Author Topic: 3 Phase Breaker Tripping  (Read 29418 times)

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Offline phmade

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3 Phase Breaker Tripping
« on: September 06, 2014, 08:32 AM »
I recently upgraded some equipment in the shop and now I'm troubleshooting an issue.  I have a 7.5HP 3 phase dust collector (Nederman) that continues to trip a breaker on the 3 phase panel.  The nameplate on the motor states a max draw of 21Amps so I put in a 30A breaker and #10 wire.  I should also mention that I'm using a rotary phase converter to generate my 3rd phase.

When I turn on the dust collector, the motor starts and turns but before it reaches full RPM, the breaker trips on my 3 phase panel.  I have very little experience with 3 phase power and I'm really stumped.

I did swap out circuit breakers with another 30A breaker (in the event that I may just have a bad breaker) but that did not resolve the problem.  Does anyone have any recommendations? 

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Offline tjbnwi

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Re: 3 Phase Breaker Tripping
« Reply #1 on: September 06, 2014, 09:13 AM »
New dust collector or purchased used? Can you tell if the unit is turning the proper direction? Do you have other 3 phase equipment that functions properly? Are the inlets to the dust collector open?

Tom










Offline Steve Rowe

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Re: 3 Phase Breaker Tripping
« Reply #2 on: September 06, 2014, 09:40 AM »
Does the breaker trip immediately or is there a delay?  If immediate, I would be looking for a short.


Offline tjbnwi

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Re: 3 Phase Breaker Tripping
« Reply #3 on: September 06, 2014, 10:14 AM »
Does the breaker trip immediately or is there a delay?  If immediate, I would be looking for a short.

"When I turn on the dust collector, the motor starts and turns but before it reaches full RPM, the breaker trips on my 3 phase panel.  I have very little experience with 3 phase power and I'm really stumped."

Above is the second line from the op. I read it as the unit starts to spin up then the breaker trips.

Tom

Offline Sparktrician

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Re: 3 Phase Breaker Tripping
« Reply #4 on: September 06, 2014, 11:43 AM »
On the surface, it sounds like high inrush current is tripping the breaker before it gets up to operating speed.  Might be a good idea to get a qualified electrician to check it out with proper instrumentation. 

- Willy -

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Offline Steve Rowe

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Re: 3 Phase Breaker Tripping
« Reply #5 on: September 06, 2014, 12:11 PM »
What Willy said.  Need more info on voltages, currents, length of wire run, etc. 

Offline Loren Woirhaye

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Re: 3 Phase Breaker Tripping
« Reply #6 on: September 06, 2014, 12:18 PM »
I have a little 7.5hp wide belt sander which I run off a 10hp rotary converter.  I can barely start it without tripping the 50 amp breaker the converter is wired into the single phase panel through.  It's the startup load. 

Assuming the motor is spinning in the correct direction on the DC (you can look through the grill on the back to observe the motor cooling fan direction),  I would think it's air resistance to spinning that big impeller.  Take the impeller off and that motor may fire up, no problem.  Then you'll know it's the load of pushing the air.  You could go to a 5hp motor, or  upgrade the system feeding the dust collector.
« Last Edit: September 06, 2014, 12:22 PM by Loren Woirhaye »

Offline Rick Christopherson

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Re: 3 Phase Breaker Tripping
« Reply #7 on: September 06, 2014, 01:33 PM »
I should also mention that I'm using a rotary phase converter to generate my 3rd phase.


The most likely cause is with your phase converter. Check the phase voltages and see how far out of balance it is. The voltage from phase-A to Phase-B should be 240 volts, as that is line voltage. However, the voltages from A to C and B to C will be different from this. Even on a properly functioning rotary converter these will be above and/or below 240. If you find them significantly out of whack, then you probably lost a run capacitor on the phase converter, or worse, the converter's start capacitors are not disengaging.


Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #8 on: September 06, 2014, 02:06 PM »
Thanks for the replies.  I just picked up a clamp-on amp meter so I'll report back shortly. 

