3 Phase Breaker Tripping

[Rick Christopherson]

Phil,
I wouldn't hesitate to get these voltage readings before installing this startup kit. I have never seen a rotary converter that needed a startup kit for the tools. Its mere existence implies that the converter isn't doing its job in the first place.

With the exception of the dust collector that is failing to reach running speed, you are not going to damage the tool motors by running them at no-load in order to take these measurements. Just avoid excessive back-to-back restarts and don't leave them running for a long time.

If you have already taken some of these measurements, then tell me what they were. The more information I have, the better I can help you diagnose the problem. I also want to avoid putting a bandaid on something that winds up masking the true problem.

I'm a little concerned that this "startup kit" is nothing more than a static phase converter, and putting it on the motor will simply mask the true problem.

 

[stvrowe]

I suspect the "startup kit" is just a capacitor bank across your line inputs to the phase converter.  This supposedly helps maintain the voltage during start of large loads.  Kay Industries provided a similar device when I was having problems with very hard starts on my saw.  The capacitor bank helped but did not completely solve the problem.  I eventually went with the Phase Perfect digital phase converter and haven't had a problem since. 

 

[phmade]

Thanks guys - I too am concerned about the "startup kit".  As I understand it, it is a bank of capacitors that only serves the dust collector.  Hopefully this company can resolve the issue but I'm starting to doubt them.  I definitely don't want them to just mask the real problem if it will damage any of my equipment over the long-term.

Rick, here are some of the numbers for you.  I wasn't able to get all of the information yet, but hopefully this will help.

Without the motor connected and WITHOUT the tablesaw running:
A-B: 242.1
B-C: 243.6
A-C: 272.5

Without the motor connected and WITH the tablesaw running no-load:
A-B: 241.8
B-C: 238.9
A-C: 258.8

With the Motor connected and WITHOUT the tablesaw running:
A-C: 174

With the Motor connected and WITH the tablesaw running no-load:
A-C: 182.9

I should note that when the tablesaw was running, the dust collector was up to speed in 7 seconds instead of 9 although it still tripped the breaker.  I'm not sure what it means but perhaps it's a move in the right direction?  Does it mean that my idler motor needs to be bigger?  The overall goal is to start the dust collector in a shorter length of time; is that correct? 

A crazy though although I'm not sure it would be safe:  Could I start the dust collector and turn it off before the breaker trips - then restart it while the impeller is still spinning?  It seems like it would be giving it a "push start."  Thoughts?

Thanks again for all of your help.
-Phil

 

[junk731]

PH, I hope you get your problems solved. The RPC guys seem to try and solve everything with another bank of caps. The computer on your your saw or any other future piece of equipment with a computer  will want to see a stable voltage. If you truly get fed up with an RPC take a look at Phase Perfect Digital Phase Convertors. Some may have sticker shock but like Festool you get what you pay for. I've been using their 10Hp unit for almost 5 years now with no problem or noise.

John

 

[Rick Christopherson]

Phil,
Nothing is jumping out with the numbers. So I think it is boiling down to the phase converter being less than advertised, and undersized. If there is a nameplate on their motor, see if you can snap a picture of it. Come to think of it, open the control panel and get some detail pictures of the phase converter so we can check that everything in there is connected properly. Take enough pictures so that I can trace all of the wires.

I want to be able to check these dust collector voltages after the motor gets up to speed. I don't care how it gets to speed, as long as it does. Use your other motors to help get the dust collector up to speed, and then check the voltages before turning off the other motors as well as with only the dust collector running.

Even if this startup kit is just a static converter to kick start the dust collector, that is still OK as long as the run voltages are close to balanced. I would like to see pictures of the startup kit though.

A crazy though although I'm not sure it would be safe:  Could I start the dust collector and turn it off before the breaker trips - then restart it while the impeller is still spinning?  It seems like it would be giving it a "push start."  Thoughts?

Oops, I almost forgot this. No, this will not help because the thermal on the breaker will still be heated up and still trip. However, using something like a pull-string before hitting power might help a little, but kind of doubtful on a motor this large.

You've had a couple people mention electronic controls to you. It's not a big deal. Controls are always just single phase. So all you have to do is make sure they are using phases A and B.

