The SE Relays 831 series voltage sensor, single-phase AC voltage sensing device is designed to be wired across terminals A1 and A2 with the voltage being monitored. Voltage sencor is capable of monitoring and reacting to overvoltage and undervoltage conditions. The Umax dial is used to set the upper trip-point of 85VAC to 150VAC for the voltage sensor. The Umin dial is a 3099% of upper preset of the Umax dial and is used to set the lower trip-point for the voltage sensor. Relay has SPDT silver alloy contacts, rated 15A at 12VAC. The timing dial is used to delay the transfer of the contacts, from 0s to 10s, when a set point has been violated. Three-state indication LEDs indicates normal state by green LED and two types of faulted states by blinking red LED as timing state and steady on red LED as energized relay. Direct mount on a 35mm DIN rail, narrow width 17.5mm makes this relay ideal for tight spaces.