Phase-A-Matic rotary converter randomly starts in different direction

jariou · May 11, 2020

Hi,

The title of the post states my problem clearly, I have a rotary phase converter that starts spinning in a random direction every time I turn it on. Here is a little background.

I bought 2 used Phase-A-Matic 5 HP rotary phase converters maybe a year ago. Here is a link to the company's rotary converters information. By the way, those are based on Baldor motors, so not some random crap. After getting them, I tested that they both would spin and produce 3 phase. Then I picked one and wired it up for my Deckel FP1 mill and got no problems with it at all once I educated myself a bit about a few details. All of this to say that I now know for sure how to wire those.

A couple of weekends ago, I decided to set the other one up for a cold saw and a surface grinder projects that were put on the back burner for too long. I wired it up and connected it to the cold saw and it turned in the wrong direction. Ok, no big deal, switch the two input legs and try again. Well, it started in the wrong direction again. After double and triple checking my initial wiring and the direction of the spinning saw, I came to the conclusion that the rotary converter itself must be spinning in different directions from one start to the next. I was able to check and see that the spinning direction of the saw changed according to the spinning direction of the converter's rotor. So this means that what we are dealing with here is a motor that starts in a random direction.

I called the company's tech support last week and after I read the output's line to line voltages, I was told that the capacitors were no good. I got a set of new capacitors and got the exact same result, i.e. unpredictable spin direction.

So, now, I am completely lost. I have no idea what else I should look at or what else I can try or test. Does anyone have a suggestion?

Jacques

Rob F. · May 11, 2020

Is there any motor shaft to give it a little kick start in the right rotation?

johansen · May 12, 2020

verify the potential relay is working and the start capacitors have current flow during startup.

thermite · May 12, 2020

jariou said:
Hi,

The title of the post states my problem clearly, I have a rotary phase converter that starts spinning in a random direction every time I turn it on. Here is a little background.

I bought 2 used Phase-A-Matic 5 HP rotary phase converters maybe a year ago. Here is a link to the company's rotary converters information. By the way, those are based on Baldor motors, so not some random crap. After getting them, I tested that they both would spin and produce 3 phase. Then I picked one and wired it up for my Deckel FP1 mill and got no problems with it at all once I educated myself a bit about a few details. All of this to say that I now know for sure how to wire those.

A couple of weekends ago, I decided to set the other one up for a cold saw and a surface grinder projects that were put on the back burner for too long. I wired it up and connected it to the cold saw and it turned in the wrong direction. Ok, no big deal, switch the two input legs and try again. Well, it started in the wrong direction again. After double and triple checking my initial wiring and the direction of the spinning saw, I came to the conclusion that the rotary converter itself must be spinning in different directions from one start to the next. I was able to check and see that the spinning direction of the saw changed according to the spinning direction of the converter's rotor. So this means that what we are dealing with here is a motor that starts in a random direction.

I called the company's tech support last week and after I read the output's line to line voltages, I was told that the capacitors were no good. I got a set of new capacitors and got the exact same result, i.e. unpredictable spin direction.

So, now, I am completely lost. I have no idea what else I should look at or what else I can try or test. Does anyone have a suggestion?

Jacques

Well.. your maker does not seem to publish schematics? Kinda "blind" as to what is "there" or external and "where" as to making and breaking input and output side power circuits?

LOAD side should not be connected until the RPC has gotten up off it's knees.

Reversing a RUNNING load-motor now and then reverses the idler as well. Hitting a load motor in an unpredictable rest position before the idler has come up to speed might have the same effect?

Don't know, as I just don't DOOO that.

Another possibility...

If... the main contactor (is there such?) that applies 1-P to the input has its 2-Pole contacts SO closely in sync the minor change in the "bump" as builds-up as they break.. can apply one or the other as "first make" from one start to the next.

It takes TIME for a coil to build a magnetic field or a cap to build a charge. The symptom smacks of your having accidentally acquired a bistable multivibrator, AKA "flip-flop"!

What happens you shunt one leg so you are switching only one, not both, try several cycles that way, see if the direction becomes the same, each go?

2CW

jariou · May 12, 2020

Rob F. said:
Is there any motor shaft to give it a little kick start in the right rotation?

Unfortunately, no, no shaft coming outside the body of the converter.

jariou · May 12, 2020

johansen said:
verify the potential relay is working and the start capacitors have current flow during startup.

What do you mean by "the potential relay"? There is no relay in my wiring, just a switch. And there is no starting capacitors that I can see, just 3 running capacitors in parallel totaling 150 micro farad.

jariou · May 12, 2020

thermite said:
Well.. your maker does not seem to publish schematics? Kinda "blind" as to what is "there" or external and "where" as to making and breaking input and output side power circuits?

