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Thread: Conquest T42: Opening main collet more than few seconds trips hydraulic motor breaker

  1. #21
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    Default Re: Conquest T42: Opening main collet more than few seconds trips hydraulic motor bre

    This morning, the temp outside was -2. Opened the garage door from a balmy 17 degree C shop, so I knew the oil was not an issue. In retrospect, I don't think oil temp was ever the issue. I thought it at the time, but I've since changed my mind. Bad oil however still may be an issue. To be verified.

    My first objective is to find the right balance of capacitors so that when the lathe is sitting idle, collets closed, the hydraulic motor sees a perfect balance. At least with this, I can have the lathe on and not worry that diagnosing for hours will harm the motor. From previous observations, I know that when the system is balanced, the current through each leg in the 3phase hydraulic motor is well below the FLA of the motor. The problem will then be how to balance the RPC so that during longer cutting operations when the spindle causes imbalance, it isn't so much that it trips the hyd motor breaker in the middle of the job.

    For now, this is the data I compiled for various tunings. I first start by getting the system reasonably balanced with just the RPC running and no load whatsoever. When I get close, I start adding load. First, I just turn on the breaker to see how the load changes (this is where I wish I could actually measure the current flowing through the single and three phase lines). Once I get close to a balanced system under that load, then I turn on the control and activate the hydraulic system (what I refer to as "steady state" - the state I figure the machine will be in most of the time when it's not performing work). I will add a fourth state called operation which will be when the machine is actually cutting. But for now, I needed to look at the data compiled so far, presented here:

    Conquest T42: Opening main collet more than few seconds trips hydraulic motor breaker-rpc_balance_chart-jpg

    Having previously observed this steady state become grossly imbalanced again during spindle operations, I am having serious doubts as to my RPC's ability to handle the load. I think I need a much STIFFER voltage from the RPC. The problem with my RPC from WNY is that it only has capacitors between A-B, and B-C. There are no capacitors at all between A-C... unless the start caps are somehow involved, but I don't think so. Their "GOLD" series which I never new about has three banks and claims to have better balancing (?). Given this two-bank design, it is quite possible that my RPC is irreparably undersized. I also don't have a clamp meter to help me better understand the current draw on this system (relative to the RPC's supposed capacity of 20HP). I will head out today and get one; I need current draw to factor into my spreadsheet.

    From here, I will progress to conduct more measurements with a new state called "Operating", which will be the instantaneous voltages during spindle/cutting operations. I think I will need to wire more of these meters into the hydraulic system so I can watch both the hydraulic motor, and the overall system voltage. If I can figure out a compromise between the two where the voltage drops during cutting operations, but not long enough (or imbalanced enough) to trip the hyd breaker, I might get away with my current RPC.

    I strongly doubt I will achieve this with my current RPC though, but it's worth a try. I have a 20HP RPC, combined with a 20HP 4-pole Toshiba 3ph motor. When I get my ammeter and start measuring real currents in steady and operating states, I'll probably answer my own question as to whether this system is sized well enough.

    The FLA on my lathe is a whopping 82A @ 230V, but that is the max with everything running full blast. My main spindle is actually 10HP (states 15HP but for no more than 30 minutes), my sub is 5HP, but they will NEVER be cutting at the same time. The FLA on the hydraulic motor is 3.8. Axes are what they are... 2kw each maybe, and then there are the various fans, pumps, control, relays, bells, whistles, etc. Boy, I really need an ammeter. I think I'll head out now and pick one up.


    Torin...



  2. #22
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    Default Re: Conquest T42: Opening main collet more than few seconds trips hydraulic motor bre

    I meant after the circuit breaker/overload device attached to the contactor.

    One thing. I see you are using a single phase buck boost. I have had nothing but problems trying to use an autotransforming buck boost. They cause 2 things that I see.
    1 they dont alter the voltage on one leg at all. All the bucking is done to one leg of the single phase. Making your voltages all screwey.
    2 they make that bucked leg sag like crazy under load. Mine said it could deliver 108 amps at the configuration I was running it.
    I have tried both with my 10hp and new 15 hp RPC. Finally said enough and now am looking for 20kva 3p 240-208 type. Because I too see 250 volts from my utility and Fanuc regen to line makes my butt pucker.

    You have something going on with your hydraulics, not electrics.
    Does it ever even reach a "idle " state?
    The pumps that are used here throttle themselves based upon flow demand. Low flow required, the pump throttles down but maintains pressure.
    You could plug all four of the collet closer hoses in your case and it should not present any more load than normal.

