By Joe DeMonte
Senior Thermography Course Instructor
Infrared Training Center (itc)
ASNT/PdM TIR Lvl III

Animal Guards have nearly eliminated electrical outages caused by interference from wildlife coming in contact with high voltage bushings in switch yards. These products have proven their worth time and time again. However, one issue does exist with these installations: visual and infrared inspections are not easily performed through the solid poly designs. I would like to point out the difficulty in performing the necessary inspections in this issue of the Inframation Newsletter.

Fig 1: Vice holding the 40Watt soldering iron

I took two different styles of “critter guards” and put them through some simple tests using a LW (8-12µm) IR camera to find out how difficult the inspections were. As you can see from the visual image in Figure 1, the heat source in this initial study (with more to follow), was a 40 watt soldering iron. The actual temperature of the iron was measured with a thermocouple (Omegaette HH306 Data Logger Thermometer) during each of the events.

   
Fig 2: Critter guard 1

As we can see in the thermogram and visual image in this 1st example, we cannot easily do a visual or infrared inspection. Although the soldering iron appears through the poly design, the temperatures measured by the thermocouple inside were actually 870ºF while the LW infrared camera could only muster a value of about 120.9ºF. This equated to a very low transmissivity, and a warning to those who view the smaller .05” thick solid bushing guards: ANY TEMPERATURES TAKEN FROM THE OUTSIDE SHOULD BE CONSIDERED INDIRECT IN NATURE. IR TECHNICIANS SHOULD NOTE THIS IN THE INSPECTION AS ACTUAL INTERNAL TEMPERATURES WILL BE MUCH HIGHER THAN MEASURED FROM THE OUTSIDE USING INFRARED CAMERAS.

   
Fig 3: Critter guard 2

The actual temperature taken with the thermocouple in figure 3 was again, 870ºF. Due to the lower emissivity of the somewhat new metal of the iron, the IR camera only measured 513ºF without the see through guard and 488.6ºF with the guard. The first error is, of course, not something that will be covered in this paper. The second error of about 25ºF between having the guard off and then on was due to the fact that the hottest area of the soldering iron was not seen by the camera with the mesh covering it. It is clearly plain that the ease of which the infrared and visual inspections can be made with this style of “critter guard” in place, gives it an advantage to those who wish to keep unwanted outages from happening and still perform these types of inspections with greater ease and accuracy.

   
Fig 4: Critter guard 3

This image is of the .08” thick large solid “critter guard”. One interesting fact is shown by analyzing these images and comparing the thinner .05” design with the thicker poly of this larger design. We cannot “see” through it with the LW IR camera like we could on the thin specimen (although barely), and we cannot see through it with our own eyes. Be careful when performing IR tests on this type of guard. It measured at 873ºF contact temperature on the inside. The outside shows no rise at all.

   
Fig 5: Critter guard 4

The large guard shows the same ease of inspection for both visual and infrared as the smaller design.

Conclusions

Infrared friendly design can go a long way in helping the electrical maintenance community. I have many more tests to conduct on these products and will publish those tests later on this year. Tests that have been conducted but not included in this article include the effects of distance on the small mesh holes in the see through guards, and tests have also been conducted using MW (3-5µm) IR cameras. Other tests on heat transfer effects will also be addressed. As long as companies recognize the need for safe and effective product design, I hope that they will continue to think of how to improve that product for the growing infrared inspection needs.

Straight from the World Wide Web, here is what's going on in the world of infrared thermography.

• Using Thermal Imaging to Solve Lubrication Problems
  Machinery Lubrication
  ...Thermography can be used to identify and analyze thermal anomalies for condition monitoring of machines. These thermal anomalies are usually caused by such mechanisms as operation, improper lubrication, misalignment, worn components or mechanical loading anomalies.

• Oil Analysis, Vibration Analysis and Thermography Deliver Savings at Manufacturing Plant
  Reliability Case Studies World - July 2005
  ...The preventive maintenance team at American Axle and Manufacturing (AAM) addressed an issue found during a routine preventive maintenance work order. Relying on their skills and field experience, they corrected the issue with minimal effect on productive time. Catching the issue in a timely manner saved the company an estimated $50,000.

• Infrared Camera Spots Bearing Failures
  Reliability Case Studies World - March 3, 2005
  ...Initial scans with an infrared camera did not detect the faulty bearings because the machine speed is slow and the bearings do not have a significant increase in temperature. However, if the carousel is operated in "lube" cycle, it allows continuous running and the bearings will heat up if a binding condition occurs.

• Traces of hidden Leonardo sketch revealed
  Guardian Unlimited, UK - Jun 30, 2005
  ... Under an infrared camera, layers down, beneath the drawings for the present painting, an entirely different image shone out: a kneeling woman, one arm folded ...

• Step by Step
  TheHorse.com, KY - Jun 28, 2005
  ... the joint surfaces. Infrared thermography can be used in some cases to help diagnose a case of osselets. Your veterinarian will ...

