Electronics > Beginners
How to wire up a 240VAC receptacle
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Spork Schivago:

--- Quote from: IanB on May 18, 2018, 05:30:26 am ---
--- Quote from: IanB on May 18, 2018, 04:51:11 am ---
--- Quote from: Monkeh on May 18, 2018, 03:52:21 am ---Change your PDUs for the type with double pole breakers and use your existing supply, or have an electrician (yes. really. please don't do it yourself.) install the transformer. Either will work.
--- End quote ---

It's not clear that there are any HPE PDUs with double pole breakers. The HPE literature divides the product range into two categories: NA/Japan which expects 200-208 V AC single phase, or INTL which expects 220-240 V AC single phase. In either case it is clear that this voltage is measured line to neutral, as is typically found in commercial premises.

--- End quote ---

OK, I stand corrected. The P9S13A does have a double pole breaker, as listed here: https://h20195.www2.hpe.com/v2/GetDocument.aspx?docname=a00002909enw

So it does appear that 240 V line to line or phase to phase should be acceptable for this particular PDU.



--- End quote ---

But then we're back to the power supplies being fed split-phase, aren't we?   It wasn't me who picked out the PDU or the PSUs.   And like I've stated, HPE could have been wrong during their power analysis, but after their power analysis there was one power supply that was available, and only one, the one we have.    And then when it came to a proper PDU, there was no PDUs available that would work with our PSUs and our split-phase, however, there were ones available that would work with 1-phase 240VAC or the 3-phase.   And eventually, we went for the 1-phase 240VAC out of the choices, because of the 3-phase being too much.
Spork Schivago:

--- Quote from: oPossum on May 18, 2018, 05:17:44 am ---
--- Quote from: IanB on May 18, 2018, 04:38:29 am ---HP expects commercial power to be available in North America in two flavors of single phase: either 120 V AC ("low-line") or 208 V AC ("high-line"). The 208 V power would be derived from one leg of a three phase transformer and would be true 208-0 V single phase line to neutral.

--- End quote ---

240 and 480 phase to phase is also common commercial power.

208 is phase to phase, not phase to neutral. Phase to neutral is 120.

That is why there are two pole breakers on those PDU.

240 phase to phase would not be a problem.

--- End quote ---

I'm trying to understand all this.   How does the 208VAC work exactly?   You say it's phase to phase, that's like my North American Residential Standard Panel Input 240VAC split-phase, right?    240VAC from one 120VAC hot, and from the other 120VAC hot line coming in.   Phase to Neutral is 120.   With 208, you say Phase to neutral is 120.   So the other phase is 88VAC?

And when a device can run off split-phase, does it combine the two phases internally to get the 240VAC or does half the circuit use 120VAC and the other half use 120VAC?
Spork Schivago:

--- Quote from: Bratster on May 18, 2018, 08:12:21 am ---@Spork

What are you not clear on understanding of how to wire up the Transformer?

The drawing I sketched out gave you the basics of what is going on with it.

Let's stop beating this dead horse.

Whether we like it or not you need a 240-volt line to neutral power service.

The only way you're going to get that from your existing house supply is with a Transformer.

So focusing on that point, what are you having trouble understanding so that everybody can help you out in that aspect?


PS. This post was not meant to come off as offensive or anything like that, I'm sleepy and it looks like this thread is starting to go in circles again.

Night all

Sent from my Moto x4 using Tapatalk

--- End quote ---
Yes, your drawing was amazing.   It's the actual multiple configurations of the wirings that Mr. Crowley and I talked about, I'm still not 100% clear on that.   I understand what wires get tied together in transformer, but I'm not 100% clear on where the two 120VAC's would run to which wires in the transformer and where the neutral would run.   And then I'm not 100% clear on the output side, which wires would get ran to the new breaker panel.   I wasn't picturing the transformer running to a new panel, I was picturing the transformer running to the receptacle to power the PDU.   However, I think your drawing is the correct way to go and is what the electrician that I've contacted would have said, once he finds the time to get back to me.   He's good, he's expensive, but knows the codes and works generally with larger companies.   One of the businesses I deal with recommended him because when they cannot wire something up, they hire him.