    And you keep referring to "open" as it is some different state than closed.
    The push and pull states of the closer present the same work to the hydraulic system. It is a double acting cylinder. There is always collet closer pressure on one side of the piston. Some types of work holding use the pull to close and grip the work. Others use the push. There is no relief when open as open for a pull chuck is closed for a different type of workholding.

    Your popping filter indicator means there is something amiss. Along with your having been into the closers. Plugging the hoses might be something to try.



  3. #23
    Community Moderator Jim Dawson's Avatar
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    Default Re: Conquest T42: Opening main collet more than few seconds trips hydraulic motor bre

    Nice looking chart. That was a lot of work.

    Sorry I don't have anything useful to add to the conversation.

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: Conquest T42: Opening main collet more than few seconds trips hydraulic motor bre

    I understand now why you only provided one reading. Your CNC reads the same open or closed, so no need to provide two readings.

    Though whereas your CNC has no load difference between the open and closed state, mine does. The sound is different (more laboured when the collet is open), and I have a distinct voltage drop that only occurs when each collet is in the open state. As I stated earlier, it is more pronounced on the main than the sub, but both have more load in the open state.

    Until late Sunday, I had no clamp meter and could only take readings through my fused bench meters. I had a Mastek (chinese) clamp meter I bought 25 years ago, but it never worked, so I picked up a new one late Sunday and was finally able to get readings. I felt like I was blind my whole life and could finally see.

    I measured my hydraulics in the steady state 2.7A/2.6A,2.7A and the mains voltage at 225 or so, then I quit for the day. I will try to get to this on Tuesday when there are no extracurricular activities.

    Now armed with a working tool, I will go back in and perform these same tests but adding the operatiing state I mentioned earlier. I will record all voltages, currents (both through the mains and in the hydraulic unit) with and without the spindle running. I will try to find the right tuning that keeps the hydraulic motor below the FLA in the steady state (say, with the middle leg slightly high) and the correct balance when the spindle is running (middle leg saggy, but not enough to imbalance the hydraulic motor to its trip-point.), I will determine the minimum (steady state current) and maximum (operational current), and I will also assess the voltage drop on the mains. Lastly, I will show the difference both in voltage and current when the main, sub, and both are in their open/closed positions so you can both see the actual effect. I'd make a you-tube video to record the sound too, but voltage/current readings out to be enough to illustrate how my machine behaves.

    To answer your questions about the buck:
    #1 I only see a three volt drop between no-load RPC and 14.3A steady state. I don't know yet what the drop will be when the spindle is running. Can't wait to measure this and find out! I will measure at the mains going in, and the RPC legs going out, as well as on the hydraulics. Good thing I bought ten of those bench meters back when they were on sale...
    #2 I don't see how lowering the voltage of one leg on the mains would make voltages "screwy", since voltage to my RPC is simply the difference between the two lines. Please explain the theory of this effect you're describing, if you could please.

    Hydraulics - I see two things going on with my system. Big imbalances cause one line on the hydraulics to sag, thereby causing the other two to pick up the slack. Originally, when it was terribly imbalanced, I saw 4.1A/1.5A/3.9A at the hyd motor junction box. With a protective circuit set to 3.6A, it was tripping the breaker and shutting down my machine. When I corrected the balance, it stopped happening. The second is in what I describe as open vs closed. Open, for whatever reason, puts a big load on the motor which again exceeds the protective breaker's threshold. I am sill trying to figure that out.

    Yes, my filter popping does indicate something wrong. Don't know what though. I will start with clean fluid and a new filter, and I will write a program that cycles each collet open and closed repeatedly and see if the cycling can dislodge sludge, shellaq, or anything else that might be causing the main to draw more current in the open position.

    Quick note: This past week I noticed after sitting with the machine running for about 45 minutes that the hydraulics in the open position began to get more and more noisy. So I closed the collet, opened it, closed it... I kept cycling the main collet until the noise reduced. A gremlin is lurking in there somewhere. Just haven't found him yet.



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    Default Re: Conquest T42: Opening main collet more than few seconds trips hydraulic motor bre

    Not a problem. I love the feedback so far, and I'm glad to have you watching. Sometimes it really helps to talk through one's problems.

    Now armed with my clamp meter, I will really start generating data. I know I will eventually stumble upon the solution.


    Torin...



