motor resistence rising

[puckman]

I megged a 100hp sump pump motor about 6 weeks ago when it was below water . It megged out at about .8m . It was taken out of service and has been setting outside waiting to be replaced . When it was taken out maintence did some pm and never said anything about water inside the oil. Today I megged it again with the same megger and it megged at 49m.
Is this because it dried out inside? If anyone has any ideas i could use the help. Thanks in advance.

 

[zog]

I megged a 100hp sump pump motor about 6 weeks ago when it was below water . It megged out at about .8m . It was taken out of service and has been setting outside waiting to be replaced . When it was taken out maintence did some pm and never said anything about water inside the oil. Today I megged it again with the same megger and it megged at 49m.
Is this because it dried out inside? If anyone has any ideas i could use the help. Thanks in advance.

What were the winding tempatures at the time of the 2 different tests?

What was the duration of the 2 different tests?

 

[puckman]

first time motor was below water, this time it was above ground today 50f. I really don't know how to get the windings temp. the time of the test was for 1 minute and then 10 minutes. the readings i used were from the ten minute test. the boss is getting a AEMC 1060 megger in a day or 2, its suppose to be a better meter and does the test for you when you don't know what you are doin with it. would the readings be different on the same motor if it just was running as oppose to when it just sits there and off line ?

 

[zog]

first time motor was below water, this time it was above ground today 50f. I really don't know how to get the windings temp.

the time of the test was for 1 minute and then 10 minutes. the readings i used were from the ten minute test. would the readings be different on the same motor if it just was running as oppose to when it just sits there and off line ?[/QUOTE]

Yes, the tempature makes a huge difference. The readings need to be tempature corrected to 40 degrees C to be compared and depending on how warm the windings were your .8M at a high tempature, say 70 degrees C could be the same real vaule as your 40M at 10 degrees C.

the boss is getting a AEMC 1060 megger in a day or 2, its suppose to be a better meter and does the test for you when you don't know what you are doin with it.

It is a good tester but won't do anything to help you know what to do with it, you need some training, not a new meter.

 

[puckman]

yes i do . thanks again

 

[zog]

yes i do . thanks again

Have you read "A stich in time"?

 

[puckman]

some of it .