HRDI Series - Interval Timer

Littlefuse Interval Relays
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The HRDI Series combines an electromechanical relay output with microcontroller timing circuitry. It offers 12 to 230V operation in five ranges and factory fixed, external, or onboard adjustable time delays with a repeat accuracy of ±0.5%. The output contact rating allows for direct operation of heavy loads, such as compressors, pumps, blower motors, heaters, etc. This series is ideal for OEM applications where cost is a factor.

Operation (Interval)
Upon application of input voltage, the time delay begins. The output relay is energized during the time delay. At the end of the time delay, the output de-energizes and remains de-energized until input voltage is removed.
Reset: Removing input voltage resets the time delay and the output.

Access specifications, certifications, check availability and order parts below

Catalog #Input
Voltage (V)
Storage Temperature (F/C)Time Delay RangeSample capableCompare
HRDI117S12VDCSPDT non-isolated-40° to 85°C (-40°F to 185°F)7s fixedNo
HRDI421120VACSPDT non-isolated-40° to 85°C (-40°F to 185°F)1 - 100s onboard knobNo
HRDI422120VACSPDT non-isolated-40° to 85°C (-40°F to 185°F)10 - 1 000s onboard knobNo