  6. #26
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    Default Re: Conquest T42: Opening main collet more than few seconds trips hydraulic motor bre

    So, yesterday was a bust because of kids activities, but I managed to squeeze in a little test.

    IT'S TOTALLY PRELIMINARY. I was just playing with my new clamp meter, and I decided to try out my Fluke's data capture for the first time.

    Here's what I have:

    Conquest T42: Opening main collet more than few seconds trips hydraulic motor breaker-current-jpg

    1 millivolt AC = 1A. This data is captured on the incoming single-phase line.

    1. I turned on the RPC, started the meter recording, then turned on the breaker. (Spike #1) Machine is now drawing ~10A.
    2. Walked around to the front of the machine and turned on the control, which also started the hydraulics (spike #2. Machine now drawing 15~16A)
    3. Started my program which starts the sub spindle, performs several facing cuts (big spike), then the main spindle startrs (tall thin spike) and the sub moves toward the main for a spindle transfer.
    4. I then cancelled and ran back into the house to play with my new data.

    So ... opinions? Jim? I'm running at 15A without even doing anything, then it looks like I'm running at around 25A while performing various operations.

    25A 1ph is about 25 x 100/173 = 14.4A 3ph. The motor's full current rating is 25 though... so don't think this current draw explains the severe voltage sagging. But then it might to a subject matter expert like yourself.

    But this is preliminary. More tests to come.

    I have my eyes on a 30HP baldor, but it's 3600 RPM and I would prefer 1800 in case the fan is too noisy. I don't mind the noise, but I'm afraid 3600 might sound like a jet engine compared to my relatively quiet 1800 rpm toshiba.


    Torin...



  7. #27
    Community Moderator Jim Dawson's Avatar
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    Default Re: Conquest T42: Opening main collet more than few seconds trips hydraulic motor bre

    Interesting readings. And a very cool graph. What Fluke meter do you have? Mine have no provision for data recording, a 87V and a 32 Clamp Meter. I'll get some readings from my lathe tomorrow morning.

    Do you have any power factor correction caps across L1-L2? Those really reduced my input current.

    Here is my as built schematic

    Conquest T42: Opening main collet more than few seconds trips hydraulic motor breaker-rpc-built-jpg

    And the panel meters under idle load with the hydraulics running, spindle off. These meters agree with my Fluke meters. Not bad for $14 each.

    Conquest T42: Opening main collet more than few seconds trips hydraulic motor breaker-img_1803-jpg

    Attached Thumbnails Attached Thumbnails Conquest T42: Opening main collet more than few seconds trips hydraulic motor breaker-rpc-built-jpg   Conquest T42: Opening main collet more than few seconds trips hydraulic motor breaker-img_1803-jpg  
    Jim Dawson
    Sandy, Oregon, USA


  8. #28
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    Default Re: Conquest T42: Opening main collet more than few seconds trips hydraulic motor bre

    Mine is a Fluke 289. I operated with a Radio Shack Multimeter for nearly 30 years, and had many models including the three (of ten) benchtop meters I photographed earlier. I also had this Fluke 100Khz to 2.1GHz signal generator sitting in my basement from my old ham-radio days, but I just never really used it. One day, I saw the Fluke 289 on Kijiji (Canada's craigslist) and the guy accepted a trade. He got the better deal, I thought, until I made that graph :-)

    Yes, I saw your schematic before - the one with the switches. I actually have some ideas for how one could make those switches of yours programmatic (during operation that is), but I won't share here. Not just yet. Possibly patent-able IP :-)

    What values are you using for those caps? And if you were to double your RPC capacity from 15HP to 30HP, what would you do to modify it? I have to do that with mine. I'm at 20HP now, and must boost to 30HP. I don't know if it's a simple linear equation (i.e. just double the capacitors.) Many RPC manufacturers are unwilling to share the inner details of their units.

    No, I don't have a power-correction capacitor across L1-L2. The guy at WNY warned me to be careful (not to add too many lest the voltage get too high for my machine), but I don't exactly know how to add them proportionally. Any advice? WNY actually sells a "gold" version of their RPC which Jacques claims better balances for CNC and it has three groups of caps rather than two. I tried calling him and leaving a message, but no call back.

    The meters you have on your RPC are incredible. I don't think I saw them before. They are exactly what I need. Where did you get them? What ebay vendor?

