Electronics > Beginners
How to wire up a 240VAC receptacle
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Richard Crowley:

--- Quote from: Spork Schivago on May 16, 2018, 12:58:25 am ---So when HP speaks of 1-phase and lists NA/JP for the models, they're really meaning split-phase, for the higher than 120VAC PDUs, correct?   
--- End quote ---
NO!!!!  Single-phase (or "1-phase")  NEVER means the same thing as "split phase"  Single-phase (at least here in North America) implies that one side ("Line") is "HOT" and the other side ("Neutral") is essentially at zero-potential (i.e. GROUND).  In North America, the convention is that Neutral (white wire) is connected to Ground (green wire) at the breaker panel.  And the equipment is designed on the assumption that Neutral will be effectively at zero volts.  If you connect it to 120V you are just asking for trouble.


--- Quote ---And split-phase is what we have coming into our house, not 1-phase, right?   120VAC - 0 - 120VAC. 
--- End quote ---
Each side (120VAC to neutral/ground) is a "1-phase" circuit.  What you have coming into your house (and virtually everyone's house in North America) are two "single-phase" circuits.  You can get 240V from one "phase" to the other because of the North American convention established long before we were born.  But those two sides are not REALLY "phases".  Electricians call them "phases", but electronic engineers do NOT call them "phases" because they are not.

Appliances that are designed to operate on 240V in North America are designed to have the two 120V sides at 120V above ground.  They are typically resistive heaters (water heaters, forced air furnaces, cook-stoves, ovens, etc.)  And BOTH sides are well insulated and assumed to be always HOT. 

But what you have is a piece of industrial equipment that was designed with the assumption that it would be connected to a source of GROUND_REFERENCED 240V. That is what THEY mean by "single-phase".  Your PDU was designed on the assumption that the Neutral line will be essentially zero volts.  Connecting it to 120V is a monumentally terrible idea.  Before you identified what your mystery load was, we were assuming that it was some kind of gadget that might operate on "split-phase power.  Perhaps a domestic welder or air-compressor, etc.

But you have a sophisticated piece of industrial equipment which has a bunch of sensitive and expensive loads (computers) connected to it. And that is a whole different ball-game.


--- Quote ---I would rather try wiring it up myself, properly.
--- End quote ---
 
By operating a business in your home, you create a hugely gray area.  Technically you should take out a permit and have an inspection.  Else your can cancel your fire insurance because they won't pay off if you have done something like this and your house goes up in flames.  Be sure and have a good off-site daily backup/archive scheme in operation.


--- Quote ---Are you familiar with the brand name at all?   Are they any good?
--- End quote ---
I would feel perfectly comfortable using that transformer if I were in the position of needing something like that.  If you have any qualms, be sure and buy a transformer with proper approval stamps (UL, etc.)  See Dave's recent video on this topic.


--- Quote ---When I said Where I wouldn't be violating any codes, I was speaking strictly about the NEC, not the modifications (more like additions, from how I read the rules) that my local jurisdiction (Steuben County) can make to the NEC.   Would this violate any of the NEC that all states must follow?   If I cannot get passed that, there's no point going to my local governmental jurisdiction.   As I understand it, they can add to the NEC, but they cannot remove stuff from the NEC.   So if it fails the NEC right  now, no matter where I live in the USA, no local governmental jurisdiction can modify the NEC in such a way where it'd pass.

--- End quote ---
That is why getting a plan from a licenced professional engineer will help you do something that is legal.

You won't find big industral transformers like that with "IP" ratings.  They are designed for harsh, outdoor conditions.  They are not designed to be impervious to water, they are designed to operate with rain-water washing through them.  I can't imagine that there is any condition in your basement that would exceed what they would face every day outdoors. Of course, this assumes proper installation where the outer case is very well bonded go a good earth ground.  Because the transformer is completely enclosed in a ground steel case, it should be safe from animals and children.


--- Quote ---Finally, is 7.5KVA the correct rating for this unit? 
--- End quote ---
Dunno?  What is the power rating of the (unidentified) loads NOW?  What are your expansion plans?  If you are already starting out with 5KW load, then perhaps it might be wiser to get a 10KVA (or 15KVA) transformer.

