Topic: Power supply question 240volt 3phase power vs 1 phase - page 3. (Read 4924 times)

You could engineer/wire it in a way that it pulls from two of the phases straight from the panel so you could use such an outlet on a three phase panel. That may be what he is doing and probably the norm. I'm setting up my datacenter with 3 phase PDU's so I bring all 3 phases out from the panels to closer to where it's used. More efficient that way, less metal to conduct more power.

That is a NEMA L6-30. for Single phase 240v applications, the three conductors you see there are for hot-hot-ground. Three phase will have either 4 or 5 conductors. They would be hot-hot-hot-ground, or alternatively hot-hot-hot-neutral-ground.

https://en.wikipedia.org/wiki/NEMA_connector#NEMA_6

okay the guy's shop has a ton of 3 hole twist-lock receptacles . I think I need to measure the power on them as

I thought they looked like this





these would have 2 hots and a ground  each hot would be a 120 if you went hot to ground.  but if you go hot to hot you get 240.

if  measure his power and get that result  it would be more like 1 phase.

your description has me a bit confused maybe his  shop wiring is doing what you say if I understand you correctly  3 hots feed into his shop.

and each 3 prong twist plug he has is using 2 of the 3 hots.

So if I want to load balance. with the 3 hots named 1 2 3

    I make 3  receptacles

  1+2+g is the first plug
  2+3+g is the second plug
  1+3+g is the third plug

each one does a evga 1300g2 running at 1000 watts   and we are load balanced

This confused me too at first before I did some research into three phase. I like to think of it like this (and please pardon my newb explanations):

Single phase AC has two hots, with each hot maximum potential 180degrees out of phase each cycle(hertz)

Three phase AC has three hots, with each hot maximum potential 120 degrees out of phase each cycle. Think of this like a triangle instead of a teeter totter.

You can use Three phase as single phase, just use two hots from the three phase. Of course this will only put a load on one 'side' of the three-phase triangle. The additional trick needed for three phase is 'balancing' the load of all three 'sides/phases' of that triangle so power is pulled evenly. Ammeters on each phase can provide a visual representation of what is going on, or you can just depend on careful calculation and wiring. Transformer life and many other thinks can quickly deteriorate if you are running unbalanced in any significant way.

So with just one more hot with 3 phase, you essentially can pull single phase from three points.

An example with a 3 phase pdu I have: 3 phase power cord, 60A, @ 208V. It has 6 C-19 outlets on it. Outlets 1-2 are connected to Phases A-B. Outlets 3-4 are connected to phases B-C. Outlets 5-6 are connected to phases C-A. It will not self balance, but requires that similar loads are put on these groups of outlets.

Here is a number you should memorize (it is not exact but gets you close enough)

1.732

To calculate wattage available from 3 phase : AMPS X 1.732 X VOLTAGE

Hope some of this helps, three phase is cool beans!

okay I have a glut of power supplies

 Evga  1300 g2
 Evga  1300 g2
 Evga  1600 p2

Seasonic 1200 plat
Seasonic   750 plat
Seasonic   650 gold
Seasonic   650 gold

Antec       600 plat

Intel server   1000 watt 120vol  1200 watt 240 volt plat

I finally wired one socket to 240 volts in house and I have a good improvement.


but all of the above is back ground info.  I have a friend that can give me 30 amps of 240 volt power at 7 cents a kwatt  but it is 3 phase so pardon some lack of knowledge on my part can an atx psu run on 3 phase power source.  I know the power wave on 3 phase is staggered but at that point I run out of knowledge. 

Short of plugging in an atx psu to test for shorting overloading or shaky 12 volt pc output, what is the story on 3phase vs 1 phase for atx psu's.

I think all of my psu's have active  PFC if that is helpful.