Author Topic: 3 Phase Breaker Tripping  (Read 23978 times)

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Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #30 on: September 07, 2014, 07:09 PM »
Here is the photo of the nameplate on the motor.  I should also mention that this is Dantherm (now branded Nederman) S-750 Dust Collector.

Thanks again for all of your help.

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Offline kcufstoidi

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Re: 3 Phase Breaker Tripping
« Reply #31 on: September 07, 2014, 07:13 PM »
PH is the dust collector the largest motor your starting. Also you said you had a 10HP RPC. Is the the size of the RPC Motor or what the RPC is rated to run.

John

Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #32 on: September 07, 2014, 07:20 PM »
Quote
PH is the dust collector the largest motor your starting. Also you said you had a 10HP RPC. Is the the size of the RPC Motor or what the RPC is rated to run.

Hi John,
My sliding tablesaw (Altendorf) is also 7.5HP with a 1HP scoring motor.  It starts and runs fine.  It also draws over 100amps on startup but it is running at full RPM in less than 1 second and then the current draw drops below 10A.
The phase converter is rated to start a 10HP motor and is rated to run 25HP combined.

Phil

Offline Rick Christopherson

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Re: 3 Phase Breaker Tripping
« Reply #33 on: September 07, 2014, 07:48 PM »
Regarding the startup time, I never accurately measured the startup time until today; therefore, I believe that it did not change; it was only my hopeful imagination.  Today, I measured the startup time at 9 seconds before the breaker trips.  I believe that the motor is still not up to full RPM at 9 seconds.   

The main thing you need to focus on is why do you have such a long startup time. This is what is causing the secondary symptom of the tripping 30 amp breaker. Don't focus on the breaker, because it is doing exactly what it is supposed to do.
  • Check the motor for free rotation. Make sure the impeller or motor shaft spins freely and continues to freewheel after you stop turning it by hand. If it doesn't freewheel easily, then look for obstructions such as dust. If no obstructions, then it is likely that the motor bearings are shot.
  • Disconnect the motor, energize the motor contactor (turn it on), and then check the voltages A-B, A-C, & B-C at the motor. These voltages should be the exact same as they are back at the output of your phase converter.
  • Reconnect the motor and repeat the above voltage measurements. It is expected that they will be slightly lower than the voltages at the phase converter, but it shouldn't be a huge drop.
    You will only have 9 seconds to take each measurement, so it is expected that you may need to do this 3 separate times for the 3 readings. Let the motor cool down a little bit between each attempt. For the 9 seconds, the windings will have high amperage and they will get hot pretty quickly.
  • If the C-phase voltages recorded in step 3 dropped really low, then start your tablesaw with no sawblade (no load) and repeat step 3. Your tablesaw will actually act as a secondary idler motor of the phase converter.

I also checked the current draw near the breaker and it is over 100amps for that entire startup period.  On one startup attempt, the breaker did not trip and the current draw was between 12-13amps. 

This would suggest that on at least one occasion the motor did reach full speed. Given the amperage of about 50% of full load, then it also suggests the motor was successfully running at no-load (inlets blocked and bearings not seized).

One thing we haven't discussed much is your phase converter. You said it was a rotary converter and I assumed that to be correct. So let's confirm this. Does it have an idler motor that runs when the converter is started? If it doesn't have a big motor, then it is not a rotary converter. A static converter is not recommended for a dust collector motor.

Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #34 on: September 07, 2014, 08:59 PM »
Quote
Check the motor for free rotation. Make sure the impeller or motor shaft spins freely and continues to freewheel after you stop turning it by hand. If it doesn't freewheel easily, then look for obstructions such as dust. If no obstructions, then it is likely that the motor bearings are shot.
The motor and impeller spin VERY freely.  In fact, it takes about 5 minutes for it to stop spinning after a startup attempt.
I will complete the other 3 steps in the morning. 

I think it would be odd if the motor bearings are shot as it worked fine 2 weeks ago when I purchased it from another shop.  I was careful during transport; however, I did lay the motor on a 45 degree angle when transporting.  I wonder if this could have caused oil/grease to drain from around the bearings?  I'm not familiar with the internals of these motors...

Quote
This would suggest that on at least one occasion the motor did reach full speed. Given the amperage of about 50% of full load, then it also suggests the motor was successfully running at no-load (inlets blocked and bearings not seized).
The motor did reach full speed on the first attempt and the breaker did not trip.  I ran it for about 2 minutes before turning it off.  Most of the inlets are blocked, but I have (2) 4" inlets still open.  I think that's pretty minor on a dust collector this size. 

Quote
You said it was a rotary converter and I assumed that to be correct
Yes, this is a rotary phase converter with a large idler motor.  I purchased it from ARCO electric.  Here is the link to the exact product (It's a model B).  http://www.arco-electric.com/Product.aspx?ProductID=1

You mentioned the motor getting hot.  Are you talking about the DC motor or the phase converter idler motor?  I noticed that the Idler motor had gotten quite warm (I could hold my hand on it but it was pretty hot) but the DC motor was still cool to the touch. 