    I am pretty impressed with the Fluke for showing me that data, and I'm eager to perform more of these tests but I want to write a program first. One that incrementally adds more load to the system representative of what I might actually encounter during a program that cuts my products. My plan is to write the program, trigger the fluke to start recording using threshold value (so it always starts at the same place), then use the meter to record Current on mains (L1-L2), then voltage on each of the phases (T1-T2, T2-T1, T1-T3), and perhaps I'll also monitor my hydraulic motor since it's the big pain in the ass in this scenario. When I'm all done, I will take all of the data and overlay them onto the same graph giving me a readout of current consumption, voltage drop, and balance effect on the hydraulic motor.

    On a completely different note, I was able to get wiring details from Baldor on their gen-purpose 20, 30, and 40HP motors figuring that if I could somehow relate the baldor 20HP motor's winding resistance with the voltage drop I'm seeing, I could somehow translate that to a proportionally lower drop on the 30 and 40 HP motors because of the larger motor's lowered resistances. Unfortunately, I haven't figured out the relationship (math) to give me the ratio I'm looking for. I need to measure the current through each of T1, T2, T3 during the imbalance to figure out why the generated leg is so saggy. Otherwise, I will have trouble deciding on which of the 30HP or 40HP motors to buy.

    Sorry... too many questions and topics in one thread. I do tend to go on :-) Gotta go and find me those meters.


    Torin...



  9. #29
    Community Moderator Jim Dawson's Avatar
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    Default Re: Conquest T42: Opening main collet more than few seconds trips hydraulic motor bre

    https://www.ebay.com/itm/100A-AC-LCD...EAAOSwldRaAvwb

    The capacitors were roughly calculated to give me the starting point by this formula:

    L1-T3 = 4 to 5 times the motor horsepower
    L2-T3 = 10 to 15 times the motor horsepower
    PF COR = 30 MFD (10+5+5+5+5), and could use more

    Interestly enough when I first fired it up to bench test it was drawing about 25 amps (L1) with no load and with no caps switched in. Then I hooked it to a load bank, three 2200W stove top elements, and it was still drawing about 25 amps. The stove top elements got hot and the idler motor load seemed to have just vanished.


    Jim Dawson
    Sandy, Oregon, USA


  10. #30
    Community Moderator Jim Dawson's Avatar
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    Default Re: Conquest T42: Opening main collet more than few seconds trips hydraulic motor bre

    Here are my readings:

    Conditions: Controls on, various fans on, 1 servo powered up, spindle VFD powered up, but not enabled

    L1 10.1 amps
    L2 9.9 amps
    242 volts

    The control transformer and some fans are on T1-T3
    T1-T2 3.3 amps, 241 volts
    T1-T3 3.4 amps, 242 volts
    T2-T3 3.0 amps, 239 volts

    Hyd Pump
    T1 2.1 amps
    T2 2.1 amps
    T3 2.1 amps

    I wasn't able to run the spindle because I'm working on the software and it's a PITA to run manually with a mouse. That's tomorrows project, getting the turret dialed in today.

    Jim Dawson
    Sandy, Oregon, USA


  11. #31
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    Default Re: Conquest T42: Opening main collet more than few seconds trips hydraulic motor bre

    Thanks for those readings. Your readings aren't far from mine, but I think I'm drawing more because my RPC doesn't have PF caps. Not sure this is important for overall balance, or just for efficiency. Frankly, I don't care about the cost (of being inefficient). I only care about burning out a very expensive machine because of imbalance. What happens to the balance when you run an operation (cutting, facing, whatever)? What does your lathe/RPC peak to when the Spindles ramp up? Are you using the RPC to drive the VFD that drives your spindle, or is it on a separate circuit?

    I was stoked to get into the garage today to start running tests, but it's SNOWING where I am, and I have to have the garage door open to measure from the backside of the lathe. So I'm sitting at my computer instead wishing the weather wouldn't suck. But, I've also been doing research, and calculations, and wanted to run something by you.

    By measuring the operation of the lathe both while idle (my so-called "steady state"), and while running (the "operating" state), I have determined there are basically two states I want to calculate for: At steady state, the machine draws 15A from the single phase, and when operating a program it appears to be drawing approximately 25A with occasional but momentary peaks to as much as 55A.

    At present, I have balanced the RPC to within 2% while the machine is in the steady state, but when I run programs the imbalance jumps to ~12% which could potentially trip the hydraulic motor's protective relay and shut down the machine. If I balance for operation, then the hydraulic motor will be unbalanced while sitting idle (which is far more often) which will either trip the breaker, or reduce the lifespan of the hydraulic motor.

