HRDI421 - HRDI Series

Series: HRDI Questions? Contact Littelfuse Support
Littlefuse Interval Relays
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.

Property (Mouseover for details) Value
Input Voltage (V) 120VAC
Input Tolerance (%) -20% - 10%
Input AC Line Frequency (Hz) 50/60Hz
Output Type Electromechanical relay
Output Form SPDT non-isolated
Output Load Rating (VA) General Purpose: SPDT-NO: 125/240VAC ≅ 30A; SPDT-NC≅15A; Resistive: SPDT-NO≅30A for 125/240VAC 20A for 28VDC; SPDT-NC≅15A for 125/240VAC 10A for 28VDC; Motor Load: SPDT-NO≅1 hp for 125VAC 2hp for 240VAC; SPDT-NC≅1/4hp for 125VAC 1hp for 240VAC
Time Delay Type Microcontroller circuitry
Time Delay Range 1 - 100s onboard knob
Time Delay Tolerance (%) ±5%
Recycle Time (ms) ≤150ms
Repeat Accuracy (%) ±0.5% or 20ms whichever is greater
Setpoint vs Ambient Temperature and Operating Voltage (%) ≤ ±2%
Surge Protection IEEE C62.41-1991 Level A
Insulation Resistance ≥100 MΩ
Dielectric Breakdown ≥2000V RMS terminals to mounting surface
Circuitry Encapsulated
Life Mechanical - 1 x 106; Electrical - 1 x 105 3 x 104 for 1hp 6 000 for 1/4hp 1hp and 2hp
Power Consumption ≤4VA
Termination Type 0.25 in. (6.35mm) male quick connect terminals
Mounting Method Surface mount with one #10 (M5 x 0.8) screw
Operating Temperature -40° to 60°C (-40°F to 140°F)
Storage Temperature (F/C) -40° to 85°C (-40°F to 185°F)
Humidity 95% relative non-condensing
Dimensions 3.00 x 2.00 x 1.50 in. (76.7 x 51.3 x 38.1mm)
Weight (lbs/g) ≅3.9oz (111g)
Sample capable No