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  1. MitchusMaximus

    General VFD Enclosure Cooling Question

    Thanks for all the tips regarding this topic. The enclosure does need to be outdoor rated, so I'm looking at NEMA 3R. A think a 12" fan would do the job for keeping the drive cool enough even if this box is out in the sun.
  2. MitchusMaximus

    General VFD Enclosure Cooling Question

    Thanks for the replies! In this case I would be looking at an assumed worst-case of 30C outside the enclosure, my drive is rated to run up to 40C before needing to be derated, so I'm going to aim for that internal temperature. There would be two drives going in this box, each with a heat load of...
  3. MitchusMaximus

    General VFD Enclosure Cooling Question

    Hi all, I have a question regarding cooling an enclosure housing one or two VFDs. Maybe this belongs in the Heat Transfer and Thermodynamics forums, but I will start asking it here. Let's say I use a tool such as the Hoffman NVent Cooling Selection Tool to determine the size of a VFD enclosure I...
  4. MitchusMaximus

    Machine Voltage/Phase Mismatch and Retrofit

    Honestly, my first suggestion was to just get a phase converter and be done with it. Would have saved me a lot of trouble. We used to build rotary converters but got out of that game, we still provide digital phase converters and a company in my province manufactures rotaries, so there are...
  5. MitchusMaximus

    Machine Voltage/Phase Mismatch and Retrofit

    Thank you for your suggestion, we actually are the local motor repair shop, and we might be able to rewind the motors to get them into 240V 3-Ph, but we couldn't reconfigure them to be single phase, and two rewind jobs would be more expensive than the drive + transformer route. Plus I would...
  6. MitchusMaximus

    Machine Voltage/Phase Mismatch and Retrofit

    My customer was looking into getting 3-phase brought in, but it sounds like it was even more cost-prohibitive. It is good to know that the load side auto transformer can work without needing a neutral connection, my transformer guy says that with a little upsizing it will be able to absorb the...
  7. MitchusMaximus

    Machine Voltage/Phase Mismatch and Retrofit

    Good day, I am helping a machinist getting some equipment operational that he has purchased with mismatched voltages. I'll lay out what he has: -240V single phase power -51kVA 230 - 460 step-up transformer -12.5HP 460V lathe -3HP 575V mill -A tight budget My plan is to use an oversized 480V...
  8. MitchusMaximus

    VFD Heat Loss on Single-Phase Input

    Thank you for the input, it sounds like I can use this model and could be able to look at smaller outdoor enclosures when I'm derating drives in this way. I'd love to do some experiments to measure the temperature when a drive is fully loaded vs using a smaller motor off a single phase input...
  9. MitchusMaximus

    VFD Heat Loss on Single-Phase Input

    Hey everyone, in my region we help a lot of farmers set up 3-phase motors for their grain augers or dryers from their single phase 240V service by using oversized VFDs. Occasionally I will have a customer who needs a weatherproof enclosure in order to install the drive outside near the...
  10. MitchusMaximus

    VFD High Input Current

    We measured the line voltage at 123V from each phase to ground, and 210V between phases. The voltage was pretty good and even between phases. I don't think my customer has let the drive run long enough to tell if the drive gets extremely hot when he saw the input current measurement, but 4-5kW...
  11. MitchusMaximus

    VFD High Input Current

    It makes sense to me that even the True RMS Fluke 323 meter would not be able to distinguish harmonic current from actual current drawn by the drive, but does it make sense that the parameter displaying the input current on the drive itself would also show such a high current without accounting...
  12. MitchusMaximus

    VFD High Input Current

    I forgot to mention the frequency output, I believe it is being run full speed at 60Hz. Bringing the speed down should reduce the output current, I wonder if it would be able to bring the input reading down to normal levels.
  13. MitchusMaximus

    VFD High Input Current

    Here is a picture of the nameplate, for reference. It looks like the Power Factor of the motor is 82.0. The current was being measured both with a clamp True RMS meter, but I'm not sure if it has the filtering required to get a proper measurement, and with a read only Input Current parameter on...
  14. MitchusMaximus

    VFD High Input Current

    Hi everyone, I've got a customer who set up a TechTop TD350-011G-2 VFD for a 15HP pump application. On a whim he measured the input current, and measured 60-62 Amps. This is about 20 Amps higher than the VFD's rated input current, and he measured this range on all three input phases, which tells...
  15. MitchusMaximus

    VFD Shaking Loads and Regenerative Braking

    I have another question regarding brake resistors. I understand the theory and application of using a brake resistor to quickly stop a high-inertia load and protect the drive from tripping due to overvoltage reasonably enough. But I am wondering how one would spec a brake resistor for a shaking...
  16. MitchusMaximus

    Speccing a Brake Resistor with missing information

    Hi, all. I work in VFD and electrical controls sales, and I have a customer who is looking to apply some faster braking to his VFD driven motor when he is balancing straw choppers. We are driving a 40HP 1725 rpm motor, being run at a top speed of 1294 rpm. He did some experiments and recorded...

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