Dynasty 350 on a 20 HP American Rotary Phase Convertor

[Don52]

Recently I purchased a lathe and a vertical saw that require three phase power. I got a quote of $10k from the power company to run three phase power 1/5 of a mile to my house. Because of the high cost, I am considering purchasing an American Rotary 20 HP rotary phase convertor with a digital control to power these machines. In the future I'd like to purchase a water cooled Dynasty 350 welder. Once I purchase the rotary phase convertor for my other machines, I was thinking that I would be able to run the future Dynasty 350 on it on three phase power to improve the duty cycle from 10 to 30%. Attached is a link to the rotary phase convertor in question:

http://www.americanrotary.com/20-HP-rotary-phase-converters.html

You will notice that the ±5% voltage balance can be achieved with this phase converter up to 32 amps, which is the input requirement for the Dynasty 350.

• Will this combination improve the duty cycle of the Dynasty to ~30%?
• Has anyone used the Dynasty 350 with a rotary phase converter?
• Is there anything else I should be aware of for this application?

(I did a search on this topic but couldn't find specific answers to the questions.)

[shovelon]

Interesting idea. But it is not the duty cycle that will improve, but the power output.

I do think your are going to suffer a loss in efficiency, as the 3 phase converters are a bit power hungry. But if it delivers the 300amps you may need to do a job, it would be worth it.

Maybe you could have a single phase outlet as well as the 3 phase outlet when you need the increased power.

What the heck, you are using the converter anyway.

Let us know how it goes. I have 3 Dynasty 350s and they are fantastic.

[cruizer]

Lots of horror storys on this one, usually a blown up $$ machine. Best to rethink your plans to a digital phase converter if you intend on running your high dollar Dynasty on 3 phase.

[Broccoli1]

Interesting idea. But it is not the duty cycle that will improve, but the power output.

I do think your are going to suffer a loss in efficiency, as the 3 phase converters are a bit power hungry. But if it delivers the 300amps you may need to do a job, it would be worth it.

Maybe you could have a single phase outlet as well as the 3 phase outlet when you need the increased power.

What the heck, you are using the converter anyway.

Let us know how it goes. I have 3 Dynasty 350s and they are fantastic.

The Power out put is the same on Single and 3-phase power-

it IS the duty cycle that changes.

http://www.millerwelds.com/pdf/spec_sheets/AD5-0.pdf

[cruizer]

It's not so much the rotary converter it's the unstable, unbalanced and out of synch voltage comming off it as the welder is loaded, you drop the wrong phase and bad $$ things will happen to the Dynasty as well as transformer machines, where you'll bake a coil. Running a mill or motor at a single speed is great on a converter but not so much on a varied load welder.

The digital converters while high priced don't appear to loose that signal

[shovelon]

The Power out put is the same on Single and 3-phase power-

it IS the duty cycle that changes.

http://www.millerwelds.com/pdf/spec_sheets/AD5-0.pdf

This is what the product description entails;

"Input Power
* 208-575 V, 3- or 1-Phase Power

Rated Output
* 3-Phase: 300 A at 32 V, 60% Duty Cycle
Single-Phase: 225 A at 29 V, 60% Duty Cycle

Welding Amperage Range
* 5 - 350 Amps

Net Weight
* 135.5 lb (61 kg)
* 268.5 lb (122 kg), with TIGRunner®"

I take that to say that 3 phase will give me 300 amps, while the single phase gives me 225 amps. Both @ 60% Duty Cycle. This is in conflict with the spec sheet, but makes sense to me. http://www.millerwelds.com/products/tig/dynasty_350/

[Lund Machine Works]

I would recommend forgetting the rotary phase converter and look into a Variable Frequency Drive (VFD). It will give you variable speed on your machine tools.

To the best of my knowledge converting to 3 phase from single, no matter how you do it will not work for a welder.

[Broccoli1]

This is what the product description entails;

"Input Power
* 208-575 V, 3- or 1-Phase Power

Rated Output
* 3-Phase: 300 A at 32 V, 60% Duty Cycle
Single-Phase: 225 A at 29 V, 60% Duty Cycle

Welding Amperage Range
* 5 - 350 Amps

Net Weight
* 135.5 lb (61 kg)
* 268.5 lb (122 kg), with TIGRunner®"

I take that to say that 3 phase will give me 300 amps, while the single phase gives me 225 amps. Both @ 60% Duty Cycle. This is in conflict with the spec sheet, but makes sense to me. http://www.millerwelds.com/products/tig/dynasty_350/

That is RATED output.

Total Welding Amperage output is 350amps
Single or 3 Phase

[shovelon]

That is RATED output.

Total Welding Amperage output is 350amps
Single or 3 Phase

Ok, I see that now.

[Pass-N-Gas]

Need more input..

Will your current electrical service meet your future needs?

What is you avg. monthly electrical bill? (might pay off over the long run to pay the 10K) the base rate is higher on 3 phase yet you get more KW's / mo.

My 20HP A/C, 350P and 1250 are on 3 phase my electric bill is cheap..

How many of what HP motors are three phase? Check into some single phase motors(new or used) to replace them.. or possibly having the current ones rewound to a single phase configuration..

The future Dynasty 350 will probably due just fine on single phase..

