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fburgos

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Posts: 670
Reply with quote  #1 

This ID fan was balanced by me somewhere in 2017 I still remember arguing about use direct grounding to the fan, since we had no way to bring the soldering machine or the ground cable (lazyness and short time), supervisor solution was to solder a metal rod to the metal casing and then to the fan.

Couple of months back a change of bearings replacement was done, as usual the bearing was cut in half lying on the floor waiting for his trip to the trash bin, I am always curious about inspecting the old bearing and found found this on just one of the rollers

FJIMG_20190705_183728.jpg 


I believe this is electrical arc damage from that time.

this is the vibration data, BSF an FTF harmonics.
img00022.png 

img00024.png  img00025.png 

Attached Images
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jpeg 20190705_163004~01.jpg (224.04 KB, 1 views)

106Bones

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Posts: 35
Reply with quote  #2 
Seems likely that you were correct on all counts, bad grounding practice in 2017, electrical arc damage on the depicted parts and thats the resultant of the poor grounding practice. The method you describe is just as likely to pull its common ground through the fan bearings as it is to get it from the rod attached to the fan casing. Regardless of difficulty placing  a dedicated, not common, ground cable directly to is critical to avoid this predictable result. 
Danny Harvey

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Reply with quote  #3 
It's not often that you get to be right and prove it as well.

Well done, Ferdy.
Dan Timberlake

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Reply with quote  #4 
Got any 2017 spectra from before balancing and immediately after ?
fburgos

Sr. Member
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Posts: 670
Reply with quote  #5 
unfortunately I have no spectra from 2017, it was another vibration system and the database got corrupted and lost everything, but your question made me go back to my data and found balancing in 19/8/2018, I did remember a balancing job but I swear it was on another ID fan 6, but anyway damage go back this date 10/16/2018.


To be honest I was not expecting to find any phisical damage.


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png img00029.png (30.26 KB, 5 views)
png img00030.png (28.56 KB, 4 views)
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