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IEC Sizing

IEC Sizing

IEC Sizing

I'm under the impression that when a contactor is to be operated in AC-4 conditions more than ten times per minute, one should select a contactor that is one size larger than if it were not operated this frequently.  I just wanted to clarify whether going the next size up was referring to the next highest current rating or the next highest frame size for an IEC contactor.  Any insight is appreciated, thanks.

RE: IEC Sizing

Correction, ten times in ten minutes.

RE: IEC Sizing

Most manufacturers will list an AC-4 rating, or be able to advise you. I'd expect to go up a frame size.

The relevant standard is IEC 60947-4-1. The nearest standard class for intermittent operation is Class 120 per IEC 60947-1.

If we learn from our mistakes I'm getting a great education!

RE: IEC Sizing

Thanks for the input ScottyUK.


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