Offline RJNeal

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Re: 3 Phase Breaker Tripping
« Reply #35 on: September 07, 2014, 11:48 PM »
 [popcorn]
I'm watching this tread for I have a three hp,16" jointer I'm trying to run off a 7.5 hp rotary phase converter. It was running fine with a long start up. (5-7seconds). Then it started to trip it's breaker. Found a loose connection. Ran fine again then started to trip again.
I haven't looked at the wiring yet.

Thanks Rick for all the great info and trouble shooting. I now have info to look in to this problem.

Good luck phmade
Rick
Have you walked your saw today?

Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #36 on: September 08, 2014, 11:28 AM »
More new developments to report:

I tested voltages at the motor during startup and... Once again, Rick is correct!
The C Phase Voltage dropped from 270V to 170V.  I've been on the phone with the Phase Converter Manufacturer and they believe they need to add another bank of capacitors.  Luckily, they are a local company about 30 minutes from me so I'm hoping to get this repaired/replaced today.

I have not tried running the tablesaw without the blade yet.  Could that damage the tablesaw motor?  This is a new tablesaw and I definitely don't want to damage that motor!

Thanks again for all of the assistance.  I will post more as I have updates.  Once again, the FOG is proving to be the best forum online - filled with knowledgeable, generous people!




Offline Rick Christopherson

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Re: 3 Phase Breaker Tripping
« Reply #37 on: September 08, 2014, 01:31 PM »
You've already been running the tablesaw for quite a while, I assume. So running it unloaded to take these measurements will not cause any new damage to the motor. I recommend that you complete the 4 steps listed above and present the results. Make sure you tell me everything, and don't withhold anything that you think is unimportant.

I do want to see if there is a difference between the tablesaw running and not running. As a matter of fact, lets add one more set of measurements.

Measure the voltages with only the tablesaw running. Then measure the voltages of the dust collector both with and without the tablesaw running.

Offline kcufstoidi

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Re: 3 Phase Breaker Tripping
« Reply #38 on: September 08, 2014, 03:23 PM »
As a side note, if your saw has any computerization I would have a concern about the wacky voltage the RPC is producing.

John

Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #39 on: September 08, 2014, 05:58 PM »
Quote
As a side note, if your saw has any computerization I would have a concern about the wacky voltage the RPC is producing.
My saw does have a computer controlled fence and blade height/angle.

Quote
You've already been running the tablesaw for quite a while, I assume.
I have NOT been running this saw.  I am in the process of installing (3) machines: the dust collector, the tablesaw, and an edgebander.  I recently purchased all 3 machines and they have never been run in my shop.  The phase converter is also a new purchase to run these machines.

I spent most of the day on the phone with ARCO (phase converter manufacturer) and tech support for the other machines.  ARCO seems to think that a start-up kit will be necessary to start the dust collector quickly.  I'm not really sure what is included in a start up kit, but they are providing it as a solution.  It should be ready for installation tomorrow.  I have also been speaking with tech support for the tablesaw and edgebander to verify that I connect the high-leg from my phase converter in the correct location.  I have taken more voltage readings than I ever cared to, but I think we're getting close to solutions.  Hopefully I have good news to report tomorrow.

Rick, I think I'll try the start-up kit for the dust collector tomorrow if it arrives early enough.  If it doesn't arrive, then I'll follow your steps with the tablesaw running.  Thanks again.

-Phil

Offline Rick Christopherson

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Re: 3 Phase Breaker Tripping
« Reply #40 on: September 08, 2014, 06:34 PM »
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.

Offline Steve Rowe

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Re: 3 Phase Breaker Tripping
« Reply #41 on: September 08, 2014, 07:11 PM »
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. 


Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #42 on: September 08, 2014, 09:11 PM »
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

Offline kcufstoidi

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Re: 3 Phase Breaker Tripping
« Reply #43 on: September 09, 2014, 07:56 AM »
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

Offline Rick Christopherson

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Re: 3 Phase Breaker Tripping
« Reply #44 on: September 09, 2014, 12:55 PM »
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
« Last Edit: September 09, 2014, 12:59 PM by Rick Christopherson »

Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #45 on: September 09, 2014, 09:59 PM »
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.

Offline wow

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Re: 3 Phase Breaker Tripping
« Reply #46 on: September 09, 2014, 11:04 PM »
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!
Trying to be one of the most helpful members on the FOG.

Offline Rick Christopherson

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Re: 3 Phase Breaker Tripping
« Reply #47 on: September 09, 2014, 11:53 PM »
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.


Offline wow

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Re: 3 Phase Breaker Tripping
« Reply #48 on: September 10, 2014, 07:28 AM »
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]
Trying to be one of the most helpful members on the FOG.

Offline leakyroof

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Re: 3 Phase Breaker Tripping
« Reply #49 on: September 10, 2014, 08:30 AM »
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]
Not as many Sanders as PA Floor guy.....

Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #50 on: September 10, 2014, 10:50 AM »
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:


Offline Rick Christopherson

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Re: 3 Phase Breaker Tripping
« Reply #51 on: September 10, 2014, 03:12 PM »
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.




Offline wow

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Re: 3 Phase Breaker Tripping
« Reply #52 on: September 10, 2014, 03:18 PM »
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.
Trying to be one of the most helpful members on the FOG.

Offline Rick Christopherson

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Re: 3 Phase Breaker Tripping
« Reply #53 on: September 10, 2014, 04:06 PM »
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.

Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #54 on: September 27, 2014, 05:10 PM »
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