The CM-MPS.21S is a multifunctional relay from the CM three-phase monitors range. It operates with a rated control supply voltage / three-phase measuring voltage of 180-280 V AC 50/60 Hz and has a 2 c/o (SPDT) output with contacts rated at 250 V / 4 A. This relay is also suitable to monitor single-phase mains. It monitors all phase parameters such as over/undervoltage, phase unbalance, phase failure as well as an interrupted neutral. The corresponding threshold values are adjustable. Phase sequence monitoring as well as an ON or OFF tripping delay are selectable. The tripping delay is adjustable over a range of instantaneous to 30 s (0, 0.1-30 s). A sealable transparent cover for protection against unauthorized changes is available as accessory. The device offers screw connection technology with double-chamber cage connection terminals.