HLVA Series – Voltage Monitor Series - Littelfuse HLVA Voltage Monitoring Relays Provide Superior Protection

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The HLVA (HLV) series is a single-phase undervoltage monitor designed to protect sensitive equipment from brownout or undervoltage conditions. Time delays are included to prevent nuisance tripping and short cycling. The 30 A, 1hp-rated, SPDT relay contacts allow direct control of motors, solenoids, and valves. The output relay can be ordered with isolated SPDT contacts to allow monitoring of one voltage and switching to a separate voltage. Two undervoltage trip point ranges allow monitoring of 110–120 V ac or 208–240 V ac systems.


Upon application of input voltage, the output relay remains de-energized. When the input voltage value is above the pull-in voltage, the restart delay begins. At the end of the restart delay, the output relay energizes. When the input voltage falls below the trip point, the trip delay begins. If the input voltage remains below the pull-in voltage for the entire trip delay, the relay deenergizes. If the input voltage returns to a value above the pull-in voltage during the trip delay, the trip delay is reset and the relay remains energized. If the input voltage falls below the trip point voltage during the restart delay, the delay is reset and the relay remains de-energized. Reset is automatic upon correction of an undervoltage fault.


Removing the input voltage resets the output relay and the time delays.


  • 30 A, SPDT, No output contacts
  • 1–240 V ac input voltage
  • 70–220 V ac adjustable undervoltage trip point in two ranges
  • Restart delays from 3–300 s
  • Trip delay 1–20 s fixed
  • Isolated or non-isolated relay contacts

Access specifications, certifications, check availability and order parts below

Catalog #Input
Voltage (V)
Termination TypeMounting MethodDimensionsWeight (lbs/g)HumidityInput AC Line Frequency (Hz)Insulation ResistanceOutput Load Rating (VA)Output TypePower ConsumptionPull In VoltageRepeat Accuracy (%)Reset Time (ms)StockSamples
HLVA6I23Min RMS Voltage: 70 Vac; Max RMS Voltage: 264 VacIsolated SPDT0.25 in. (6.3 mm) male quick connect terminalsSurface mount with one #10 (M5 x 0.8) screw3 H x 2 W x 1.5 D in. (76.7 x 50.8 x 38.1 mm)0 Kg95% non-condensing50 / 60≥100General Purpose: SPDT-NO: 125/240 Vac 30 A; SPDT-NC 15 A; Resistive: SPDT-NO: 125/240 Vac 30 A; 28 Vdc 20 A; SPDT-NC: 125/240 Vac 15 A; 28 Vdc 10 A; Motor Load: SPDT-NO: 125 Vac 1 hp; 240 Vac 2 hp; SPDT-NC: 125 Vac 1/4 hp; 240 Vac 1 hpElectromechanical relay≤4 VA105% or trip point voltage±0.5% or 20 ms whichever is greater≤150 msCheckOrder
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