# Upconvert 110 or 220VAC to 500VAC

Discussion in 'The Projects Forum' started by TechSully, Jan 30, 2015.

1. ### TechSully Thread Starter New Member

Jan 30, 2015
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I can't figure this out! Question: How to get 110/220VAC to 500VAC at 2.6Amps?

I am working on a (theoretical) project and have searched Google, eBay and the web in general for a way to upconvert (if that is the correct term) 110/220VAC to 500VAC at 2.6Amps. The reason is to send the 500VAC over light gauge wire and upconvert on the distant end.

The distant end: I would like to get 24VDC @ 40A and get it there with light gauge wire.

Siemens has a device that can accept 3AC 400V - 500V and down it and phase it to 24VDC at 40Amps. I would prefer not to go 3 phase for this project, but will if need be.

Last edited: Jan 30, 2015
2. ### #12 Expert

Nov 30, 2010
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What you need is some transformers...expensive transformers. Hint: You don't have to use all 3 phases of a 3 phase transformer, but the primary current will be limited to the current it was designed for if you were using all 3 phases.

My first thought was, "Hammond". They make audio transformers and power supply transformers for old vacuum tube amplifiers. Lots of voltage in there, but a kilowatt size is not a likely audio product. Expensive, too.

3. ### TechSully Thread Starter New Member

Jan 30, 2015
12
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Thanks!!! "Hammond transformers" searches are turning up some interesting results.

Stupid question... I know the source voltage goes to the primary windings and the load to the secondary, but can it function in reverse??? If I apply 110/220 to the secondary inputs of a transformer, can I use the 480V voltage on the primary for the load?
I am looking at a transformer that has 600V primary 3KVA 120/240V Secondary.

EDIT: Reviewing Transformer Basics, the answer in No!
"The primary winding of the transformer is connected to the AC power source which must be sinusoidal in nature, while the secondary winding supplies power to the load."

Last edited: Jan 30, 2015
4. ### #12 Expert

Nov 30, 2010
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Yes, you can run a transformer backwards. Just be careful to calculate the maximum current it was designed for in the secondary winding so you don't overheat it.

planeguy67 likes this.

Jan 15, 2015
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I agree with #12 as to using a transformer. Hammond, Acme and a host of others make them. Rather than think about 500 Volts I would consider 480 volts in the interest of keeping things simple. Transformers are rated in KVA To calculate kVA when volts and amperes are known: KVA = Volts x Amps (load) / 1,000. Since you mention 500 Volts and 2.6 Amps we get 500 x 2.6 = 1.3 KVA. Hold that thought. This is a good read on the subject from our friends at Hammond. Transformers really don't care which way things are going, not for what you want to do anyway. Transformers also come in steps, for example the KVA ratings:

You are, based on your numbers, looking at a 1.5 KVA transformer and given a choice I would go with a 3.0 KVA transformer. Yes, and per #12 expensive transformers. Typically 1.5 KVA will be in the \$200 range and 3.0 KVA in the \$325 range from suppliers like McMaster Carr Supply or any electrical supply company. You take the 240 VAC and step it up to 480 VAC, run your lines, then step it down or use the Siemens supply you mentioned running on 480 VAC. Going from 240 VAC to 480 VAC is only going to half the current carrying capability you need. Read the link and heed what #12 mentions:

Ron

Jul 18, 2013
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Where did you obtain that from? I have used transformers reverse connected in a pinch, on some larger Kva types they have a 'compensated' winding so when used in reverse you may not get quit the same ratio.
https://www.geindustrial.com/sites/geis/files/gallery/XformerWhitepaper2.pdf
Max.

Last edited: Jan 30, 2015
7. ### TechSully Thread Starter New Member

Jan 30, 2015
12
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I interpreted it as No because in several sources I did not read where it could be used in both directions, complete ignorance and bad assumption on my part. Electrically, it seemed possible. It is good to know transformers can be used in a reverse direction although the ratio may not be the same.

8. ### TechSully Thread Starter New Member

Jan 30, 2015
12
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Thanks Guys! Will do.

9. ### tcmtech Well-Known Member

Nov 4, 2013
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If things do not have to be electrically isolated from one stage to the other you can also set up a common commercial power transformer in a autotransformer configuration and get by with less transformer VA rating.

Using an off the shelf second hand set of 115/230:230/460 transformers with the primaries and secondaries in series to get 600 volts would get you more than enough voltage while only needing around 1 KVA of transformer to carry the load on the cheap.

I rarely pay more than \$25 - \$30 for used 1 -1.5 KVA transformers.

Jan 30, 2015
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11. ### Kermit2 AAC Fanatic!

Feb 5, 2010
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microwave oven transformers.
large enough to handle high power. output high voltage. higher than 600 volts.
use two of them. one to send hi voltage and the second one to step the voltage back down to 120.

12. ### tcmtech Well-Known Member

Nov 4, 2013
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At somewhere around \$650 - \$700 for the step down device I would be looking at other far cheaper options if all you need is 24 VDC at ~40 amps.

What are you powering and how far away from the main power source are you?
Us knowing that will help refine the start to finish process considerably.

13. ### #12 Expert

Nov 30, 2010
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Yes. At these prices, you could buy a really long wire.
240V at 4 or 5 amps will run on standard house wiring, 14-2-g with a 15 amp circuit breaker.

14. ### TechSully Thread Starter New Member

Jan 30, 2015
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I would like to power equipment that is lifted by ballon, blimp or UAS. The weight of the power supply and feed line needs to be kept to a minimum. 500 to 1000 feet of 22/2 or 22/3 is a lot lighter than 14 gauge
I should have described this earlier, my apologies.

Added... the ground equipment can be heavy/bulky.

#12 likes this.
15. ### TechSully Thread Starter New Member

Jan 30, 2015
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Currently I have and will be testing this afternoon a 220VAC power supply weighing in at a whopping 2.2lbs. This is nice, but I know at higher voltages it can be done better, reducing my feedline size (weight). My feedline is 16/2 @ 135' in length and I will be taking amp and temp readings while testing.

16. ### tcmtech Well-Known Member

Nov 4, 2013
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Do you need the 40 amps continuously?

If it was me I would be tempted to run the power up as a higher voltage DC and do the step down with an off the shelf SMPS or two to get the 24 volts and 40 amps output.

Taking regular 240 VAC and rectifying it will give you roughly 340 VDC and 1000 feet of 22 ga wire has about 18 ohms of resistance.
Given approximate line losses and power supply efficiency you would be sending about 3.4 amps through the wire which it could handle well enough given the open air and long distance.
The down side is initially you would need to add about 60 more volts to the power end to get past the line losses but thats not hard to make up for by adding a small 120/240:24/48 ~250 VA buck boost autotransformer to raise the input voltage a bit more before rectification and filtering.

17. ### TechSully Thread Starter New Member

Jan 30, 2015
12
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~30A continuous at this point. 40A is the goal to accommodate expansion.

I had not considered letting the line do the voltage drop for me... that is well worth testing. I had done the loss calculations if using DC and swung to AC quickly, maybe too quickly. Thanks again TCMTech!

Jan 15, 2015
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Then power everything using 400 Hz. power.

Seriously, you have one heck of a challenge.

Ron

19. ### TechSully Thread Starter New Member

Jan 30, 2015
12
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Yep! There aren't many challenges I've walked away from. I had enough of 400 Hz on the heavies in the Air Force.