3phase

[Taylortractornut]

Does anyone here know of a welding vender or company that produces 3 phase pasma cutters. Last month the power company ran 3 Phase to the shop but it seems i cant get it through my suppliers head that i want a 3 phase machine. Id buy a new or used one if I could. Best reguard Taylor Lambert

 

[chim]

Here's one:

http://www.welders-direct.com/merchant2/merchant.mv?Screen=PROD&Store_Code=WD&Product_Code=1-1252-1

Is there a particular reason you want 3 phase? There appear to be some really hefty cutters running on single phase...............chim

 

[Anonymous Poster]

Miller's larger machines are either 3 phase or single phase, depending on how you connect them up.
A 3 phase machine would pull less amps, thus lowering your demand factor, big bucks when it comes to the electric bill.

 

[Anonymous Poster]

Actually, most of the welders......and this may also include plasma cutters......are only "two leg" power, so they would only use two of the three legs of your three-phase system anyway. My Miller 35 is that way....220 or 440, two leg power.........and obviously if the shop were on 440 it would be three phase. That is probably what is corn-fuzing your welding products supplier. You remember the bullet-head DC welders from the fifties....heck they go back to the shipyards of WWII.......THOSE machines were actually motor-generator sets which required THREE LEGS of three phase power. In that case, it was necessary to have a three-phase shop, either 220V or 440V three phase.

 

[wroughtn_harv]

My Miller Dialarc 250 can be wired up single or three phase. I also have a Miller Spectrum 1000 Plasma cutter that I've never hooked up because it's three phase and I've only got single in my shop, one of these days.........

Your best source for three phase is machinery auctions. You won't be bidding against many folks because few have three phase. Single phase on the other hand is what everyone else wants. So if you do buy new you'd better plan on keeping it.

 

[Taylortractornut]

My main reason for wanting a 3 phase is to keep all the local race car owners i work for from wanting to borrow it, if its a single phase machine they get agravated cause im cautious about who i loan stuff to. When they here its 3 phase they dont ask any more. Plus i like the duty cycleof a larger machine.
I had one a few years ago but i couldnt run it on my converter i built. Id rent a large 3 phase generator to run it. So now the power company needing some good PR ran it to the shop free. But i sold my plasma cutter.
Im only 23 but i worked for a compan when i was 17 in the summer as a machinist and welder they had Migs but when i die broke we welded them with an old Lincoln with the barrel type body Then we had another that was a Lincoln with the upright norrow dome i called it R2D2. The head machinist hated having to drag out all the extension cord to move it to the press room so he mounted a governed 12 horse motor to the top of an upright motor welder to turn the generator. It worked pretty good.
Harv any chance you want to sell your 3 phase plasma cutter. I was gonna buy one from the trailer plant i worked for but they closed the other day and one of the clean up crew rolled it off the storage balcony to avoid having to lower it with a forklift. Thanks for the information fellas my Welders Supply here is a little parts house and the owners never has even attepmted to weld. They think since they dont have 3 phase that i dont so there a bit one sided.

 

[JohnMiller3]

Hi Taylor,

You may want to investigate the “minimum” monthly costs related to having 3-phase brought to your building first… then after it’s established find out the minimum billing cycle your utility company will keep you on it… /w3tcompact/icons/blush.gif /w3tcompact/icons/eyes.gif

Here in NY, we had it in an old factory building my Father had purchased… we couldn’t shake the 3-phase minimum billing for something like 24 months and then the “kw rate” remained high for like 36 months (don’t hold me to the exact periods/rates as this occurred in the early 80’s when electric rates were actually cheaper than today)

This was a legal method for the utility company to gouge the customer, is the best way I can put it… /w3tcompact/icons/sad.gif

If you went 3-phase… it may be cheaper for you to “buy” your buddies their own equipment versus your planned work-around solution… /w3tcompact/icons/shocked.gif

 

[Taylortractornut]

Well i actually own alot of 3 phase equipment, I own a 15 horse lathe with a 30 inch swing, a 6 foot swing 5 Radial arm drill and 5 horse metal plane and a 4 horse Sheetmetal shear. I still have to buy a mill, surface grinder and a Quorn rotary tool grinder. I was using a 3phase converter but they get very hot and is something ese to fail. I do pay 2 dollars a month more service charge. Its hard to find and sometimes convert every thing over to 220, Being alot of machins have special motor casings and seals. Plus most 3 phase machinery is cheaper to buy and operate.

 

[chim]

We have different plasma cutters at work, but the only one I'm familiar with is what we call the "suitcase plasma". I've seen our guys do some serious stainless cutting with that 110v model. Without further exposure to the world of plasma cutters, it seemed to me you'd need to be doing salvage work on an old battleship to need one that required a 3 phase hookup.