I purchased this dust collector used, and it was running fine when I disconnected it.  It was run on true 3 phase power in the previous shop - not a phase converter. 

I'm heading out to the shop to test now.  Thanks again.

Phil

Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #9 on: September 06, 2014, 02:28 PM »
Quote
Can you tell if the unit is turning the proper direction?
Yes, it wasn't initially, but we switched the 2 120V wires and now it is.

Quote
Do you have other 3 phase equipment that functions properly?
We have an Altendorf sliding tablesaw that appears to be working correctly.  It starts and continues to run without any problems.  We installed it at the same time as the Dust Collector (this week).

Quote
Are the inlets to the dust collector open?
Yes, the inlets are open.




Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #10 on: September 06, 2014, 02:34 PM »
Quote
it sounds like high inrush current is tripping the breaker before it gets up to operating speed
I doubt this is the problem; the breaker that powers the phase converter is not tripping.  It is a 100amp breaker with #2 wire so I don't think that's the problem.  My phase converter is a 10HP so it should be able to start a 7.5HP motor ok. 

Here are the results of my voltage testing (C is the manufactured leg):
Voltage from A to B Phase: 243.2
Voltage from A to C: 243.6
Voltage from B to C: 273.7

These measurements are taken when the DC is not running.  Should I measure this on startup? 
So there is definitely an imbalance but I'm not sure what is considered acceptable.

Offline Rick Christopherson

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Re: 3 Phase Breaker Tripping
« Reply #11 on: September 06, 2014, 02:35 PM »
Quote
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.

Offline Rick Christopherson

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Re: 3 Phase Breaker Tripping
« Reply #12 on: September 06, 2014, 02:46 PM »

Here are the results of my voltage testing (C is the manufactured leg):
Voltage from A to B Phase: 243.2
Voltage from A to C: 243.6
Voltage from B to C: 273.7

The 273.7 is a little high, but I don't believe this is causing your breaker to trip on startup. During startup that voltage will probably come down. It may be something to look at for the future, but for now it is probably fine.

I see that you have another 3-phase tool--tablesaw. You could recheck the voltages with the tablesaw running to see how close to balance you have with a tool motor running. Each additional motor you operate on a rotary phase converter will help bring the generated phase closer to the ideal value.

Offline Rick Christopherson

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Re: 3 Phase Breaker Tripping
« Reply #13 on: September 06, 2014, 02:57 PM »
Quote
it sounds like high inrush current is tripping the breaker before it gets up to operating speed
I doubt this is the problem; the breaker that powers the phase converter is not tripping. 

To the contrary, inrush current is the root problem, but you need to discover what is causing it. No, the single phase breaker is not tripping nor should it be. The inrush current on the dust collector motor is tripping the 3-pole breaker feeding it.

The current through an induction motor will be at it highest when the motor is running at its slowest. When the motor is stalled, the windings appear as a near short-circuit with the only resistance being the resistance of the copper wire. As the motor begins to turn, the magnetic field in the motor creates additional resistance (called reactance) in the windings that is proportional to the speed of the shaft. So the faster the motor turns, the higher the resistance of the coils, and the lower the amperage. Yeah I know. That's more than you really needed to know.

Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #14 on: September 06, 2014, 03:21 PM »
We just closed off the dust collector to see if that made any difference and it did not.

Rick - when I start the tablesaw, the C Phase does come down in voltage.  I can't remember what it came down to, but I think it was about 230V from 273V.  I have tried starting the saw first and then the Dust Collector but that didn't make a difference. 

Here is another question:
Sometimes, the 3 phase breaker for the Dust Collector doesn't actually trip but the Thermal Overload protector is tripping.  I think that's called the Thermal overload protector? It's in the ON/OFF box of the Dust Collector.  I'll take a picture and post it.  Could that be the problem?

Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #15 on: September 06, 2014, 03:37 PM »
Here is the photo inside the ON/OFF box on the dust collector.


