The Model 171 is an AC current monitor for detecting undercurrent conditions. The monitor contains a proprietary microcontroller-based circuit monitoring current passed through an internal shunt resistor and driving an electromechanical SPDT relay. Two status lights are provided to indicate relay status, fault condition, and timing. An adjustable trip delay is provided to prevent nuisance tripping and an adjustable restart delay has been provided for applications requiring a delay to start an additional load.