Windmill on a 3 Phase Static converter

I am wondering if anyone is running a windmill on a static 3 phase converter. The machine is 3 phase, I am aware of the advantages of using a rotary converter but was wondering if anyone is using a static converter? Is the loss of power a serious constraint?

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All three of my windmills have a static converter on them. No problems what so ever. Mainly the third leg is for starting on smaller HP motors, that’s why large HP motors need to run on a rotary.

dwallen, Have you considered using a VFD? Much less power loss than a static converter if any, plus you get speed control.

Thanks very much for your comments. I will purchase a static converter. They are very moderately priced compared to a rotary converter solution. I will give it a go.

I found this unused microdrive for $NZ200 - it’s perfect. Lovely soft start as well.

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I can’t use the VFD when my helper is around, the motor squeals too much, he is very sensitive.


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Well, I tried the static converter. It squeals for a few seconds before it comes up to speed, but after that it runs smoothly and quietly. Louie, my shop helper complained about the start up noise too.

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I’ve been using a static convertor for five years. One possible reason for the squeal is that the belt is slipping—this would be more pronounced if the speed is not turned the minimum before you starts. Alternatly you may have oil on the belt. I run a single phase machine elsewhere and the three phase motor—even on a static phase convertor is much quicker to start.

dwallen, my helpers are saying hello to your helper, Abbot is very cute. It got busy around here, I had to ‘hire’ the second helper! Of course I was exaggerating them being too sensitive, we got used to the noise.

On my set-up ( not a static converter ) the squeal does come from the motor and not from the belt. The noise ramps-up then stays steady. I am pretty sure that I don’t even hear the higher harmonics my dogs can hear. It is clearly the sound of the frequency modulation. My original motor was not intended for VLT drives. The Eddie-Current will eventually finish it off. One day the VLT detected ( and I don’t know how ) that the motor was overheating. It stopped working for a few minutes, then I could re-start it. The new motor, designed to be used with VLTs is standing by for replacement. It is only 1HP, 1150RPM, brand new and the best $35 on Craigslist I ever spent!
It is smaller and slower than the original motor, but it goes on my foil-stamping Heidi, so it will give me longer “dwell’ time.
According to the manual: the Pulse Width Modulation ( Carrier Frequency ) can be set from 2.5KHz to 14KHz. The PWM should be set to the lowest value which yields acceptable sound levels. Higher PWM decreases efficiency. These frequencies are right in the middle of the hearing range. Well, it depends on your age of course.


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Congratulations on your new hire Louie as well as a great score on that motor.
I am keeping an eye out for a new motor myself. The press works fine with the converter other than the whining when it starts which usually is only about 6 seconds. But, I have other drive problems.
A problem I am having is that the grub screws in the variable speed cone keep working loose. That lets the cone slide out on the shaft of the motor. When this happens I have to stop the press and realign the cone on the motor shaft and retighten the grub screw. This is most annoying. The motor shaft has a key that fits into the cone so it keep it rotating but slides back and forth.
The press came with one grub screw and the cone had two threaded holes so I added a second set screw. They seem to tighten really well but always work loose. I think a new motor with a different shaft configuration might be the answer. Hope I am as lucky finding something on Craigslist.

If you clean out the threads well with solvent and let it dry, you can use one of the Loctite products to keep screws from working their way out, particularly in cases where they do not require adjustment on a frequent basis.

Loctite will probably fix the symptom but you do have an underlying cause for the pulley to get loose. Could the source of the problem be the belt? You mentioned the loose pulley sliding back and forth on the motor shaft. I don’t have experience with these kind of issues, but I would expect the loose pulley to slide to it’s ‘desired’ position and STAY there. The various forces acting on the pulley would balance out in that position, but in your case something makes the pulley oscillate on the motor shaft. The obvious reason would be the belt introducing a pulsing lateral force to the pulley which slowly loosens the grub screw.

I wonder, by flipping the belt, so that it rotates in the opposite direction as it used to rotate for decades, could introduce vibration in to the drive system.


If there is enough depth, you can also use two short setscrews in place of one long, so the outer screw acts as a lock screw.

parallel_imp, that is a sneaky suggestion, I like it, but I can also imagine the puzzled face of a person in the future trying to take the pulley off the shaft, not realising that there is a second screw under the loosened top one !

I can’t resist, here is the story of my second Heidi:

Somehow I did not trust the previous owner of my Heidi because there was no circuit breaker marked for it. I had a gut feeling about this and I asked him to turn on the Heidi so I can see it work while I am turning off the circuit breakers. I turned off all the circuit breakers, even the main power switch, the Heidi was still running in the dark !!!
( LOL … excellent German engineering … runs even with the power turned off … but probably he was running it from his neighbours electric meter in the past 30 years !!! )
Of course he had no valid explanation for the phenomenon. I put on rubber boots, gloves and with an insulated side cutter I cut off the Heidi from the LIVE 3 phase 600V line.

Sometimes it is worth to stick to industry standards.


Hey thanks, these are some great suggestions.

I think the belt was replaced just before I got the press so I am not sure Louie if reversing it would make much difference, but this problem has made me an expert at removing and replacing the fly wheel cover so it would be easy to try.
I have aligned the motor with the flywheel very carefully following the instructions in the manual. When running at low speed the belt is precisely in alignment with the outer edge of the flywheel and travels inward toward the press as speed is increased as it should.
When the grub screw (or screws, I have tried both one or two) is tightened and the press running the belt does flutter very slightly but it does not seem excessive and there is no noticeable noise coming from the belt when running or during shutdown.

