Info on understanding static phase converter limits

[Kelvin]

Howdy all,
Well i've been fooling around with the idea of switching over to an electric mill someday.  I'm looking at a 15hp woodmizer.  my question is about a couple of static phase converters i bought the other day from a farm operation.  They are labled "Ronk" and have 20hp on the plate.  Each one weighs about 200 lbs and have big copper coils and piles of capacitors.  I've built a 15hp rotary phase converter and know these are better for loaded machines like my planer, but my question is are there better static converters?  What type of machines could be run with these in a wooshop setting?  Most are loaded pretty good, but maybe these are better than normal?  I looked on ebay for big static converters and the one the list to handle 20hp weighs 30#'s, could this actually handle the same type of equipment?  I have two of the converters so i'm thinking of selling one to help pay for the other.  The owner said he paid a couple thousand for each, who would i find to be interested in something like this?  I wonder how much copper salvage is going for, couple hundred pounds might be pretty good?  It would be easier to hook this up to some of my machines, like my planer, and future moulder, but i would imagine that they aren't good for these?
Any ideas would be helpful.
thanks
kelvin

[solidwoods]

Ronk is a good maker of converters.
The capacitors means it is one switch start vs. spinning the converter to rpm then applying elec.  Its convenient just to hit a switch.
I've seen written we can only draw 75% or 80% of the hp of the converter (rotary).
I'd go with the 75%.
You can only use 1 converter on the 3ph system,, don't put 2 together (big sparks).

To go la'cheep purchase a large 3ph motor 50 - 60 hp. (I got a 60hp for $200) depends on total load,  pre spin it and use it for a converter (breakers at the feed line begining ,, also at the driven motor is nice).
Big problem I've seen is the 3rd line created by the rotary converter is a higher voltage.  So the driven motor has 2 lines and the 3rd will have higher voltage.
jim

[logwalker]

The third leg is usually higher, that's why they call it a wild leg. But what Kelvin has are static converters which are a much different animal than a rotary. My understanding is they will operate a motor at about 65% to 75% of the plate rating. They can't supply the required amperage to the third leg. But if the manufacturer is still active they would be the best source of info on the units.

I am running a 15 hp WM off a 20 hp unit and it is working great. It is assembled from a Lincoln Electric motor designed to make a Rotary converter. I don't think I would run from a static. But given the right static converter I could be wrong.

Joe

[Bibbyman]

We have a Ronk 50hp rotary phase converter that we run our 25hp WM, 10 hp edger and 7.5hp hydraulic power pack unit.  We are also using it to run our 10hp jump saw.  But we can't (or haven't) ran all the machines at one time as it would be over the rated load of the converter.

Ronk worked with Wood-Mizer in specing out the right converter.  It's been running over 6 years now with zero problems so I guess they got it right.

Here is a link to a piece I put in the knowledge base about our phase converter.

https://forestryforum.com/tips/tips.cgi?display:1048263552-19768.txt

[Dave Shepard]

The HP rating on a phase converter is how much it will handle. My former boss just got one to run the sawshed, and it is a 60 HP unit, with a 20 HP max motor starting capacity. There should be no nead to derate a phase converter manufacturers rating, only a homemade one from an electric motor. The 60HP unit was probably originally at least a 75 HP electric motor. I think it was Rotophase brand.


Dave

[den]

Kelvin
A standard static phase converter uses capacitors to get power to the 3rd leg for starting only.
While the motor is up and running the phaser does nothing. So you only have 2 hot legs,
2/3 of the power. Their not good for starting or running under heavy loads.
I think you have a phaser for a single motor app. that has start+run capacitors+something
to balance out the system.
A system like Bibbyman's you can run more then one motor at a time, but start only one at a time.
The more motors you add the better the system balances out...5-10hp motors ( or any combo)will balance out better then 1-50hp
I would call Ronk and explain what you have...Mod. Ser. #'s
Remember the transformer on the pole will blow if it's not big enough. Let the Light Co. know what your up to.$$$$ The size should be on the transformer in big #'s
A friend told the REA Light Co. but they didn't know, so said to try it. Well it blew at their$$$

