Correctly choosing a relay in term of breaking current

currentdesignrelay

I would like tu interrupt a resistive load on AC of about 1 kw at 220 Vac.
I'm looking at this relay, that claim to have a 10A current ( that sounds enought to me )
but the breaking current is just 0.12A at 220 V. What does it exactly mean? Would this relays just guarantee to break without damage a current of 0.12 A ? Which breaking current should I design for a load as described ?

Best Answer

You were applying the DC1 specs to your AC load application by mistake.

The life cycle rating is limited by surge starting current and the breaking switch off current more than the steady state current of 10A. It is the energy dissipated across the contacts that matters or the V*I product during switching.

But in DC1 the curves are significantly derated becuase the breaking current is always the same as the steady current for "pure" resistive loads.

In AC loads with sinusoidal current most of the time it is less than the peak current so the average temperature rise is lower on the contacts, which controls life cycle time.

For conservative design, increase the current rating.

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