Wild leg on RPC is 230 V... TO GROUND!!!

My wild leg to ground is 216 (I just checked it) Other legs to ground are 125 volts. leg to leg (Today) are 250-249-251

non-generated

I get ~195 vac to ground on mine loaded, I haven't checked no-load in a while.

I guess the moral to this story is

1. Don't use yer rotary to power a standard 3 ph circuit breaker panel and
2. If you do, don't use any single pole breakers!!!

Man, 'tis a mine field out there...

---------------------------- Mr. P.V.'d formerly Droll Troll

Absolutely no problem whatsoever, thats exactly how we run all of our 3 phase stuff.

Correct in that's not advisable, as you generally don't have any neutral buss in a 3ph panel--that's a ground buss in there and it should only be treated as such.

Our wild leg is 230. We buck it down to 208 on our machines with a buck/boost transformer on each machine.

We had a new machine rigged in last Friday and as the electricians were running conduit I realized I forgot to order a transformer for the machine. Service guys were coming in on Monday from Long Island to do the install. Luckily McMaster Carr had the correct transformers in stock available for Saturday delivery.

DanL

I never knew so many areas of ths country do not have 3 phase power. But, come on, Yonkers must!

Will

I ran a rotary for 16 years, powering all manual machines. The generated leg is alway "hot" to ground or neutral for that matter. I put the output of my convertor to a three phase panel, how else do you put overload protection on each feed?

To follow the NEC code you need to put the hot leg on the middle, Phase "b", and mark it orange, either with tape or orange wire.

My new three phase power is a 240/120 open delta, AKA only two transformers out on the pole, this still gives me a "hot" or "wild" leg. Still no problem, just make sure no 120 volt loads are on that wild leg. Check each machine so you know where it gets it's control power from and where all the lights are wired into.

remove 333 to email reply. Thanks, Randy

But not all sections/zones. Some of the drug operations here are pretty power-intensive, so I think if the drug dealers lobbied a little, we'd have more 3-ph in more areas. I'll have to talk to them, mebbe organize them.

---------------------------- Mr. P.V.'d formerly Droll Troll

A panel certainly makes sense to me, and that's how I in fact did it. I was just thinking that the risk of a single pole breaker on that leg was sort of an NEC no-no. I guess it's Installer Beware.

I had previously installed a 220 panel right next to the 3 phase panel, for dedicated use, unwittingly. When I re-did the shop, I thought the 220V panel was redundant, and removed it. Now I see it wasn't a bad idea.

Oh, and over here, 3ph, at least mine, has a neutral bar.

Funny, in all the prep'n for my shop, fadal, etc., all the talk, all the websites, all the rpc how-to's, etc., I "heard about" where to put the wild leg, that it was a ""good idea"" not to run controls off it, blah blah, but really "laissez faire/do-whachoo-wanna-do hedging-style", and I thought it was just cuz the wild leg wasn't as regulated as the other legs, ergo, "wild", but no big problem, per se.

But no one said, Dude, the fukn wild leg is *230 full-assed volts to ground*!!!!!!!! That, to me, takes a whole lot of *precedence* over a lot of other waffle-y issues!! Or, as I would put it, you'll PV yer equipment (and yerself, or yer employer) placing the wild leg indiscriminately--no hedging about it!

Anyway, ahm goin to my favorite place, Home Despot, for day-glo orange paint.

---------------------------- Mr. P.V.'d formerly Droll Troll

Two 120v legs and one leg at 240v isn't three phase? My understanding was that it was the difference between a wye and delta configuration.

DanL

Izzat the diff? One config has three equal voltage legs (120), and the other config two-120s and one 240?? Goodgawd...

I remember doing the effing trig years back, and back then, three 120V legs (to ground) at 120 deg phase angle gave you 208 V leg-to-leg. Almost exactly.

This is, in fact, what NYC has, pretty much throughout all 5 boroughs, but which seems to be rare elsewhere. You go, NYC!! You is mathematically correck!!

I understood the origins of this be right from the generator: The very geometry of the giganto rotors/stators in the generator put out three sine wave (AC) voltages, at 120 deg phase angle. Done-- no deltas, wyes, transformers, no finagling. In NYC.

What's goin on elsewhere is absolutely beyond me...

All I know is, now that ahm in fukn Yonkers, I turn on my rpc, flip on the fadal, 'n' it lites up--now w/o burnin up! Ecclesiastical, sort of... I feel like one of the gorillas in the opening of 2001 Space Odyssey. My Fadal is my fukn obelisk. Now, where's my club?? I hear some drug dealers outside...

---------------------------- Mr. P.V.'d formerly Droll Troll

Oh yeah,

In the 120/120/240 V system:

If the two 120 legs were 180 deg out of phase, you'd get 240 V leg to leg. OK. But now, at what phase angle is the 240 leg? Seems to me it would have to be 90 deg, w/ either 120 V leg.

