A transient voltage suppression device that protects elevator control electronics from lightning and switching surges.
Full Definition
An elevator surge protector (SPD — Surge Protection Device) is an overvoltage protection device installed in the elevator power supply and control circuit to clamp transient overvoltages caused by lightning-induced surges, utility switching events, or load-generated transients before they reach sensitive electronics — the main controller PCB, motor drive (VFD), door operator, and communication boards. EN 81-20 does not prescribe SPD installation directly, but EN 60664-1 and IEC 61643-11 / IEC 61643-12 govern the selection and installation of SPDs for low-voltage installations. Elevator SPDs are classified by installation location: Type 1 (Class I) at the main distribution board to handle direct and partial-lightning current; Type 2 (Class II) at the elevator controller cabinet to clamp residual surges to the protection level (Up ≤ 1.5 kV); and Type 3 (Class III) at individual PCB or terminal level for fine protection. The SPD must be coordinated with the upstream overcurrent protection device (OPD) and the follow-current interruption capability must exceed the prospective short-circuit current at the installation point. Ground (earth) bonding of the SPD enclosure is mandatory; improperly earthed SPDs provide no protection. SPD condition indicators (colour-coded windows or LEDs) must be visible for routine inspection; a tripped or degraded SPD must be replaced before the next thunderstorm season.
