Message Board Thread - "Come on guys, lets have an open discussion about this image"

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Come on guys, lets have an open discussion about this image fazlye 6/10/2008
This is a electrical motor connected to a water pump
50Hp, Ip 56 rated. Operating on-off based on timer of 12 hours, Trefl=32.4 C, Distance- 2 meter. Question- what is the best practice in conducting IR
on rotating equipment? what we should look at? Bearing Housing, Fan blade? etc

Thanks
 
Re:Come on guys, lets have an open discussion about this image Carl M 6/11/2008
I'll start.
When I do an inspection of a facility I'll have the client identify critical motor driven equipment to image for baseline. Making sure the motor has been running and up to temperature, I'll note the amb temperature and image the motor case and end bearings. During future inspections I'll be looking for variences from the heat signature of my baseline images. I also look for proper fan cooling (also visually, you want to see a clean motor with no dust or material build up as debris will hide the actual case temperature and prevent proper cooling), and end bearings, which will normally be cooler than the case temperature.
 
Re:Come on guys, lets have an open discussion about this image TDLIR 6/11/2008
You all remember this song from your childhood....

"One of these things is not like the other! One of these things just doesn't belong! Can you tell me which one is not like the other?! By the time I finish my song?!"

Temps are usefull and needed for a good trend, but comparing to others motors is "one" of the best ways to weed out the good motors from the bad one.

I enjoy singing this to my IR students.

Regards,

Sonny James
http://www.learnndt.com

 
Re:Come on guys, lets have an open discussion about this image fazlye 6/12/2008
thanks for the reply guys1
But from my experience different pumps & motor will have different type of characteristics and temperature. if we want to go for a trending for each and every pumps and motor we'll have to check all the couplings, bearing cover, fan blade, etc but when what if, lets say a motor shaft bearing has been replaced, then the all the trending for the motor will start all over again, correct? any better way to actually come up with some reference to the pumps and motor?
 
Re:Come on guys, lets have an open discussion about this image Carl M 6/12/2008
"...lets say a motor shaft bearing has been replaced, then the all the trending for the motor will start all over again, correct?"

I'd say, no. Just the part replaced should have a different heat signature. All other aspects should be about the same.



"any better way to actually come up with some reference to the pumps and motor?"

Again, I'd say, no. Actual images of the baseline installation operating normally is the best reference for that particular motor, pump, whatever. Am I missing something here?
 
Re:Come on guys, lets have an open discussion about this image TDLIR 6/12/2008
If you are looking at serious motor and rotating equipment trending and diagnostics then you must go at it in a holistic way. There is only so much information that IR can give you. You must know the extent of information you can gain with IR on your equipment. You will then have to confirm, compare, quantify, diagnose, etc… with other technologies such as VA, MCA, UT, OA, etc…

Determining what part to inspect or trend and how frequent depends on many things such as equipment and it’s priority and failure history.

A good model of trending with IR is by using the same tending process as VA noting that frequency of inspection may still be different with both technologies.

It’s really up to you and your company. How much money do you have to spend? How much time do you have to spend on testing? How critical is your equipment? What is your failure history? What is the stock on your inventory? What is the replacement time and cost for equipment and parts? How much can you afford to lose? Does it matter? Do you care? All these will determine what to inspect how to inspect them and how often to inspect.

“What did I get myself into?” said the inspector to himself.


Hope this helps.

Sonny James
 
Re:Come on guys, lets have an open discussion about this image Doctir bob 6/12/2008
With IR windows or sight glasses, we can now look at the connections in the motor junction box, off limits when I was doing IR in the '90s. This is a key area of electrical problems for motors as the environment is typically hot, dirty and has lots of vibration.

Also, when we did IR on very large motors at the electric power plant, we also used vibration, oil analysis and MCA as other key diagnostic technologies. In fact, oil analysis and vibration were the primary technologies. But for smaller motors IR thermography is often the most effective technology. I gotta learn that song, because we're in the comparison business. Trending is comparing the same component over time often to a baseline image, but the thermogrpaher also compares with like equipment under like load and environment. And sometimes there are variations, hot spots, on the motor case itself that give clues to problems.

I think all the feedback you've gotten so far is pretty realistic.
 
Re:Come on guys, lets have an open discussion about this image Bruce R 7/1/2008
When I am checking a motor, comparsion to the other motors will tell you a lot. I look at the motor casing to see if there any hot spots, that could indicate a loss of resistance in the internal windings or plugged cooling vents coming from the fan. I look at the area around the bearings at each end of the motor, excessive heat in this area could indicate a bearing on it's way to failure a comparsion to another motor will help you diagnose excessive temp.
 
Re:Come on guys, lets have an open discussion about this image Expediter 7/5/2008
In testing motors, I believe that you should test the bearing housings , the couplers and even belts if aplicable to check if there is excess heat in those locations. If there is, this could be from missalignment and show why perhaps that the windings are getting hotter prematurly if bearings or couplers are causing excess friction, the motor will have to work more to overcome the friction in those areas. There could be hotspots on the windings as well, if there was a bad winding somewheres, so checking the case for hotspots is not a bad idea either.
Checking the motor leads for bad splices is always a good idea.
The fans,, well I don't know if i would give more than a curseratory (did i spell that right?) glance at them, however a bad bearing giving heat at that side could possible indicat an out of balance of the fan causing early wear.
for bad bearings you can as well invest in a ultrasonic tester, i forget the frequency but something like 28khz ??44khz?? anyway that tester is about 10k$ complete
But I'm just a level 1 tech/ Journeyman Electrician.
 


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