Help making a 3 phase unit from a 3 ph motor SOLVED!!!

Kelvin · December 22, 2006, 06:48:13 PM

Howdy all,
I've gotten info about making a phase converter, and have been told by people (maybe wrongly) that you can get a 3 ph motor to spin on 1 ph power if you get it spinning with a smaller jack motor. I've got a brand new Baldor 15 hp 3 ph motor i want to make 3 ph power for a 10 hp planer motor. I'm awfully anxious to get this thing running as i bought the planer on ebay and haven't even been able to run it yet. (its got a byrd shelix head!) Can't wait to try it out, but i can't get the blasted motor to run.

I followed the wiring diagram inside the motor to make it run on 220v. I've got the jack motor running it up to speed, and then i throw the circut breaker to send the 220v to the motor. It dims the lights and buzzes a little but nothing. Now i know there is all sorts of info about balancing the legs and what not, but i just want to make the motor run for now. Shouldn't i be able to do this? I tried most of the combinations with the 3 leads on the 3 ph motor, to no effect. Tried switching the jack motor around in case the motor wanted to spin the other way. I've been told, and read, that people run 3 ph this way, what ami i missing? I have the 15 hp motor on 6 gauge copper wire (should be enough for a no load 50 amp motor) and a 100 amp circut breaker to handle the start up amps (had a 50 but it would pop off in about 5 secs of trying). I know some of you out there know about this stuff. Any help? maybe i'm not getting the motor up to a high enough speed? though i've been told you can pull start the 3 ph motor with a rope cord and flip the switch, though i don't know if this is true. I have a much larger pulley on the 3 ph motor, so i bet i'm only getting it up to 1/2 its running rpms. What do you think? Help!
Thanks for the time, and Merry Christmas! HO HO HO!
Kelvin

GregS · December 22, 2006, 07:29:35 PM

Kelvin,
I think this jack start method works but I have concerns trying to get all the mechanical linkages, rpms and directions correct. I opted for the capacitor start method. Wiring in a starting cap is easy. Your static motor runs on 2 hot legs and the third is synthesized using a starting capacitor. Let me try a diagram...

---------hot leg #1---------------------------------------------> to static motor
---------hot leg #2---------------------------------------------> to static motor
|
|-leg#3-----|push-switch|---|capacitor|--> to static motor

The push switch only gets activated for a second while the static motor gets up to speed. The capacitor value is 70 microfarads per horsepower and at least 250volt rating.

Once the static motor is running then you have your 3 hot legs for the other motors. this method has worked well for me for many years.

Note: This does not show a running or balancing capacitor because I have never found the need to use one.

I hope this make sense....

Dave Shepard · December 22, 2006, 07:52:14 PM

Kelvin, I am not sure if I understand what you are doing. Are you using the 15 HP as a phase converter? To run three phase on single you have to have an idler motor, in this case the 15hp. The 15hp is not hooked to anything, it just runs, or "idles". You would then take three phase power off of the 15hp to run your 10hp. I have been studying this at practicalmachinist.com. They have an entire section on phase converters. I hope this helps.

Dave

I reread your post a couple of times and I understand what you are trying to do, but not what you are doing wrong. I hope the above link will help.

easymoney · December 22, 2006, 08:32:40 PM

what you have is an ideal situation with a larger motor for an idler motor. if you are going to spin it up to speed make sure your starter motor will get it up to full speed. if it does not when you apply voltage to the idler motor it will just groan and come to a halt. also if you apply too much load to a running motor and it loses a little speed it will come to a halt. you just have to shut everything down and statr over again. capacitors work fine also as a method of starting a three phase motor.i have used both methods with motors from 1 hp to 25 hp with good results. go to search on your computer and type in three phase motor conversion and you will find all the information you need. if you are handy with wireing and motors.

Kelvin · December 22, 2006, 08:37:37 PM

Yeah, the rpms is the only thing i could think of. If i got it up to say 1800 rpms and through the switch it might not be enough? I can get different pulleys but i couldn't imagine it would make that much difference.

Yes the 15 hp is the idler motor. The capacitors must be what they sell on ebay to make your own rotary phase converter. Looks like a box with 3 capacitors. They call them "heavy duty oil filled capacitors" Its $250 plus shipping, so if i can make it work with the jack motor that would me good to test things out first. Any one out there with an idea? I bought the "new" baldor 15 hp motor off ebay. Maybe it was just bad? Motors are so simple, can't imagine. They said it was old overstock. maybe something funny about the motor? It does say the volts are 210/420 which is odd. It usually says 220/440v from what i've seen. I assumed it was all the same. Maybe its the wrong freq? 60 hrz i think, from europe? I think they have 50 hrz?
Help!
Kelvin

