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Gunsmithing 3 phase oven on single phase

STR

Gunny Sergeant
Full Member
Minuteman
Jan 1, 2010
1,414
26
Miami Florida
I'm writting about this as it might help those considering a commercial oven for home use. As most already know, I have shut down my rifle shop, but kept my equipment for hobby work.
One of those tools is my 3 phase oven, which I thought needed to be converted to single phase to use at home. This is per the people who built the oven mind you.

Being in the electrical feild for over 25 years told me they were full of crap. They also went on to say that it could not be run from a three phase converter. Also BS. Before converting the oven, I thought I'd give my three phase converter a chance to run the oven. Hooked it up, turned it on, ran for 5 minutes, and the overload breaker on the motor contactor opened, which also kills the power to the elements. The phase converter just kept on running. I thought the breaker on the converter would trip out first.

I ran the motor by it self, no problem, ran as long as I wanted. So, I hit the on button for the heat, and took an amp reading on each of my three phase converter out put lines and found that one leg was pulling over 40 amps, 30 on another, and 25 on the third one. Looked at the rating plate on my converter, and found it had a max output of 22 amps.

I called the guys at American Rotary Converters where I got my coverter, and asked if I could run my oven using a converter. The answer was as I expected, a big YES. Just had to use the correct size. I didn't feel like spending another $1700.00 right away so I thought I would reduce the load. I removed the element cover and found that I was feeding four seperate elements. I disconected 2 and went for trial run. Now the oven ran great for the 2 1/2 hours at 225 degrees F required to cure Cerakote. The oven pulls 20 amps, 10 amps, 10 amps on the three seperate phases. The oven originaly was built to have a max temp. of 600 degrees F whichI don't need.

The converter is running at full load, but if it burns up, then I can justify a new 15 horse unit. I am and always have been happy with the oven, and it does a lot more than I need, just not happy with the " you bought it, it's your problem now" customer service I got from JC Metal Fabricators. They are a hugh company that builds quality products, so I still don't get it.

Point is, you can run a three phase oven with the correct size three phase converter. Below are some pics of mine. Hope this will help some of you.

DSC_0173-1.jpg


DSC_0172-1.jpg


DSC_0174-1.jpg


DSC_0175-1.jpg
 
Re: 3 phase oven on single phase

Ozzy,

You're right. You'd think the manufacturer of an electrical unit like your oven would know that if you reduced the total connected heat load that the total FLA would also be reduced. Very nice oven BTW, I'm gonna have to come play at your house one day.
 
Re: 3 phase oven on single phase

what is the power factor on your converter? if its anything like a distribution transformer, you can probably overload it a bit. up here, this summer with the heat, we had 25 kva distribution transformers with over 340 amps on them. 25kva/240 volts line to line equals 104 amps at 100% loading. so, at 340 amps, the 25s were loaded to 327%. the secondary off of em burnt up but the fuse for the trans didnt even blow. point being, converters/transformers are pretty tough pieces of equipment. on the converter what is the voltage line to line and also line to ground?
 
Re: 3 phase oven on single phase

Are you a lineman? Sounds like it. You are correct, they are made to be overloaded, TXs that is. Most of our over head pots at FPL are overloaded, and they work fine. I didnt look at the PF, but I'm sure it can handle the load no issues. Thanks bro.
 
Re: 3 phase oven on single phase

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 65nut</div><div class="ubbcode-body">we had 25 kva distribution transformers with over 340 amps on them. 25kva/240 volts line to line equals 104 amps at 100% loading. so, at 340 amps, the 25s were loaded to 327%. </div></div>

What over load factor vs T&T are they? The reason I ask is there are many 40Kva cans sold an stamped as 25's when the contract spec's are ink'ed as 25's.
 
Re: 3 phase oven on single phase

not sure what you mean by t&t. over load factor on our stuff is to load to 110% initially allowing for load growth to 140%. We will allow by our "standard practice" up to 180% loading before we go to the next size can or pad mount. we have 10 kva, 25 kva, 50 kva, 100 kva and 167 kva cans. for single phase o.h.
 
Re: 3 phase oven on single phase

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 65nut</div><div class="ubbcode-body">not sure what you mean by t&t. over load factor on our stuff is to load to 110% initially allowing for load growth to 140%. We will allow by our "standard practice" up to 180% loading before we go to the next size can or pad mount. we have 10 kva, 25 kva, 50 kva, 100 kva and 167 kva cans. for single phase o.h. </div></div>

T&T is a industry std for max KW,(not Kva) Time vs Temp. rise.
All electrical wiring an devices have many different ratings ie, Prime vs standby, insulation temp rise over a X ambient ect. current, an peak to peak voltage.