What, then, is the leg to leg diff. between either 120 and the 240? Just using right angles, the diff. appears to be a little under 270 V.

Don't know if this type calc is equiv to the real trig. analysis, but I done long since fergot how to do dat.

But at the least, one can say w/ some certainty that a 120/120/240 leg system is NOT equi-angular, phase-wise.

FWIW. Which could be a lot, if wave symmetry were important.

---------------------------- Mr. P.V.'d formerly Droll Troll

I replied before, but the post got eaten apparently. Look at the three phase power as three legs 120 degrees apart, That is what they are. Period. Now,...... The nuetral could be anywhere...

Let us try the geometric example to visualise this. The three legs forn an equilateral triangle. You could get those three legs from three transformers, say arranged in the triangle. That would be Delta power. Draw the triangle. Do it. This has gone on way too long... The neutral could be balanced in the center of the triangle, but it doesn't have to be. If you were in charge of the world, you call one of the legs neutral if you wanted to. But don't do that. If you had three transformers in the delta (triangle) configuration, you could take the center tap of one of thos transfomers as the neutral. Draw it out.... Now, each transformer has 240 volts output. So from any leg to any other leg, is a 240 volt transformer, and sure enough you measure 240 volts from any leg to any other leg. Now put the neutral in center tap of one of those transformers. Sure enough, either of those two legs now measure 120 volt to neutral. They better, they are on either side of the center tap, and the center tap has been to be nuetral. They are 180 degrees out of phase with each other, and provide 120 volts to neutral, and 240 volts across each other. They are also 120 degrees form the center of the triangle, but that is where neutral is connected in this type of system. But the other leg is now a "wild leg" it is 208 volts from nuetral to the "wild leg" Draw it out, it is now simple trig to see this is so, and why. This sytem is called a corner grounded Delta system. It is handy when you have a bunch of 120 volt loads, and some three phase loads. If a motor connects to the three legs, and does not connect any of it's windings to the "neutral" it will never know or care where the neutral is in relationship to the normal or wild leg. So, you get 120 volts, when you need it, and three phase for motors or transformers when you need it. All of the 120 single phase loads are connected to the same phase input. This is also neat that you can get by with only two transformers on the pole. A big one for the phase that provides 120/240 volts, and smaller one for the "wild leg" just for the three phase loads. Did you draw the triangle? erase one of the transformers that feed the 'wild leg" See how it all still works? In rural areas, many times there are only two of the three phases on the poles, to save money, and many miles of wire for the third wire. Most of that equipment will have a 240 volt to 120 transfomer in it, so you never connect the "wild leg to a 120 volt via "neutral". The input of the transformer always sees 240 volts even if it is connected to the wild leg.

The RPC basicaly provides corner grounded delta, or close enough to it. The first two legs are single phase, and come from the single phase power panel. The third phase is generated locally and not as stable as the single phase input.

SO WITH AN RPC, MAKE SURE THAT NO SINGLE PHASE LOADS, TRANSFORMERS ETC, HAVE ANY CONECTION TO THE WILD LEG. GET THE SCHEMATICS AND MAKE SURE! THE GENERATED WILD LEG IS ONLY THERE FOR THE THREE PHASE LOADS. THESE LOAD DO NOT USE THE NEUTRAL, SO DO NOT CARE WHERE THE NEUTRAL IS REFERENCED TO.

Is this assertive anough for you now?

Another system in common use is the WYE system, Draw the triangle again. this time all the transformers feeding have 120 volt outputs, and connect in a center point. The "neutral" in this system is really balanced in the center, and all legs read 120 volts to neutral, However, the leg to leg voltage is 208 volts. Now any leg can provide

120 volts for a load, It is possible to balance the 120 volt loads across all the three phases. You need all three transformers, and all three wires out in the country.

Three phase 480 volts has a WYE connection, and the transfomers are 277 volt output. Any leg is 277 volts to neutral, and 480 volts leg to leg.

Draw it out!!!!!

All these same questions over and over, waste the time of those who are trying to help. Once you draw it out, it is much easier to understand.

There are a lot's of other possible systems, but the principles are the same.

Pete

Dammm....

Haven't read all of it yet, but I feel like I owe you some tuition, or sumpn... :)

Weeelllll. I don't know how they do it in the rest of the country, but here in the Big Apple we have three approximately 120v legs ( depends on the brown out condition at the moment ) out of phase with each other. So the difference between any two 120v legs is 208v. Take any leg and use it with a neutral and you have 120v.

I just checked and with my Radio Shack volt/ohm meter, I have 124 volt legs and 212 volts between legs. All three combinations on legs have the same 212v. Guess my meter's calibration is off, but you get the picture.

Will

From what you're describing it sounds like you have a WYE configuration?

Admittedly I haven't put a meter on our incoming power but my understanding from our electrician was that we had two legs that were 120v to neutral and the third leg was 240v to neutral. I was told this was a Delta configuration.

Kinda like this:

DanL