Thermal scanning is used to detect abnormal temperature rises that indicate potential electrical problems. Cable temperatures rising above design limits can cause insulation degradation over 50% faster for every 10°C increase. Thermal scanners work by detecting infrared radiation emitted by objects, converting it to a thermal image using a microbolometer sensor. Accuracy depends on factors like emissivity, reflected temperatures, and camera sensitivity/resolution. Thermal scanning can help identify if high temperatures are caused by contact resistance issues or improper heat dissipation from high ambient temperatures.

1. ELECTRICAL SCIENCE SOLUTIONS
ELECTRICAL SCIENCE SOLUTIONS
Thermal Scanning Basics – Part 1
Prasad Gore ; prasad@electricalsciencesolutions.com Sept 2017.
Abstract: There always need explanation for thermal scanning requirement of installations and
how it works. This paper is very basic attempt to provide level1 information.
1. Why thermal scanning?
 Abnormal temperature rise is basic symptom of any electrical problem. Here we are
considering electrical issues only.
For example,
 Design issues – Underrated sizing.
 Operational issues – Improper maintenance, power quality issues.
We will discussed issues that can be addressed by thermal scanning one by one.
‐ Cable
 As cable forms the main part of electrical network it requires high reliability. And insulation
material is always decide reliability.
 Cables are design with particular operating temperature , deciding factor is PVC insulation
and its physical property , there are lot of reason for cable temperature to rise such as
undersize cable ( Design Issue), loose connections, or high ambient temperature (
Operational Issue)
 Detoriation of polymer takes place due to overheating and that is called thermal
degradation of polymer. In thermal degradation of polymer below changes are seen,
1. Decolourisation 2. Hardening and cracking 3. Reduction is insulation resistance
 As per some of the technical papers thumb rule is that every 10 °C rise above rated
operating temperature there is 50% reduction in design life.
 So thermal monitoring of cable is most important part of its predictive maintenance.
 Basic logic is same for other part of electrical system as well, we will take those in other
papers
2. Thermal Scanner Working Principle
 Any body above which is having temperature above absolute zero emits energy in form of
radiation. Heat is emitted in form of infra red electromagnetic radiations , so to get the
temperature there must be a device which can read these waves.
 So thermal imager is developed with microbalometer, which senses these radiations and
convert them into thermal image with help of microprocessors.

2. ELECTRICAL SCIENCE SOLUTIONS
ELECTRICAL SCIENCE SOLUTIONS
 Courtesy Google Image
3. Factors Affecting Right Readings
 There are other important parameters which affect accuracy of temperature measurement.
A. Emissivity – We can explain like this that black body emits 100% of heat, i.e. its emissivity is 1.
Here in electrical network, most insulations are made up of polymers and hence we set emissivity at
0.93‐0.95 range
B. Reflected temperature – infrared radiations emitted by other hotter bodies gets reflected from
body under thermal scanning and then a thermal camera reads that temperature too. And accuracy
will be on toss. So need to set temperature of reflected radiations. We set it at 20‐22 or 30° C.
C. Camera Sensitivity and Resolutions‐ This need lot of comparisons. Sensitivity indicate least count
that camera identifies between two points in thermal frame. And resolution is as pixel, i.e number of
points that scanner can measure temperatures.
4. Find Right Culprit
 There are two things contribute temperature.
A. Heat loss due to high contact resistance, or higher power loss
B. Improper heat dissipation methodology (higher ambient /room temperature)
 Measuring contact resistance there are lot of calculations factor such as DC/AC resistance,
thermal resistivity of different material etc, are considered also the same case with room
temperature.
 However we at ESS are able to develop a very basic tool which can help indicate what is
going wrong.
 Lets have a look. PART2 YOUTUBE VIDEO CLICK HERE