with entirely relay-logic controllers, the relay board is the primary logic element. On modern controllers it is a peripheral interface only.