Run some numbers (for 5-10 yrs) on all of the variables.. Keep in mind the 3 phase service would add value to the property.

[jake]

Rotatory phase converters have a hard time keeping the frequency where it is supposed to be and with the frequency variations the total harmonic distortion becomes a problem. Solid state phase converters I do not think would be a solution either, with the solid state converters they do not have a smooth sine wave like a rotatory can produce, a large enough rotatory can keep up with the loads without sagging much but with the electronics inside I would not think it would be a good idea. You would be better off with a 3 phase generator to power the equipment. Also Variable frequency drives do not like running off a phase converter

A variable frequency drive will not solve the problem of having a single phase source to drive the 3 phase equipment.

[Don52]

Thank you for all of the responses I really appreciate the time you all took to respond.

Lots of horror storys on this one, usually a blown up $$ machine. Best to rethink your plans to a digital phase converter if you intend on running your high dollar Dynasty on 3 phase.

It's not so much the rotary converter it's the unstable, unbalanced and out of synch voltage comming off it as the welder is loaded, you drop the wrong phase and bad $$ things will happen to the Dynasty as well as transformer machines, where you'll bake a coil. Running a mill or motor at a single speed is great on a converter but not so much on a varied load welder.

The digital converters while high priced don't appear to loose that signal

In addition to the American Rotary digital controlled rotary phase convertor which runs $1255.5, I am also considering the Phase Perfect PT300 digital phase convertor which runs $2875.

The PT300 has a continuous three phase rating of 35 amps. It has a 4 second rating of 150 amps. Do you think that this would be adequate to power the Dynasty 350?

http://www.phaseperfect.com/files/pt330specs.pdf

I would recommend forgetting the rotary phase converter and look into a Variable Frequency Drive (VFD). It will give you variable speed on your machine tools.

I have a VFD on my Bridgeport milling machine and I love it. In this case I was investigating the possibility of using one convertor for my two new three phase machines as well as the future machines such as the Dynasty 350. The lathe is a Clausing/Coldchester 15" with lots of speeds. The Saw is a DoAll with two ranges of continuous speed control, so the variable speed feature of the VFD is nice to have rather than required for these machines.

Will your current electrical service meet your future needs?

I currently have a 100 amps of disconnected power going to a 200 amp distribution panel in the garage. This is adequate for now. I plan on upgrading main service and garage disconnect to 200 amps when I get the Dynasty 350 and a 5 HP air compressor.

Run some numbers (for 5-10 yrs) on all of the variables.. Keep in mind the 3 phase service would add value to the property.

I am a weekend warrior and it would take forever to pay off the $10 K for the new three phase drop. If the Digital phase converter will work I would rather put the rest of the $10 K towards the Dynasty 350. I agree that three phase would add value to my property, especially for people like us.

Rotatory phase converters have a hard time keeping the frequency where it is supposed to be and with the frequency variations the total harmonic distortion becomes a problem. Solid state phase converters I do not think would be a solution either, with the solid state converters they do not have a smooth sine wave like a rotatory can produce.

The Phase Perfect PT330 claims to have Sinusoidal output with 3% Total Harmonic Distortion with Phase-to-phase Voltage Balance better than 1% (NEMA MG1 Standard for Voltage Unbalance) so I am thinking that it might work. What do you think?

Thanks again for all of the responses.

Don

[Broccoli1]

Don,

KB Fabrications runs a welding business and uses his 350 on Single Phase.

Weekend Warrior... why even bother with messing around with trying to run the 350 on a Phase Converter?

[Country Metals]

I live out in the boonies like a lot of welding companies here in south jersey. I have single phase in my shop and it will stay that way. I have talked to a lot of welding companies that have tried to use a 3 phase converter. IT DOES NOT WORK FOR WELDERS. It DOES work for all other machines like lathes, ironworkers, saws, mills, air compressors, ect. I can give you 4 owners of companies that you can call and they will tell you that first hand. The reason why it does not work is due to the imense constant electricity required for welding. Standard equipment requires a lot on start-up like 8,000 watts then go down to 2,000 watts to stay running. 2,000 watts on 460 3 phase is about 4.5 amps. No problem for a 3 phase converter to change over. For a phase converter to change over 35 amps constantly would blow up the phase converter. Everyone I have talked to say the welders are not harmed but the new phase converters die in about 30 seconds.

Before you purchase a converter, talk to a real rep, not a guy who just needed a job. Ask them for references of where they have sold them and call them up. Best thing to do is find someone who has tried to use it for a welder.

John

[Don52]

I ran your input by Miller Tech support and American Rotary and here is their recommendations.

• Either the rotary phase converter or the solid state type will work to provide three phase power which will improve the duty cycle for the Dynasty 350 welder at 350 amps from 10% to 30%.
• If you use a rotary type you need to upsize it by 40-50%. So to get 32 amps of three phase current @ 240 volts, which the Dynasty 350 requires, you need a 20 HP rotary unit which can put out 53 amps of three phase power @240 volts.
• If you use too small of a rotary type phase converter you could burn it out.
• The digital type such as the Phase Perfect PT-330 doesn't need to be derated. The PT-330 is rated at 30 amps @240 volts of three phase output but it can output 36 amps continuous, with a four second peak of 150 amps, so it would be ok.

Thanks again for your input,
Don