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RIGDESIGNER
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Join Date: Nov 2010
Posts: 2

Power Conversion 480VAC 3-Phase to 208VAC & 120VAC Single Phase

11/03/2010 7:47 PM

I have an industrial shop receptacle providing 480VAC 3-phase at 30amps. I want to run this to a rig and convert that power to qty (1) 208-240VAC single phase 15 amp circuit and qty (3) 120VAC single phase 20 amp circuits.

What is the least complex way to do this?

I believe that I can:

1. Run the 480VAC 3-phase to a power distribution unit (PDU) that converts it to 208VAC 3-phase power. Then I can:

2. Run the 208VAC 3-phase into a remote power panel (RPP)/cabinet level power distribution unit (CDU) and produce the qty (3) 120VAC single phase 20 amp circuits and the qty (1) 208VAC single phase 15 amp circuit. I can live with 208VAC vs. 240VAC for the 1 rig circuit.

3. Is this a valid approach?

4. Are there any commercially available PDU's/RPP's that could do this job (from McMaster-Carr maybe)?
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Pathfinder Tags: 120 VAC 240 VAC 480 VAC POWER CONVERSION
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Tornado
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#1

Re: POWER CONVERSION 480VAC 3-P TO 208VAC & 120VAC 1-P

11/03/2010 8:40 PM

Assuming indoor installation, something like this?:

7131K41: 480x208Y/120 transformer, 9000va (but verify first)
6914K33: 6-space circuit breaker box
6782K11: 20A single-pole circuit breakers (3x)
6782K21: 15A double-pole circuit breaker
480/30 plug to match existing receptacle
Grounding rod and lug
Wire etc.

Total ~$1500.

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wareagle
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#2

Re: Power Conversion 480VAC 3-Phase to 208VAC & 120VAC Single Phase

11/03/2010 10:39 PM

Install a 480 volt to 120/240 volt single phase transformer of the proper size for your load. That's all you need.
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Anonymous Poster
#3

Re: Power Conversion 480VAC 3-Phase to 208VAC & 120VAC Single Phase

11/03/2010 10:43 PM

shakin head in amazement
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PWSlack
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#4

Re: Power Conversion 480VAC 3-Phase to 208VAC & 120VAC Single Phase

11/04/2010 5:16 AM

The least complex way is to consult a qualified electrician locally. It is also the safest.

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TonyS
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#5

Re: Power Conversion 480VAC 3-Phase to 208VAC & 120VAC Single Phase

11/04/2010 7:53 AM

I'll agree with PWSlack on this, we have to make to many assumptions to come up with a safe option. A local electrician will have probably come across the same situation and know the answer straight off.

480V seems a strange voltage to me, but then again you Americans are strange, (sorry couldn't resist it).

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JRaef
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#6

Re: Power Conversion 480VAC 3-Phase to 208VAC & 120VAC Single Phase

11/04/2010 9:00 AM

A standard standard off-the-shelf transformer is available that will transform 480V 3 phase to 120/208 3 phase. On the 120/208V side, voltage between any 2 phases or all 3 will be 208V, voltage from any phase to neutral will be 120V. That's how this is done.

People like Siemens, Square-D and Cutler hammer all make pre-packaged units called something like "Mini Power Centers" that will consist of a transformer and small circuit breaker load center all mounted as a single unit. On a 9 kVA power center, the smallest 3 phase unit they make, the maximum size secondary branch breaker is 25A, so no problem for your application. For an example, a Siemens part #3LPC009.

Still a good idea to have this done by a licensed electrician though, there are specifics to wiring and grounding that are too detailed to be dealt with over the internet.

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Anonymous Poster
#10
In reply to #6

Re: Power Conversion 480VAC 3-Phase to 208VAC & 120VAC Single Phase

11/04/2010 6:41 PM

Thanks for the supplier, but single phase load from 3 phase line makes unbalanced arrangement ?
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PWSlack
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#13
In reply to #10

Re: Power Conversion 480VAC 3-Phase to 208VAC & 120VAC Single Phase

11/05/2010 4:05 AM

Yes. So what?

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Anonymous Poster
#11
In reply to #6

Re: Power Conversion 480VAC 3-Phase to 208VAC & 120VAC Single Phase

11/04/2010 7:22 PM

Hi

You mentioned you location is:

Location: "California, USA, where the Godless live next door to God." Is that you mean you equate your self with God ? Just inquiry. Thanks
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Anonymous Poster
#12
In reply to #11

Re: Power Conversion 480VAC 3-Phase to 208VAC & 120VAC Single Phase

11/04/2010 8:33 PM

Definitely ,that is the beginning of the great fall.
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JRaef
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Location: California, USA, where the Godless live next door to God.
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#14
In reply to #11

Re: Power Conversion 480VAC 3-Phase to 208VAC & 120VAC Single Phase

11/06/2010 3:39 PM

Oh brother, I have to explain a joke...

No, it just means this is "God's country". It's a common expression here in the US to say that wherever you live, it's so good that God chooses to live there too. But here in California, many people consider us to be generally wicked and Godless. So my joke was to imply that California is so beautiful that God still lives here even though the place is full of Godless freaks.

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Anonymous Poster
#15
In reply to #14

Re: Power Conversion 480VAC 3-Phase to 208VAC & 120VAC Single Phase

11/06/2010 8:08 PM

Your repentance is acceptable.

God bless you.
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fixitorelse
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Join Date: Aug 2010
Posts: 687
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#7

Re: Power Conversion 480VAC 3-Phase to 208VAC & 120VAC Single Phase

11/04/2010 9:18 AM

If you have to ask this question, you need an electric an period.
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RIGDESIGNER
Participant

Join Date: Nov 2010
Posts: 2
#8

Re: Power Conversion 480VAC 3-Phase to 208VAC & 120VAC Single Phase

11/04/2010 11:57 AM

Much obliged for all the good advise/comments gents!...(Tornado, JRaef and the rest). This is my team's first rig/fixture using 480VAC 3-P shop power as the primary supply and the advice is appreciated. We have used 240VAC and 120VAC 1-P on previous. Our final GSE Assembly Drawing(s) and Schematic(s) do require our Electrical & Safety & Test Engineering functions sign-off...as many have recommended! That is s.o.p. here.

So back to the Pro/E WF4 Salt Mine.

Thank you for this forum CR4.

Mechanical Design Engineer,

Los Angeles, CA

a.k.a RIGDESIGNER
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TonyS
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Location: Resting under the Major Oak
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#9
In reply to #8

Re: Power Conversion 480VAC 3-Phase to 208VAC & 120VAC Single Phase

11/04/2010 12:21 PM

I'm some what aggrieved by this, you're running a company that employs electrical design staff and yet you come on the Internet for "advice". Who are you checking up on? Don't you trust your staff?

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Users who posted comments:

Anonymous Poster (5); fixitorelse (1); JRaef (2); PWSlack (2); RIGDESIGNER (1); TonyS (2); Tornado (1); wareagle (1)

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