Burnt out kstep :(


Results 1 to 4 of 4

Thread: Burnt out kstep :(

  1. #1
    Registered
    Join Date
    May 2013
    Location
    Canada
    Posts
    5
    Downloads
    0
    Uploads
    0

    Default Burnt out kstep :(

    Hi all, my name is Curtis.

    I am using a kflop/kstep board and have been getting great performance with my initial motor testing. I was testing with a 48V power supply and a nema 34 5.5amp motor. The motor was running great so I installed it on my machine and wired it in with a longer motor cable. Then i turned on my 48V power supply and I saw sparks at the kflop motor terminal. Keep in mind this is before the kflop\kstep was powered. All the current jumpers were installed on axis 0 and I triple checked the wiring.

    Heres where I may have messed up, can anyone comment what may have been the cause of the failure?

    1. the voltage clamp had two jumpers installed. for my 48V power supply it should have been none installed.
    2. my motor spec sheet did not make a distinction between A- A+ etc. my motor wiring is labeled as A A B B not A+ A- B+ B- so its possible the pair polarity was switched. I have wired this setup multiple times like this so if this was the cause it would be weird that it only happened now.
    3. when I measure the unloaded voltage of my power supply, it reads 52 volts. is this too high for the kflop to handle? The motor was working perfectly with this input voltage before I rewired.

    Now after all of this it appears that 3 of the fetts have been blown open and 5 of the resistors feeding them have blown. No visible damage to the chip. All of this points to a bad wiring issue but I cant seem to find my mistake. Both Kflop/Kstep power on fine but none of the motor outputs work anymore. Now I am going to order a new kstep but I dont want to blow that one too. Where did I go wrong?

    Thanks,

    -Curtis

    Similar Threads:
    Attached Thumbnails Attached Thumbnails Burnt out kstep :(-kstep_top1_800_bad-parts-jpg  


  2. #2
    Gold Member TomKerekes's Avatar
    Join Date
    May 2006
    Location
    USA
    Posts
    2526
    Downloads
    0
    Uploads
    0

    Default Re: Burnt out kstep :(

    Hi Curtis,

    Sorry to hear this. The max allowed motor supply voltage is 48V. 52V is clearly over spec but wouldn't have expected that to be enough to cause the failure. What kind of power supply are you using? Regulated or unregulated? Is it isolated from earth/frame GND?

    Having no +5V would keep the FETs disabled with no current flow, but the driver chips would still be susceptible to over voltage.

    Having the voltage Clamp set to 25V would have caused the voltage clamp to fail or give up quickly so the voltage would go to 52V.

    Regarding:

    #1 - that is bad. Even with no jumpers installed the supply should be clamped to 49V

    #2 - reversing + and - on a stepper will just reverse the direction it rotates. It should not cause any other problem.

    #3 - the peak unloaded voltage should be 48V or less.

    What are your motor specifications?

    Are you sure your wiring was correct? Did you check with an ohm meter from coil to coil and from coils to GND?

    Regards

    TK
    http://dynomotion.com


  3. #3
    Registered
    Join Date
    May 2013
    Location
    Canada
    Posts
    5
    Downloads
    0
    Uploads
    0

    Default Re: Burnt out kstep :(

    Hi Tom, thank you for replying.

    I am using a regulated power supply that is isolated from frame ground.

    The motor I am using is here:
    https://catalog.orientalmotor.com/it...y-/pk299-f4-5a

    I am quite sure that my wiring is correct but I did not check with an OHM meter. I will do this next time for sure.

    Unfortunately my power supply has no voltage adjust so I think it is a bad idea to use the 52V power supply. I am buying a new 12.5A 48V power supply with voltage adjust just to be safe.

    I think if I do all that and learn from my mistakes I should be good second time around.

    Question: do you think it is odd that all 4 drivers would be not working? Would removing the affected fetts allow the other drives to potentially work?
    Question2: is it better to turn the motor PS on after kflop power up or before?

    Thanks again for your help, I am happy with the products you have made and I just put an order in for another kflop for a work project.

    -Curtis



  4. #4
    Gold Member TomKerekes's Avatar
    Join Date
    May 2006
    Location
    USA
    Posts
    2526
    Downloads
    0
    Uploads
    0

    Default Re: Burnt out kstep :(

    Hi Curtis,

    Actually 48V might be somewhat high for those motors. I like to keep the supply voltage to be 10~20X the nominal motor voltage. Otherwise regulating small currents becomes problematic.

    How are the motors wired? Series or parallel? You said they are 5.5A but the spec says 6.5A in parallel configuration.

    With KStep set at full 5A and a motor resistance of only 0.33 ohms the motor voltage would only be 1.65V

    48V / 1.65V = 29X

    But that wouldn't explain a failure with 5V off and FETs off.

    It shouldn't matter the order of turning on the supplies. But it probably makes moresense to have 5V on before the high voltage.

    Regards

    TK
    http://dynomotion.com


Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


About CNCzone.com

    We are the largest and most active discussion forum for manufacturing industry. The site is 100% free to join and use, so join today!

Follow us on


Our Brands

Burnt out kstep :(
Burnt out kstep :(