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I'm trying to switch medium power 110V AC loads (10-20A) and I'd like to use an automotive rated relay. Naturally most of these are rated for DC loads.

Would it be ok to use a relay like this to switch a 110V AC load? My understanding is that typically there could be issues the other way round (AC relay for DC) because of contact arcing, but presumably using it this way is ok? Are there any other things to watch out for? It will be driven by 12VDC.

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No, this is not okay: High-current DC relays such as the one you linked have magnetic arc extinguishing features which require current to flow in a particular direction through the relay contacts. This is mentioned on the last page of the relay's datasheet. When used to switch an AC load, this arc extinguishing feature will not work properly. Additionally, this relay is not suited for inductive loads, which is also spelled out on the last page of the datasheet (again due to the magnetic arc extinguishing).

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  • \$\begingroup\$ sad :( do you have any suggestions for AC relays that can operate in high vibration environments that are not crazily expensive? \$\endgroup\$
    – BeB00
    Mar 13, 2023 at 22:13
  • \$\begingroup\$ A solid-state relay is likely your best bet when it comes to high currents and high vibration. You can also build your own to your exact specs by combining a photovoltaic optocoupler with a pair of anti-serial MOSFETs. \$\endgroup\$ Mar 13, 2023 at 22:30

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