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Relay Question — Parallax Forums

Relay Question

ArchiverArchiver Posts: 46,084
edited 2001-08-12 00:12 in General Discussion
I am using relays to control a higher current and I have a question about
relay specs. I understand that if the coil voltage is 5 V is requires 5 V to
switch but when the specs for the contact voltage are 28VDC and the contact
current is 30A, do you need to pass 28VDC and will it work with only 12VDC @
12 A? I want to use this high amp rating to ensure that the relay will work
with spikes in the current draw of the motor.

Thank you,
Sean


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Comments

  • ArchiverArchiver Posts: 46,084
    edited 2001-08-12 00:09
    Two separate set of specifications here. The coil voltage / current is
    what is necessary to turn on the armature or coil of the relay. Once is
    is on the N/O or N/C contacts switch a current and voltage according to
    the specification of the contacts. It's usually OK to switch a lower
    voltage and or current (never higher on the current, maybe the voltage)
    than the specs say of the contacts, but the specs on the coil must be
    followed exactly.


    kind regards,

    Leroy

    sean975@a... wrote:
    >
    > I am using relays to control a higher current and I have a question about
    > relay specs. I understand that if the coil voltage is 5 V is requires 5 V to
    > switch but when the specs for the contact voltage are 28VDC and the contact
    > current is 30A, do you need to pass 28VDC and will it work with only 12VDC @
    > 12 A? I want to use this high amp rating to ensure that the relay will work
    > with spikes in the current draw of the motor.
    >
    > Thank you,
    > Sean
    >
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    --

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    * Loveland, Ohio - USA 45140-2404 *
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    *******************************************************
  • ArchiverArchiver Posts: 46,084
    edited 2001-08-12 00:12
    At 8/11/2001 Saturday 06:49 PM, sean975@a... promulgated:
    >I am using relays to control a higher current and I have a question about
    >relay specs. I understand that if the coil voltage is 5 V is requires 5 V to
    >switch but when the specs for the contact voltage are 28VDC and the contact
    >current is 30A, do you need to pass 28VDC and will it work with only 12VDC @
    >12 A? I want to use this high amp rating to ensure that the relay will work
    >with spikes in the current draw of the motor.
    >
    >Thank you,
    >Sean
    Hi Sean -

    As long as the voltage and current ratings are at or above those required,
    the relays ought to adequately serve your purpose.

    Regards,

    Bruce Bates




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