1. Safety
Clearly the first step in any successful thermography inspection is to ensure all work is done as safely as possible.
2. Master Your Imaging System
A qualified thermographer knows how to use the infrared imaging systems fully— focus, adjust the image manually, capture data with care, use measurement tools appropriately, correct for emissivity, background and transmission, etc—and, importantly, also understands the limitations of the system and technology. If you don’t know how to use a tool properly and fully, you will not obtain consistent, high-quality results.
3. Open, Inspect and Close
Best practices now suggest a preliminary look at the enclosures prior to opening any of them; if one is abnormally warm, additional precautions may be warranted to gain access.
4. Where Appropriate, Consider Using IR Windows or Viewports
More and more often, safety concerns suggest we should minimize the opening of electrical enclosures while they are under load, and yet, not doing so can severely limit our ability to get good data.
5. What is the Load?
Only two things are certain about inspections performed when loads are light and will increase: (1) some anomalies may go undetected and (2) those that are detected may be underestimated because they will generally appear cooler than when loads increase.
6. What is the Thermal Gradient?
If conditions are poor for an inspection, a lightly loaded system or wind, for example, a relatively insignificant indication exhibited by a large gradient component may go undetected. To better understand the significance of findings, it may be useful to categorize gradients as either small (connectors viewed directly), moderate (breakers or large connectors) or large (oil-filled devices and bus ducts).
7. Bare Metals Are Difficult to Understand
One of the most poorly understood issues thermographers must contend with is the low emissivity (and high reflectivity) of bare metals. The result of this inherent physical property is that bare metals not only don’t reveal their true temperature easily but they also tend to mask over it with untruths!
8. What to Expect and When?
The task of assigning a frequency of inspection is one that is all too often either over simplified (“annually”) or made far too complex. Initially the driver for frequency will be based on the resources available for inspection. Those should be distributed in such a way as to provide the greatest returns on the investment after considering such factors as the age of the equipment, its duty cycle, whether or not it is housed in a cooled area, the history of failures, etc.
9. Note Everything That is Abnormal, No Matter the Temperature
Too many thermographers make an arbitrary decision to only note “hot ones.” This is a mistake for several reasons.
10. Measure Temperature, but Do It Well
While it is often challenging to make accurate measurements of electrical components, every effort should be made to do so while also understanding the degree of confidence inherent to a particular measurement.
11. Prioritize Findings Based on All Relevant Factors, Not Just Temperature
Best practices suggest prioritization of findings be based on all relevant factors, including temperature, but also including the reliability of the data, the criticality of the equipment, the potential for injury, etc.
12. Re-inspect After Repairs
In many companies, and for many different reasons, 50% of repairs are not effective the first time. Therefore, it is crucial to re-inspect after repairs have been made.
If you want to find out more please check the article on our website 'Thermal Imaging: 12 Steps Toward Better Electrical Inspection'.