I know and I agree, here is an extract of what they are saying about it.

"The rotary portion of our converter is proprietary, custom built to our specifications by Baldor Electric,.... It is a true phase converter and not a modified electric motor as most of our competitors use. "

thermite said:
LOAD side should not be connected until the RPC has gotten up off it's knees.

No problem there, I switch the converter on, then walk over to the machine and wait a bit to make sure the converter is going full speed before switching the load on.

thermite said:
Reversing a RUNNING load-motor now and then reverses the idler as well. Hitting a load motor in an unpredictable rest position before the idler has come up to speed might have the same effect?

Don't know, as I just don't DOOO that.

I don't either.

thermite said:
Another possibility...

If... the main contactor (is there such?) that applies 1-P to the input has its 2-Pole contacts SO closely in sync the minor change in the "bump" as builds-up as they break.. can apply one or the other as "first make" from one start to the next.

It takes TIME for a coil to build a magnetic field or a cap to build a charge. The symptom smacks of your having accidentally acquired a bistable multivibrator, AKA "flip-flop"!

What happens you shunt one leg so you are switching only one, not both, try several cycles that way, see if the direction becomes the same, each go?

Trying to make sure I understand your suggestion here. Are you saying that one leg is connected directly from the wall panel to the converter and only one leg is switched? I can certainly try that I suppose. Is that what you mean essentially?

thermite · May 12, 2020

jariou said:
Are you saying that one leg is connected directly from the wall panel to the converter and only one leg is switched? I can certainly try that I suppose. Is that what you mean essentially?

I'm presuming that BOTH "hots" of the single-phase are on separate contacts of the SAME switch, disconnect, or contactor - the key player being whichever it is that you use "last" to energize the unit.

And that it would be "informational" to try it with but the one switched, the other always-on.

For TEST.

Even so, the culprit introducing "randomization" may be within the envelope of the RPC.

Phase-a-Matic is more notorious for crappy STATIC converter AFAIK, but either way have always shipped with a large ration of posturing, pompous, BULLSHIT incorporated into the product.

"As was to be demonstrated" - you've just gotten a whiff of it yerself.

Ex; The "random crap" they brag of for the idler? Got f**ked in a similar manner. Bought a "NOS" T.B. Woods DC motor. On Arrival? F**king Mexican Baldor! Merely house branded for T.B. Woods!

No Fear. Got a proper "pre ABB debacle" Reliance for the application, so the pretty on the outside, ugly on the inside BaldWhore won't need to be connected to anything as risky as "electricity". Prolly just bury it in the back garden.

MichaelP · May 12, 2020

First of all, please clarify which motor you mean when you describe that it starts in random directions: the idler of the RPC, the saw motor or both?

Then disconnect your saw and tell us what happens when you start the RPC only. Turn it ON and OFF a few times allowing the rotor to stop completely before turning it ON. Does the idler rotate to the same direction every time you turn the RPC ON?

jariou · May 12, 2020

MichaelP said:
First of all, please clarify which motor you mean when you describe that it starts in random directions: the idler of the RPC, the saw motor or both?

I thought it was clear, but abundance of clarity is rarely a bad thing,so let me clarify.

What I initially observed is that the saw motor started in a random direction.

Eventually, I diagnosed that the culprit was the idler motor starting in random direction.

And I never witnessed a case where for a given direction of the idler motor, the saw motor would start in random direction. So, the idler first starts in random direction. But given that direction, the saw motor's direction is fully predictable, meaning that whatever is random is in the idler motor. Whatever the saw does is fully predicated by the direction of the idler.

So, a short and naive answer to your question would be, "both motors start in random direction". But all the randomness is in the idler.

I hope this makes it crystal clear.

jariou · May 12, 2020

MichaelP said:
First of all, please clarify which motor you mean when you describe that it starts in random directions: the idler of the RPC, the saw motor or both?

Then disconnect your saw and tell us what happens when you start the RPC only. Turn it ON and OFF a few times allowing the rotor to stop completely before turning it ON. Does the idler rotate to the same direction every time you turn the RPC ON?

Sorry Michael, it looks like I responded before you finished your question. Or maybe you edited it as I was responding.

I have done what you suggest, the idler does start in random direction. Regardless of it being attached to a load or not.

I believe I have isolated the issue to the idler, it has nothing to do with the saw.

Thanks for looking and replying.

Jacques

jariou · May 12, 2020

thermite said:
I'm presuming that BOTH "hots" of the single-phase are on separate contacts of the SAME switch, disconnect, or contactor - the key player being whichever it is that you use "last" to energize the unit.

And that it would be "informational" to try it with but the one switched, the other always-on.

For TEST.

Even so, the culprit introducing "randomization" may be within the envelope of the RPC.

