new toy for shop, need 3 phase info please

[KRK Sr.]

Just got a new "toy" for the shop: 3 phase 208 volt, surface grinder. Hanging on the wall for the last 13 years has been a box marked 3 phase. It has three hot legs, when I use a volt meter I find that all three legs have 110 volts. When I look at the control box of the machine, it has leg 1, 2, 3. the "motor" diagram shows leg one and three at the side of the motor and leg (2) two coming into the top. I figure this makes (2) the "high leg" and the other two will make it spin LH or R hand depending on if I hook them up correctly. So... it sound easy but a few questions: what meter do I need to be sure the panel box on the wall was wired for high leg on the center leg? The 208 volts on the grinder refers to the "other two 110V legs" making a typical 220 motor run?

I figured to plug and unplug this and a mill. My Leviton plugs and receptacles have X,Y,Z. (not L1, L2 L3), the X hot has the bent 90 degree tang... Is this the one you put the high leg hot on? how about the Y and Z? L1 and L2 have a code preference to get left or right rotation of the motor? Does this make sense to you? Anyone out there have nothing to do and want's to come do it for me? HAHAHA. thanks, Karl

[nearchoclatetown]

Karl, what brand surface grinder did you get? My electrician buddy won't let me touch any wires but I can give you an instructional course on the grinder if you need. Did you get the service manuals?

[KRK Sr.]

Doug, Mitsui model 200mh with fine adj handle, with sony dro, No, I did not get the manual, called Mitsui and they said they had one they would photo copy and send one, about 40 pages. That was about a week ago. Mail man did not show up with that yet. Right now I can only look at the new toy! Karl

[Guest JT]

First off be sure and check that your 3 phase power source matches your power tool requirements in amp rating.

All three legs for a three phase motor should be the same so there is no "high" leg. If the motor runs backwards just switch any two of the legs. Don't forget that the equipment must be grounded making for a total of four connections.

If you are going to use a plug instead of hard wiring you must use the correct 3 phase nema plug and outlet for your voltage and amperage rating. This will also contain a ground connection.

[Ron Green]

JT is correct regarding all.

Don't worry about the high leg in a 3 phase circuit. Switching a leg will reverse motor rotation. If you want to get that warm and fuzzy feeling check voltage between the phases and not just to ground. A to B, A to C and B to C and you should read 208 volts each time.

As a friend once said "wiring not a hobby"

Good luck.

[KRK Sr.]

JT and Ron, thanks for the info. Last night I did try doing just what you said, a to c etc, and found 208 each time. The box on the wall had only a on/off switch with the panel box 400 foot away. So the plan is for safe wiring with a breaker box at this location... at the machine. Amp loads are fine. I don't expect to run more than one machine at a time so that's the reason for the plugs and not hard wiring...One other thing I am wondering is what will my demand meter bill next months electric at with this new usage. Most months run a "5" demand, sometimes a "6". I will let you know how I make out. Karl

[nearchoclatetown]

Mitsui? you must be one of those Pierce Arrow guys. A DBer can only afford a Boyer- Shultz. I think the law is they have to give the manuals at the cost of printing. I've gotten manuals for some pretty old machines, even my Big 10 inch Johnson. Bandsaw, that is.

[Guest imported_49packard]

When you fire the thing up it will draw about 6x whatever the nameplate amp(full load)-this is where the demand will hit. I doubt you will see any change. The watts usage is 1.73x volt x full load amps x the power factor. The power factor is probably around .8. You multiply the watts x the time in use thus watt hours which is what they measure. Unless you use this thing alot-I doubt you will see any change.

[KRK Sr.]

Doug, A Boyer what??? The guy who sold me this one had two if you want to upgrade... My Mitsui dealer in Phila said he would just do it as a favor, Genuine manual was $40, however I did spend monies on other things...

49 packard, thanks for the info, I see 3.7amp loads on the motor, but was not sure what the demand on start up would be 3 phase vs single... I can tell you that the months that bill at the 5 level now are ones that the Mig welder stays unplugged. Now that is not a reason to not make any machine move, but just another cost of being open that the residential cust. has no idea that we pay for electric in this manner.thanks, Karl

[Guest imported_49packard]

If that is 3.7amps 3 phase-then the demand will be about 6 x3.7 or about 24 amps. If you have 3ph for residental you are fortunate. It is much more efficient as well as trouble free

[nearchoclatetown]

Boyer- Shultz, kind of like Chevrolet,apple pie, and baseball. Not Mitsui, as in Lexus, shoeshe, and socki, and those other words I can't speel, if you get my drift. Good luck bud.

