ptonsparky
Tom
- Occupation
- EC - retired
Now you've opened another can of worms, you can explain at a later date.
Over correction
- Thread starter ptonsparky
- Start date
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Now you've opened another can of worms, you can explain at a later date.
Phil Corso
Senior Member
- Location
- Boca Raton, Fl, USA
TopGone...
Good catch! It should have been 1773, making FL-slip = 27rpm => 1.50%
Thanks, Phi
Good catch! It should have been 1773, making FL-slip = 27rpm => 1.50%
Thanks, Phi
May we suppose the no load KVAR of motor to be 25% of its full load KVA i.e 29.1? In that case it is 0.25*29.1=7.28 or roughly 7KVAR. On applying a further 85% reduction on it gives 7*0.85=6KVAR which is the size of the capacitor to be used.
The size of the actual capacitor used may be calculated using the following data:
Phil Corso
Senior Member
- Location
- Boca Raton, Fl, USA
| Gentlemen, Part 2 Surface and Down-hole values based on using nominally-rated parameters, including the motor-design listed in Part 1! SURFACE VALUES | |||||
| Vs, Volts | Is, Amp | PFs | Ss | Ps, kW | Qs,kVAr |
| 460 | 36.1 | 0.833 | 287.7 | 239.6 | 159.2 |
| DOWN-HOLE VALUES | |||||
| Vm | Im | PFm | Sm | Pm, kW | Qm,kVAr |
| 455 | 36.1 | 0.830 | 284.6 | 236.2 | 158.7 |
Part 3, will cover the same situation, but using off-nominal parameters.
Part 4, will be based on PtonSparky's pre-PFC data, but using off-nominal parameters!
Part 5, will be based on PtonSparky's pst-PFC data, but using off-nominal parameters.
Phil
Phil Corso
Senior Member
- Location
- Boca Raton, Fl, USA
Gentlemen...
Thank you for your patience. Following is Part 3 of the series! Please note using the original V, I, PF values in PtonSpark'y data, resulted in kVA, kW, & kVAr values different than the measured ones! I used the former values, i.e., V, I, PF values! Also note this calculation is based on operation w/o PFC!
PART 3:
CALCULATED SURFACE VALUES
Vs Is PF kVA P, kW Q, kVAr
496.2 39.9 0.790 34.3 27.1 21.0
CALCULATED SUBMERSIBLE CABLE VALUES
Vc Ic PF kVA P, kW Q, kVAr
4.5 39.9 0.99 0.42 0.42 0.05
CALCULATED DOWN-HOLE VALUES
Vd Id PFd kVA P, kW Q, kVAr
491.7 39.9 0.790 33.9 26.7 20.5
CALCULATED MOTOR VALUES
Vm Im Mtr Loss Pmech,kW Hp N, Rpm
491.7 39.9 1 kW 25.7 34.3 1,777
Phil Corso
Thank you for your patience. Following is Part 3 of the series! Please note using the original V, I, PF values in PtonSpark'y data, resulted in kVA, kW, & kVAr values different than the measured ones! I used the former values, i.e., V, I, PF values! Also note this calculation is based on operation w/o PFC!
PART 3:
CALCULATED SURFACE VALUES
Vs Is PF kVA P, kW Q, kVAr
496.2 39.9 0.790 34.3 27.1 21.0
CALCULATED SUBMERSIBLE CABLE VALUES
Vc Ic PF kVA P, kW Q, kVAr
4.5 39.9 0.99 0.42 0.42 0.05
CALCULATED DOWN-HOLE VALUES
Vd Id PFd kVA P, kW Q, kVAr
491.7 39.9 0.790 33.9 26.7 20.5
CALCULATED MOTOR VALUES
Vm Im Mtr Loss Pmech,kW Hp N, Rpm
491.7 39.9 1 kW 25.7 34.3 1,777
Phil Corso
Phil Corso
Senior Member
- Location
- Boca Raton, Fl, USA
Finally, a conclusion...
As long as voltage remains the same, down-hole conditions are not at all affected by the PFC!!!
Why? The PFC is in parallel with the series circuit comprised of the down-hole cable and motor.
What, then, is affected? Just the supply current to the PFC location.
It can be proven quite easily by PtonSparky, when he is able! Simply measure three currents: 1) current from source; 2) current to down-hole feeder; and 3) current to PFC!
Also, because the off-nominal voltage is ~ 1.08 times higher than nominal, motor speed will, repeat, will, increase. It's rather easy to test. Just measure the motor's speed! And if you need help with "how", let me know!
PtonSparky... reur puzzlement over "imbalance factor":
The inductive-reactance of a flat-cable configuration is unbalanced because the distance between conductors is unsymmetrical. It is a serious problem for very deep for wells, resulting in motor failure. One cure is to "roll the cable" as is done in long distance transmission lines, yes, even long distance LV cables!
In some situations, when the cable can't be adequately rolled, a special device called a phase-equalizer is installed at the surface that controls phase-current imbalance, but that's a topic for another thread!
Regards, Phil Corso
As long as voltage remains the same, down-hole conditions are not at all affected by the PFC!!!
Why? The PFC is in parallel with the series circuit comprised of the down-hole cable and motor.
What, then, is affected? Just the supply current to the PFC location.
It can be proven quite easily by PtonSparky, when he is able! Simply measure three currents: 1) current from source; 2) current to down-hole feeder; and 3) current to PFC!
Also, because the off-nominal voltage is ~ 1.08 times higher than nominal, motor speed will, repeat, will, increase. It's rather easy to test. Just measure the motor's speed! And if you need help with "how", let me know!
PtonSparky... reur puzzlement over "imbalance factor":
The inductive-reactance of a flat-cable configuration is unbalanced because the distance between conductors is unsymmetrical. It is a serious problem for very deep for wells, resulting in motor failure. One cure is to "roll the cable" as is done in long distance transmission lines, yes, even long distance LV cables!
In some situations, when the cable can't be adequately rolled, a special device called a phase-equalizer is installed at the surface that controls phase-current imbalance, but that's a topic for another thread!
Regards, Phil Corso
Last edited:
Phil Corso
Senior Member
- Location
- Boca Raton, Fl, USA
PtonSparky… regarding my original admonishment concerning over-correction of PFC…
Such a condition is highly unlikely to occur in your situation. Upon de-energization of the motor, check-valves will prevent water-column collapse, thus it can’t overhaul the motor!
Phil
Such a condition is highly unlikely to occur in your situation. Upon de-energization of the motor, check-valves will prevent water-column collapse, thus it can’t overhaul the motor!
Phil
ptonsparky
Tom
- Occupation
- EC - retired
Pump/well motor also has a ratchet that allows spin in only one direction No backspin when power is removed.
jjs
Member
- Location
- Puryear, TN, USA
thanks to all the participants. I enjoyed the thread.
one question, is down the hole measured at the motor at the point it sits in the well(hole) or does that mean something else?
one question, is down the hole measured at the motor at the point it sits in the well(hole) or does that mean something else?
ptonsparky
Tom
- Occupation
- EC - retired
This comment was for a typical hollow shaft, not the submersible used here.
ptonsparky
Tom
- Occupation
- EC - retired
Phil Corso
Senior Member
- Location
- Boca Raton, Fl, USA
JJS...
Downhole conditions (the motor) are calculated from measurements made on the surface.
Phil Corso
Downhole conditions (the motor) are calculated from measurements made on the surface.
Phil Corso
- Status