A protective device installed in elevator electrical panels that limits voltage spikes from lightning or switching transients, protecting drive and control electronics.
Full Definition
Surge arresters (also called surge protection devices, SPDs) are connected across supply and control circuit conductors in the elevator controller and motor control panel to clamp transient overvoltages to safe levels. Voltage spikes caused by nearby lightning strikes, utility switching, or large motor switching on the same supply can instantly destroy variable-frequency drives, microprocessors, and programmable logic controllers. Type 2 SPDs with a discharge current capacity appropriate for the installation are placed at the main incoming supply and at sensitive sub-circuit entrances. Coordination between Type 1, 2, and 3 devices is required per IEC 61643-11. Failed SPDs (indicated by a status window turning red) must be replaced immediately to restore protection.