    Reading some papers on RPC and voltage/current imbalance, I decided to calculate for an in-betwen balancing. Tuned for slightly more voltage than required for steady state (but keeping within the hyd motor's FLA), and less voltage than required during operation but enough that the voltage wouldn't drop enough to trip the hydraulic motor the other way.

    Because I've been told getting a bigger idler can stiffen the voltage, I got data from Baldor and used their general purpose TEFC motors in 20HP, 30HP, and 40HP as a basis for calcs. Mine is actually a toshiba, but slight variations shouldn't matter - it's the ratio between the HP ratings that's relevant for determining if I should upgrade my idler.)

    Looking at my spreadsheet, I used the Motor FLA and derived how much imbalance there would be as a percentage of that value. Granted, these calcs may be flaky - I derived the three-phase current the single-phase divided by 1.732, then divided those into the motor's FLA to get percentage.

    Conquest T42: Opening main collet more than few seconds trips hydraulic motor breaker-calcs-jpg

    What I ended up with is, using 20A as a balancing target, I can still use my current RPC with a +/- 6% current imbalance and stay within the hyd motor's nameplate rating (3.8A). By increasing to a 30HP motor, I reduce this imbalance to 4%, and at a whopping 40HP (really, I mean a whopping 430lbs of motor) I can reduce it to 3%.

    Note that the current imbalance calculations are probably wrong because I'm using straight multipliers to get current as a percentage instead of watching voltage. Papers show a small voltage imbalance actually results in a much larger current imbalance, but I don't have the math (or courage) to do these calcs myself. Instead, I will have to wait to test in the real world with an ammeter to see if my assumptions hold true. Anyway...

    I'm currently balanced to less than 2% while under steady-state (idle, hydraulics running) and getting ~2.7A per phase on the hydraulic motor.
    I will then boost the tune for 25A (operating) and compare the hydraulic motor current draw to what I estimated in my spreadsheet
    I will then balance for the mid-way point between these two and compare again.

    Crossing my fingers and hoping it will stop snowing so I can go test this all out.


    Torin...

    Last edited by torinwalker; 04-14-2018 at 05:33 PM.


  12. #32
    Community Moderator Jim Dawson's Avatar
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    Default Re: Conquest T42: Opening main collet more than few seconds trips hydraulic motor bre

    I fired up my spindle yesterday, but still not making chips. Running steady at 81% load, ~26 amps (about 500 RPM, at full torque output from the VFD), I got the following voltage readings. I did not change any caps.

    L1-L2 239 volts

    T1-T2 239 volts

    T1-T3 238 volts
    T2-T3 239 volts

    I didn't check the current.

    I'm avoiding my shop just because it's a little cool out there. I guess I'm spoiled Besides I'm working the lathe CNC software, so I can sit in my warm office




    Jim Dawson
    Sandy, Oregon, USA


  13. #33
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    Default Re: Conquest T42: Opening main collet more than few seconds trips hydraulic motor bre

    According to your previous and recent readings, your machine is balanced to 0.69% when idle, and to 0.27% (yes, each less than 1%) when loaded with 80% spindle?

    Columns A, B, C, D
    241, 242, 239, 0.692520776
    239, 238, 239, 0.279329609

    Where Column D is =MAX(ABS(AVERAGE(A5:C5)-A5), ABS(AVERAGE(A5:C5)-B5), ABS(AVERAGE(A5:C5)-C5)) / AVERAGE(A5:C5) * 100

    What is your RPC and Idler rated for again? 15HP, right? (Mine is 20HP and I get WAY more variation than that only between 15A and 25A, as measured from the single-phase line in)


    Torin...



  14. #34
    Community Moderator Jim Dawson's Avatar
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    Default Re: Conquest T42: Opening main collet more than few seconds trips hydraulic motor bre

    Yes, 15HP. The idler motor is a Baldor SuperE, 4 pole. The spindle motor is a 200V, 5.5/7.5 KW, 1500/6000 RPM, Fanuc, driven by an Automation Direct GS3-2010 VFD, running in sensorless vector mode.

    It could be that running at full line voltage rather than having a buck transformer in the system is the difference. Maybe having the RCP rating closer to the load size makes a difference also.

    Last edited by Jim Dawson; 04-15-2018 at 02:51 AM.
    Jim Dawson
    Sandy, Oregon, USA


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Conquest T42: Opening main collet more than few seconds trips hydraulic motor breaker

Conquest T42: Opening main collet more than few seconds trips hydraulic motor breaker