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  1. ozmosis

    Inverter, Atex motors, star, delta

    Joe9 If this application is an actual real requirement, you should note to following: Using the Invertek drive on an ATEX EEx e designated motor is not permitted unless you independently test and certify the combination of drive and motor, or Invertek do this for you. You will invalidate any...
  2. ozmosis

    Extreme Motor Vibration and Now Motor Failure on VFD in Desperate Need of Help!

    Thanks John. It's really a star to the author. Maybe you should look at the acceleration time of the drive and reduce it, to run on the (correct) 4 pole motor. For VTP's, it is important to get the system up to speed as quickly as possible as the thrust on the bearings is a result of the fluid...
  3. ozmosis

    VFD Testing using Incandescent bulb load

    I can see a mushroom cloud over Sweden...
  4. ozmosis

    Extreme Motor Vibration and Now Motor Failure on VFD in Desperate Need of Help!

    I've referenced this article before and read Allan Budris' reports numerous times, it might be worth a read and then re-think the VFD as the cause...
  5. ozmosis

    Use of PFC with Non Linear Loads (VSD)

    I agree, I see no major issue with the data presented. If the PFC are out of circuit, and you are seeing a PF on average of .97, that seems pretty good to me. THD seems ok if this represents a 24hr average. Gunnar: some drives out there use the plastic film caps on the DC link. Overall, they...
  6. ozmosis

    Use of PFC with Non Linear Loads (VSD)

    Gunnar Not all types of VFDs out there will be too happy with 3% or 4% line reactors. Those with the 'slim DC capacitance' on the DC link will potentially introduce bigger problems by adding an inductor. The > IZ, the > the problem, usually. @JimDaly: better understanding the network...
  7. ozmosis

    Wrong refrigerant charge pressure gauges-High head pressure

    Cjrac I'm no expert (there are plenty of those in this forum) but it sounds like you may have a number of problems. You have two refrigerants that function at different pressures, and the wrong gauge. Yes, I would say this is an issue. Then, someone else telling you that you have an...
  8. ozmosis

    Harmonic Suppression

    As jghrist says, you won't get much better harmonic mitigation than with what you already have. It should be typically <5% THiD with the robicon units.
  9. ozmosis

    Which VFD to avoid GFCI tripping?

    Be careful. Using a drive on a domestic supply shouldn't just be viewed with the ( common) problem of tripping the breaker due to the leakage current. It should be viewed for protection. A fault on a device with a non-linear load ( eg a VFD) could a be a non-sinusoidal earth fault and not...
  10. ozmosis

    1hp irigation pump hooked up wrong

    I would say if there's smoke coming from it, it doesn't sound good. Smoke will usually be the varnish on the windings having overheated somewhat. I'm surprised your upstream protection ( fuse or breaker) didn't provide any trip to the circuit.
  11. ozmosis

    looking to get something like a variable frequency drive, but don't need something that costs $850

    As many have pointed out, I don't understand why the discussion is referring to power (hp) all the time. I would say you need to get back to first principles and determine the torque required to do the task in hand. A VFD is essentially a constant torque device and is linear power between the...
  12. ozmosis

    how to prevent temperature increase in pump system

    I'm no pump expert but always great to read an expert at work. Excellent advice Littleinch
  13. ozmosis

    Two speed AC compressor

    Looking at it from a VFD manufacturers perspective. We develop specialised drives for refrigeration applications, including compressors. Lubrication is an important aspect and has necessitated a function to be developed whereby the drive can be configured to activate, on a timed basis, a 'full...
  14. ozmosis

    Recommendations on a Megger

    Hi Keith If you're only using it a couple of times or so a year, why not rent one? Then you can get a good one. At least it is easier to amortise into your customer invoice with a fixed rental cost, than trying to spread over three years or so.
  15. ozmosis

    250HP Induction Motor - Greater Phase to Phase current Imbalance

    Friend81, As Mark highlights, I'm surprised that no sine wave filter has been incorporated. Most borehole pump manufacturers would specify the dv/dt levels and this would often necessitate an output filter. In doing this, and with the length of motor cable involved, it would also be important to...
  16. ozmosis

    IEC Motors

    IEC 60038 states a standard voltage of (now) 230/400v +/- 10% as the 'nominal' voltage covering the LV range (690vac exception). I would be asking why someone wants an IEC Motor outside this range and, if the are going to reduce by 25% or increase by 75%, what else is on the circuit.
  17. ozmosis

    Overspeed with a VFD

    MKMason I didn't mean my comment to be disrespectful in any way. It was just a comment to highlight the need to keep focused the basics in the application, and that always starts at the prime mover. This is also coming from someone who is in the VFD business for a living and needs to ensure the...
  18. ozmosis

    Overspeed with a VFD

    MKMason I think you need to get back to the basic requirements, all the way up the chain to the core requirements of the application. Forget a VFD for the moment, forget what a motor can and cannot do, forget your voltage supply. You are pumping slurry. You need to change what you have and...
  19. ozmosis

    Overspeed with a VFD

    MKMason Firstly, it would be useful to know what your application is. Do you know the load (torque) characteristics? Secondly, why do you want to over speed? This is a good starting point.
  20. ozmosis

    sizing of a power cable between a motor and inverter drive

    A key question is the distance the cable will run. Can you advise?

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