... asymmetry, incorrect phase sequence faults. ZHRV1 series voltage monitoring relayZHRV1 series voltage monitoring relay can set precisely,monitor against phase ... singlechip, with high precision; applied in the circuit of AC 50/60Hz 220V, 230V, 240V, 380V, 400V, ... compensation, switch boards, air condition systems, motor etc.Conform to: IEC60947 5 1 standardOpeating conditions:1. Altitude: ≤2000m2 ...