Relay Outputs - HID Mercury MR16in-S3 Installations And Specifications

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2.4 Relay outputs

Two Form-C contact relays are provided for controlling door strikes or other devices. Load switching can cause abnormal
contact wear and premature contact failure. Switching of inductive loads (strike) also causes EMI (electromagnetic
interference) which may interfere with normal operation of other equipment. To minimize premature contact failure and
to increase system reliability a contact protection circuit must be used. The following two circuits are recommended.
Locate the protection circuit as close to the load as possible (within 12 inches [30 cm]), as the effectiveness of the circuit
will decrease if it is located further away.
Use sufficiently large gauge of wire for the load current to avoid excessive voltage drop.
Diode selection
Diode current rating > 1x strike current.
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Diode break down voltage: 4x strike voltage.
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For 12 V DC or 24 V DC strike, diode 1N4002 (100V /1A) typical.
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PLT-05250, A.1 8
HID® Mercury™ MR16in-S3 Processor
Installation and Specifications
August 2022