Relay ratings

[BigE]

Hi,

This is a totally newbie question.

If a relay has a continuous current carrying capacity of 10A@250VAC, then does it follow that the current carrying capacity will increase at lower AC voltages? 10A@250VAC is 2500 VA.

So, if the relay is operating at 125VAC, does the current carrying capacity go to 20A?

Thanks!

 

[sofaspud]

I can't locate an authoritative reference, but I would say no.
If you look at switches, even they aren't built and spec'd the way you describe.

 

[Elvee]

Relays have whole sets of specifications, depending on their duty, type of current, etc.
If you take one set, just plain AC for instance, you have maximum current and voltage ratings, and breaking capacity.
Current is expressed in ampere, voltage in volt as you would expect and breaking capacity in VA. Note that the breaking capacity is always smaller than or equal to the max I*V product.

When there is no other indication, the breaking capacity equals the I*V product, but otherwise it can be much smaller, in particular for demanding duties, inductive loads, etc.

The datasheet normally details all these aspects, if the relay is intended to do that kind of job, of course.

PS:

This means of course that a relay specified for 10A will never be able to pass 20A, even if it has to interrupt only 1V.