Rewinding of submersible pump motor

[SA07]

Hi
Is it possible to rewind a borehole pump motor? A new pump has operated for about 1 year and has faulty winding. Motor is 220 kW 400 Vac. Motor is VSD driven.

 

[waross]

Pictures?


--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[SA07]

We have not dismantle the motor. Please see attached data sheet of pump/motor

 

[Gr8blu]

SA07 Are you sure the winding is faulty (e.g., manufacturing defect) and not something caused by the application / drive / filter (or lack thereof)? Be sure of the root cause before repairing/rewinding, or else risk having the same issue crop up during the repair's warranty period.

As to the motor winding itself - it's a 220 kW 2-pole operating at a nominal 400/3/50 (depending on drive setpoint). The exterior material(s) are stainless steel; the diameter is very small (stator ID will be roughly 6-7 inches). End turn length and support will be critical to performance. Quite possibly a "potted" coil construction, where the ends of the coil are encapsulated in a non-conductive, non-reactive material. Ingress protection (meaning seals and fits) is IP68 or better - which is not trivial.

Note that the specification sheet indicates that THE MOTOR IS STARTED DIRECTLY. That typically means it is not intended for use on a VFD!! The "range of operation" shown in the spec graphs is NOT an operating range, it's an application range - meaning operation is only at one point anywhere on the curve.

Converting energy to motion for more than half a century

 

[waross]

My submersible well pump failed about a year ago.
External tests showed a winding shorted to ground.
When the pump was pulled, we found that due to poor installation, the insulation had been worn through on one of the leads where it entered the motor.
We installed a new pump and kept the old one for a possible spare, after repairs.


--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[SA07]

Hi
Is it true that we should set acceleration time 3s for submersible pump? Else it may be damaged?

 

[jraef]

Is it true that we should set acceleration time 3s for submersible pump? Else it may be damaged?

That's a question for the pump mfr.
Most of the time they WILL state a maximum acceleration time, especially if it affects the bearing lubrication.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[Gr8blu]

ALL
This is a continuation from the previous thread ( thread248-509051 ) where the OP was asking about use of sine wave filters.

As noted in the previous thread there are a few requirements around acceleration for this pump/motor combination.
1) Do not operate the pump/motor at a frequency higher than the maximum frequency listed on the motor nameplate.
2) The motor cannot be operated below 30 Hz - slower results in insufficient cooling.
3) The motor must accelerate from 0 to 30 Hz in less than 6 seconds to prevent thermal damage to the windings.
4) The switching frequency (for the drive) should be set somewhere between 3 and 5 kHz - note that in the OP's original post, it was indicated this had been set to 2.5 kHz.
5) According to the drive manufacturer documentation, A SINE WAVE FILTER IS REQUIRED - REGARDLESS OF CABLE DISTANCE BETWEEN DRIVE AND MOTOR. Note that the information in the original post essentially indicated that the OP had obviously been trying to run without one.


Converting energy to motion for more than half a century