I have not considered using Loctite. Just never thought of it. I will consider it now. I am concerned about how difficult it would be to remove though. It would not be subject to adjustment often but the motor is getting on and I can’t help but think the 2 phase start-ups may shorten its service life. This seems like a very simple fix, but, I have never used Loctite, do you have any experience removing screws it has been used on?

I have considered using 2 short set screws. I think there is enough depth in the cone assembly if I can find two short enough set screws. I have not been able to find 8mm set screws short enough yet, but was considering making some by cutting down longer ones I have found, or special ordering them. I am sure they are out there.

Ok, I think my research leads me to using a blue Loctite to start.
Thanks again, for the suggestions.

Is it just possible, (as has as yet, NOT been suggested) the actual Parallel Key is worn, the one that Keys the motor output shaft to the Coned pulley assembly.
It (the Key) takes a lot of torque, is generally regarded as sacrificial rather than components it protects, and the compression spring, when compressed in *SLOWER* speed range creates a lot more friction and drag, the humble little *KEY* takes its biggest pounding then,??

Is there any perceivable Lost Motion in the speed control mechanism, even a small amount of such will allow the Belt to *Bounce* which will show up, eventually as *Chatter* on the Key and associated factors.!!!

Louie,? Parallel,s >sneaky suggestion< is generally seen and understood, as fairly standard practice, to those who have been, Around The block a few times.??

Are you a fan of the Sound of Music by any chance, because you have dragged *Heidi* into the picture 5 times in one tiny “Epistle” and then added Insult to injury by subjecting *Her* to LIVE 3 Phase at 600 Volts (SIX HUNDRED, perming any 2 from 3 seems a little unusual to say the least) ???

Or, offered in another light, the New Devotees seem to have more than enough anomolies to cope with already.

*** None intended. ***?

Thanks Mick, the key appears to fit quite snuggly. Certainly in the motor shaft it needed to be pressed in firmly to fit.
Just prior to my adopting this little marvel someone changed the belt. The motor was not properly aligned when I got it. One of the two set screws in the cone was missing, the other not secure. When the motor is properly aligned and the set screws tightened it runs very smoothly. I would of course like to find the underlying reason the set screws come loose, but, finding a way to keep them snug would suffice for now.

D Wallen,? as Yul Brynner sings (sung) in *The King and I*.
>Tis a Puzzlement< ….few more options/possibilities but stabbing in the dark:- is it possible to see any exposed portion of the motor Output Shaft even 1/4” between the bearing casing and the inner flange of the Pulley arrangement.

If so (although you specify that the Key is snug in the motor shaft rebated slot) with expanding jaw grips, we call them Water Pump Pliers, they ratchet out in several steps, but leave the jaws parallel over the grip range, if possible and without disturbing the Pulley unit, grip the shaft with piece of emery cloth as protection, one pair of hands for the *Gripping* a Buddy testing the Pulley unit, for Backlash, to prove or disprove wear in the unseen part of the bore of the slave unit.!!

Next, as you imply that it is possible to pull the assembly from the shaft, sorry to suggest, but one more time, pull the unit of, examine the Key fairly closely, checking for Grub Screw (Allen Screw) marks caused by previous attempts at securing/locking. … The principle involved being, marks from one of 2 variations of screw(s) both normally High Tensile with 2 variations to bottom out and Hold on the Key,
A. has a concave point and sits flat on the Key or the shaft, but more prone to any side thrust,!!!
B. is usually with a very distinct *Convex* point and tends to dig in to the Key or shaft, tends to stand up to side thrust etc. and the working Tip/Convex is normally the same rake and angle as standard High Speed drill bits, hence a tiny recess drilled in to the Key or Shaft, as little as .010” helps.

The same syndrome as Parallel,s double screw(s) can be aided as well, by using the required/desired grub screw as the primary lock, (concave or convex) but followed by the convex variety as the secondary lock, the Convex tip will locate in to the back end of the primary screw (Allen Key fitting) make a tighter fit, with Loctite as well, of course.

If you really (Still) feel the need, >as My Dad would have said 60 years ago<, for Belt, Braces, Suspenders, and more,???, Read on.

We have genuinely employed the following as well:- crude and barbaric, YES, but extreme frustration does funny things, especially when the Coffee has run out.
The method *stake* the last 1 or 2 threads to enter the hole in question, not 100% shake-proof but close.

D.W. Apologies Seminar ends here for the, Time being,

A. One is fresh out of ideas, momentarily, and

B. Your,! Mary Chapin Carpenter is telling me to, Get on over to the Twist and Shout, Saturday Night etc. but in the authors case, it is probably, get to the Late night Wall Mart for the Sleep Sweeter = Bournvita, available in North America, apparently. Mick.

I will keep all these suggestions in mind. I won’t stake the last one or two threads yet Mick, I’ll save that as a back-up plan.
I have fabricated a number of set screws to the appropriate size using a hacksaw and tiny grinder. I have used a die to clean up the threads on them so they will fit the 8 mm threads in the cone assy. I am pretty sure I have room to fit two short ones in.
I’ve also added Loctite to my tool box.
I hope this will do the trick.
I will also check for slack where the key on the shaft fits into the cone just to see if there is any movement there.

I just want to follow up on this and offer thanks to those who contributed.
Two tiny setscrews machined to fit the in the treaded shaft of the cone have secured the shaft of the motor adequately. After a day of operation with stops and starts no loosening or shifting of the drive mechanism has been detected. The Loctite remains in the tool box (along with Q-tips to clean the threads) ready just in case there is any further problems. Thanks again.