Over/Under Voltage Protector Buying Guide for Global Procurement
In regions with unstable grids, the priority is matching protection thresholds and switching capacity to local supply behavior. Confirm the rated switching current (commonly 40 A, 63 A, or 80 A single-phase) and that the internal relay or contactor can make and break the full load without contact welding. The defining feature is adjustable protection: an over-voltage trip (typically 250–300 V), an under-voltage trip (140–200 V), and a configurable auto-recovery delay so the load is not re-energized until the supply is stable.
Response time should be well under 0.5 s to protect motor-driven appliances from sustained over-voltage. For three-phase systems, look for combined functions — phase-loss, phase-sequence, open-neutral, and three-phase unbalance protection — which prevent the single-phasing and reverse-rotation damage that destroys three-phase motors. Integrated metering (V, I, kWh) adds diagnostic value, and a password lock prevents unauthorized threshold changes. Confirm CE and RoHS conformity for the target market.