Three Phase To Single Phase

yes yoiu can use a converter or inverter system, but its too expensive for your target.

in fact, you can use a so-called scotte tranformer or T-type transformer to drive your trailer at the 3phs system. boot up the 208v to240v.

you can find the past threads dicussed at the forum.

When I worked at a factory they had their working area rewired and the contractor misread the drawing and only put in 3 phase system so they had to buy several dozen transformers as you describe. The contractor had to pay half the cost.

Almost every 240 volt appliance or motor will function quite well at 208v. The motor labels will generally read 208/240 volts, and the ampacity would read 12/10, meaning 12 amps at 208 or 10 amps at 240 v.

Your 120 volt lines will be more accurately 120 v to neutral, as most single phase is supplied at 115/230 volts. just remember your neutral feeder will be carrying the same amperage as either leg, to make up for the missing leg.

Use it as a 120/208 v 3 wire (+ ground) rather than 4 wire (+ ground) system.

Unless you end out getting billed for power factor, you will do fine.

RichH

NoSciFi said it all.

Just use 2 of phase lines which will give you "1 phase 208 Volts."

The supply company will see it as normal 3 ph.4 wire unbalanced load and bill you on actual energy drawn-unless nosy types come sniffing for" unbalance unauthorized loading"

I agree with NoSciFi. Unless you have to run some very sensitive equipment, (Such as some RF diagnostic equipment for example) you will not need to step up the voltage.

Rich is correct for this installation.

The only thing that I might add would be, use a separate equipment grounding conductor, not the neutral, to protect occupants of the trailer in the event of a ground fault or short circuit within the trailer.

The equipment grounding conductor would originate from a ground lug at the source of the 208 vac and end at the trailer sub feed panel ground lug. That same ground lug should also be bonded to the trailer frame.

Assuming that you are going to feed the 76 amp trailer load with a 100 amp service, the NEC allows you to use a #8 wire, bare or if insulated, taped green at both ends.

Also, as Rich pointed out, the neutral will need to be the same size wire as the main feeders.

Good luck with this project!

Jeff

Try to source for a inverter that can convert 3 phase to single phase. One of the brand name is Delta

Hi...

I think some are reading your problrm in reverse..

I would hire a generator if this requirement is for a short time, if you had time then a transformer would be the way, you may have to have one made.

You do not say the type of load... So I would not recomend an inverter ( we use lots ) if not a transformer then a 3ph motor coupled to a single phase alternator (may get surplus quite cheap ) would be another way, allowing a solution that still not knowing the type of loading.

if for some reason you absolutely have to have 240, just look on ebay .. if this is temporary, or there are several large elec equip resellers ..... for a buck boost setup or just get a 240 to 208 step down and run it in reverse to step up. you will need 125 % of what you want out to feed in ie in a 480 X240 setup @ 30 kva you would feed approx 35A 480v to get 75A 240v but to reverse you would feed 100A 240v to get 35A 480v but i agree w/ previous posts most if not all equip runs just fine on 208v

If I were temporarily hooking up a trailer (1 a/c, lights, fridge, hot h20) I would use the straight 208. After connecting 2 of the three legs (and a neutral/ground) use an accurate meter to read your actual voltage & amperage when each appliance is switched on independantly. As long as the maximum amperage drawn isn't more than 10% over the full load amperage, everything should work well. Be sure to check the nameplate amperages and compare the actual current of each device separately. Turn power off & check for excessive heating of device and wiring. Then, switch everything on at once while observing the actual current - and if within 10% of FLA, you shouldn't smoke anything. (Be sure to check potential to neutral - if 110 or near- OK for lights and such)

PS>>>be sure to use heavy enough wire and fusing or circuit breakers!!!!

It's simple. Get a transformer that converts 3 Ph to single ph. Winding will be simple as the 3 phase Arc Welding transformer. You can try a good Arc WElding transformer is it can give 208 V between work & holder. My ID: kvsubramanyam@hbl.in

WOW!!!

We would love to be re-educated.

Why don't you draw what you said and post.

A transformer can be manufactured to transform from 3 phase to 1 phase. However, due to the pulsating nature of the 1 phase load, the three phase supply will remain unbalanced.

Greg

Polyethylene--I have read all the posts to date and see one question unasked, although various posts have talked around it. You say you have 208V 3-phase power. Is this a 3-wire delta (no neutral) or a 4-wire wye (with neutral). If it is a wye, with neutral present, then the posts are generally good, because most loads are line to neutral, 120v, which you already have. Those loads that are line to line will run at a lower voltage, but are generally OK, as also stated.

If, however, you have a 3-wire delta, then the only safe way to do things is to put in a transformer (which can often be found from surplus houses, as mentioned). It would need to be: 1) single-phase 208v primary and single-phase 120/240v secondary, or 2) three-phase 208v delta primary and 3-phase 120/208v wye secondary. If it is the second of these two options, you would only need to use two of the three phase leads. It may be that you have a wye system with no neutral brought to your panel, but I hope not.

I recommend a transformer because it has a much lower loss than a motor-generator set and is probably more available. Suggestions that you simply find a ground point and use it as the neutral as well as the ground are potentially very dangerous. If it is a delta system, it could be an ungrounded one, or a corner grounded one (one line is attached to ground), or even something less common, such as an impedance grounded system. If you have to use a transformer, make sure that the neutral exists and is grounded, because it is considered a "separately derived system" by the electrical code.

Let us know what you have and what you do. Regards--JMM