The WU monitoring relays are used to monitor overvoltage or undervoltage. The selector switch on the front is used to choose between overvoltage or undervoltage with or without a memory function. If the monitored voltage in overvoltage mode exceeds the threshold for longer than the period set on the front, the output relay opens. As soon as the voltage falls below the threshold minus the hysteresis, the relay closes again immediately. If the monitored voltage in undervoltage mode falls below the threshold for longer than the period set on the front, the output relay opens. As soon as the voltage rises above the threshold plus the hysteresis, the relay closes again immediately. Approvals: UL and CSA.