[Bibbyman]

Remember the transformer on the pole will blow if it's not big enough. Let the Light Co. know what your up to.$$$$ The size should be on the transformer in big #'s
A friend told the REA Light Co. but they didn't know, so said to try it. Well it blew at their$$$

Vary good point.  we worked with our local REA and they ended up putting in a new, larger transformer and heaver service line to a new meter base.  Maybe in many places, the extra, intermittent load won't be a problem,  but they were concerned about the load on an otherwise light rural residential use area. 

We had a problem for a while and talked to REA about it.  They studied the loads, etc. and could find nothing wrong.  They did have a lineman come out and check out the voltage at our motor on the mill.  He said it was right on normal but bumped up the voltage on the line just a little to the high side of the tolerance they could allow.  Then a few days later everything smoothed out and we had no more complaints.  I suspect they knew all along that there was a problem but just were not willing to fix it.  (In fact,  one linemen told us there was a bad tap changer at the substation that was callusing a problem but they wouldn't change it out.)

[Kelvin]

Howdy,
Thanks for the info.  Yes, i have a 15hp rotary already in my shop, but i was curious as to why these static converters where so huge and heavy and what the giant copper windings inside were.  I've seen stactic converters and they are just capacitors to start the motor.  I was wondering if there are differenct static converters or whether there capacities would all be the same.  Seems like people say... rotary this, and or static that.  These static seem to be different then the usual ones i've seen.  Well, i'll will follow the advice and get ahold of Ronk and see what they are.  I think the farmer said they ran freezers and what not for the poultry application.  Maybe freezers aren't a heavy or consistant load.  I wonder if there is any market for these things if i can't use them in my shop in any way.
Thanks
kelvin

[Kelvin]

Intersting, found it right off the bat on google.  I'll have to call them about what this is but here it is i believe...
http://www.ronkelectrical.com/add_a_phase.html
case looks the same and the insides.  Guess i'll have to find out what the loads are and if they can be combined and what not. 
Thanks guys,
Kelvin

[Kelvin]

Hey i just thought of something.  If i run an idler 3 phase motor with these static converters don't i have a rotarty converter?  thats all that seems to be in those boxes that come with rotary converters.  I have a 20hp baldor i bought somewhere or the other, if i start that with no load, i would think i'd be good with a rotary converter balance.  Hmmmm.... i'm sure there are some differences, but i'll still talk with Ronk in the next day or so about this.  What i would like to do is combine a couple to start my 40hp idler motor....
We'll see,
Thanks
kelvin

[Don P]

Looking at the Ronk link real fast, I didn't read it thoroughly, jogged a wiring diagram. There is a third method of adding a phase. I think it's called an auto transformer or auto-forming. It looked over my head but was described as quite efficient and gave balanced power. Maybe some of the others know more about it. There is no idler and it is not just a capacitor driven "thumper". Don't gut 'em yet  ;).

Found it;
The incoming pair of 240 lines feed 2 phases of the motor, they also feed the windings of a transformer. One of those lines also feeds the start capacitor and switch. That leg is also connected to the run caps, the tapped leg of a transformer and the missing leg of the motor. The transformer is tapped at a point found by experiment according to load. "For a motor running under a constant load this is the best converter circuit"

I've got a real basic description and sketch and you're welcome to it, but I'd bet Ronk could give you or an electrician the full specs for theirs.

[Kelvin]

don,
Do you think this means this could handle a heavy load like a planer then?  it does seem different than standard static converter.
Thanks
Kelvin

[kelLOGg]

 If i run an idler 3 phase motor with these static converters don't i have a rotarty converter? 

Kelvin,

Yes is the answer to your question. There's a lot on the FF about this. That's what I do for my 5HP planer.

Bob