LXPRT-4W Phase Sequence/Failure/Under Voltage Relay

  • Under voltage monitoring
  • Monitors own three phase, 4-wire supply
  • Detects incorrect phase sequence, phase and neutral loss
  • Adjustable Trip level and Time delay
  • SPDT Relay output
  • 17.5mm wide, DIN Rail mount
  • UL Listed

The product monitors it’s own three-phase supply and for the output relay to energise, all phases (and neutral) must be present, the phase sequence correct and the phase to neutral voltages above the set trip level. If any of these conditions are not met, the relay will de-energise.

  • Monitoring function: Under voltage
  • Monitored supply voltage: 230V (400V) AC (Order Code: 99-4104)
  • Under trip level: 173 – 288V
  • Hysteresis: ≈2%
  • Time delay: 0.2 – 10s
  • Output: SPDT 8A @ 250V (AC1)
  • Dimensions (mm): W:17.5 x H:89 x D:66.5
Distributors Stock Code Link
RS Components 8505389 (230VAC(400VAC)) Go to product
Farnell 2677806 (230VAC(400VAC)) Go to product

Typical applications include:

  • Lift and elevator control panels
  • Industrial laundry machinery
  • Building ventilation systems
  • Process machinery with neutral-fed controls

Key benefits:

  • Helps reduce low-voltage operation — Under-voltage monitoring releases the output relay when the monitored supply falls below the operating threshold, allowing equipment to be inhibited.
  • Helps prevent incorrect motor rotation — The relay requires correct phase sequence before energising, allowing a motor contactor to be inhibited when the incoming phases are reversed.
  • Responds to phase and neutral faults — Phase-loss detection and neutral-loss detection in the supported four-wire arrangement can release the control permissive when the incoming supply is incomplete.
  • Helps avoid unnecessary voltage-fault trips — An adjustable fault delay allows brief voltage deviations to be tolerated before the relay changes state, subject to the documented immediate-trip conditions.

Alternative product:

Icon: switch product
LPRT/2 Three Phase Under Voltage Monitoring Relay
  • Under voltage monitoring
  • Selectable nominals for popular 3-wire or 4-wire supply voltages
  • Detects incorrect phase sequence, phase and neutral loss
  • Adjustable Trip level and Time delay
  • 2 x SPDT Relay output
  • 17.5mm wide, DIN Rail mount
  • UL Listed
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