IR – Indoor Electrical
Electrical inspections are the most commonly known and practised infrared application. The benefits are obvious, since electrical failures can easily cause personnel injury and death, equipment damage, material loss, and downtime.
Unfortunately, this familiarity has made many maintenance personnel and thermographers dangerously casual in their approach. It is too easy to simply pick a camera up and go looking for “hot spots.” While it is true that any substantial temperature rise between phases should be treated as a high priority repair, there is a lot more to electrical infrared thermography.
One important factor is the load on a component. The load exponentially affects the power in a circuit and the resulting temperature rise. A small temperature difference under a load of 1A may be crictical under a load of 20A. There are still many maintenance personnel and professional thermographers who do not correlate load and temperature rise, and this causes a false sense of confidence when serious problems still exist. The load or temperatures are not always referred to in following samples, but that information was used in determining the criticality of the faults.
It is also important to understand the theories involved in how infrared radiation works and how heat transfer is affecting the objects in a thermal image. Concepts such as emissivity, thermal reflections, thermal conductivity, and indirect temperature measurement are crucial to the identification and diagnosis of electrical problems.
Although infrared electrical inspections are often carried out for insurance purposes, thermography’s true value is as an integral part of a predictive maintenance program. Combined with other technologies and performed conscientiously, thermography will have cost benefits that vastly outweigh the costs.
Anyone performing infrared electrical inspections has to remember what is at stake, and make the effort to do the job properly. The risk of serious injury, death, or huge loss of profit inspired us to pick up the camera in the first place, and the identification of a few “hot spots” will not eliminate that risk.