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 Post subject: Modeling a Static Phase Converter
PostPosted: Wed Mar 20, 2019 11:14 am 

Joined: Sun Mar 03, 2019 9:58 am
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I am doing an arc flash study on a number of remote natural gas wellsites that are fed by a single phase distribution line and delivered to the site at 240V single phase. To drive the three phase pumps a static single phase to three phase converter is used to convert the single phase power to 240V three phase power and is distributed through a panel to several motors and miscellaneous three phase loads. My question is, how do I model the phase converter as a three phase source. I'm not having much luck obtaining from the manufacturer the behavior of the converter under fault conditions. Any thoughts would be appreciated.

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 Post subject: Re: Modeling a Static Phase Converter
PostPosted: Sun Mar 24, 2019 8:22 am 
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Joined: Tue Oct 26, 2010 9:08 am
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Location: North Carolina
It is quite literally just a VFD except it is running at a constant output frequency. The word static is just to separate themselves from the rotary phase converter market. Internally a diode bridge converts single phase AC to DC. Then a three phase inverter converts DC back to AC. The output is generally limited because the inverter thyristors are rated in AC RMS units and thermally have very little mass for efficiency reasons so generally can’t exceed around 150-175% of name plate. The overall unit will be conservatively built a little larger to absorb surges. The power structure is usually 6 pulse. It can be quite exotic (“clean power”) but from a modeling point of view this is not important except for power quality. Most people just buy a cheap VFD programmed to just start instantly and run at constant output frequency. You can also get them in voltage doubling (240 to 480) versions.

The maximum current is usually written as some sort of surge or overload specification but never exceeds about 200% of name plate. So just model as a VFD.

That being said I doubt you will be even 1-2 kA which is why nobody can answer your questions...will you even exceed 1 cal/cm2?

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