If at any point you feel that Arco is giving you the runaround, you could casually drop my name as the person helping you. If the technician has been in the business long, he probably will recognize it. A few years ago the #1 hit for googling "phase converter" was me. Even though I haven't updated the article in 10 years, I still come up higher in the ranking than Arco.
http://www.waterfront-woods.com/Articles/phaseconverter.htm

 

[phmade]

Ok- finally a successful update.  We picked up and installed the start-up kit and the dust collector now works!  Our start time went from 9 seconds to about 5.5 seconds. 

I just came in from the shop but I will take photos and voltage measurements in the morning.
Rick do you want me to check the dust collector voltages at the motor?  Or can I check them at the output of the thermal overload?

Thanks again to everyone - especially Rick.

 

[wow]

Ok- finally a successful update.  We picked up and installed the start-up kit and the dust collector now works!  Our start time went from 9 seconds to about 5.5 seconds. 

I have been following this thread but stayed out of it since you were getting excellent advice and help. Good job, Rick!

Now that you've isolated the issue, I thought I'd throw out one comment. Capacitors deteriorate over time. Eventually they will dry out and fail - usually at the worst possible time. The fact that a start-up kit fixed the problem tells me that it's likely that your capacitors are reaching (or have already reached) the end of their life.

The good news is that they are easy to replace and relatively cheap at that!

 

[Rick Christopherson]

Rick do you want me to check the dust collector voltages at the motor?  Or can I check them at the output of the thermal overload?

Yes, it is fine to check the voltages at the thermal overload where the terminals are easy access.

I can't remember where we were at with this, but I think with the starting kit installed, the only thing we want to confirm is that the phase converter and the starting kit are acting in a healthy manner for your motors. Unless I am forgetting something I asked you to do previously, you now should take voltage readings from the dust collector by itself and then again with each other tool motor running. Because this is a new install for all of these tools and the phase converter, you are checking that all of the motors and all combinations of those motors will be getting healthy power as they run during normal usage.

Capacitors deteriorate over time. Eventually they will dry out and fail - usually at the worst possible time. The fact that a start-up kit fixed the problem tells me that it's likely that your capacitors are reaching (or have already reached) the end of their life.

The capacitors typically (and hopefully) used in a rotary phase converter should be the metallic can, run-type capacitors. Hopefully the starup kit also uses run capacitors even though they probably disconnect from the circuit once the motor is running. These are oil-filled sealed cans, and do not have the same failure mode as the black-can start capacitors you are probably thinking about due to their common usage in single-phase motors.

 

[wow]

Capacitors deteriorate over time. Eventually they will dry out and fail - usually at the worst possible time. The fact that a start-up kit fixed the problem tells me that it's likely that your capacitors are reaching (or have already reached) the end of their life.

The capacitors typically (and hopefully) used in a rotary phase converter should be the metallic can, run-type capacitors. Hopefully the starup kit also uses run capacitors even though they probably disconnect from the circuit once the motor is running. These are oil-filled sealed cans, and do not have the same failure mode as the black-can start capacitors you are probably thinking about due to their common usage in single-phase motors.

I just replaced three of the metal can capacitors in the charger for my Stock Picker. One was open, one was shorted, and one was weak. i discovered this while I was in the process of converting the charger from 3-phase to single phase.

OK, to be fair - they were manufactured sometime in the 1970's.

[wink]

 

[leakyroof]

Capacitors deteriorate over time. Eventually they will dry out and fail - usually at the worst possible time. The fact that a start-up kit fixed the problem tells me that it's likely that your capacitors are reaching (or have already reached) the end of their life.

The capacitors typically (and hopefully) used in a rotary phase converter should be the metallic can, run-type capacitors. Hopefully the starup kit also uses run capacitors even though they probably disconnect from the circuit once the motor is running. These are oil-filled sealed cans, and do not have the same failure mode as the black-can start capacitors you are probably thinking about due to their common usage in single-phase motors.

I just replaced three of the metal can capacitors in the charger for my Stock Picker. One was open, one was shorted, and one was weak. i discovered this while I was in the process of converting the charger from 3-phase to single phase.

OK, to be fair - they were manufactured sometime in the 1970's.

