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  1. #1
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    DYN2 drive issues

    I recently make the jump from steppers to servos on my taig mini mill. I run linuxcnc through mesa 5i25 & 7i76 cards. I had the system up and running for a total of 10 hours before I started running into issues. Now I tend to blow a DYN2 drive after a couple minutes of operation. DMM first suggested that I add additional capacitors to my system after the PSU so I did. I tested this and broke yet another DYN2 drive. Anyway, here is the schematic for the power side of my system:



    I have 120 coming from the wall (through a power strip) into a 60V DC PSU. The 3 fuses that are shown are 15A slow blow fuses (digikey pn: F1776-ND). Both times I have fried a DYN2 drive, the fuse on the X axis has blown. The first time a drive was fried, it was when my mill was decelerating in the X from 300 IPM to 0. I was manually jogging (with the keyboard) the second time so it is difficult to know exactly when it happened. I do not have any of the alarm pins on the DYN2 hooked up at the moment.

    System setup
    Max velocity: 5 IPS (300 IPM)
    Max acceleration: 20 inches per second per second
    Ball Screw Pitch: 2.5mm (for maths sake, lets call it 0.1")
    DYN2 drive PN: DYN2-TLAS-00
    Motor PN: 57N-DHT-6ATD1

    I sent the first fried DYN2 back to DMM and this was their response:

    The drive you returned had two burned power transistors caused by over voltage, so we will need to invoice for the drive repair and will send a payment link now. Make sure to put the capacitors at the 60VDC power supply output to smooth and voltage fluctuations.

    I added the two capacitors as they suggested and fried a second drive. At this point, I believe they are just taking guesses and hoping the problem goes away. But at $150 and 1 week lead time, I do not want to keep taking guesses. I personally don't understand how a single drive can be failing due to over voltage from the PSU since all 3 drives are connected in parallel. Does anyone here have any ideas on what I can/should test? The last kit I purchased from them (due to arrive tomorrow) includes two 48V PSUs (to get the necessary power), a new motor and a new DYN2 drive. I will have a total of 4 working drives once this package arrives (X,Y,Z & spare).

    Thanks,
    Travis

  2. #2
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    Jan 2005
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    11124

    Re: DYN2 drive issues

    Quote Originally Posted by Travis1581 View Post
    I recently make the jump from steppers to servos on my taig mini mill. I run linuxcnc through mesa 5i25 & 7i76 cards. I had the system up and running for a total of 10 hours before I started running into issues. Now I tend to blow a DYN2 drive after a couple minutes of operation. DMM first suggested that I add additional capacitors to my system after the PSU so I did. I tested this and broke yet another DYN2 drive. Anyway, here is the schematic for the power side of my system:



    I have 120 coming from the wall (through a power strip) into a 60V DC PSU. The 3 fuses that are shown are 15A slow blow fuses (digikey pn: F1776-ND). Both times I have fried a DYN2 drive, the fuse on the X axis has blown. The first time a drive was fried, it was when my mill was decelerating in the X from 300 IPM to 0. I was manually jogging (with the keyboard) the second time so it is difficult to know exactly when it happened. I do not have any of the alarm pins on the DYN2 hooked up at the moment.

    System setup
    Max velocity: 5 IPS (300 IPM)
    Max acceleration: 20 inches per second per second
    Ball Screw Pitch: 2.5mm (for maths sake, lets call it 0.1")
    DYN2 drive PN: DYN2-TLAS-00
    Motor PN: 57N-DHT-6ATD1

    I sent the first fried DYN2 back to DMM and this was their response:

    The drive you returned had two burned power transistors caused by over voltage, so we will need to invoice for the drive repair and will send a payment link now. Make sure to put the capacitors at the 60VDC power supply output to smooth and voltage fluctuations.

