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Motor


bob

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Hi,

 

I have go a 90 kW immersed pump which was working trouble free before. We just started to get overload conditions on this pump. The FLC of the motor is 160 Amps. The current measured on the three phases are 165 A, 150 A and 148 A. The imbalance tends to increase with increased laod

There is no voltage imbalance. I suspect something is wrong with the motor.

Any omment.

 

Bob

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Hello Bob

 

It sounds like you have a high impedance in series with one phase or one winding to do that.

Typically, submersible pumps have a high magnetising current and this makes them sensitive to any imbalance in voltage at light load, but the imbalance improves as the load increases.

To have an imbalance that gets worse as the load increases suggests that the voltage across one winding is reducing with load.

I would first try a low resistance check of the circuits that you can get at to see if you can measure any variation. It may be a joint that is going high with temperature, so I would also do a resistance check as soon as possible after the pump has been running.

I assume that you have measured the voltage while the pump is running at a high imbalance just to be sure that there is not a high impedance phase upstream of your control equipment.

 

Best regards,

Mark.

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  • 2 weeks later...
  • 2 weeks later...

Hello Mark,

 

Bingo. We removed the motor from the well yesterday and one of the three phase cable joints in a very bad condition. The motor was supplied with only a short lead and joints had to be made. This is a case of a very bad workmanship.

Thanks again.

 

Bob

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Thanks for the update Bob,

Lets hope that is the answer!!

 

Best regards,

Mark.

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