[wink]

  hah Hah, just to be fair though.... [poke]  sounds like a pretty good service life.  [wink]

 

[phmade]

Ok - here are some pictures and measurements:

Voltages with only Dust Collector Running:
A-B: 243
A-C: 254
B-C: 235

Voltage with Dust Collector and Tablesaw Running:
A-B: 242
A-C: 254
B-C: 233

Voltage with Dust Collector, Tablesaw, and Edgebander Running:
A-B: 242
A-C: 242
B-C: 232

Hopefully these are favorable measurements! 
Rick, when we started the Dust Collector after installing the start-up kit, the startup was still slow (9 seconds) and tripped the thermal overload on attempt #1.  On the 2nd attempt, the startup was much much quicker (5.5 seconds) and the thermal did not trip.  I assume that the first attempt was "charging" the capacitors?  Will this need to be done every day? 
Again, I'm not pretending to understand all of the concepts but I'm trying to learn!

Here are the photos:

 

[Rick Christopherson]

I just replaced three of the metal can capacitors in the charger for my Stock Picker. One was open, one was shorted, and one was weak. i discovered this while I was in the process of converting the charger from 3-phase to single phase.

OK, to be fair - they were manufactured sometime in the 1970's.

[wink]

OK, to be fair, those are DC filter capacitors intended to remove ripple from the rectified power.

 

[wow]

I just replaced three of the metal can capacitors in the charger for my Stock Picker. One was open, one was shorted, and one was weak. i discovered this while I was in the process of converting the charger from 3-phase to single phase.

OK, to be fair - they were manufactured sometime in the 1970's.

[wink]

OK, to be fair, those are DC filter capacitors intended to remove ripple from the rectified power.

Nope - these are AC caps in the ferro-resonant circuit.

 

[Rick Christopherson]

Hopefully these are favorable measurements! 
Rick, when we started the Dust Collector after installing the start-up kit, the startup was still slow (9 seconds) and tripped the thermal overload on attempt #1.  On the 2nd attempt, the startup was much much quicker (5.5 seconds) and the thermal did not trip.  I assume that the first attempt was "charging" the capacitors?  Will this need to be done every day? 
Again, I'm not pretending to understand all of the concepts but I'm trying to learn!

Well your run voltages look OK. They are a little high when only the small motors are run. So it looks like the phase converter was designed around maximum load. I don't have a phase converter to play with anymore, so I don't know if the converter can be tweaked for a broader range or not.

If you ever have any spare time, you could experiment with trying to balance the converter a little more. The article I linked to previously explains it. However, I am now having second thoughts about how variable the balancing is when operating a wide variety of motor sizes. In other words, if you balance it for a small motor, will it maintain a reasonable balance for larger motors. That you would have to check.

The converter is very simple, and I am surprised it doesn't have a start circuit. In a sense, your idler motor is always in start-mode until it gets loaded, and then the capacitor size becomes more appropriate. This is why you are noticing the idler motor being a little warm when idling.

If I was still doing this kind of stuff, the added starter kit gives me the idea of designing a variable load phase converter that would kick in more capacitors as the load increases. This is comparable to a starter circuit on an idler motor, where more capacitors are put into the circuit when the generated leg reaches a low voltage. It's possible that your existing starter kit could be re-purposed and cannibalized for parts to make the converter more variable. But this would take some time and experimenting to do.

 

[phmade]

Just wanted to give a quick update... I've been using the machines and everything seems to be working fine.  Maybe someday I'll have some time to experiment a little more on the issue.  Thanks again to everyone, especially Rick.

Phil

 

[fouber]

Are the inlets to the dust collector open?

Yes, the inlets are open.

Although not necessarily the primary problem, this can be a contributing factor. Granted, if the inlets are wide open and unrestricted, it could actually be the sole problem.

Dust collector impellers are under maximum load when there is no restriction to the inlets. On the face of it, that may sound counter intuitive compared to other tools such as saws. However, when there is no restriction to the inlet, there is maximum air movement through the impeller.

For initial testing, you should completely block the inlets so no air can enter the system, but make sure the outlet is unrestricted so that any air that is present in the system has an evacuation path.

Reviving ancient posts is probably bad etiquette, but I wanted to take a moment to thank Rick for this advice.  Until I restricted the inlet on a used dust collector, it kept tripping the breaker after about a minute.  Were it not for this post, I probably would have junked the old girl.  Now it runs great, with no end in sight.

[member=191]Rick Christopherson[/member]

 

[Michael Kellough]

Nothing at all wrong with bring good information long buried to the attention of the current crop of members.

 

[greg mann]

Never bad etiquette to thank someone for help they provide.  [thumbs up]