rotary converter problems

[kelLOGg]

I re-connected all wire nuts and re-greased the main (Al wire) to the shop and re-torqued.  It made no difference.
I made voltage measurements on the output of the contactor and added it to the table below. As best as I could read my analog meter there was no difference in input and output voltages, so I think contacts and heaters are OK.

L1 - L2          L1 - L3         L2 - L3
210                115               150               output of contactor while revving up
210                110               150               input to contactor while revving up
240                245               247               planer motor only running (from a previous post)

Bob

[Gary_C]

After reading this, I still believe you have a high resistance connection, most likely in the Al wire. I have seen some connections cause problems that required cutting off the end of the wire and reconnecting it using plenty of lubricant and using a torque wrench on the connector. And it could be in the buss bar in the panel. Look for discoloration around anything and even use a temperature gun to find any hot connection.

If that all fails to find the problem, you still could have a bad breaker. Switching them to start motors is not a good practice. Plus you do need a contactor in that circuit so if there is a momentary power interruption, you will have to manually restart. Its never good to automatically start a converter with the load connected.

[Den Socling]

It sure will be interesting when this problem is nailed down!

[Al_Smith]

Well face facts it's nearly impossible to trouble shoot anything over the internet although we all try to do our best at it .

To be quit honest those voltage reading are so screwy I have no idea what the problem is and all I can  do is guess .Now granted myself and a dozen others could probabley figure it out in ten minutes if we were there but we aren't .

Grabbing at straws it could be one of the windings became undone because it  rattled loose from a connection .Most industrial motors are connected within the motor junction box with ring terminals and screws .I've seen a connection come apart right at the "stakon" .Then you are running with one leg disconnected from a parrellel winding of a three phase moter connected for low volatge  IE: 240 volts

It does some wierd stuff then .Oh it'll be something simple once it's found but at present is like looking for the proverbial needle in a hay stack .

FWIW I've been at this biz since I was 19 years old and I'm 64 now .I've seen a lot but I certainly haven't seen it all . :D

[kelLOGg]

I have ordered replacement capacitors and while I am waiting for them I am going to try to disassemble this 1200 lb machine to see what I can see. I can turn the sheave by hand and there is a lot attached to it: cutterhead, gearing and belts and mechanical feed controllers. It is a dirty, greasy job. >:(
Bob

[Al_Smith]

If that motor is belt driven ,unbelt it and listen to the motor .If it moans and groans like a threshing machine it could have a bad bearing .If so by the armature walking around it will cause some real problems .Being a planer with all the machine goodies connected it would wake the dead anyway and you'd never hear a thing if it were under power much less running a board through it .

Aluminum wire was mentioned which in my opinion should be outlawed .Never the less if so it's entirely possible the connections are funky especially if it's connected with Scotch locs .Best thing to do in that case is cut the wire back and reconnect the joints using compound with crimped connectors rated for aluminum .

Aluminum is a good enough conductor but the oxide of aluminum is an insulator .It resembles glass under a microscope .Fact aluminumm oxide is used for sand paper if that tells  you anything .

[kelLOGg]

Motor runs very quietly. I don't have Scotch Locks but I do have split bolt connecters for aluminum in my crawl space. I re-lubed them and re-torqued.

Long Link

[Al_Smith]

Say is that aluminum  buried in the ground per chance ???

If so  all it takes is a pin hole in the insulation to cause big problems down the road .Aluminum is what's called a sacrificing metal .Meaning it's very susceptable to galvanic reaction causing the metal to be leached out of the conductor .

You might for example take a voltage reading under a no load condition and it may be right up where it's supposed to be .If however one of the conductors has experianced some deteriation because of electrolisis ,once a higher amperage load is placed upon it those voltage figures will do some strange things .

Now that I have seen not only on direct burial cable but also those within steel ridged conduit .

[Al_Smith]

I have no idea what you have being 7-800 miles away .If you have a roll of number 10 romex and the planer etc aren't a mile away from the source you could always stretch out a temporary line to either confirm or rule out if the aluminum feeder  has gone funky on you .You could probabley wing it with a number 12 just for a short test .

[kelLOGg]

Yes, it's #4 Al about 200 - 300 feet underground.

[Al_Smith]

If I were a betting man I'd say that's the problem then .Well shucks .

I'd suggest testing  the line side with a load ,and without .If the voltage changes dramatically that's your problem .

Now if you used aerial triplex with a bare ground/messenger instead of direct burial most likely the bare gave up the ghost .If so early on like 35 years ago I mistakenly did the same thing .If you have regular direct burial triplex insulated try changing the ground over with one of the hot wires IE : the one that's  showing low voltage .

[kelLOGg]

That's a good measurement to make, Al. Here's what I found.

I meaured across the main (line-to-line and line to ground) in the shop breaker box as the planer was turned on starting to ramp up.

The line-to-line changed from 240 to 225
line to ground changed from  125 to 115  (same data for both lines)

I did the same measurement but only on the line-to-line at the house which supplies the shop and found

The line-to-line changed from 240 to 230 during ramping up.

