# Converting from single phase 120V to three phase 480V?

Discussion in 'General Electronics Chat' started by Liv Tanguileg, Jun 26, 2015.

1. ### Liv Tanguileg Thread Starter New Member

Jun 24, 2015
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0
Hello,

I am trying to use an electric heater that is 480V/3phase/30.1 A/25kW but unfortunately I am dealing with a good ol' 120V single phase outlet in my lab. I understand that I could get a three phase unit (lack of a better term) installed but I'd rather purchase equipment that could help me with this task since it will be temporary.

I looked at step up transformers but I don't think those will be able to convert my single phase power to three phase.

I have a general background in EE but I can't seem to put together the pieces to solve this problem. If you could point me in the right direction, I would really appreciate any help!

Thanks!!!

Jul 18, 2013
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You have a background in EE then presumably you would realize the current you would require to operate the 25kw load on 120v?
In any case it would not be step up but step down.!!
What is the capacity or your present supply?
Max.

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3. ### #12 Expert

Nov 30, 2010
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Let's start with some basic math. 25KW of 120 volts is over 200 amps. I have never seen a residence with that kind of power available. Where are you and what quality of power is already available in that building?

and Max got here first with basically the same question.

Jan 15, 2015
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I don't see this working and here is why. There are motor generators to get from single to poly phase as well as inverters. However look at your demand of roughly 25 KW. At 120 VAC you would need in excess of 200 amp service, about 208 amps before we even consider the inefficiencies of whatever you use. 120 VAC 225 amp service isn't found every day.
Most 480 VAC heating elements I have worked with consisted of a pair of 240 VAC elements in series. Unfortunately if there is a way to do what you want to do I do not see it. If this is an industrial setting you had better start looking for 480 3 phase service.

Ron

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5. ### Hypatia's Protege Distinguished Member

Mar 1, 2015
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For reasons stated on other posts the OP's cause is, indeed, a lost one... --- That said, single-phase to three phase 'conversion' may be (somewhat inefficiently) accomplished via employment of a three phase induction motor as a 'transformer', as it were
Well I recall implementing such a scheme via a (1950's era) 60HP 'lift motor' let me tell ya -- it was no 'feather'!!!

Best regards
HP

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6. ### WBahn Moderator

Mar 31, 2012
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If this is just a resistive electric heater and IF (huge IF in this case) your electrical service could provide the power (the 200+A), then you might tear into the units and put the six units (probably three sets of 240 VAC elements total) in parallel and then power them from your 240 V service (which I assume you have available). That's still 100 A, though.

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7. ### Liv Tanguileg Thread Starter New Member

Jun 24, 2015
2
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I wasn't paying attention to the kW, thank you for pointing out that ridiculous number. Something I have to work on is looking at the big picture. I am going to have to revisit the specs on this electric heater and maybe consider a different one all together.

Thank you for info as well! Once I have articulated a question with more (correct) details I will return.

Jan 15, 2015
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When it comes to heating elements the engineering staff at Watlow is great. They not only are helpful but will help you make a heating element for a custom application. I used them several times for custom manufactured heating elements. If you have a custom project or application you may want to contact them. Additionally their engineering tools found in the link can be very useful.

Ron

9. ### ian field Distinguished Member

Oct 27, 2012
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In the UK, a common size for electric room heaters when we had really cold winters, was 3kW. So if you say 8 of those takes you up to 24kW - just exactly how big is your lab?!!!

10. ### #12 Expert

Nov 30, 2010
16,704
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I get the impression that a pack of hunting dogs just saw a typo and ran into the woods barking for all they are worth.

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11. ### ian field Distinguished Member

Oct 27, 2012
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They'd be rather crispy hunting dogs at that sort of heating power.

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Jul 18, 2013
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Hot dog anyone??
Max.

13. ### ian field Distinguished Member

Oct 27, 2012
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It was probably Elektor that did a piece on cooking hot dog sausages directly with mains current.

Some sort of contraption with a row of nails at each end wired up. Throw the switch and get sausages with bolts through their necks.

14. ### shortbus AAC Fanatic!

Sep 30, 2009
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You could buy them at most stores here in the States. Late 1970's -1980's. Pretty popular at the time.

Jan 15, 2015
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During the 1950s a gentleman named John T Frye wrote for the magazine Popular Electronics and did stories about Carl and Jerry. My dad subscribed to PE Magazine and every month I waited for the next story. Cooking hot dogs with nails is nothing new and there was a story about doing so in the February 1959 Issue, here is the story.

http://www.copperwood.com/Carl_and_Jerry-V10N02-Dog_Teaches_Boy.pdf

I cooked my share of dogs using mains here in the US. As to hot dogs? I have been into Boar's Head all beef casing type lately. A good hot dog should "snap" when you bite into it and a good hot dog does not contain pices and parts of chickens or turkeys. Catchup or Ketchup should never be used anymore than using mustard on a hamburger. Mustard on hot dogs and Ketchup on burgers plus any additional condiments.

Also, for those who read the story there is a very strong underlying safety message the boys convey. Also interesting is in 1959 here in the US polarized AC line plugs were not in use and 3 wire grounded outlets & plugs were not yet in use. Thus the reference to a 50/50 gamble on AC hot.

Ron

Last edited: Jun 27, 2015
16. ### #12 Expert

Nov 30, 2010
16,704
7,354
The locals seem so distractable today!
Not enough demand from the visitors to keep us busy.

Just a note, threads are going, "Off Topic a lot today.
and don't try to stop me putting mustard on my burger.

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17. ### WBahn Moderator

Mar 31, 2012
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Sounds good!

In the meantime we'll probably keep meandering around talking about frying dogs by shoving live wires into both ends.

But we'll be here when you get back to us.

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18. ### BReeves Member

Nov 24, 2012
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How did we ever live through the 50's and 60's most everything was a hazard to our well being.

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19. ### #12 Expert

Nov 30, 2010
16,704
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Our parents were allowed to spank us for playing with matches.
Now, they aren't, and our government is trying to pass enough laws to substitute for our real parents.
(I wonder if it will work.)

20. ### WBahn Moderator

Mar 31, 2012
18,088
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Increasingly I miss the 70's (and increasingly appreciate the freedoms that people enjoyed in the 50's and 60's). We had firecrackers -- BIG firecrackers. We made pipe bombs using black powder. We explored storm drainage tunnels. We went plinking in the fields with our BB guns and pellet guns. We were true miscreants. Hell, we even rode bikes without helmets!

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