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

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

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

(OP)
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 ?

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

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.
 

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

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

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.

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

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

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

(OP)
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).

  

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

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

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

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

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

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.

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