UPS Gu-rus
- Thread starter shaw0486
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![IMG_1411[1].jpg](https://forums.mikeholt.com/data/attachments/2/2472-7fcbbc8f420021bf92e3110c29450e5b.jpg "IMG_1411[1].jpg")
Not a guru, but I have a preferred method.
First I would probably choose a preferred equipment manufacturer and then approach them for their design, engineering expertise. Let the manufacturer put an equipment package together.
First look, I would be considering the bypass and UPS at 480 line and load, probably remote from the critical load. Then the run to the load after the UPS is 480 delta and the step down transformer and critical panel is located close to the load. The electronics are rated for current handling and may be smaller or slightly more efficient running less current at the higher voltage.
The UPS produces significant heat and could be located near the feed, in a basement, lower level, away from conditioned IT space, where the cooling is provided for or used to heat an otherwise unconditioned space. Could provided a better footprint for servicing. The longer run to the load is 3 ph 3 wire at 480, so there could be a copper savings distributing at 480 delta and stepping down to 120/208 at the load. It's my opinion, but I believe the inverter pumping directly into the primary of the step down transformer gives it a known calibrated load impedance, which should be a better match, compared to pumping directly into the IT stuff, which is an unknown, and varies. I believe this topology has advantages that running the UPS at 208 (and close to the load) do not provide.
At the design stage it is certainly valid to ask the manufacturer about both approaches.
First I would probably choose a preferred equipment manufacturer and then approach them for their design, engineering expertise. Let the manufacturer put an equipment package together.
First look, I would be considering the bypass and UPS at 480 line and load, probably remote from the critical load. Then the run to the load after the UPS is 480 delta and the step down transformer and critical panel is located close to the load. The electronics are rated for current handling and may be smaller or slightly more efficient running less current at the higher voltage.
The UPS produces significant heat and could be located near the feed, in a basement, lower level, away from conditioned IT space, where the cooling is provided for or used to heat an otherwise unconditioned space. Could provided a better footprint for servicing. The longer run to the load is 3 ph 3 wire at 480, so there could be a copper savings distributing at 480 delta and stepping down to 120/208 at the load. It's my opinion, but I believe the inverter pumping directly into the primary of the step down transformer gives it a known calibrated load impedance, which should be a better match, compared to pumping directly into the IT stuff, which is an unknown, and varies. I believe this topology has advantages that running the UPS at 208 (and close to the load) do not provide.
At the design stage it is certainly valid to ask the manufacturer about both approaches.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Superstorm Sandy demonstrated a few things to keep in mind when planning this.
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