Offline Rick Christopherson

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Re: 3 Phase Breaker Tripping
« Reply #16 on: September 06, 2014, 03:41 PM »
Here is another question:
Sometimes, the 3 phase breaker for the Dust Collector doesn't actually trip but the Thermal Overload protector is tripping.  I think that's called the Thermal overload protector? It's in the ON/OFF box of the Dust Collector.  I'll take a picture and post it.  Could that be the problem?

If it was only the breaker or only the thermal, it would be easier to say that that device was the problem. However, since both of them have tripped, it is more likely the motor (although still may be breaker/thermal).

How long does it take before the motor sounds like it is approaching full speed? With the inlets blocked, this should take just a couple of seconds. If it is coming up really slow, that would be why both of these devices are tripping.

Oh, I just thought of something. Since this is a new dust collector for you, have you checked to make sure it is not configured for 480 volts (460 on the nameplate)? You previously said you once ran the motor, but simply getting it to run does not guaranty that it isn't configured for the higher voltage. This of course assumes that it may be a dual voltage motor. Not all motors are dual voltage, but it is still pretty common.

If you are not sure, open up the junction box on the side of the motor and inspect how the wires are connected together. If it is a dual voltage motor, it will typically have a connection diagram printed on the inside or outside of the junction box. If you don't have a diagram, at least count how many wires are going into the motor (not counting the 3 supply wires entering the junction box). If my fuzzy memory serves me, it should be either 9 or 12 wires.

Your newest post came in while I was typing. I'll take a look at that picture in a minute.

Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #17 on: September 06, 2014, 03:51 PM »
Quote
How long does it take before the motor sounds like it is approaching full speed?
It doesn't sound like it ever gets up to full speed.  It sounds like it's accelerating for about 10 seconds and then the breaker and/or thermal overload trips. 

I checked to see if it was wired for 460 and it's not.  It is wired for 230.  I had the same exciting thought last night and then was sorely disappointed this morning...


Offline Rick Christopherson

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Re: 3 Phase Breaker Tripping
« Reply #18 on: September 06, 2014, 03:58 PM »
It sounds like it's accelerating for about 10 seconds and then the breaker and/or thermal overload trips. 

I was in the middle of typing another post, but this is way more important. 10 seconds is way too long for a normal startup. This is why the breaker/thermal are both tripping.

Double check the wiring at the motor. I know you said it was set for 240 volts, but triple check it then.

Also, get your volt meter in there and check the voltages at the motor. You might have lost a phase. So check the voltages just like you did previously from A-B, A-C, and B-C.

Inspect the wire connections inside the motor junction box to ensure there isn't a loose wire under one of the wire nuts.

Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #19 on: September 06, 2014, 03:59 PM »
I found a troubleshooting guide for the Marathon Motor (the motor on the DC).  One of the listed problems is slow acceleration of the motor and the cause is too small of wire size.  I'm currently running #10, should I switch to #8 and see if that makes a difference?  It's a relatively short run (about 15').

Offline Rick Christopherson

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Re: 3 Phase Breaker Tripping
« Reply #20 on: September 06, 2014, 04:02 PM »
No, the wire size would not cause this long of a startup time. A loose wirenut could, but I have a feeling you lost a phase somewhere.

Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #21 on: September 06, 2014, 04:11 PM »
I'm heading back to the shop now.  I'll report back shortly...

thanks

Offline Rick Christopherson

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Re: 3 Phase Breaker Tripping
« Reply #22 on: September 06, 2014, 04:29 PM »
I looked at your picture. You have an Allen Bradley contactor (A26-30-10) and overload (TA25DU25). This is NOT your main problem, but the overload setting is a little low. Right now it is just slightly over 20 amps, but your motor is rated at 21 amps. Because it is a dust collector, it will be running close to full rated load.

After you diagnose the long, 10-second, startup, if the thermal overload trips under normal use, you could dial it up slightly. If it doesn't trip, then leave it where it is.

