More information means: 1) drive type and manufacturer, 2) motor type and manufacturer (and possibly rating), 3) cable type and manufacturer, 4) how the cable is attached (at both ends), 5) whether the cable is shielded - and how, 6) whether there are other nonlinear loads and/or sources connected to the same bus as the drive input, 7) how tolerant the process is of small torque/speed variations, and 8) what specific insulation materials are used in the motor winding(s).
Converting energy to motion for more than half a century
Please see info below
1) drive type and manufacturer: VSD Schneider ATV630C25N4 250 kW 380-440 V
2) motor type and manufacturer (and possibly rating), Submersible Pump Saer S 302 A-4/A Impeller stainless steel 220 kW 400 Vac Duty point 350 m3/hr 13 bar 50 m cable directly connected to motor
3) cable type and manufacturer, single core
4) how the cable is attached (at both ends), directly connected to motor, directly connected to VSD
5) whether the cable is shielded - and how, Non shielded
6) whether there are other nonlinear loads and/or sources connected to the same bus as the drive input, 1 soft starter for another pump
7) how tolerant the process is of small torque/speed variations, and : do not know
8) what specific insulation materials are used in the motor winding(s). according to supplier PE+PA
We want to know after what length of cable it is recommended to install a sine wave filter? Some people are saying 20m, 100m, 100feet
Our motor has just failed. The insulation winding is faulty with earth just after 700 hrs of operation.
It seems a VSD is not appropriate for submersible pump. What is recommended acceleration, deceleration time?
Any other precautions to take?
What other means can we use to operate the pump? direct on line, soft starter, auto transformer, star-delta?
{b]SA07 : [/b] Submersible pump operations on variable frequency drives is (now) fairly common.
Part of the question becomes - have you hauled the "failed" motor up to find out whether it was the motor winding or the power cable that is now "grounded"?
Direct from the motor manufacturer's instruction book:
1. Rewindable waterfilled motors (MS series) require the PE=PA insulation to be suitable for inverter duty operation.
2. Max operating frequency should never exceed nominal frequency of motor.
3. Minimum frequency should always ensure adequate cooling, i.e. always > 0.1 m/s. Applied frequency (for steady-state operation) should always meet or exceed 30 Hz.
4. Enable all the protective elements for the drive (over-voltage, over-current, surge limit, etc.).
5. Start time: accel ramp 0-30 Hz in less than 6 seconds. Decel ramp 30-0 Hz in less than 6 seconds.
6. Enable torque boost (if available as a drive function).
7. (Max) number of frequency variations per minute = 8.
8. Set switching frequency somewhere between 3 to 5 kHz.
9. NOTE: Usual cable length tables in VFD documentation is not applicable to submersible pump application.
10. NOTE: Sine wave filters between drive output and motor terminals IS REQUIRED. Standard dv/dt filter is not sufficient (due primarily to high frequency switching and length of lead cable).
Converting energy to motion for more than half a century
Yes we have removed the pump/motor, cables are good.There is no damage on the motor.
Submersible pump was installed in Nov 2021. But we had to wait for permit from authority. It is in operation since March 2023. It has run for about 700 hrs and then it failed.
Please see pics
Over the years I have seen a couple of cables that looked perfect when checked with a multi-meter but failed at higher voltages.
One of those cables took out a VFD but still checked good with a multi-meter.
Have you told us the cable length from the VFD to the motor?
Almost all submersible pumps need a filter.
When in doubt, use a filter.
-------------------- Ohm's law
Not just a good idea; It's the LAW!
