SLA Series Three-Phase Monitoring Relay

The SLA Series Three-Phase Monitoring Relay from ATC Diversified Electronics is designed to provide cost-effective protection against from phase loss, under voltage, and phase reversal conditions that can contribute to premature motor or equipment failure and downtime.It is designed for use with three-phase systems (Delta and Wye), such as those typically found in motor control centers or other critical motor and pump monitoring applications.

For UL Listed units, with field wiring terminals, copper wire with 60°/75°C rating must be used for control circuitry connections. NOTE: When a phase is lost while the motor is running, a condition known as regeneration occurs where a voltage is induced into the open phase nearly equal in magnitude to the normal phase-to-phase voltage. However, with the exception of lightly loaded motors, enough change is detected by the SLA to provide the required protection when properly adjusted.



  • Monitors up to 480 VAC
  • Protects three-phase equipment from:
    • Phase loss
    • Under voltage
    • Phase reversal
    • Delta or Wye systems
  • Fixed, lock shaft, or screwdriver adjustment
  • Several enclosure styles


  • Critical motor and pump monitoring
  • Water and wastewater plants
  • Sewage plants
  • Booster stations
  • Grinders
  • Irrigation equipment
  • Petrochemical
  • Machine Tool
  • Conveyors
  • HVAC/R
  • Elevators/escalators
  • Utilities
  • Processing equipment
  • Agricultural machinery and equipment
  • Renewable energy – wind power turbine monitoring