The DUB01 series Monitoring Relay with 1-phase true RMS AC/DC over or undervoltage. It is a precise TRMS AC/DC over or under voltage (selectable by DIP-switch) monitoring relay. Owing to the built-in latch function, the ON-position of the relay output can be maintained. Inhibit function can be used to avoid relay operation when not desired (maintenance, transitions). The LEDs indicate the state of the alarm and the output relay.