Relay rating explanation

Question

Let say we have a relay rated for 12 VDC - 80 A

This relay is connected to a 4 Ω load and a 300 VDC power supply (charged capacitor) for a few milliseconds. The current in this case is 75 A.

My question is: when the voltage of the circuit exceeds the voltage rating of the relay but not the current rating, will this damage the relay?

Andy aka · Accepted Answer · 2022-09-03 14:40:44Z

0

Think about it...

You have a relay rated for 80 amps and you are asking if 75 amps might damage it.
You have a relay rated at 12 volts and you are asking if 320 volts might damage it.
You have an amazon relay with no data sheet and therefore no guarantees it is any good.

I'd use a MOSFET and make sure the load inductance back-emf can be adequately handled.

answered Sep 3, 2022 at 14:40

Andy aka

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\$\begingroup\$ That is what i am asking about, if the current in the range of the relay but not voltage, i think the voltage will not matter significantly like the current, unfortunately can not use mosfet as seitch in my project \$\endgroup\$
– Marco David
Commented Sep 3, 2022 at 15:02
4

\$\begingroup\$ If the relay is not rated for 320V, don’t expect it to work properly regardless what you ‘think’. Things like contact gap and insulation factor into the voltage rating. You can give it a try but set your expectations low. \$\endgroup\$
– Kartman
Commented Sep 3, 2022 at 16:14
\$\begingroup\$ @MarcoDavid Even if the relay could drive a 12V load at 80A, or 960 watts (it likely can't), you are expecting it to drive a 320V 75A load that's 24000 watts? \$\endgroup\$
– Justme
Commented Sep 5, 2022 at 21:55

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