SLJ Series Phase Sequence Under Voltage Monitor

The SLJ Series Phase Sequence Under Voltage Monitor from the ATC Diversified Electronics division of Marsh Bellofram Corporation has a built-in Delay-on-Make Time Delay. The SLJ continuously monitors the three phase lines for adverse conditions such as PHASE LOSS (single phasing), UNDER VOLTAGE (brown outs), and PHASE REVERSAL (improper sequence). When any of these conditions occur, the internal relay will de-energize (DROP-OUT). When the fault is corrected, the field adjustable delay-on-make delay begins. Upon completion of the time delay, the internal relay will energize (PICK-UP). Any subsequent interruptions will reset the delay period. The SLJ’s phase monitor operates the same as the SLA Series. It will drop-out for a phase loss if any phase drops below 83% of its nominal setting and it will also drop-out for under voltage if all three phases drop below 90% of its nominal setting. It is phase sequence sensitive and will not allow start-up if the three phases are reversed.

The SLJ is available in the same standard operating voltage ranges as our other Phase Monitors (see table below). The delay-on-Make Timer is field adjustable from 0.2 to 8.0 minutes. There are two LED indicators. The green indicator glows when all conditions are normal, and the red indicator glows when the internal relay is energized. The SLJ Series Phase Sequence Under Voltage Monitor is ideally suited for multiple equipment installations to stagger start equipment after a fault condition.



  • Models available up to 480 VAC
  • Protects 3-Phase Equipment Against:
    • Phase Loss
    • Under Voltage
    • Phase Reversal
  • Adjustable Delay-on-Make Timer
  • Lock Shaft Adjustment for:
    • Operating Voltage
    • Operate Time Delay
  • Delta or Wye Systems