My $45 homemade 10 HP phase converter is WORKING!!!

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wrote:

No. Sorry. I dont swing that way.
Ask Richard Gere.
Gunner
Liberals - Cosmopolitan critics, men who are the friends of every country save their own. Benjamin Disraeli
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wrote:

Glad you liked it. So how about posting a picture of your husband?

Gunner
Liberals - Cosmopolitan critics, men who are the friends of every country save their own. Benjamin Disraeli
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Goonie wrote:

Fetch fido. Here boy...
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wrote:

Snicker
Gunner
Liberals - Cosmopolitan critics, men who are the friends of every country save their own. Benjamin Disraeli
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Gunner wrote:

That site is pretty disturbing. What kind guys build those machines? I thought metalworking was a nice, innocent hobby :-).
Incindentally, those trolls don't think like engineers. Why spend hundreds of bucks building something with your Kmart tools when you could just rent a jackhammer for a day?
Chris
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On Thu, 28 Jul 2005 16:17:58 +0000 (UTC), Christopher Tidy

They are for that special woman..the gift that keeps on giving <G>

Gunner
Liberals - Cosmopolitan critics, men who are the friends of every country save their own. Benjamin Disraeli
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"To announce that there must be no criticism of the president, or that we are to stand by the president right or wrong, is not only unpatriotic and servile, but is morally treasonable to the American public." -- Theodore Roosevelt
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wrote:

"Far better it is to dare mighty things, to win great triumphs, even though checkered by failure, than to rank with those poor spirits who neither enjoy much nor suffer much, because they live in the gray twilight that knows neither victory nor defeat." --Theodore Roosevelt
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Thanks Gunner... I tend to think that making a 10 hp phase converter for $45 is exciting...
i

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On Thu, 28 Jul 2005 16:42:20 GMT, Ignoramus9394

Actually..so do I. And Ive had a brand new 3600 rpm 10hp motor tucked away for a year or more..I think you have given me reason to build my bigger one.
Gunner

Liberals - Cosmopolitan critics, men who are the friends of every country save their own. Benjamin Disraeli
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That's great! I am sure that with your welding machines etc, you can build a much better looking enclosure than what I did.
i
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On Fri, 29 Jul 2005 10:45:25 +0000, Ignoramus27279 wrote:

My RPC went through several enclosure schemes before I was happy with it. This is a 2 HP RPC. I started out trying to build the whole thing inside of an old Heathkit DX-100 Ham Radio cabinet, thinking that keeping everything self-contained was a smart idea. It turned out to be too big a bulky for my tiny workshop. I finally found a smallish metal utility box, like the kind you might have on a desk to keep paperwork or keys and other odds and ends in. It was kind of cramped but I mounted all of the components for the RPC in it -- relays, balancing and start caps, start/run and on/off switches, and fuses. I bolted this guts box to a plank and using EMT connectors to run the wiring through I attached it to the idler motor (which was bolted to the plank as well). On top of this guts box I mounted two outlet boxes with a 4-wire twist lock outlet in each. This is 3-phase output. Rather than cutting the shaft off of the idler motor, I decided to make a shield for it out of aluminum wire mesh (stucco screen).
This arrangement has worked out great. Its much more compact and expandable in the future. The only thing I'd like to change is to replace the wooden plank with a frame made of welded angle stock and some rubber feet. I'll get around to that one day.
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Very interesting, and good food for thought.

I am building an enclosure right now:
http://igor.chudov.com/projects/Phase-Converter/03-Enclosure /
I am doing that with various junk wood pieces lying around. I did not want to use any more valuable materials. My objective is to make a compact enclosure on wheels, with top that I can use to put stuff on, like a mini cart of sorts. That way at least, it will not effectively take any space away from me.
i
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Forgot to say, I am hoping to use my phase converter as a base for my Sears table saw. That way I will kill several birds with one stone, so to speak, I'll have a phase converter and a base for table saw. This way, the table saw will take up the minimum of space. I'll see how it works out.
i
On Fri, 29 Jul 2005 18:33:58 GMT, Ignoramus27279

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| thanks to everyone for your thoughts! | | Many pictures and the story in several chapters: | | http://igor.chudov.com/projects/Phase-Converter / |

I don't know jack about RPC's, so I just ask this as a sounding board for those among us who can verify my concern. Should your contactor have an overload on it? The overload's job is to protect the equipment if an overcurrent exists on any or all legs. In essence, it shuts all three phases off even if one has shorted to ground. Your supplier will have some or you can trade the contactor in for one that has it. Overloads come with a holding contact that turns off power to the contactor if an element overheats. I know that current in one leg will be lower in an RPC, but as long as it doesn't exceed the overload element's rating it will work just fine.
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Yep, Carl is right about the protection considerations.
The overload protection devices aren't just to protect against the motor developing a short to ground, they react to protect the motor from being overloaded by a jam or machine malfunction/breakage, stalled or any other condition that causes the current to rise to a point where the motor would be damaged/destroyed by the resulting heat in the windings. The OLP's heaters are selected from a chart of currents for the specific motor being used. Some OLPs have adjustable trip settings so that heaters don't need to be selected. Each type of OLP will cause all 3 phases to be opened/interrupted.
The OLPs are also available as a separate device, but are commonly integrated into the overall starter/contactor box.
The best setup for an RPC would be a magnetic starter/OLP rated for the size of the RPC motor, and a separate (specifically sized) starter/OLP for each machine motor that's powered from the RPC. Choosing not to use a second, separate OLP for the (usually) smaller machine motor will not offer any protection for the machine motor.
WB .................

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Hm, I am confused. I agree with you on the need for overload protection. I will install something, for sure.
What I am curious about is, can I simply use motor rated fuses on both incoming 240V legs? That should provide all necessary protections for the idler.
I do not mind installing an overload relay, as such, except that it is a cost issue. Fuses are cheaper. (unless I can find something at that junkyard). Realistically speaking, the idler is not going to bind. If contacts to capacitors break, yes, I could have a stall issue, which would be addressed by properly sized fuses.
A relay is more exciting and possibly a little more convenient (it is resettable, I do not need to buy new fuses when a fuse burns out), but in reality will provide about same protection.
Am I mistaken?

Yes, I saw some on ebay last night...

Agreed.
Agreed also.
i
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Ignoramus9394 wrote:

The overload units in a motor starter are have a very narrow operating range like 57.5 - 61.3A that can be very closely matched to the motor rating. Picking between a 50-60-70A fuse doesn't give much protection. Also overloads are designed to allow the starting inrush and are designed to match the thermal characteristics of the motor for overload. Even time delay fuses have to be much larger than the motor rating or they will blow on the starting inrush. Fuses can be sized at up to 175% of the motor rating and circuit breakers up to 250%(NEC). The fuses in a motor circuit are intended to provide short circuit protection, not overload protection.
Bud--
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I
Fuses can be expensive and overload heater type contactors are even more expensive. If you use this RPC and tool fed by it, are used only when you are "in attendance", you wont need any fuses, your 60 amp breaker will trip before you burn anything up. If the 3 phase tool motor stalls for any reason, just hit the kill button on the RPC.
Jerry
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Hm, that's nice to hear. I will think about it.
i
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