HRDB321 - HRDB Series

Series: HRDB
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Littelfuse products are not designed for, and shall not be used for, any purpose (including, without limitation, automotive, military, aerospace, medical, life-saving, life-sustaining or nuclear facility applications, devices intended for surgical implant into the body, or any other application in which the failure or lack of desired operation of the product may result in personal injury, death, or property damage) other than those expressly set forth in applicable Littelfuse product documentation. Warranties granted by Littelfuse shall be deemed void for products used for any purpose not expressly set forth in applicable Littelfuse documentation. Littelfuse shall not be liable for any claims or damages arising out of products used in applications not expressly intended by Littelfuse as set forth in applicable Littelfuse documentation. The sale and use of Littelfuse products is subject to Littelfuse Terms and Conditions of Sale, unless otherwise agreed by Littelfuse. "Littelfuse" includes Littelfuse, Inc., and all of its affiliate entities.

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


Operation (Delay-on-Break)
Input voltage must be applied before and during timing. Upon closure of the initiate switch, the output relay energizes. The time delay begins when the initiate switch is opened. The output remains energized during timing. At the end of the time delay, the output de-energizes. The output will energize if the initiate switch is closed when input voltage is applied.
Reset: Reclosing the initiate switch during timing resets the time delay. Loss of input voltage resets the time delay and output.

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Product Literature

For Technical Questions

Call +1 800-832-3873 or email us at relays@littelfuse.com 

Property (Mouseover for details) Value
Input Voltage (V) 24 V dc
Input Tolerance (%) -15% - 20%
Output Type Electromechanical relay
Output Form Isolated SPDT
Output Load Rating (VA) General Purpose: SPDT-NO: 125/240 V ac ≅30 A; SPDT-NC ≅15 A; Resistive: SPDT-NO ≅30 A for 125/240 V ac and 20 A for 28 V dc; SPDT-NC ≅15 A for 125/240 V ac and 10 A for 28 V dc; Motor Load: SPDT-NO ≅1 hp for 125 V ac and 2 hp for 240 V ac; SPDT-NC ≅1/4 hp for 125 V ac and 1 hp for 240 V ac
Time Delay Type Microcontroller
Time Delay Range 1 - 100 s onboard knob
Time Delay Tolerance (%) ±5%
Reset Time (ms) ≤150
Initiate Time (ms) ≤20
Repeat Accuracy (%) ±0.5% or 20 ms whichever is greater
Setpoint vs Ambient Temperature and Operating Voltage (%) ≤±2%
Surge Protection IEEE C62.41-1991 Level A
Insulation Resistance ≥100
Dielectric Breakdown ≥2000V terminals to mounting surface
Circuitry Encapsulated
Polarity DC units are reverse polarity protected
Life Electrical: 1 x 10⁵ 3 x 104 for 1 hp - 6000 for 1/4 hp 1 hp and 2 hp; Mechanical: 1 x 10⁶
Power Consumption ≤2 W
Termination Type 0.25 in. (6.35 mm) male quick connect terminals
Mounting Method Surface mount with 1 #10 (M5 x 0.8) screw
Operating Temperature -40° to 60°C (-40° to 140°F)
Storage Temperature (F/C) -40° to 85°C (-40° to 185°F)
Humidity 95% relative : non-condensing
Dimensions 3 H x 2 W in. (76.7 x 51.3 mm)
Weight (lbs/g) 0 Kg
Dimensions 3 H x 2 W in. (76.7 x 51.3 mm)

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