Made a new 17.5 HP phase converter

My old 10 HP phase converter could barely survive my 200 amp welding machine, and the third leg sagged a lot and it vibrated etc.
So, today my wife and son left me alone for a whole day, and I made a new phase converter out of the old one.
The new phase converter lives in the enclosure from an old Ferrups UPS that I demolished a year ago. I put it on 4" casters for ease of moving.
It actually has two idler motors. One is a 10 HP idler, and another is a 7.5 HP idler. The first motor to start is the 10 HP.
If I decide that I need more power, I press a momentary push button switch after the first motor spins up, and that makes the second motor come up. It stays up until the system is switched off.
WITHOUT the second motor, my phase converter is a simple phase converter with starting capacitors between legs 1-3 (3 being the generated leg).
When the second motor is switched on, it also switches on extra capacitors between legs 2 and 3. Thus these capacitors (two between legs 1-3 and two between 2-3) instantly become balancing capacitors.
Effect of this on noise and vibration is very nice.
So, now basically I have a mercedes of phase converters. Some things need to be finished, such as properly placing that pushbutton, adding a distribution system for 3 phase, etc.
I used one Allen Bradley starter for the 10 HP motor, and a simple contactor for the second one. The A-B starter has W63 heaters.
I sawed off the shaft of the 7.5 HP motor with a Harbor freight bandsaw, and was impressed with its performance. (it did not fit the enclosure well).
No pictures yet, as my wife took our camera.
The new one takes about as much space as the old one, but it is taller, it has two levels. On the bottom level, the 10 HP motor lives, and on the upper level, everything else lives -- the 7.5 HP motor and electrics. The 7.5 HP and electrical shit are separated by a wall.
There is a fan on the bottom section and I need to add another fan for the top section.
It looks actually not so bad in the ferrups enclosure, like if it cost me $2000 or some such amount. The ferrups enclosure has better appearance than particle board.
Another helpful thing was putting carpet underneath the motors, thanks to Gunner's earlier suggestion. It helps tremendously. The new RPC only makes a nice humming sound, helping me know it is running.
i
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On Mon, 12 Dec 2005 02:27:36 GMT, Ignoramus27731

Ive got this really really nice heavy duty 20 hp cast iron open frame 230vt 1700 rpm motor if you ever come this way......
Gunner
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
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Thanks... I am afraid that I will blow my house's 200 A main breakers if I try to start a 20 HP motor... 3X starting current could be 180 amps or so.
i
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BIG SNIP

That's why it's a bit easier on the household systems to use Jim Rozen's advice to run up the 10HP plus stuff with a pony motor. Does away with a lot of the electrical contortions too. No problem doing a "direct drive" or tight-belt mounting either, as the power required to drive the un-excited pony is nil once the main "motor" is running. Best if they are the same RPM to start with though.
I tried to use some very nice 25HP wound rotor motors I had, but when they drew WAY too much current even at idle, I dropped back to 10HP.
Take care.
Brian Lawson, Bothwell, Ontario.
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You are completely right. Pony motor may be a pain with small converters, but could be the only way to go with big ones.

My 17.5 HP combo, running at idle (no load), draws about 15 amps. That's with both 10 HP and 7.5 HP idlers running.
i
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On Mon, 12 Dec 2005 17:08:00 -0500, Brian Lawson

Thats also why I used the pony motor concept when building my 10 hp rotory. I only have 100 amp service.
Gunner
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
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wrote:

There's only one true cure for that one - a healthier main service, either 200A or 400A. Single-phase if that's your only option, 3-phase if you can talk the utility into it. 120/208 Y is best for a house, no 'Wild Leg' screw ups - just ask PV about that one.
Gunner, the offer still stands to come up there and waste a weekend either changing the one pedestal over to a 200A 1Ph, or better, installing a separate 3-phase feed and meter for the "shop".
I'm sure I can find enough homeless "Stuff" around there that needs hauling off to a useful home to make it work. Might even haul off something purring, you never know...
First you have to call PG&E and have the meter spotter come out, and see what they'll allow you to do without huge fees. Then one of us needs to scrounge up a panel, and you might have to call in that favor to borrow a backhoe...
--<< Bruce >>--
--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
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wrote:

