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Recent content by MKMason

  1. MKMason

    Overspeed with a VFD

    OK, I'll accept that. This means I really can run the induction motor to 150%(-ish) speed? And not freak about overheat if I'm staying at constant torque?
  2. MKMason

    Overspeed with a VFD

    Ozmosis: I know my pumps pretty well, and understand the issues around pump curves. It's the Process Engineers that do not understand what can and cannot be done and there is my battle. Sometimes I must re-rate pumps with VFD's on the motors, sometimes buy new pumps, and other times the...
  3. MKMason

    Overspeed with a VFD

    Yes, jraef is correct. The pump speed N1/N2 CUBED is = the power ratio (HP1/HP2), I could easily jump from 300 HP to 2000 HP going from 1800 rpm to 3600 rpm. Sooooo... I will use an 1800 rpm motor with the VFD, run normally at 25% less, cut it down 50% more when I need that lower pump head...
  4. MKMason

    Overspeed with a VFD

    WOW. I'm sure getting a lot of great advice here. I don't think the client will like the transformer idea, and has already stated that 600V is not available. It needs to be a VFD, they say. I TOTALLY forgot about the critical speed issue. That could be the achiles heel. Thanks for the...
  5. MKMason

    Overspeed with a VFD

    Thank you Lionel. You are obviously not in the USA. Will this idea you have also work for 480V on a 4160V system? It's a much bigger delta-V. I calculated my required overspeed, and it will likely be 125%.
  6. MKMason

    Overspeed with a VFD

    Oh dear, it seems I've over-simplified the question. The driven equipment is a high flowrate slurry pump, ~500 HP, and the client is attempting to vary the developed pump head to match an increasing downstream restriction that there is no other way around. One could overspeed to raise the...
  7. MKMason

    Overspeed with a VFD

    Hopefully this is an easy question. Which motor is capable of going overspeed, induction or synchronous? How? What would be the maximum increase allowable (%)? Does service factor figure into the equation, ie, does a motor (power) SF of 1.15 limit the speed also to 1.15 x synchronous speed...
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