By the way, the other 2 dials appear to be set correctly, and they just control whether the thermal overload uses manual versus automatic reset.

P.S. When you are checking wirenut connections described previously, don't forget to inspect all of the terminal lugs on both the contactor and overload blocks.

Offline Rick Christopherson

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Re: 3 Phase Breaker Tripping
« Reply #23 on: September 06, 2014, 04:51 PM »
This is really a huge stretch and not likely to be true, but it is worth asking simply because I have seen people do this.

Some people mistakenly think that a wye configured motor means that it is supposed to be connected to power in a wye configuration too. This is not correct. Motors should always be connected as Delta (just 3 wires) to the incoming power. They can get away with it if they have 3-phase wye (120/208) power, but you do not. So make sure the previous owner did not connect either the neutral or ground to any of the wires inside the motor. The ground should be going to the metal frame of the motor, but not to any of the motor leads.

Your phase converter is the equivalent of an open-delta, and the neutral point is not a center point. (See the image I posted earlier). If the neutral or ground are connected to the center of the motor's wye configuration, it will pull the generated C-phase down to a low value.


Offline Michael Kellough

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Re: 3 Phase Breaker Tripping
« Reply #24 on: September 06, 2014, 04:54 PM »
Quote
it sounds like high inrush current is tripping the breaker before it gets up to operating speed
I doubt this is the problem; the breaker that powers the phase converter is not tripping. 

To the contrary, inrush current is the root problem, but you need to discover what is causing it. No, the single phase breaker is not tripping nor should it be. The inrush current on the dust collector motor is tripping the 3-pole breaker feeding it.

The current through an induction motor will be at it highest when the motor is running at its slowest. When the motor is stalled, the windings appear as a near short-circuit with the only resistance being the resistance of the copper wire. As the motor begins to turn, the magnetic field in the motor creates additional resistance (called reactance) in the windings that is proportional to the speed of the shaft. So the faster the motor turns, the higher the resistance of the coils, and the lower the amperage. Yeah I know. That's more than you really needed to know.

Thanks for that explanation Rick. I've puzzled over that more than once.

Offline Rick Christopherson

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Re: 3 Phase Breaker Tripping
« Reply #25 on: September 06, 2014, 05:02 PM »

Thanks for that explanation Rick. I've puzzled over that more than once.

You're not alone, Michael. A lot of people assume that motors don't conform to Ohm's Law because current and voltage appear to be inversely proportional during an under-voltage condition. They don't realize that resistance is not a constant in a motor, and it is what is changing that makes it appear that current and voltage are inversely proportional.

Motors still follow Ohm's Law, but resistance is a mathematical function of frequency.

Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #26 on: September 06, 2014, 08:23 PM »
ok - partial success.  I connected another 3 phase machine (edgebander) and it runs perfectly at the same time as the tablesaw.  So I focused my attention on the dust collector wiring.

All wire nuts and connections are secure and correct at the motor.  After inspecting the overload, I noticed that the reset button was "sticky" and inconsistent.  I decided to bypass the thermal overload as a quick test.  The dust collector starts within 5 seconds and the 3 phase breaker does not trip!  I'm going to pick up a new thermal overload on Monday morning and confirm that's the problem. 

Rick - I know you said that's not the main problem.  Please let me know if you think there is something else incorrect here.  I really just cannot figure out what else could be wrong.  Especially since (2) other machines are running perfectly...

Thanks again to everyone.  I'll post another update on Monday.

Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #27 on: September 06, 2014, 08:27 PM »
Rick - I will review the motor wiring tomorrow to confirm.  I don't think the ground or neutral are connected to any motor leads but I will double check.  Thanks so much for your assistance.  I really like a thorough explanation and you've given me one!

Offline Rick Christopherson

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Re: 3 Phase Breaker Tripping
« Reply #28 on: September 06, 2014, 09:18 PM »
Not enough is known here. Previously you said you had a 10 second startup and now it is 5 seconds. Is this a change, or were you just not specific on the previous time?