 Of course, this also begs the question how much power do you have coming into your house from the electric utility?  Typical domestic service that I have seen is 240V @ 200A which is 48KVA (minus what the rest of your house uses).  Do you have/need air-conditioning for all this?  Remember that when it comes down to it, a computer is just a really expensive heater.  If your computer uses 1000W, then you need enough air conditioning for a 1000W heat source.  So a rule of thumb is to plan on enough power to keep everything cool as well as powering it.
Richard Crowley:

--- Quote from: Spork Schivago on May 16, 2018, 01:11:58 am ---Also, that transformer lists the input as 240,480VAC.   It also lists it as single phase.   240x480 on the primary, 120x240 on the secondary.   With it being one phase, wouldn't that put us in the same predicament that we're in now?   Or am I misunderstanding something here?
--- End quote ---
That is a single-phase transformer.  There is only one core.  Than makes it single phase.  All the input (primary) and output ( secondary) wires are isolated from ground so that you can connect it whichever way you need.  You can connect the primary to anything from 216 to 504 volts.  And you can wire the secondary for either 120V or 240V.


--- Quote ---So I'd connect the primary lines to H1-H3 and H2-H4, then I'd connect the secondary lines to X1 - X4?
--- End quote ---
No, you will blow up the transformer and burn down your house if you do that.

You need a straight-across, 1:1 transformer from your 240V "split-phase" source to a 240V, ground-referenced single-phase output.

The table shows that for 240V input, one side goes to H1 and H7 connected together, and the other side goes to H10 and H4 connected together
And the table shows the for 240V output it comes from X1 and X4, with X2 and X3 connected together.

If you connect X1 to ground, then X1 becomes "Neutral" and X4 is the source of your ground-referenced 240V SINGLE PHASE.

Please note that I am NOT a professional electrician, and I am not a licensed practicing engineer.  You should seek competent advice from a professional licensed in your jurisdiction.  High-power engineering advice, like legal advice is never completely reliable from a stranger on the internet.  Just common sense.
Gregg:

--- Quote from: Spork Schivago on May 16, 2018, 12:02:20 am ---I cannot use the P9S13A's.   That's 208VAC outlets.   I need 220VAC+.

--- End quote ---
The HPE P9S13A shows on page 8 of the HPE G2 Switched Power Distribution Units.PDF as having input of 1-ph 200-240V 24 amps with L6-30P plug on the cord.  It has the same footprint, the same outputs as the P9S16A.  The two are probably exactly the same except for input cable, plug and internal breakers. 
There is zero chance that the P9S13A can magically reduce the input voltage of 240 down to 208 volts.
The HPE website is anything but user friendly and seems like it is a product of marketing with almost total disregard for engineering; in other words, business as usual.  The places that state it is 200-208V are most likely cut and paste errors by the person that made the document. :-//
Richard Crowley:

--- Quote from: Gregg on May 16, 2018, 02:18:00 am ---The places that state it is 200-208V are most likely cut and paste errors by the person that made the document.
--- End quote ---
208V is a very common mains voltage in 3-phase power distribution.  As is 277V. 
They seem odd to us who mainly see single-phase utility power.
C:
With
P9S16A
HPE G2 Swtd 7.3kVA/60309 2U INTL PDU

In the USA in a house, I see one of three things happing.

1. You burn your house down and insurance will not cover loss.
2. You get someone hurt, probably criminal charges.
3. You destroy some equipment.

HP lists four major categories of models

220-240V Input, Single Phase, International
Not a standard in USA.

200-208V Input, Single Phase, North America/Japan
Is using one phase of a three phase power source. Only industrial not in a house.

100-240V Input, Single Phase, Worldwide

This only matches the 110-120 used in USA.
And
HP makes a model for this
100-120V Input, Single Phase, North America/Japan

USA's 220-240Volt house standard does not match any of above.
As has been stated many times it is split phase with two hots and a common or center tap.

So the outlets of P9S16A with a transformer will still be non-standard in the USA and that will probably get someone/thing hurt!

C





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