I assume there would be some advantage to keeping your load balanced on the electrical service, but not knowing what it takes to run the plasma cutter kinda makes it hard to quantify. The current could be so low that mixed in with your other loads it's inconsequential.

There's also a general misunderstanding over just how much can be gained financially by using 240v vs. 120v or 3 phase vs. single phase to run equipment. There usually is an efficiency gain, but you buy power, not amps. It takes power to run machines. Power is what you pay for, although some utilities penalize you if your power factor is poor. This is the result of inductive loads. Anyhoo, you'll get the same bill for running a 10A load on 120v single phase as you would for a 5A load at 240v single phase.........................chim

 

[Anonymous Poster]

The savings in 3 phase as opposed to single phase come 3 ways.
First, a 5hp 3 phase motor draws less amps per phase, so smaller wires & conduit service the same horsepower.
Second, Amps drawn are divided by 3, this becomes a major consideration if you are paying demand charges.
Third, there is a lot of surplus 3 phase equipment available in the used marketplace.
You can also employ larger motors on 3 phase than you can on single phase.

 

[Anonymous Poster]

And one other thing that might be mentioned Franz, is that there are no pesky starting circuits or capacitors, or switches, or,...or...or... SO MUCH LESS machinery with the squirrel cage induction motors!!! Three-phase IS nice to have, no doubt about it. The modern conversion to 208V three phase for light industrial uses is an attempt to be able to use all three legs for single phase loads such as in hospitals, office buildings, and schools. Some of the early stuff had a "stinger" leg which was high voltage and useless for the 120V circuits. I have got "burnt" a few times buying used equipment that was 240 volts ONLY and just would not run on 208. In large buildings, even the lighting is three-phase with 480V on the power leg. Good way to get killed if you don't know about it.

 

[chim]

Franz, I think we're talking the same language. My question was just how much difference it makes to a Harry Homeowner setup. A real shop / factory would deal in values of a much greater magnitude. Whether a guy with a shop in the barn needs to go 20' with 2# 8's or 3#10's really doesn't matter a whole lot. The 5HP motor in the example would draw roughly 32A on each of two wires or 17A on each of three wires at full load. Power consumption is the same.

I haven't been involved in demand metering to any extent. I have done installations of services with 4000A at 480V three phase though, and all we did was check to insure there weren't any major unbalances between the phases. That never was a problem. You'd almost need to plan to get them unbalanced. I did speak with a couple customers who have load-shedding programs..................chim

 

[Anonymous Poster]

Demand charges can be the budget killer for a lot of small businesses, primarily because people never think about them till the bill arrives. About the best site I've found for an explanation of Demand Charges is http://www.niagaramohawk.com/youracct/aboutbill/elecdemand.html
Depending on the utility, getting rid of unjustified demand charges can be an exercize in brutality as it has been with NyMo.
An interesting reality regarding demand charges, is that utilitys are perfectly willing to sell high demand power to municipalitys without demand charge for resale to muni customers, but won't budge for commercial or industrial customers.
I've been away from Peak Shedding machines for a while, since the cost of diesel went above 85 cents a gallon. That was the rough figure we used back in the early 80s when customers considered cogen systems.

 

[wroughtn_harv]

Thanks for the <A target="_blank" HREF=http://www.niagaramohawk.com/youracct/aboutbill/elecdemand.html>link</A> Franz.

A bud was telling me his father's shop bill was through the roof because of the three phase service. I couldn't understand why. Your link explained it in such a way that even a dummy like me got it. Makes sense, cents too.

 

[JohnMiller3]

<font color=blue>...Demand charges can be the budget killer for a lot of small businesses... Depending on the utility, getting rid of unjustified demand charges can be an exercize in brutality as it has been with NyMo....</font color=blue>

Hi Franz...

Boy, did we ever find out the hard way... once you get on a demand meter... you're stuck!

Owning worthless stock in the utility company, I think would be cheaper... /w3tcompact/icons/blush.gif

 

[Anonymous Poster]

You're not necessarily STUCK, but getting back off the Demand metering is a lot harder than getting on.
I recommend carefully reading your provider's tariffs reletive to Demand metering. Most utilitys routinely violate their own tariffs, after all, they profit from doing so, and SCREW customers who only occasionally meet Demand criteria.
Small businesses often find themselves victims in this game because they regualrly deal with "electricians" who don't offer them all possible alternatives before installing more equipment. A real electrician will be worth his charges because he will show you how to employ things like peak shedding to avoid Demand charges. He also won't do things like run Romex in a commercial situation.
Then again, customers usually get what they pay for, and keep paying for the cheap price forever.