Thermography or Thermographic Inspection – What Is It?

28 nov Thermography or Thermographic Inspection – What Is It?

Thermographic inspection, or simply thermography, is a type of predictive maintenance used to detect heating points in connections and components. Thermography is employed to identify areas with excessive heating, primarily caused by increased electrical resistance. By detecting these hot spots, corrective actions can be taken before a component failure occurs, thus preventing system breakdowns, productivity losses, and safety hazards.

Since a rise in temperature in electrical connections or components is a clear sign of failure, thermography is the best method for diagnosing defects in electrical systems at an early stage, when the degradation process is just beginning and simple corrective actions can permanently solve the issue. This is the main reason why insurance companies often require thermographic inspection reports: to detect and prevent defects before they cause damage to installations, equipment, or people.

The device used for thermographic inspection is called a thermal imager or thermographic camera. It is capable of capturing images that highlight the thermal profile of a component, making it possible to detect any abnormal heating that deviates from the component’s standard thermal pattern.

Fundamentals of Thermography

All materials emit radiation due to the thermal agitation of atoms and molecules. The higher the temperature of the material, the greater the amount of radiation it emits. Most of this radiation is emitted in the form of infrared light, which is not visible to the naked eye. Thermal imagers function like photographic cameras, but instead of being sensitive to visible light, they are sensitive to infrared radiation. In this way, thermal imagers are capable of capturing thermal images of the objects under inspection, even from a certain distance. These images are called thermograms.

In practice, the thermal imager measures the infrared radiation emitted by objects and, due to the proportionality between radiation and temperature, displays the images using a color scale that corresponds to different temperatures. It is important to note that the radiation measured by the camera depends not only on the object’s temperature, but also on the emissivity of the material from which the object is made. Additionally, the total infrared energy leaving an object’s surface is the sum of the transmitted, emitted, and reflected components of infrared radiation.

Problems Detectable in a Thermographic Inspection of Electrical Installations

• Loose or deteriorated connections;
• Overloads;
• Open circuits;
• Load imbalance;
• Induction heating;
• Third-order harmonics;
• Current leakage in insulators;
• High energy consumption due to component overheating;
• Faulty equipment.

Benefits of Thermographic Inspection in Electrical Installations

• Reduction in unplanned downtime;
• Increased equipment lifespan;
• No need to interrupt production during inspection;
• Reduced risks to people and equipment;
• Lower repair costs for equipment;
• Increased profitability;
• Fire prevention;
• Reduced insurance policy costs;

Even New Installations Can Have Defects

In electrical installations, increased resistance can be caused not only by component wear, but also by oxidation, dirt, improper tightening of connections, or the low qualification of the professionals responsible for the assembly.

Figure 1 – Detection of a Hotspot at the Circuit Breaker Connection – Loose Connection

Figure 2 – Detection of a Hotspot on the Disconnector Insulator – Current Leakage

Figure 3 – Detection of a Hotspot on the Panel Structure – Current Flow by Induction in the Structure

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Electrical panels can exhibit various problems that lead to overheating, such as poor connections, corrosion, overload, induction, current leakage, and more.

A thermographic inspection can improve reliability and minimize the risks of failures, irreversible damage, and even fires.

Figure 4 – Detection of a hot spot at the circuit breaker connection – poorly crimped compression terminal

Before any electrical component or equipment fails, it will almost certainly begin to overheat. Thermography, when used in periodic inspections, can detect excessive heating in electrical or mechanical components, which is often the first sign that a serious issue is developing.

Poorly made connections, unbalanced circuits, defective breakers, blown fuses, overloaded circuits, improper maintenance, intrinsic material defects, and many other irregular conditions can lead to overheating and eventual failure of electrical components.

Thermography can detect problems in their early stages, allowing corrective maintenance to be performed before the issue worsens, ultimately reducing repair costs and unplanned downtime.

Thermographic inspections should be an essential part of any predictive maintenance plan in industrial environments and should be performed regularly. They should also be included in the commissioning plan for any new electrical system or one that has undergone modification or expansion.