3ph Input to UPS, Single Phase or 3ph Inverter

[jimmy2times]

I have a 3ph 380V 50Hz input available for a UPS (~150kVA).

As I only need to supply single phase loads (240V + Neutral).

Would it be better to purchase a 3ph output inverter UPS and supply loads on 2ph or purchase a single phase inverter UPS ?

 

[ScottyUK]

If you use only two phases of a three phase UPS you will need a UPS 33% larger in rating to supply the same load because the capacity of the third phase is unused.


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Sometimes I only open my mouth to swap feet...

 

[DanDel]

3-phase input and output converters are typically used to supply single-phase loads, using 3-phase panels with single-phase C/Bs. Using a 3-phase UPS will provide a balanced 3-phase load on your 380V system, no matter what the UPS output feeds.

 

[Skogsgurra]

Agree fully with Dan and Scotty.

Just a question (that may be quite important): Are you going to supply 150 kVA over a single-phase system? That is not very common.

Are you sure that your seemingly single-phase loads are not connected to different phases? I.e. wall outlets connected to different phases + neutral

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[jimmy2times]

We have about 30 independent loads most circa 4-5kVA each.

Just to clarify:-
The input rectifier would be 3ph to DC link.

Then I was unsure whether the best option would be to use either:-

1. a single phase inverter; or
2. a 3ph inverter and share the single phase loads across phases (2 phase distribution).

 

[itsmoked]

It depends on whether the facility is panelled for three phase power now or single phase. Normal single phase loads are usually not 4-5kVA so you might actually have a 3phase wired facility now.

Or is this all new - ground up?

Keith Cress
Flamin Systems, Inc.-

http://www.flaminsystems.com

 

[waross]

I would use an inverter that supplies 240/416 volts 3 phase and feed a 3 phase panel.
Connect the loads phase to neutral.
respectfully

 

[rcw retired EE]

With a three phase inverter and distribution, only one third of the loads will be disturbed by a fault on a circuit. Voltge on the other two phases would not be affected.