    I added the two capacitors as they suggested and fried a second drive. At this point, I believe they are just taking guesses and hoping the problem goes away. But at $150 and 1 week lead time, I do not want to keep taking guesses. I personally don't understand how a single drive can be failing due to over voltage from the PSU since all 3 drives are connected in parallel. Does anyone here have any ideas on what I can/should test? The last kit I purchased from them (due to arrive tomorrow) includes two 48V PSUs (to get the necessary power), a new motor and a new DYN2 drive. I will have a total of 4 working drives once this package arrives (X,Y,Z & spare).

    Thanks,
    Travis
    I see you have a major problem you can not have the fuse's where you have them if the fuse blows which it will being only 15A the drive will be smoked I use 70V DC supply on the new Dyn2 drives

    What is the power supply you have I would start at this point and the fuse's have to go from where they are you can only have one before the caps and must be at least 20A

    The caps may be to low as well there Breakout Board has 2200uf and the original had 4700uf
    Mactec54

  3. #3
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    Re: DYN2 drive issues

    Quote Originally Posted by mactec54 View Post
    I see you have a major problem you can not have the fuse's where you have them if the fuse blows which it will being only 15A the drive will be smoked I use 70V DC supply on the new Dyn2 drives

    What is the power supply you have I would start at this point and the fuse's have to go from where they are you can only have one before the caps and must be at least 20A

    The caps may be to low as well there Breakout Board has 2200uf and the original had 4700uf
    So if I understand correctly, what you are suggesting is this with the fuse being 20 amps:



    Please forgive me, but I don't understand how this changes anything. I will gladly make the switch, but I want to understand why this should fix my problem. Why is it a problem having the fuses where they are?

    I am using a 60V switching PSU. This one:

    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    I also have added additional capacitors (Per DMMs recommendation) and am currently at 3200uF.

  4. #4
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    Apr 2005
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    1230

    Re: DYN2 drive issues

    Travis;
    In your original fused configuration, if you drop a leg (blow a fuse) it may cause some kind of surge. I have always been warned against fusing single line input to the amps. Give it a try and hope it helps.
    On another subject, I'm trying to install Linuxcnc on my old router with dyn2 drives and 750 watt motors. Would it be possible to get a copy of your ini and hal file? I'm trying to learn this op system so anything I can get my hands on is appreciated.
    Good luck.
    Bill
    billyjack
    Helicopter def. = Bunch of spare parts flying in close formation! USAF 1974 ;>)

  5. #5
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    Re: DYN2 drive issues

    Quote Originally Posted by Travis1581 View Post
    So if I understand correctly, what you are suggesting is this with the fuse being 20 amps:



    Please forgive me, but I don't understand how this changes anything. I will gladly make the switch, but I want to understand why this should fix my problem. Why is it a problem having the fuses where they are?

    I am using a 60V switching PSU. This one:

    https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

    I also have added additional capacitors (Per DMMs recommendation) and am currently at 3200uF.
    Yes that is the best way to do your wiring and the fuse will have to be a minimum of 20A that power supply will also have a fuse inside on the input power so no other protection need for the power supply

    Twist the wire pairs as well this will help with EMI

    The caps should be ok the problem with the fuse's where you had them once they blow there is nowhere for the Back EMF to go and this would overload the drives in deceleration, if it still gets to high you may need a braking resistor but not sure if they can be fitted to the Dyna2 drives, but have never seen the need to have them either, so this should fix your problem with this change, attached photo of packages I used to do you will see the Twisted wiring
    Mactec54

  6. #6
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    Re: DYN2 drive issues

    Quote Originally Posted by mactec54 View Post
    Yes that is the best way to do your wiring and the fuse will have to be a minimum of 20A that power supply will also have a fuse inside on the input power so no other protection need for the power supply

    Twist the wire pairs as well this will help with EMI

    The caps should be ok the problem with the fuse's where you had them once they blow there is nowhere for the Back EMF to go and this would overload the drives in deceleration, if it still gets to high you may need a braking resistor but not sure if they can be fitted to the Dyna2 drives, but have never seen the need to have them either, so this should fix your problem with this change, attached photo of packages I used to do you will see the Twisted wiring
    I just ordered some 20 amp fuses and will try this once they arrive (the 11th). Just out of curiosity, what wires are you twisting, power or signal? That setup is a lot cleaner than what I am working with...

