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by ontheropes
3 phase in refers to a 440/480 voltage supply. It's generally used to power heavy industrial equipment that runs 3 phase electrical motors more efficiently.
Single phase is like household wall outlet voltage. Unless you're running equipment that requires a 3 phase voltage, you're going to need to stick with single phase.
by saad_iqbal
1- The equipment is heavy duty industrial machine that doesn't require a 3 phase supply.
2- Three phase supply is available on site.
3- The advantage that I could think of is that if there is a voltage drop in one phase the UPS doesn't go on backup - three phase input is more balanced than the single phase
by hal 9000
The only advantage of a single phase in and 3 phase out would be to save rewiring the place to 3 phase. But at the moment I can't for the life of me think what a 3 Phase UPS would be used for in any Office or Home environment.
If you are talking Mainframes then there is a case for 3 phase but nothing else.
I can not see any benefit of having 3 phase in and single phase out unless you only have 3 phase outlets available.
Col
by hal 9000
OK I'll ask 5.5 KVA with a 30 minute backup time what are you wanting to drive?
That's a lot of power for a simple computer system and if it's a mainframe the UPS would be part of the install.
Something like that is powerful enough to drive a High End CAM Lath for quite a while.
For general purpose computers I get in excess of 45 minutes off 1.1 KVA and that UPS is driving several computers and their monitors and associated hardware.
by saad_iqbal
1- The equipment is heavy duty industrial machine that doesn't require a 3 phase supply.
2- Three phase supply is available on site.
3- The advantage that I could think of is that if there is a voltage drop in one phase the UPS doesn't go on backup - three phase input is more balanced than the single phase
by hal 9000
Well if you have 3 phase available and you only require single phase that may be the way to go although it would most likely be a very expensive alternative to all single phase UPS.
There is also the possibility that the UPS could overload at startup and cause the system to shut down as any heavy industrial equipment draws a lot of power at startup compared to actually running the equipment. That is something that you'll have to consider as well.
Col
by wlbowers
If you are in a facility that has 3 phase available for the input it is more effecient.
3-phase ac is 3 separate circuits of 120vac that are 120 degrees out of phase.
If you use a single phase ac circuit to provide the ups the current required will be higher than using 3 phase.
Lee
These units will completely buffer the ac as it comes in. The load runs on the ups at all times.
by wlbowers
If you have a 3 phase ups that lets one phase drop without going into protection it is broke.
Lee
by kbornman
is your ups a 3 phase unit or only a single phase unit and you have 3phase supply,then all you have to do is only use one of the phases you have and the neutral wire this gives you the 240ac volts you require from the 3 pase 400vac supply.
Regards Kenny
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