Hello there,

I want to get more insight on how one would go about mathematically calculating the best option for replacing an existing UPS with either a Three Phase or Single Phase. The technical details: 2017 VA static load, powered from a 208V/120V AC Wye Transformer, with Ia = Ib = Ic = 5.6A draw. The price of a replacement single-phase UPS is $18,000 versus a $27,000 three-phase UPS. Lastly, the assumed utility cost is $.11/kWh. I have run various calculations myself using three-phase power loss calculations versus single-phase with the cost of electricity trying to justify purchasing a three phase UPS with $9k more upfront costs or going with the cheaper single phase.

Would love to see a power expert take a wack at this mathematically and see if my results came close.

Thank you for your Time power lovers!

 

Also, you may assume PF = 0.8.

 

I seem to be missing something there. What's the configuration of the existing UPS? If it's three phase feeding loads that need three-phase power then you will need a three-phase replacement, right?

 

I seem to be missing something there. What's the configuration of the existing UPS? If it's three phase feeding loads that need three-phase power then you will need a three-phase replacement, right?

Yes so the three phase transformer (208/120 WYE) is powering a three phase ups but we can configure the transformer to give two legs and and a neutral to make a single phase system work (technically and we've don it before).