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  • Users: MAGTiger
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  1. MAGTiger

    bearing currents vs. common mode current

    Is anyone aware of documented research which relates bearing life to the magnitude of rms or peak(pulsing) current? I can measure and reduce common mode current near the motor terminals and must assume that most of the common mode current in this location particularly the peaks (current...
  2. MAGTiger

    SCCR withstand and let through, UL 508A, SB4 question

    We have a simple circuit that consits of a line (feeder?) at 480v, and a parallel circuit, we'd call a branch, with a low SCCR. My understanding is that SB4.4.1 does not allow you to consider the current limiting capabilities of a current limiting fuse when it's located in a branch. I've been...
  3. MAGTiger

    Viryd

    Anyone know the status of this company "Viryd". about a year ago they were pushihg their technology (some sort of continuous variable transmission for wind power I believe)to try and get funding. But I haven;t seen any new press on them since last February. Just wondering if they are moving...
  4. MAGTiger

    Green Power Claims

    When will we get to the point of truth about renewable energy? I read in the local newspaper last weekend that a Biomass plant in Wisconsin costing $250,000,000 will produce 55MW and supply "electricity" for 40,000 "typical" homes. Ok, that's 1375 watts each. The same paper published that a...
  5. MAGTiger

    1ph vs 3 ph cost savings??

    I am aware that some areas, primarily in the western US, both irrigation and downhole pumping are using single phase source to a VFD acting as a phase converter then the 3 phase pump motor. But I'm having a problem seeing the cost justification in this scheme. It seems to be mainly 5 to 70hp...
  6. MAGTiger

    CSI front end characteristics question

    Should it be considered normal for a CSI drive to draw significant triplen and even harmonics? We are seeing as much as 14-18% even harmonic distortion and 10% 3rd harmonics. Total harmonic distortion is like 35%. The drive is running at about 50% of rated hp. Neil
  7. MAGTiger

    Heat Transfer at different ambients vs thermal efficiency

    I am a EE and had 1 heat transfer class 29 years ago so bare with me. If I test a transformer in a 25C ambient and a 50C ambient. In both cases to equilibrium. Will the temperature rise be different? My memory is telling me that the higher temperature will yield a lower rise. Thanks Neil
  8. MAGTiger

    Torque limit

    How does torque limit in a VFD? Is it reducing rms voltage? Neil
  9. MAGTiger

    Field Weakening Point

    Can someone explain the significance of the "Field Weakening Point" parameter in VFD's? Thanks Neil

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