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  • Users: BigLe
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  1. BigLe

    VFD driven induction motor has flickering currents at lower speed

    Thank you for the analysis, skogsgurra. The drive I was using is a MagneTek GPD205 model CIMR-XCBD21P5. rated for 3hp 0-230Vvac input and 2.7kVA 7A output. max freq 400hz. it was on a 3phase main when the problem occured. I will check the balance of the ac main later then. But the other drive...
  2. BigLe

    VFD driven induction motor has flickering currents at lower speed

    I have a 3 hp Dayton induction motor which is rated at 208-230/460V 9.7-9.4A/4.7A at 60hz. 4 pole and sf=1. when driven with a v-hz type drive with a const v/hz gain 208/60, it behaves strange in the range of 20 to 30hz or so. the three phase currents flickered and the sound from the motor...
  3. BigLe

    Stator/Rotor Resistance/Leakage Information

    Parameters of the motor are not a function of hp, but its intrinsic properties. There are ways to measure/calculate the parameters you mentioned and it involves usage of power meter and running the locked-rotor test, no load test, etc. There is an IEEE procedure described in some thread before...
  4. BigLe

    12 volt dc to power vfd controllered 3 phase motor

    good point.. just noticed it was 'sign wave'..
  5. BigLe

    12 volt dc to power vfd controllered 3 phase motor

    Did you start the motor with load? Can you try to start the motor with the same drive configuration but don't load it yet, if there is still an overload error, would you double check the winding of the motors and its grounding? also for the drive, i assume it's a v/hz type one, would you double...
  6. BigLe

    12 volt dc to power vfd controllered 3 phase motor

    how did you configure the battery pack? did you load the motor while it failed? did you measure the battery voltage before, during and after your inverter failed? and by 'fail', is there a failure code given by the inverter?
  7. BigLe

    nameplate speed on induction motor??

    jraef's answer was clear. the name plate speed is acquired under rated condition. with no load you can pretty much reach 99.9% of the synchrous speed if lube is good. for example if you have a 4 pole machine the synchronous speed is 1800rpm, with no load, you should be able to observe 1799 rpm...
  8. BigLe

    PWM DC MOTOR at low frequency...

    What's the rational to change the pwm frequency? if it's a dc-dc converter type of drive.. switching frequency would be fixed for most applications.
  9. BigLe

    Motor Nameplate speed

    To get a thorough understanding of the load needs more tests. As aolalde pointed out, power factor and efficiency are to be provided.But from my personal experience.. efficiency may not change much within +/-20% full load but power factor may. If it's hard to measure these two quantities in your...
  10. BigLe

    Motor Nameplate speed

    With small slip, load is proportional to square of the voltage and proportional to slip itself. for norminal case: slip =14/1800=0.0077777. Under your case slip=10.5/1800=0.0058333. See if you have the same voltage as rated, 0.0058333/0.007777 = 75%. But when you are running at 4162Volts instead...
  11. BigLe

    VFD Puzzler

    Did you put the 2 screws away? It is not terribly difficult to remove the front panel of the drive and you can at lease see if there are more screws stuck in between the boards..
  12. BigLe

    Small High Torque Motor

    leonar, are you sure about the requirements? a 25 oz-in at 1800 rpm translates to 33.25 Watts mechanical output. The 28W input won't work.
  13. BigLe

    Over excited motor

    jraef is absolute right in the explanation. One thing I forgot to mention is the load. if the load in your application is always less than your rated W/(100*2pi) N-m, it won't trigger an overload on those advanced drives, which will start the 'field weakening' operation above the base speed(so...
  14. BigLe

    Over excited motor

    if your motors are rated at 60Hz and you happen to use the V/Hz type drives, you might need to modify some of the parameters on the drives so that the motor would not be operated under much-higher-than-rated voltage for long time. check a so called 'field weakening' operation of the induction...
  15. BigLe

    measurement of 3 phase input currents and voltages

    I would suggest using a digital scope or daq unit instead doing a high-power to logic-power conversion on your own. some scopes, check if you have some Yokogawa ones, can store quite a lot data (2G and more... ) and some advanced multimeters (fluke.. ) get the interface to the computer... check...
  16. BigLe

    Induction motor parameter determination.

    Hi, I need to measure all the parameters of an induction motor(squirral cage). While I found some standards on Nema and Ieee, they are not that straight forward. Any one gets links or documents that describes a "standard" proceedure to do the measurements? ( Rr, Rs, Lr, Ls, M ) .. thanks in...
  17. BigLe

    Help on Flux Measurement in IM

    Thanks, guys, by observer, i mean to reconstruct the flux information from the measured stator currents and the knowledge of machine parameters. it's "calculated/estimated" flux, which is used in Indirect Field-oriented Control of IM motor. Talking about coil, I do have one wound around a...
  18. BigLe

    Help on Flux Measurement in IM

    Any one gets some experience on the measurement of magnatic flux position in an induction motor? I'm in the middle of a project that need such direct information instead of observers. the flux magnitude is not that important, just the position. Thanks a lot

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