KRDR321B4 - KRDR Series

Series: KRDR
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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 KRDR Series is a compact time-delay relay measuring only 2 in. (50.8 mm) square. Its solid-state timing circuit provides excellent repeat accuracy and stability. Encapsulation protects against shock, vibration, and humidity. The KRDR Series is a cost effective recycling timer for OEM applications that require small size, isolation, reliability, and long life.


Operation (Recycling - ON Time First)
Upon application of input voltage, the output relay energizes and the T2 ON time begins. At the end of the ON time, the output de-energizes and the T1 OFF time begins. At the end of the OFF time, the output relay energizes and the cycle repeats as long as input voltage is applied.
Reset: Removing input voltage resets the output and the time delays, and returns the sequence to the ON time.


Operation (Recycling - OFF Time First)
Upon application of input voltage, the T1 OFF time begins. At the end of the OFF time, the T2 ON time begins and the load energizes. At the end of the ON time the load de-energizes, and the cycle repeats until input voltage is removed.
Reset: Removing input voltage resets the output and the sequence to the OFF time.

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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%
Input DC Ripple (%) ≤10%
Output Type Isolated relay contacts
Output Form SPDT
Output Load Rating (VA) 10 A resistive @ 125 V ac; 5 A resistive @ 230 V ac and 28 V dc; 1/4 hp @ 125 V ac
Maximum Output Voltage (V) 250
Time Delay Range ON: 1 - 100 s adjustable; OFF time first: 1 - 100 m adjustable
Time Delay Tolerance (%) ≤±5%
Reset Time (ms) ≤150
Repeat Accuracy (%) ±0.5% or 20 ms whichever is greater
Setpoint vs Ambient Temperature and Operating Voltage (%) ≤±5%
Insulation Resistance ≥100
Circuitry Encapsulated
Polarity DC units are reverse polarity protected
Life Electrical: 1 x 10⁵; Mechanical: 1 x 10⁷
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 -20° to 60°C (-4° to 140°F)
Storage Temperature (F/C) -40° to 85°C (-40° to 185°F)
Humidity 95% relative : non-condensing
Dimensions 2 H x 2 W in. (50.8 x 50.8 mm)
Weight (lbs/g) 0 Kg
Dimensions 2 H x 2 W in. (50.8 x 50.8 mm)

To request product environmental information, please complete the Product Environmental Information Request Form.