• Medical Messengers--British Equine Veterinary Association
  TheHorse.com, KY - Jun 28, 2005
  ... diagnosing back pain. He said the most common diagnostic tools are X rays, scintigraphy, thermography, and ultrasound. He agreed ...

• Sleep lab at CentraState helps diagnose disorders
  Asbury Park Press, NJ - Jun 28, 2005
  ... One of the only things that distinguishes the room from a Motel 6 is an infrared camera mounted by the side of the television set, so that the technicians on ...

• Langley helping send shuttle back to space
  Virginian Pilot, VA - Jun 27, 2005
  ... damage after launch. They built an infrared camera that astronauts can use to spot sub-surface damage on the shuttle. They developed ...

• Hot Bother: Ground squirrels taunt in infrared
  Science News Online - June 26, 2005
  Ground squirrels are the first animals reported to broadcast an infrared signal, and the message seems to be "Nyah, nyah."

• Fireworks Safety
  WFMZ-TV Online, PA - Jun 24, 2005
  ... UNDER A THERMAL IMAGING CAMERA EVEN SPARKLERS HAVE THESE PROS CONCERNED. ITS ISSUING ABOUT 600 DEGREES, THE OTHER ONE WAS IN THE THOUSANDS. ...

• Titan may have an ice volcano
  Rocky Mountain News, CO - Jun 20, 2005
  ... Using an infrared camera that penetrates the haze shrouding Titan's surface, Cassini scientists spotted a bright circular feature, 19 miles across, that ...

• Mercedes releases official photos of next-gen S-Class flagship
  AutoWeek - Jun 19, 2005
  ... Different from the thermal imaging process used by Cadillac on the STS, the optional system is based around a new infrared sensor that is claimed to identify ...

• Millions of bats take flight each night in Texas - and that's good ...
  Picayune Item, MS - Jun 18, 2005
  ... McCracken's study, in its second year, uses infrared thermal imaging cameras to get a more accurate count of bats in Central Texas. ...

• Intelligent cars may make driving safer, but they aren't cheap
  The Japan Times, Japan - Jun 16, 2005
  ... An infrared camera takes pictures of pedestrians on the road to help the driver identify people not visible to the naked eye in the dark. Honda Motor Co. ...

• Researchers record coyotes stealing goose eggs
  KWQC-TV, IA - Jun 15, 2005
  ... Researchers at the Max McGraw Wildlife Foundation in East Dundee near Chicago used silent infrared camera equipment to catch coyotes in the act of pilfering ...

• When Your Horse's Muscles Ache
  TheHorse.com, KY - Jun 6, 2005
  ... evaluation is more difficult. Other potentially useful imaging modalities include ultrasonography and thermography. Radiography can help ...

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.

• Roof Survey - Large Stone Ballast
  I recently looked a leaky flat rubber membrane roof having large river stone ballast. The ballast is spread 2"-4" in thickness across the membrane. I was on the roof about 2 hours after sundown and the roof appeared uniform in temperature. Conditions seemed right for a good scan: sunny all day, low wind and clear at night. My question is should I have stayed on the roof longer or will the large ballast mask the moisture below?

• Putting holes in our lexan covers to allow IR scan
  We are looking at putting holes in our lexan covers to allow a IR scan without having to power down the tool to remove them. What is the smallest hole size required by the IR gun. Allowable IR Scan hole distances Here is what is in the current EEW Guideline. So if the lexan guard is 2" from the electrical circuit/terminal, then the max opening is 3/8". This is to ensure the lexan cover is finger safe. Can you guys give some feedback about the advantages and disadvantages of using holes of this size to scan, also has anybody used slots in place of holes.

• Motor Temperatures ?
  Is there a chart or graph for ideal running tempreatures for motors(Frame, HP, Speed)? I need something to have a refrance point? I know that every motor maybe diffrent do to age and operating condition, but I would like to have something. Can anyone help?

• infrared and ultrasound
  Does anybody use ultrasound along with their infrared?? What kind of results and tests do you do? Been doing a little research and seems they go hand-in-hand.

• 345kv Disconnect - 64C Rise
  Attached is an image of a 345KV manual disconnect. This is one of two parallel paths through which flows a total of 1250MW. First reading was 64c rise in a 7.5 mph wind. Second reading two days later approx 10C rise in a 2.5 mph wind. The total loading has not changed. Division of load between the two parallel paths is unknown (I assume it splits based on impedance of the two paths). How serious would you view this?...

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 

Here is this month's brainteaser. Readers who email us the correct identification and explanation of the thermal pattern in the thermogram are entered into a drawing to win a prize from ITC. Hint: If you were at the InfraMation conference last year you should know what this is.

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 challenge 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

It's not a hairbrush or a curling iron, so what is it? Our thermogram contributor Ken Leonard explains his thermogram:

"I was scanning a plant that mills drill bits, this is a rack of bits that have been titanium coated and were drying."

No one was even close on this one, so Ken gets the only coffee mug this month.

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