There's only one true cure for that one - a healthier main service, either 200A or 400A. Single-phase if that's your only option, 3-phase if you can talk the utility into it. 120/208 Y is best for a house, no 'Wild Leg' screw ups - just ask PV about that one.
Gunner, the offer still stands to come up there and waste a weekend either changing the one pedestal over to a 200A 1Ph, or better, installing a separate 3-phase feed and meter for the "shop".
I'm sure I can find enough homeless "Stuff" around there that needs hauling off to a useful home to make it work. Might even haul off something purring, you never know...
First you have to call PG&E and have the meter spotter come out, and see what they'll allow you to do without huge fees. Then one of us needs to scrounge up a panel, and you might have to call in that favor to borrow a backhoe...
--<< Bruce >>--
--
Bruce L. Bergman, Woodland Hills (Los Angeles) CA - Desktop
Electrician for Westend Electric - CA726700
  Click to see the full signature.
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On Tue, 13 Dec 2005 02:46:00 GMT, Bruce L. Bergman

Many thanks, again for your kind offer Bruce and its one Ill keep foremost in mind. At this point in time...I cant even afford to pay attention...with a fair amount of accounts receivable..and some very very slow payers. Though if they all paid tommorow..the bill collecters would bleed me dry in seconds.
In fact..after the first of the year, Im going to sit down, and do some number crunching..and see if I can afford to even remain in this business another year. After fighting the pneumoia last week..no dollars for a doctor, buying my meds from the pet store, etc etc...Im tired of having no life, no fun and no money. It was simply another event I dont want to repeat. As they say..when you find yourself in a hole..first thing you do is stop digging.
At 52, having had 2 back surgeries, and an angioplasty..Im not exactly the sort of "on paper" material a companies HR people wants to add to their staff..so I dont know if Im stuck with being self employed, or can find another schtick with say..a hospital, that can use my rather varied maint skills etc etc. Living here in the hinterlands doesnt help much either..but there is NO ability to move someplace closer to Da Big City on the horizon. And the being on the road 4-5 days a week, keeping the falling apart RC going, in an expensive RV park in So Cal, and making that CV to LA drive twice a week is getting really old..with a tired old truck with 385,000 miles on it..and no way to get a replacement any time soon.
Frankly..Im tired. Tired of being tired. Tired of not having ridden the BMW for 7 years, or having had one of the sail boats out for even longer..and they all simply sit rotting away while I struggle to keep things going. My piss poor career and life choices are finally catching up with me....and Im running out of life.
Now on the other hand, you are most welcome to come up for a day or a weekend, and come play in the shop, or dig through the Stacks O Shit. Grub is on me and while I dont drink..I can probably find you a soft or adult beverage of your choice, and something purrrfect to warm your lap and/or take home with you. And lots of Stuff.
I swear to God..the only thing that keeps me going and sane..is that my critters need to eat too. Chuckle. Shrug..whimper...lol
Any time you want to spend a day up here..you are more than welcome. But come to play, not work. Id like the diversion. In fact..I think I need one.
Gunner
"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.
Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner
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I use a pony motor instead of caps to spin up my 30hp to get rid of hi amps, works well. I start my 20 idler off the 30.
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That's very impressive and a huge horsepower rating! What do you use your phase converter for? What is your pony motor's HP rating?
i
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The pony is a 3/4hp single phase, it is 'geared' to spin the 30 up to 1250rpm before it switches on. I run two Toyoda CNC's (vert and horiz) and a Bostamatic off the 30hp, not all at once, I can run the vertical Toyoda and the Bosto at the same time, the Horiz must run alone. The twenty is used for a rotary 7.5hp compressor, you should use a lot of 'overkill' on three phase converters running compressors. If you want clean/balanced 3ph power, run caps are your friends, and many small ones will let you tailor the phases for good balance.
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Very nice. By the way, I once ran a 5 HP compressor off a 7.5 HP RPC. Worked okay, at least for short periods.
I agree 100% on run caps. If you look at my webpage
http://igor.chudov.com/projects/17.5-Phase-Converter/
you will see an explanation of how start caps become run caps when the second motor is switched on. I have 184 uF on each leg, or 368 uF total. Dunno if this is an optimal number.
How long does it take your 3/4 HP to spin up the 30 HP motor? I am highly impressed, they must be huge! How much did you pay for the motors?
i
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I will try to make them tonight. It's almost complete. but missing the pushbutton to start second motor, plus I want to add a nicer 3 phase distribution system.
I also bought an Omron K3NX-VD1C process meter on ebay for 19.99, I will try to build it in and make it measure the following:
- input current (single phase) - input voltage (leg 1-2) - leg 1-3 voltage - leg 2-3 voltage - leg 1 current - leg 2 current - leg 3 current
For that, I will need some current shunts and some other minor stuff like diodes and small caps.
i
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Too bad ya didn't leave the shaft on the new motor. You could have coupled them up and just switched it in as it would already be spinning in the right direction. Sort of an electric rope start :)
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There was no space for a shaft, inside the enclosure. These motors is a dime a dozen, figuratively speaking.
i
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