[RICHGONZO1]

We have a ups fed from either house or emergency generator power. There is no bypass for maintenance on the ups unit. We were thinking of tying in to another house power 480v breaker, same buss as the ups transformer (480-208/120v) and using a new "external" transformer, same exact size and flavor, same phasing. Then bring both sides of the secondary to a new 208 3 phase panel with 2 breakers and back feeding the buss to main and then feeding the ups panel. Im mainly concerned with both transformer being tied together in parallel and power not being "in phase". The only time we would put both breakers online, is when we "bypass" the ups without dropping out the whole plant, then open UPS primary and secondary to avoid backfeed. Thoughts? I'm rusty on my theory. Kinda hokey I know, don't judge me, I'm just following orders. I drew a schematic, but cannot post it until tomorrow. Thanks.

 

[Safari]

it's good to think towards that line.all the ups that I have come across have the maintenance bybass option.would Really want to see that schematic.hope you will figure out the phase sequence issues with those TX you are planning to install.
it's worth a try I think

Sent from my HUAWEI Y210-0100 using Tapatalk 2

 

[RICHGONZO1]

One line

Highlighted in orange would be the new instal. Sorry, still in pencil until we know for sure we will be ok, then I'll transfer to CAD.

 

[glen1971]

So long as your bypass doesn't create a spike or a ripple of any kind to the UPS loads.. Lots of loads are very sensitive for any voltage fluctuations. I know that the bypasses on the ones we use are done electronically and are done in milliseconds with no disruption... That being said, there is always the chance that it will still drop out when going to bypass, and the clients are all made aware of it before we start...