Protection Relays

Diversified Electronics

Protection Relays
Protection Relays
Protection relays are electronic components designed to prevent unnecessary trips, isolate faults and protect motors, breakers, and other equipment.

Modern protective relays are microprocessor-based, and use inputs and settings to intelligently compare measurements to setpoints and produce a desired output. Inputs can include variables like current, voltage, resistance and temperature. If any of those values exceed a prescribed setpoint, the relay can trigger an output like an alarm, an indicating light, a network communication, and even turn another device on or off.

Because modern protection relays use digital technology to operate, they can produce quick, reliable, repeatable outputs far more frequently over a longer lifetime. They also provide better accuracy to eliminate nuisance trips, reduced maintenance needs to improve uptime, and better efficiency to cut costs and save panel space.

SLA Series Image
  • Monitors Delta or Wye Systems
  • Monitors up to 480 VAC
  • Fixed, Lock Shaft, or Screwdriver Adjustment
  • Automatic Reset with Manual Option Available
  • Plug-in or Surface Mount Styles
With normal operating voltages applied in the proper ABC sequence, the internal relay will energize. When incorrect phase sequence or phase loss occurs, or the three-phase voltages fall below the drop-out voltages, the relay will de-energize.
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.
Protects against:
  • Phase Loss
  • Under Voltage
  • Phase Reversal
SLU100 Series Image
  • Monitors Both Delta and Wye Systems
  • Monitors up to 550 VAC
  • Automatic or Manual Reset
  • Adjustable Fault and Restart Delays
  • Din Rail or Surface Mount Options
The SLU Series multi-mode phase monitoring relay was designed fo the convenience of electricians, maintenance managers, and engineers. A single SLU Phase Monitoring Relay can be easily adjusted for the voltage, imbalance percentage, and time delay requirements to protect against unbalanced voltages or single phasing, regardless of any regenerative voltages.
SLD Series Image
The SLD Series is designed to protect 3-phase equipment against Phase Unbalance, Phase Loss, Under Voltage and Phase Reversal conditions.
With normal operating voltage present on all three phases in the proper phase sequence, the internal relay will energize (PICK-UP). When an incorrect phase sequence or phase loss occurs or the three-phase line voltages fall outside the preset unbalance or under voltage settings, the internal relay will de-energize (DROP-OUT). When all conditions return to normal, the relay will reset.
The Adjustable Release Delay is provided to ignore momentary voltage fluctuations that cause nuisance tripping.
Both Delta and Wye systems may be monitored. In Wye Systems, connections to neutral are not required.
SLM Series Image
  • LED Indicators for Fault Conditions
  • Models Available up to 690 VAC
  • Automatic or Manual Reset
  • Delay-on-Make Timer
  • Last Fault Memory
SLM series microprocessor based 3-phase monitors protect equipment against under voltage, over voltage, phase loss, phase reversal, phase unbalance, phase shift, and frequency shift.
  • Under Voltage, Over Voltage, Under Frequency, Over Frequency, Asymmetry, Phase Failure and Phase Sequence Monitoring
  • RMS Measurement
  • Power ON Delay, Trip Time Delay and Delay on Release
  • Adjustable Switching Hysteresis
  • Two Separate Alarm Relays
SLU600 Series Image
  • Monitors up to 700 VAC
  • Automatic or Manual Reset
  • Adjustable Fault and Restart Delays
  • Din Rail Mounting
  • Rapid Cycling Feature
The SLU600 Series protects three-phase motors up to 700 VAC. The Rapid Cycling feature prevents motors cycling due to load-induced line fault conditions. Powered by 120VAC, this reliable motor protection relay is unaffected by transients and disturbances from the monitored power source.
Protects against:
  • Phase Loss
  • Phase Reversal
  • Phase Unbalance
  • Phase Shift
  • Over/Under Voltage
  • Over/Under Frequency
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