The Model 279 DC Current Monitor is a single set-point DC current monitor. It can sense either 1-10 Amps DC (24VAC or 120VAC) or 0.1-1 Amps DC (120VAC). The units have an input frequency of 50/60 Hz. The standard version, the 279B, has a screwdriver adjustable trip and hysteresis setting on top of the device. The hysteresis setting adjusts from 0% to 100%, and can be set fully clockwise for manual reset operation. A remote adjust version, the 279C, has a remote trip adjustment and a remote reset button. An LED indicator is provided on both versions to indicate when the relay is energized (current above the trip setting. )

The 279B plugs into a standard 8-pin octal socket; the 279C plugs into a standard 11-pin socket.