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  1. luktek

    Can a Constant Torque VFD on Variable Torque Motor (Centrifugal Pump) cause failure?

    This problem is being caused by reflected waves and the rapid rise and fall of the pwm waveform. You mentioned load reactors and dv/dt filters on the output of the VFDs...is it both? Do the cables travel through water at all? The readings for voltage you are getting on the output of the VFD -...
  2. luktek

    Inverter motor side

    Check the output cabling, including opening up the motor termination box to see if there has been anything shorting. I am also curious as to whether you have a solidly grounded system or a high resistance grounded system?
  3. luktek

    Inverter (vfd)

    Often Engineers will use a rule of thumb in applying output filters, but it has more to than with just length. It also depends on the system voltage. For example, you should probably always have at least a load reactor on 600V vfd outputs. At 480V, the application of filters on the output of...
  4. luktek

    Frequency converter for Oil extraction

    Take a look at the Stellar Tech website: http://www.stes.ca/ They have a lot of information there you might find useful under their downloads section. I consider their product to be the most reliable I have come across, with its real strength lying in the ability of their vfd software and...
  5. luktek

    Frequency converter for Oil extraction

    Hi krsh, You do not really need any specific VFD brand for use on pump-jacks, progressive cavity pumps, or electric submersible pumps, the three systems common for oil production. That being said, many manufacturers, such as ABB, Unico, Yaskawa, Schneider, Vacon, etc..have modified their...
  6. luktek

    running a servomotor with VFD

    You will need to go closed loop and have a resolver input back to the VFD to control the firing pulses of the drive. We have done this quite a lot lately and it works very well.
  7. luktek

    CE Shielded motor leads

    Are you shipping a machine to Europe? There are three separate issues with CE, the Machine Directive, Low-Voltage Directive, and EMC Directive. Of the three, the Machine Directive is the most complex and is mainly mechanical in nature. The Low Voltage Directive is fairly straight forward. If...
  8. luktek

    Heat Transfer from stainless steel tank of waters

    Okay, I am going to have to abandon this idea, thanks for your help.
  9. luktek

    Heat Transfer from stainless steel tank of waters

    Another thought: What if we were to mount a large fan blowing on the tank to circulate air on it and create a wind-chill? Would that give us significant gains in cooling and allow for a size of tank that will work?
  10. luktek

    Heat Transfer from stainless steel tank of waters

    Yes, we can deal with large, but we have height issues. Basically, the tank can be 15 feet long but no larger in diameter than 48".
  11. luktek

    Heat Transfer from stainless steel tank of waters

    Hi rb1957 The drives will be run continuously for 6 hours, and then given 2 hour breaks.
  12. luktek

    Heat Transfer from stainless steel tank of waters

    The warmest inlet temperature we can accept is 45C
  13. luktek

    Heat Transfer from stainless steel tank of waters

    For example, lets say we were to look at a single VFD with the following characteristics: losses = 7.9kw flow rate = minimum= 20L/60s, maximum 40L/60s nominal flow rate = 25L/60s pressure drop across drive = 1.96bar @ 40L/60s, 0.43bar @ 20L/min ambient temperature 30C how big would the tank...
  14. luktek

    Heat Transfer from stainless steel tank of waters

    Hi There, We would determine the size of the tank based on how large it needs to be to reject 36,230 Btu/hr. The environment we are working in is an underground mine where water to air heat exchangers seem to not stand up to the dust. I am wondering if this might be a simpler solution.ie, a...
  15. luktek

    Heat Transfer from stainless steel tank of waters

    I am using Liquid Cooled Variable Frequency Drives and am wondering if it would be possible to cool the drives sufficiently using a large stainless steel tank full of water and then a pump to cycle water through the VFDs. The ambient temperature will be a constant 30C. I am not really familiar...
  16. luktek

    Can power factor capacitors cause additional heating in motor?

    The current and voltage imbalance that you mentioned will overtime degrade your power factor correction capacitors.
  17. luktek

    Powering Soft-Start with a VFD

    I think we are going with djs suggestion in this case. The SCRs are internal to the actuator and we would prefer not to bypass them.
  18. luktek

    Powering Soft-Start with a VFD

    I am wondering if anyone knows of any issues that could arise by powering a soft-start with a VFD. Basically, we need to use the VFD as a phase converter to supply a 3 phase actuator that has SCRs. Has anyone run into anything like this before?

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