If it is a "change", then what changed in your system to account for it? You implied that removing the overload may have caused this change. However, this thermal overload is not a circuit breaker. It does not open any circuits feeding the motor. What this overload does is tells the contactor (a motor relay) that the contactor should open. In even simpler terms, the overload block just senses the current flowing through the wires, and if the current gets too high, then the overload tells the contactor to turn off the circuit. However, the wires passing through the overload block do not get disconnected. It simply acts as a signalling device.

So if removing the contact block is the only thing you changed to go from a 10 second startup to a 5 second startup, then you probably just had a poor connection somewhere between the contactor output and the motor input. If that's the case, you should be able to reinstall the overload block and still see the 5 second startup time, because what you corrected by removing it was a poor connection.



Now on the other hand, if you were mistaken about the 10 to 5 second decrease, then the setpoint on the overload does come into play and was more significant than I suggested in my previous posting. The setpoint of the overload should be increased. Start by setting it to maximum and see if the motor runs like it did with the overload removed. If it does, then dial it down to determine where it results in a trip. Normally you could reliably set this to the motor amperage rating of 21 amps, but because you are powering the motor from a phase converter, you may have one phase with a higher than typical amperage. This overload will sense that single phase and trip prematurely.


Offline phmade

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Re: 3 Phase Breaker Tripping
« Reply #29 on: September 07, 2014, 07:05 PM »
Ok - here's an update:

Firstly - Rick, you're correct.  The problem was not solved by removing the thermal overload.  When I started the dust collector today, it tripped the 30A breaker in my 3 phase panel.  So, I reviewed all of the wiring in the motor junction box.  Everything was secure and consistent with the diagram on the nameplate.  I did not actually check the wiring inside the motor - should I?  In the junction box, there are 9 leads coming out.  Three (T4,T5,T6) of the leads are are wired together and the remaining 6 leads are wired in 3 pairs.  These pairs are consistent with the nameplate label on the side of the motor.

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. 

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. 

So now I feel that I'm back to square one.  I'm trying to be methodical now to diagnose the problem.  Could it be with the phase converter?  Would the other 3 phase machines run correctly if that were so?  My plan is to contact the phase converter company in the morning for recommendations.  They are local and have been very helpful in the past.

I am not a professional electrician but I have done a fair amount of wiring including several homes and all other machines in my shop.  I had an electrician here today (family friend) and he is equally as perplexed as I am.  He has never worked with a phase converter though... My confidence is running pretty low at this point. 

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.

Festool USA does not pre-approve the contents of this website nor endorse the application or use of any Festool product in any way other than in the manner described in the Festool Instruction Manual. To reduce the risk of serious injury and/or damage to your Festool product, always read, understand and follow all warnings and instructions in your Festool product's Instruction Manual. Although Festool strives for accuracy in the website material, the website may contain inaccuracies. Festool makes no representations about the accuracy, reliability, completeness or timeliness of the material on this website or about the results to be obtained from using the website. Festool and its affiliates cannot be responsible for improper postings or your reliance on the website's material. Your use of any material contained on this website is entirely at your own risk. The content contained on this site is provided for informational purposes only and does not constitute professional advice.


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

  • Posts: 162
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

  • Posts: 162
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

Offline fouber

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Re: 3 Phase Breaker Tripping
« Reply #55 on: February 28, 2019, 04:39 PM »
Quote
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.

@Rick Christopherson

<<edit:  tagged Rick - P.Halle, Moderator>>
« Last Edit: February 28, 2019, 06:04 PM by Peter Halle »

Offline Michael Kellough

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Re: 3 Phase Breaker Tripping
« Reply #56 on: February 28, 2019, 08:48 PM »
Nothing at all wrong with bring good information long buried to the attention of the current crop of members.

Offline greg mann

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Re: 3 Phase Breaker Tripping
« Reply #57 on: February 28, 2019, 08:49 PM »
Never bad etiquette to thank someone for help they provide.  [thumbs up]
Greg Mann
Oakland, Michigan