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Motor, Imbalance |
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 Sep 10 2008, 11:40 AM
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#1
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Member  Group: Full Member Posts: 187 Joined: 16-August 05 Member No.: 1,186  |
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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Sep 10 2008, 06:41 PM
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#2
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Posting Freak Group: Moderator Posts: 2,383 Joined: 24-April 02 From: Christchurch, New Zealand Member No.: 1 |
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. -------------------- Mark Empson administrator
Skype Contact = markempson | phone +64 274 363 067 LMPForum | LMP Tech Warehouse | L M Photonics Ltd | Empson family | Advanced Motor Control Ltd | LMP Software | Mark Empson Website |
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Sep 22 2008, 12:36 PM
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#3
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Member Group: Full Member Posts: 187 Joined: 16-August 05 Member No.: 1,186 |
Hello Marke,
Thank you for your reply. We are now organising to remove and overhaul the motor. I shall keep the forum informed. Regards. Bob |
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 Oct 4 2008, 04:10 AM
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#4
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Member Group: Full Member Posts: 187 Joined: 16-August 05 Member No.: 1,186 |
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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Oct 5 2008, 05:04 AM
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#5
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Posting Freak Group: Moderator Posts: 2,383 Joined: 24-April 02 From: Christchurch, New Zealand Member No.: 1 |
Thanks for the update Bob,
Lets hope that is the answer!! Best regards, Mark. -------------------- Mark Empson administrator
Skype Contact = markempson | phone +64 274 363 067 LMPForum | LMP Tech Warehouse | L M Photonics Ltd | Empson family | Advanced Motor Control Ltd | LMP Software | Mark Empson Website |
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