Hi Thermite, yes, that's what I meant really. I'll try that later tonight and let you know what I learn.

Thanks for helping

Jacques

thermite · May 12, 2020

jariou said:
Hi Thermite, yes, that's what I meant really. I'll try that later tonight and let you know what I learn.

Thanks for helping

Jacques

Should be enlightening as to ruling-out one more variable if nothing else.

What I am suspecting, here, given that Phase-a-Matic actually believe their own dogfood - that a "static" motor-fooler-f**ker-upper is actually a "converter" (they are anything BUT..) .. is that they may have applied some of the same tomfoolery to start their idler rolling off rest with less "apparent" drama.

And that their kinky-fuckery has gone pear-shaped as to repeatable timing.

All else comes to fail, I'd strip the Baldor idler to its leads, bin ALL the Phase-a-Matic bat guano, and build an "ordinary" set of RPC controls back onto the idler.

Cheap enough, and end of problem.

Yah still want a bit of kinky-fuckery? Just pick up a Blu-Ray of the "50 Shades" trilogy, partake in a separate container, and leave the poor 3-Phase tools out where the WORK gets done swinging in ONE direction... instead of several..

monoblanco · May 12, 2020

Very, very strange! I have had for forty years an ARCO Model M rotary phase converter, also consisting of a three phase motor and three parallel connected oil filled capacitors permanently connected between one of the input phases and the "manufactured" phase, plus a safety bleed-off resistor across the collective terminals of the capacitors. Would seem to be virtually the same as yours.
Very crude construction - when I opened it up to see what I had bought (used)I found that the shaft of the motor, which had originally extended out through the end bell, had been hacksawn off at a sloppy angle, with the opening in the end bell plugged with what looked like an automotive freeze plug.
Thus modified, I never had any way of knowing the direction of rotation of this idler and never had any reason to be concerned about it.
My lathe has a 2 speed Dahlander type motor (900 and 1800 rpm) and all original controls, with the output from the ARCO unit connected exactly as utility three phase would have been, in fact had been during the two years when the lathe and I had been employed in a shop which had commercial 3 phase power.
The lathe has always started and run with the rotation I expected when I operated the control lever on the apron, no exceptions!!
I look forward with great interest to the explanation for your unit's strange behavior.
Good luck and please keep us posted,
Monoblanco

rons · May 12, 2020

My first and last pre-built RPC was the one you have. I returned it and have no regrets. It does have a Baldor motor but it is not comparable to a
5Hp motor. The rotor is lightened and there is one or two metal can capacitors inside. If this was happening to me then I would add one or two
external capacitors to the motor (externally) which would cause a known direction for running.

thermite · May 12, 2020

rons said:
My first and last pre-built RPC was the one you have. I returned it and have no regrets. It does have a Baldor motor but it is not comparable to a
5Hp motor. The rotor is lightened and there is only one capacitor metal can capacitor inside. If this was happening to me then I would add one or two
external capacitors to the motor (externally) which would cause a known direction for running.

Useful info. Thanks for that!

Got you off "ignore" over the silly politics, even!

"PM, doing what PM does best!"

MichaelP · May 12, 2020

It would be interesting to see the schematics (fat chance, I know...) or, at least, what's physically inside. The defect presents as a commutation error, of course. But, maybe, it is an intermittent shorting in a winding?

What capacitors did you replace? The start or run ones? I assume it was the former.

Jerry's expert opinion would be invaluable.

jariou · May 12, 2020

Well, I tried Thermite's suggestion and I was rather hopeful that it would work.

Unfortunately, no joy! It started in one direction 3 or 4 times in a row. Then, it switched! :angry:

So back to square 1.

Jacques

jariou · May 12, 2020

MichaelP said:
It would be interesting to see the schematics (fat chance, I know...) or, at least, what's physically inside. The defect presents as a commutation error, of course. But, maybe, it is an intermittent shorting in a winding?

What capacitors did you replace? The start or run ones? I assume it was the former.

Jerry's expert opinion would be invaluable.

Hi Michael,

I replaced the running ones. There is no start capacitor to be seen.

Jacques

jariou · May 12, 2020

rons said:
My first and last pre-built RPC was the one you have. I returned it and have no regrets. It does have a Baldor motor but it is not comparable to a
5Hp motor. The rotor is lightened and there is one or two metal can capacitors inside. If this was happening to me then I would add one or two
external capacitors to the motor (externally) which would cause a known direction for running.

Rons, I have not opened the converter's motor to see if there are capacitors inside. It comes with 3 external run capacitors totaling 150 mfd. They are wired in parallel between leg 2 and 3, the manufactured one.

Jacques

Phase-A-Matic rotary converter randomly starts in different direction

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