During an infrared inspection, the instruments we use allow us to see problems that our eyes cannot. But that doesn't mean we should rely solely on the technology we use to reach our conclusions. If you're a trained technician with decades of field experience, your eyes might catch something that the camera just isn't designed to pick up. Maybe there are ways we can further investigate an issue before labeling it as "bad" or "needs repair" just because it appears "hot" to the instruments.
So, how do we evaluate a problem if we cannot go by just the picture or temperature? Well, how do we evaluate any problem in our lives? Do we base our decisions solely off of facts? Do we use emotions? Can we make decisions based on past experiences and outcomes? Can we phone a friend? Is there any benefit to any of this when it comes to maintaining the reliability of the electrical system at your facility?
You may have heard the terms "Quantitative" and "Qualitative" used in business or analytics before. And truth be told, they are two very powerful areas of problem-solving. So to properly understand our findings from an infrared inspection, we must use both a quantitative and qualitative approach to diagnosing the problems.
Quantitative is objective and measurable using facts and instruments.
Qualitative is subjective, interpretive, and considers patterns of observation allowing us to ask “why?”
Using both of these approaches will enable us to combine measurable findings (temperature, amps, mV, etc.) with experienced observations and shared understanding.
Long story short, in my decades of infrared field work, I've developed 5 Points that I consider the best framework to follow when performing an inspection. These are also the most critical categories one must consider (Temperature, Amps, mV Drop, Criticality of Equipment, and Physical Damage/Condition) when evaluating and prioritizing a problem.
This is our earliest warning sign, and it definitely affects how we evaluate and prioritize problems. Where the temperature is located and how far the heat is tracking tells us what is wrong and for how long. Higher temperature on a breaker or fuse can cause the fuse and breaker to prematurely trip or clear. Higher temperatures (in most cases pushing 100 °C and up) can physically affect the operation of the equipment. Higher amps will produce higher temperatures, but that is what we must be able to discern when we refer to higher temperatures. The ambient air temperature of the area we are in affects the “hot spot” temperature, while colder ambient temperatures will produce lower hot spot temperatures.
First, it will let us know if the temperature difference we see is load related or not. As stated before, higher amps produce higher temperatures, unbalance load will show excessive heat on a component, overloading of amps, low amps with higher temperatures and 70-80% load capacity running 24 hours/day are examples of this. Second, it helps us prioritize an issue. While overloading a circuit can cause us to put a higher priority on the issue, also low amps on a circuit with higher temperature.
First, it will verify that we have a problem and where the problem is located. Sometimes it is hard to tell by the temperature profile if it is a problem, but the mv drop helps to verify it. It also will help us determine what is actually wrong and how severe the problem could be. Higher resistance can indicate the problem needs more immediate attention instead of putting it off further down the road.
Criticality of Equipment
What we mean by criticality is, "if this were to fail, how bad would it be?" What the equipment is, or feeds, can affect how we prioritize an issue. After you gather the temperature, amps, and mV drop, we must ask, “What does this feed?” If the hot spot in question failed, what would be affected? What damage could this bring? What function in or to the building could be affected?
What kind of state is the gear in? Age can play a part in this evaluation, and with age comes the problems of the past. Look, document, and write everything up. Is it burnt? Discolored? Melting? Is it not properly installed? Are the blades not made up into the clip entirely? Is it missing something or are the mounting brackets broken? Is it physically loose? Is it about to go to ground? Is it glowing or producing a flame? Does it smell like it is burning or can you hear it arcing? Using your senses of sight, smell, and sound will help to assess the critical nature of the repair.
Whenever a problem is spotted, both visually or thermally, the 5 Point evaluation system is useful for assisting in prioritizing the problem. “High” priorities are first and are to be fixed as soon as possible or at a scheduled power outage. “Medium” priorities are to be fixed at the customer’s earliest convenience. “Low” priorities are third and can usually wait for the building’s regular scheduled power outage.
Earlier this month we made two videos about infrared. There is still a lot to cover on the subject, so we're planning more for months to come. And as always, if you have any questions, feel free to give us a call anytime!