They wire up furnaces, whole home generators, etc, so it's not often they need him, but when they do, he's always the one they call.   It takes him a while to get back to me for some reason though.
Monkeh:

--- Quote from: Spork Schivago on May 18, 2018, 07:58:49 pm ---
--- Quote from: oPossum on May 18, 2018, 05:17:44 am ---
--- Quote from: IanB on May 18, 2018, 04:38:29 am ---HP expects commercial power to be available in North America in two flavors of single phase: either 120 V AC ("low-line") or 208 V AC ("high-line"). The 208 V power would be derived from one leg of a three phase transformer and would be true 208-0 V single phase line to neutral.

--- End quote ---

240 and 480 phase to phase is also common commercial power.

208 is phase to phase, not phase to neutral. Phase to neutral is 120.

That is why there are two pole breakers on those PDU.

240 phase to phase would not be a problem.

--- End quote ---

I'm trying to understand all this.   How does the 208VAC work exactly?   You say it's phase to phase, that's like my North American Residential Standard Panel Input 240VAC split-phase, right?    240VAC from one 120VAC hot, and from the other 120VAC hot line coming in.   Phase to Neutral is 120.   With 208, you say Phase to neutral is 120.   So the other phase is 88VAC?
--- End quote ---

Each phase is 120VAC to the star point ('neutral'), 208VAC to each other. Three phases. As mentioned before, 'split phase' isn't really multiple phases: IT IS ONE PHASE with a centre tap.


--- Quote ---And when a device can run off split-phase, does it combine the two phases internally to get the 240VAC or does half the circuit use 120VAC and the other half use 120VAC?

--- End quote ---

There are no halfs. Both hot conductors make for a single phase of 240VAC. That's all the load cares about. With the PDU it's a distribution concern - at loads it's irrelevant.
tpowell1830:

--- Quote from: Spork Schivago on May 18, 2018, 07:50:32 pm ---
--- Quote from: IanB on May 18, 2018, 05:30:26 am ---
--- Quote from: IanB on May 18, 2018, 04:51:11 am ---
--- Quote from: Monkeh on May 18, 2018, 03:52:21 am ---Change your PDUs for the type with double pole breakers and use your existing supply, or have an electrician (yes. really. please don't do it yourself.) install the transformer. Either will work.
--- End quote ---

It's not clear that there are any HPE PDUs with double pole breakers. The HPE literature divides the product range into two categories: NA/Japan which expects 200-208 V AC single phase, or INTL which expects 220-240 V AC single phase. In either case it is clear that this voltage is measured line to neutral, as is typically found in commercial premises.

--- End quote ---

OK, I stand corrected. The P9S13A does have a double pole breaker, as listed here: https://h20195.www2.hpe.com/v2/GetDocument.aspx?docname=a00002909enw

So it does appear that 240 V line to line or phase to phase should be acceptable for this particular PDU.



--- End quote ---

But then we're back to the power supplies being fed split-phase, aren't we?   It wasn't me who picked out the PDU or the PSUs.   And like I've stated, HPE could have been wrong during their power analysis, but after their power analysis there was one power supply that was available, and only one, the one we have.    And then when it came to a proper PDU, there was no PDUs available that would work with our PSUs and our split-phase, however, there were ones available that would work with 1-phase 240VAC or the 3-phase.   And eventually, we went for the 1-phase 240VAC out of the choices, because of the 3-phase being too much.

--- End quote ---

Back to the 3 phase system, I think that you are being told $50k to install is what I read? This seems very outrageous, having done this myself in my area. The 3 phase power lines were 1/4 mile away and the power company charged me a modest $300 to install the pole and transformer, however, I had to sign a 3 year contract with a minimal $25 charge for the service. Mind you, this was in 1980, so I could see a factor of 10 at least on that price, but still can't get to the $50k figure. You would still need to provide a distribution panel and do all of the wiring, which I did myself in 1980.

Hope this helps...
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