by James Coorough
General Motors Corporation

On March 29, 2001 a production foreman asked J & R Thermography to find the source of a burning rubber odor in the area. Upon scanning the area the team discovered a 500 MCM air cooled ribbon (ribbon 1) severely overheated. Figure 1 shows the original scan of the area showing a temperature of 208 degrees C on ribbon 1. The rubber sheath on these cables is fairly loose, so true temperature readings of the actual cable are impossible. Normal operation for this ribbon is 30 - 50 degrees C. Ribbon 1 was replaced at the next down time.

Figure 1: Air cooled ribbon (ribbon 1) on the weld gun is severely overheated. Normal operation for this ribbon is 49 degrees C. Further investigation shows somewhat higher temps on the other ribbon (ribbon 2) also.

Photos in Figure 2 show the breakdown of ribbon 1 due to heat. Micro-ohmmeter measurements of the cable read 140 micro-ohms. Roughly three times that of a new cable.

Figure 2: Photos are of ribbon 1 after removal from weld gun. Photo 1 shows rubber sheath burned off in areas. Photo 2 shows internal deterioration of the cable.

Further investigation shows somewhat higher temps on the other ribbon (ribbon 2) also. Thermographic inspection after repair (Figure 3) showed normal operating temperatures on ribbon 1. Ribbon 2 also showed a decrease of 30 degrees C after repair but is still slightly higher than normal. The decrease in temperature may be due to less conduction from ribbon 1, and also less current compensation for the breakdown of ribbon 1. Reflection is not much of an issue because the emissivity of the rubber sheath is approximately 0.95. It was suggested ribbon 2 be inspected daily, and replaced when temperatures consistently reached 95 degrees C. Further inspections may reveal the need to replace the air cooled ribbons with water cooled ones.

Figure 3: Ribbon 2 shows somewhat higher than normal temperatures.

A follow up determined a time savings of approximately 30 minutes for the problems found. With production downtime costing about $5,000 per minute, this works out to savings of about $150,000. Ribbon 2 lasted approximately 30 more production days before being replaced.

James receives an InfraMation Executive Attaché Case for his newsletter contribution.

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• Focus on prevention
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  ... grew nervous during a routine drugs surveillance flight in March when their radar detected strange objects flying nearby and an infrared camera showed 11 blobs ...
   

• Indigo Systems Develops Mega Pixel IR Array
  InfraMation - May 2004
  Another milestone in Indigo's history was reached with this image captured by their first 1024 X 1024 FPA. Click the image to see this whopper in full resolution. Someday we all may be using IR cameras with this image quality!

Here is a selection of recent new threads by IR Community members. Feel free to click the links, see how people have responded, and post your own response if you like.

• Research on flame tubes NEEDS A RESPONSE, CAN ANYONE HELP?
  Hi, I'm relatively new to all of this but have some questions. We're using a single U-Tube in a replica furnace to study the effects of silicon graphite inserts and I need a way to safely study the temperature profile of the furnace. I'm using an A20 FLIR Systems camera and our furnace operates at 1800 degrees F. The high temp option is in the process of being acquired. The problem is the way to safely image without melting the camera housing. Would it be better to liquid cool the camera or to use a sight window? The maximum distance I need to read is 63" and the minimum is 13". Any suggestions are welcomed. If you need to further understand what I'm doing check out http://www.spin-works.com/

• Roof inspection of tectum or fibroplank NEEDS A RESPONSE, CAN ANYONE HELP?
  Does anyone have experience surveying a roof which is built over the fibrocementitious material tradenamed "tectum" or "fibroplank"?

• Water In Subgrade NEEDS A RESPONSE, CAN ANYONE HELP?
  Has anyone had any luck detecting water infiltration below an asphalt surface? More specifically, water in the sub grade below a road surface and being able to trace the source.

• Veterinary Infrared Seminar @ Teiky Post University
  Teikyo Post University in Waterbury, CT is sponsoring an introductory weekend seminar, June 11-13, about the use of infrared thermography in veterinary medicine. Dr. Donna Harper, a veterinarian and certified veterinary thermographer, will present the seminar. Topics related to large and small animal thermography will be presented with various sessions open to the public, persons interested in learning what is involved in veterinary thermography, and a special session for veterinarians and sponsored vet-techs. This weekend is an introduction to an in-depth 2 week course slated to be held in the fall 2004 where college degree hours will be available to participants. Please go to the web-site http://www.vet-therm.com/ and check the "training" page for the registration form. We look forward to meeting all interested thermographers in attendance.

• Inactive cable
  Has anyone out there had any experience inspecting feeder cables in manholes? What we're looking to do is to identify inactive cables as opposed to cables carrying load in a manhole.

• Insurance industry requiring FLIR scanning?
  I am very interested in learning more about the possibility hooking up with the insurance industry to receive work. What can you tell me about this? Will FLIR finance the camera? Do you think this is possible in the Connecticut area? How many insurance companies require IR scans of there clients building systems? Is there another avenue that I might be missing? Thank you in advance for your help.

• Electrical Inspections & Flash Suits
  I am researching the use of flash suits on infrared electrical inspections on high voltage equipment.
  (1) Typically, the customer is responsible for removing the the backs of 480/4160 equipment.
  (2) We then inspect the equipment, from a distance without flash suits. Our customers are electric utilities and thus do not fall under NFPA70E (as stated in NFPA70E).

  Since, this is NOT considered working on the equipment, procedures site we are not required to dress out. Due to updates in our procedures there is now a question as to wearing a flash suit or additional ppe's than normal hardhat, safety glasses, etc. We are trying to determine what is a safe distance to be from the equipment cabinets without dressing out short of calculating each individual cubicle. We are also looking at the possibility of installing some sort of port or sight glass.

  Please let me hear from you fellow thermographers out in the field that actually conduct these inspections.

  1) Do you wear flash suits for IR inspections of high voltage equipment?
  2) Is there more than one person with you during the inspection?
  3) If you have ports or sight glasses, do you wear a hood or additional ppe's?

• Market Analysis
  Which industry would most benefit from Thermography?
  Do insurance companies offer savings by having infrared maintenances performed?
  If so what type of savings are we talking about?

And of course if YOU have a question or want to start a discussion on a topic, we would love to hear from you. Just post a new thread on a message board.

Brainteaser of the Month  [top]

Here is this month's brainteaser. Readers who email us the correct identification of the object(s) in the thermogram are entered into a drawing to win a prize from ITC. Please put "Brainteaser" as the subject of the message.

Click here to email your guess

Do you have an interesting image that you think would stump other thermographers? If so please email me your image (preferably in native .img, .jpg, .tif, .tgw, or .tmw format) with an accompanying visible photo and explanation. If your image is used, you receive a gift as well.

Last month's Brainteaser is beautiful thermogram of a hot air balloon viewed from below. You can see the cool gondola in the center of the warm balloon canopy.

Our winner, all the way from Siemens in Germany, is Frank-Peter Schulze. Thanks to Robin Tanamachi at the  University of Oklahoma for the fabulous shot. Both Frank-Peter and Robin receive a special low emissivity traveling coffee mug.

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