UPS to ATS connectivity

[AJ6314]

I am being asked by my IS department to have our Eaton UPS connected with two wires to the ATS so the UPS can override or "start" the ATS to switch it over to generator power. We had a power issue a few weeks ago but I believe after discussions with our electrician and our Generac tech that the two wire control our Eaton tech and IS staff are talking about was only needed on the assumption that the ATS did not have Phase Sensing. This is of course not the case. The ATS has Phase Sensing and we reset the sensitivity of the ATS to 85% to match the UPS sensitivity. IS staff has already had Eaton install a control in the UPS to "talk" to the ATS and want the wire run. Would this cause an issue or just add a layer of harmless redundancy? I cannot get a clear answer from the Eaton UPS tech.

Thanks,

J

 

[steve66]

Assuming the ATS has an input that can be used to start the generator and transfer to em., I don't see why it would hurt anything, and it could add a little redundancy.

I would want the ATS more sensitive than the UPS, not at the same sensitivity. They will never match perfectly, and there will be a little more voltage drop at the UPS than at the ATS anyway.

Maybe it is best to just have the UPS tell the ATS "Hey, that utility voltage is not working for me."

 

[ron]

You can do it either way.

Normally we have to coordinate the low voltage setting for the ATS and the UPS so the UPS battery will never be called upon without the generator on the way.

You could have the UPS tell the ATS to get going, but often I connect the ATS to the UPS if I need to put the UPS in a current limit mode when we are fed by generator in case the generator is not big enough to handle full load and recharge current.