evaluation of hot crimp on control wiring?

[electricpete]

http://69.20.101.242/community/boards/images/1061209551_ds028.jpg

Attached is a picture of a hot-spot we are watching. Particularly interested in box#3 (left side of image) based on its position within the circuit. It started at 11C rise, went to 0C rise (above ambient marked B) for a few measurements, now bouncing around 7-9C rise. We have not measured the current, but we don't think there was any significant decrease when it went to 0.

By the way, these are fused disconnects in a 125vdc control circuit, and the hot-spot is on a lug associated with the wire connected to the fuse disconnect. In fact I believe there are 2 lugs landed on that point, and based on the thermal image, the one in front is not the hot one (the hotter one is not directly visible to the camera). This conclusion based on looking at the hot wire that comes out.

Our approach is to use 0.95 emissivity for the whole image. There is a relay to the left producing heat which elevates the background behind the point of concern. No special background compensation was applied and we compare to ambient located at a cooler part of the cabinet. Any comments on this approach?

My main questions:
1 - How would you rank the severity of this?
2 - What industry standards are available for evaluating electrical hot-spots.
3 - Is anyone aware of similar crimped connections that were failed which had thermal history available? i.e. we are interested to get some basis for answering the question: when would it fail? Have other crimps failed rapidly after showing similar rises (noting the erratic behavior?).
Thanks for bearing with my long question and looking forward to any comments.

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[eyec]

i would at the least re-land both connections with new crimps.

if you believe the bottom lead is the culprit then that makes corrective action even more of a concern. because for it to lite up the top connection a lot of heat is being transfered.

on the other hand, it could be the top lead and the equipment it is controlling is drawing current at the time of the image - and this could be normal. look at the visual color of the leads, crimps and connection for indications of discoloring. also don't overlook checking the tightness of the connection.

 

[ms14]

I am looking for material that can absorb infrared light or material that not allowed infrared light to pass through.
Please help
Thanks
MS14

 

[eyec]

simple basic answer: clear glass

 

[electricpete]

ms14 - Why don't you start a new thread and also clarify your question. Do you care about visible light performance? Do you care whether infrared is reflected or absorbed? Seems like your options are wide open. What is it you're trying to do.

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[cameraman1]

Where can I find an off the shelf device or software to convert NTSC (actually RS170 sync black and white) composite video (from an IR vidicon camera) into pseudo colorized video? (Some people call this "false colorization". The device simply converts the various shades of gray of the video image pixels into specifically assigned colors from a pallet. These devices (or software) are built-in to most IR hand held cameras now on the market.) I would like a stand-alone box that provides this function but a Windows software may be acceptable. I would like to have such a device that not only converts the gray scale to colors but which will allow me to perform some gray scale to temperature correlation as well. Thank you.
cameraman1