[KRK Sr.]

WOW, thats tough words. I said I wanted a Parker, but sales guy said " no you don't, you want a Mitsui..." Mistake? Karl

[KRK Sr.]

One more phase 3 question: Cust. was at the shop today, say "I know this guy" (this is how all good stories start) who bought a Bridgeport mill and he has no 3 phase at the house, so he uses two legs from the panel, and the other: he just fires up his Honda generator and the mill does not know the difference!! INSTANT 3 PHASE. Now I have left this rattle around the old brain today trying to decide if this "guy he knows" is the next Einstein or next Frankenstein!!! Any comments? Karl

[Guest imported_49packard]

He maybe lucky-true 3ph can be done by either a static ph converter which uses capacitors and inductors or a rotating ph converter. Basically the thing will run it you get it turning and apply power.

[KRK Sr.]

49packard, would this mean he has it running only for startup? or all the time he is using the mill? My understanding is you loose one leg you have problems? Hondas may be quiet but.... gas is $2.30 a gal. Karl

[Guest JT]

Not sure how the honda generator trick is done since each leg of a 3 phase power source is 120 degrees apart.

[Terry29-26]

Without geting the books out..(I'm lazy) there are several ways which power comp. deliver 3 ph power. Depending on transformer windings there is two types of 3 ph.. If you have 110v. to ground on all three legs you have no problem which wire goes where but if you have one leg that is 208v. to ground (known as hot leg) then care must be taken to keep this leg isolated. I have had this system on the farm for 37 years with no problems. With this system there is still 208v. between legs but one leg will read 208v. to netural/ground(and they are not the same}.

The reason one leg is seperated on machines is to isolate this Hotleg so that any thing which might use only 110v. (lights.fan motors recpt. ect..} does not get wired 208v.

If you are not shure of what you are doing spend the few $ and hire someone that does. Best life insurance you can buy.

Terry29-26

[Ron Green]

I attached a link to the explanation of how to make a 3-phase piece of equipment operate on single phase. You can buy these converters at a motor shop. My friend has a 3-P converter for his milling machine at his house (SP) and it works fine. I would find it hard to believe that the generator trick would work especially without doing damage.

A good rule of thumb is to remember; 2 wire hook-up, 3 wire screw up, 4 wire #### up.

http://www.metalwebnews.com/howto/ph-conv/ph-conv.html

[Terry29-26]

Check with your power company and ask what the time period is for your demand meter.Most are 10 to 15 min. Starting one moter will have no efect on demand.Starting every thing after power outage should not effect meter reading.Running every thing at full load longer than their time setting will raise the meter.

I hope this answers some of your questions.. Be safe.....

Terry29-26

[Guest imported_49packard]

If you can get a 3ph motor turning it will run on single ph-not very well. Three phase gives it "moving"field. Single phase without capacitors etc will not start-thus capacitors etc make it act as a 2ph system until up to speed then usually a cut out switch will take capacitors out.

A rotating phase converter uses a 3ph motor driven by a gas engine or someother external power source. Single phase is applied to one of the phases on the motor which acts as an exciter for the other 2 phases. You get 3ph off the motor. All this ain't cheap and has problems-usually cheaper to replace the motor with a single ph motor.

[KRK Sr.]

Ron, Terry, And 49packard, First, let me assure you all that "I AM NOT THE GUY I KNOW". Between the three of you I have a better understanding of what is going on in the 3 phase motors. With 120 degree pull on the armature I see how the cost to run the same horsepower motor would be less. I also see how you could end up with 208 volts in a wall outlet only if you are Frankenstein. My original question on "high leg" voltage was brought about by seeing florescent lighting at auctions bring pennies because they had transformers that said 277? volts not 110. I figured this had something to do with 3 phase lighting. Additional mis-information over the years included stories about plugging drills into three phase outlets and bad things happening... I did contact my electrician friend to check my work before I play with my new toy. Again thanks! Karl

[Guest JT]

If you're getting your 3 phase from a wye configuration you would have 120 volts from any lead to neutral (or ground) and 208 between any 2 of the three legs.

If you're using a 120/240 delta configuration from single phase you'll have 120 volts to neutral on 2 of the legs and 208 volts to neutral on the third.