TexasTimbers · December 22, 2006, 08:43:58 PM

Lots of info on the net. You can do it yourself if your time is not as valuable as the money you will miss chasing down poarts. Even buying conversion "kits" (everytihgng but the motor) does not save all that much once you fihgure your time. And 3 phase motors, unles you already have one for your convertor, are higher to junk out nearly than to by a cheapo. Butr caution: DONT buy a ROC cheapo.
Kelvin. Two rules of thumb.
#1) Your convertor motor must be bigger than your load motor.
#2) Bite the bullet and buy a quality converotor if you can afford it.
I bought a cheapo with a Chinese motor and I literally cringe everytime I start it. If you want to call me IU will turn it on and let you listen. You will be convinced. Plus it sounds like little marbles rattling around in there. You know, those high quality ROC bearings. When I turn my 60 year old Oliver 270D off it takes like 4 minutes to quit turning if I don't apply the brake. When I turn off the junk ROC phase convertor it rolls to a stop in under 45 seconds flat.
It's just a matter of time before it bites the bullet and it will hgapen when I least can afford it to.
Don't scrimp on this one. Buy an American made covertor with a motor that will outlast you and a capacitor bank that cost more than a steak dinner for two.

I should have taken my own advice. I am about to go turn the nasty sounding thing on right now to rip some RBE and I will cross my fingers.!

GregS · December 22, 2006, 09:04:22 PM

Kelvin, Before you spend all that hard earned money try the starting capacitor for around 10 bucks. Here is a link...

http://www.surpluscenter.com/sort.asp?UID=2006122219580743&catname=electric&keyword=EMSC

TexasTimbers · December 22, 2006, 09:12:27 PM

I don't have experience with that but have tread some cons.

farmerdoug · December 22, 2006, 09:17:18 PM

Kelvin,

I would checkout the electric motor or industrail supply houses in your area. They should be able to supply the capacitors you need and maybe even help you out a little. My dad get the capacitors off motors and such all the time from things he scraps. I may have a few extras I could sell you laying around. I can look and see if I have enough for you project tomorrow if you want.

Farmerdoug

farmerdoug · December 22, 2006, 09:23:42 PM

Kelvin,

Here a another group I hang with that will get you going on the phase convertor. They are great with metal equipment too. Check out the posts there and do not be afraid to ask questions. They are as good a group of guys as the ones here.

rec.metalworking

Farmerdoug

Kelvin · December 22, 2006, 09:28:53 PM

Thanks for the posts guys,
Yeah i do admit, capacitor start will be superior if i can get this thing going. any idea why it isn't working as is? I have to confirm the rpms, but they might be okay if the jack motor is 3600 and the idler is 1800 rpms. gotta go look. Any other suspicions? Shouldn't this work?
Kelvin

eamassey · December 22, 2006, 09:42:59 PM

Hello Kelvin,
I've run one of these for several years. I did it all myself. The "jack motor" will definitely work if you get the "converter motor" up near full speed. The use of "motor start" capacitors is a better method, however. Your problems can only be one of these: (1) you are not getting the motor up to speed, (2) the 15 horse motor is defective, or (3) you have got it wired up wrong. Sounds like the motor you bought was a European market model, but still should work fine on 220/230 V and 60hZ. It just should be really easy to get going. It is much harder to get really high quality 3-phase power - this involves balancing the "wild leg" with motor-run capacitors.

Dave Shepard · December 22, 2006, 10:03:45 PM

Go to MSC, at mscdirect.com. They have capacitors for about $7. They should be the right voltage, and microfareds you will need. There are some great pictures on practicalmachinist.com showing how all this stuff is wired together. They basically have a half-dozen caps, a contactor and a few pieces of wire. You already have the expensive piece, the 15 Baldor, so I wouldn't dump $2000 on a factory converter. Surpluscenter has cheap parts that are name brand. I also wouldn't shell out the beg bucks on ebay for those caps. These are just my opinions, but you sound like you are capable of doing this. Good luck.

Dave

Beweller · December 22, 2006, 10:17:51 PM

Yes, your 3-phase motor will run on one phase if started. Note that it will only be a 5 hp motor running on single phase.

The single phase voltage is applied to two of the three power leads. Running as a motor, it will draw only 20-25 amps when loaded. Loaded as a phase converter delivering near 15 hp, it will draw something like 60-65 amps from the single phase circuit. Actually, it will not power a 15 hp 3-phase load--only something smaller. It will not deliver its maximum power, less than 15 hp, unless capacitors are used.

The motor will run in which ever direction it is started. Starting at half synchronous speed should be easily fast enough.

J_T · December 22, 2006, 10:23:55 PM

My vote goes with eameassey . As I have said we got four running five to six days a weak . I would say bad motor or it is not desined for 240*440 I got a motor here that is 550v only thing I can use it for is a boat ancker ???Can you take it to a buddy that has 3ph and see if it will run ???