What do you think? Any red flags?

Bob

[Al_Smith]

Sounds within reason .So much for that idea .

[kelLOGg]

 ;D ;D ;D ;D ;D
It works now!
I installed new caps today and turned it on and it ramped up to speed fast and stayed there. Capacitors can fail under load and test OK under test conditions. Here is the link that put me onto that:

http://www.angelfire.com/electronic/funwithtubes/Testing_caps.html

I will put it all back together and re-connect the dust collector and test it under planing conditions. I hope I still have good news.  Right now I'm content to just wallow in the present good news.
Bob

[Den Socling]

 8) to you!

[kelLOGg]

After my success I installed a 2-pole switch the next day so I wouldn't have to use the breaker as a routine switch. Fired it up and  >:( >:( >:( >:( >:( same old DanG problem crept right back - ramped up slowly and tripped the breaker. I removed the idler and planer motors and took them to a shop for testing. They were fine - no problems with them the technician said.  ??? ??? ???

I found a source for rotary converter controllers Link
These units consist of everything except the idler and enclosure. They look more sophisticated than what I put together and I am thinking of buying one. What would you do? I haven't talked to the company yet but will before I buy.

Bob

[DouginUtah]

I have their 5 HP rotary converter sitting here by me. I haven't gotten around to hooking it up yet--have to have a garage sale first. It appears to be well made.

Their one-page Setup Guide was a bit disappointing, with outdated picture and information, but you won't have any problem hooking it up.

My concern is that I have a 3 HP, 208 V., 3-phase work motor and they implied that the converter puts out around 230 V.
(My idler is 240 V., 5 HP.)

[Al_Smith]

A 208 motor running on 240 volts won't hurt it .It will just put out a tad more power .

[DouginUtah]

Thanks, Al. I was hoping that you would say that.  ;D

[r44astro]

Wow did not read every post but what a pain. unless you need  close to max output at planer, buy a good static converter and run the planer, you can always use a static with a idler if more power needed, typically I only use idler on lathes because of forward reverse. use to design and build these things when I was a kid for local farmers.
Bill

[kelLOGg]

I have made progress in solving this dilemma but before cut to the chase I want to summarize.
1. The original RC I made worked for 4.5 y then started tripping the breaker.
2. Replaced all caps in it - still didn't work. The manufactured phases voltages were 110 and 150 VAC.
3. Still convinced it was an electrical problem, I purchased RC kit from WNY. (It has a nice auto detect of the third phase - something my unit lacked) Guess what. Still didn't work.

After the initial failure in 1 above I was attempting to just start the planer, not put any load on it like actually planing. So it fails to reach full rpm under no load. In all these attempts to start I began to notice two audible frequencies - one a normal hum and the other a faint high pitched squeal. Bad bearing? I asked. I removed them and they felt OK turning by hand but I purchased new ones anyway. The new bearings felt pretty much like the old ones when turning by hand. I installed them not expecting much difference. But there WAS a difference! The planer ramped up to full rpm and stayed there. The knives have been removed for sharpening so the planer is still under no load but at least it ramps to full rpm - something it hasn't done in months. Tomorrow I expect to get the knives back and I will then know to if this is the ending to the story.

My clutching-at-straws analysis is that at high rpm the bearings exhibited high load (friction) and the RCs (my version and the commercial one) could not produce enough voltage under this condition in the manufactured phases to get the speed up and the motor current draw exceded the breaker limit. What do you think?
Bob

[Al_Smith]

Wow did not read every post but what a pain. unless you need  close to max output at planer, buy a good static converter and run the planer, you can always use a static with a idler if more power needed, typically I only use idler on lathes because of forward reverse. use to design and build these things when I was a kid for local farmers.
Bill

A static converter is in essence just the same as a start circuit for a real rotary .Yes it will run a motor but only at around 58 percent power level . A lot of people use them though .

[r44astro]

Wow did not read every post but what a pain. unless you need  close to max output at planer, buy a good static converter and run the planer, you can always use a static with a idler if more power needed, typically I only use idler on lathes because of forward reverse. use to design and build these things when I was a kid for local farmers.
Bill

A static converter is in essence just the same as a start circuit for a real rotary .Yes it will run a motor but only at around 58 percent power level . A lot of people use them though .

Yes I meant that, you said better, Years ago I built a rotary converter that sensed PF and switched caps in and out, after that experience (it worked great but not worth the trouble, just buy a solid state converter) I never concern myself with amps being equal at all phases in a normal converter only if motor starts, sounds, and runs cool because of PF.

[kelLOGg]

I put the knives in today AND PLANED OAK!!!! 8)

I am still stunned that all the time the problem was bearings!!
Bob

[r44astro]

I put the knives in today AND PLANED OAK!!!! 8)

I am still stunned that all the time the problem was bearings!!
Bob

I have so often not been able to see the trees because of the forest. I repaired CNC machinery for years and have been screwed by my single mindedness all too often.