Paralleling of Two UPS's of different rating

[NickParker]

I would like to parallel two UPS's of different rating (200kVA and 50kVA).

I understand that it can be done if the two Bypass Line (for the two UPS's) are supplied from the same source.

Why am I thinking of it? The 200kVA UPS has been already purchased and now that load has been increased, 50kVA additional UPS to be purchased. I have some spare feeders in the existing UPS distribution panel(with one bus) to feed these additional 50kVA loads. So thinking to sync with the existing UPS.

Any one having done this before? suggestions?

 

[davidbeach]

"Parallel" would be both tied together source and load. That probably wouldn't end well, particularly on loss of source.

What would work just fine is that you feed about 80% of the load with the 200 and about 20% of the load with the 50 and no connections between the two on the load side.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[JezNZ]

Ask the manufacturer. Depending on model, age, etc, it's possible that the two UPS can be synchronised.