    - - - Updated - - -

    Quote Originally Posted by bill south View Post
    Travis;
    In your original fused configuration, if you drop a leg (blow a fuse) it may cause some kind of surge. I have always been warned against fusing single line input to the amps. Give it a try and hope it helps.
    On another subject, I'm trying to install Linuxcnc on my old router with dyn2 drives and 750 watt motors. Would it be possible to get a copy of your ini and hal file? I'm trying to learn this op system so anything I can get my hands on is appreciated.
    Good luck.
    Bill
    PM sent with info requested

  7. #7
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    Re: DYN2 drive issues

    I ran a loop of 100 of the following code:
    G0 X7
    G0 X0

    No issues running full speed! I did slow down the acceleration slightly, but I think I will bump it back up and try again.

  8. #8

    Re: DYN2 drive issues

    It's the rapid decel that is causing the damage. If the recovered power is greater than the losses in the system and the servo driver, the difference will end up being dumped in those capacitors ie as a voltage surge. You can't store much energy in a couple of small caps like those, so you need to either limit the max decel or fit some form of voltage clamp. Think about it, all that inertia (kinetic energy) in the work, vise, table, saddle etc moving at speed has to go somewhere, ideally as heat where it won't cause a problem.

    On my larger machine, I have a braking module that clamps the voltage somewhere between normal voltage and the max allowable voltage for the servo drives. If you don't have one of those, you simply need to limit your max decel rates. If you don't know what is happening with the voltage (have you got a volt meter or scope?), you will only know you've overdone the decels when you pop yet another drive. I think you know of some settings that don't work now - 20 ins per sec per sec from 300 IPM.

  9. #9
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    Re: DYN2 drive issues

    Quote Originally Posted by Travis1581 View Post
    I ran a loop of 100 of the following code:
    G0 X7
    G0 X0

    No issues running full speed! I did slow down the acceleration slightly, but I think I will bump it back up and try again.
    You should be good now if you rewired everything as it should be, you can max out your acceleration until the drive faults then lower it just enough and a safety factor so that it can't fault out from over acceleration

    Twisting all wires helps don't twist in any Ground wires though just power pairs and signal wires
    Mactec54

  10. #10
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    11124

    Re: DYN2 drive issues

    Quote Originally Posted by Muzzer View Post
    It's the rapid decel that is causing the damage. If the recovered power is greater than the losses in the system and the servo driver, the difference will end up being dumped in those capacitors ie as a voltage surge. You can't store much energy in a couple of small caps like those, so you need to either limit the max decel or fit some form of voltage clamp. Think about it, all that inertia (kinetic energy) in the work, vise, table, saddle etc moving at speed has to go somewhere, ideally as heat where it won't cause a problem.
    Some good thoughts but not needed in this case

    Quote Originally Posted by Muzzer View Post
    On my larger machine, I have a braking module that clamps the voltage somewhere between normal voltage and the max allowable voltage for the servo drives. If you don't have one of those, you simply need to limit your max decel rates. If you don't know what is happening with the voltage (have you got a volt meter or scope?), you will only know you've overdone the decels when you pop yet another drive. I think you know of some settings that don't work now - 20 ins per sec per sec from 300 IPM.
    A Braking Resistor was not going to help his problem, and not needed, for a normal X Y Z axis machine, he will not pop another drive now that he has it wired correct

    He can max out his acceleration until he gets a drive fault then back it off from that acceleration number
    Mactec54

  11. #11
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    Re: DYN2 drive issues

    Quote Originally Posted by Travis1581 View Post
    I just ordered some 20 amp fuses and will try this once they arrive (the 11th). Just out of curiosity, what wires are you twisting, power or signal? That setup is a lot cleaner than what I am working with.
    When you said 20 Amp Fuses, I hope that you are not using them in place of the 15A how you had it wired before, if so the same thing could happen, only ( 1 ) fuse and placed before the caps is the only place you can have a fuse in this design

    For wire being Twisted all except Ground
    Mactec54

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