I was working with a thermographer the other day and after about two days of side-by-side work, I could tell this guy was going to be an awesome thermographer. He understood heat transfer theory. I could tell he had lots of camera time by the way he handled the thermal imager. He was even able to navigate camera menu functions without even looking at the camera by counting button pushes. He also had the ability to know where to look for issues; but, that is where it all broke down.
This thermographer had very little experience in mechanical inspections and that became very clear after working with him. Finding where to look for problems is essential but so is knowing what you should see thermally. There are going to be components that should have elevated temperatures and other that should not. It is the job of the thermographer to find and identify those components that are not operating within their proper thermal limits.
I find electrical inspections to be one of the least complicated inspections. As a gear head with very little electrical experience, my largest hurdle was identifying the component. For example, sometimes a voltage regulator can look a lot like a transformer.
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| This voltage regulator can look similar to, and be confused with, a transformer, right. |
Putting identification aside, very few things in electrical inspections should be hot, other than components that contain a coil such as transformers, contactors, relays, motors and so on. Conductors and connections usually operate at or around ambient temperature depending on loads. A short list of mechanical devices would include bearings, pumps, actuators, motors, valves, engines, speed reducers, pulleys, sheaves and so on.
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| Worm gear reducer in infrared. |
The key to doing a mechanical survey is understanding how the device should look thermally. The gentleman I was working with had no clue. I feel that in order to do a proper mechanical infrared survey, it is absolutely necessary to have an intimate working knowledge of the component. Take something as common as a speed reducer. Speed reducers come in all different sizes and ratios. There are several types of reducers such as right angle, parallel shaft, worm gear, planetary and helical shaft. Each will display its own unique thermal pattern and there can be differences between them all. Differences such as the way they are driven, different ratios or speeds, differing loads, and different types of lubricants. All of these can cause this single type of reducer to display multiple thermal patterns that the thermographer must understand and be familiar with. The point being that the thermographer should have an excellent working knowledge of what he is inspecting.
I have been fully immersed in thermography for many years and I can honestly say that with every inspection I do, and every class I teach, I discover something that I did not know about infrared. The thermographer that I worked with that week was quick to admit he needed some training and experience before doing certain types of inspections on his own. We plan on keeping in touch and sharing information on his progress.