Kelvin · December 23, 2006, 02:05:44 PM

Thanks for the help. I looked at the jack motor and its 1750 rpms and the 3 phase is 3600 rpms, so i diffinitely was not turning it fast enough. i turned a new pulley on the lathe before i looked at the idler pulley as someone had told me most 3 phase is 1750 rpms. Well after i installed the new pulley, tried it again and it still wouldn't start i looked at the plate on the idler motor, duh... 3600 rmps, so i'm still only at 1/2 speed. Guess i'll have to try again with a different pulley arangement, and my 1/2 hp jack motor doesn't seem to be up to spinning the 15 hp armature. Gotta find something with more umph. Dig around in the barn. the motor sure looks brand new! Maybe it was tried and found wanting so thats why it was "surplus". Thanks for the links for capacitors.
How do they get it up to speed? Just storing enough voltage to turn it over and get it running? The manufactured rotary converters seem to have 3 capacitors. Why would this be? Balancing? I'll check out some of the links if i can get this thing to run. Maybe i can find someone with 3 phase to check it on. Don't know anyone off hand...
Thanks and Merry christmas! HO HO HO! (again!)
Kelvin

D._Frederick · December 23, 2006, 06:29:58 PM

Check your wiring of the idler motor and make sure you do not have a mix-up of 2 and 5 number lead wire wrong. Being that the motor is not loaded, it will easily start at 1/2 rpm.

Sunfield Hardwood · December 23, 2006, 09:47:37 PM

Hi Kelvin, I have two phase converters running, one 10 hp and one 20 hp I run machine tools on the smaller one and a baker edger with 15 hp motor on it also a large planer in the sawmill on the 20 horse converter. I built both of them from parts bought in Lansing for around 100 bucks each [not including motor] thay are both capaciter start. your welcome to come check them out any time.I'm about 15 mi. west of Lansing. I don't have any experience with the manual start type. Good Luck

Dave Shepard · December 23, 2006, 10:10:11 PM

http://www.practicalmachinist.com/ubb/ultimatebb.php/topic/3/1851.html

Phase converter plans, with pics.

Dave

woodhick · December 25, 2006, 08:19:40 AM

Kelvin, I have two converters that I have been running for a couple of years. A 3hp one that I start with capacitors. I have a 10 hp one that I start with a jack or pony motor arrangement. My 10hp motor is 3600 rpm and I start it with a 1/4 hp 1725 pony motor. I put a pulley on the 1/4 hp that matches the shaft size on the 10hp. 1/4 is on a plate hinged above the 10 hp. I put a v-belt on pulley and slip it over shaft on 10hp, start little motor and use a screwdriver as a pry bar to lift little motor and tension belt. when large motor gets spinning I flip power on to it and it starts right up. If you are spinining your big motor even half of it's rpm it should start. I would double check wiring and voltage of large motor. I have run my 24" planer this way for over a year with no problems. I probably should balance the legs with capacitors but it works fine as is. Hope this helps.

Don P · December 26, 2006, 07:37:19 PM

The guys that have posted have lots more experience and smarts than me about it. I've only built one, two different ways, three if you count the one I let the magic escape out of :D.

I learned a couple of things that I don't recall being directly mentioned so far.
There are 2 different types of capacitors, "start" and "run". A start is usually one of those black round, lighter, ones with paper insulation. They have higher MFD numbers on them and kick the motor into motion, but can't cool well and won't last long at all if run constantly.They are the ones usually found under the cover of single phase motors, to kick your compresser or whatever into motion. Then there's run capacitors that are usually metal, oil filled, cans. They can run constantly and are used where you balance the legs, or create a phase with capacitors. The number of capacitors doesn't matter, their rating and your needs are what determines the number. I have some in the barn that I havent tried yet that are large, have a low mfd number, and I got a box of them when a local factory shut down. In theory I think it should just take more of them.

Somebody told me once that the British slang for capacitor is "tank", that worked for me. The first converter I made used a pair of starts to get it rolling and a bank of runs, that were connected to one incoming phase and the missing leg. It stored power from the line and dumped into the missing phase of the motor when it came around (I ain't no electrician :D). That's a static phase converter and has no Idler motor. It only makes a portion of the nameplate HP though.

The next one used starts to get an idler like yours running and a couple of runs to balance the legs. I made up a harness with several slip on spade connectors and kept trying capacitors till it seemed to meter evenly the best I could get it.

A book I have suggests the idler be twice the hp of the motor being run, but goes on to say you can often stretch that. I'm stretching it a bit, a 5 running a 3 and nothing gets hot. I've also read somewhere that Delta windings work better than star wound motors.

Kelvin · December 28, 2006, 05:20:22 PM

Well, finally got it running. It was only the rpms. So for all you out there, you do need to get those rpms up before they will turn over, and getting the 15hp motor up to speed was real hard. Probably needed to be about 75% of full speed to kick over. My 1/2 hp couldn't do it, and a 5/8 could barely. Now i've got to take everyones advice and get some start up capacitors ordered. Feathering a jack motor everytime is for the birds.

Also got the planer running. Wow! Everything they've said about those byrd shelix heads is true. Quiet, powerful, smooth, no tear out. What a advance in modern science. I bet in 10 years straight steel blades in planers and jointers will be as rare as steel router bits!