hot spot detection

Hot Spot Detection with Thermal Imaging

Obtaining the precise temperature measurements of electrical equipment with the use of thermal cameras can be difficult until you know exactly what you are looking for. Because most electrical components are made of bare metal, emissivity is low which can make the temperature measurement unreliable.

Emissivity is the ratio of how well materials radiate infrared energy. Its values fall between 0.0 and 1.0. When equipment measures 1.0 it is considered a perfect radiator. However, there are no perfect radiators, because the material is the basis of an object’s emissivity. The aim of why it is hard to use infrared technology to conduct quantitative inspections which requires accurate temperature measurements, this is why many prefer qualitative inspections, it focuses on the apparent temperature difference between comparable equipment under comparable loads or the same equipment under comparable loads.

Electrical anomalies can be detected easily if you know what you are looking for. Electrical circuits with current flowing through it produce heat. That’s why each time you inspect an electrical component it is hot. The thermal pattern plays an important role in detecting electrical system anomalies. The biggest part of abnormal heating in electrical systems is normally caused by abnormal electrical resistance on a contact surface. The improved resistance could come from Phase on phase short, winding to winding resistance imbalance, and Insulation breakdown.

The area of the highest thermal energy is at the connection point; the circuit gets colder when it is farther from the contact point. The greatest amount of heat is generated at the point of resistance and then it conducts away from its point of origin, which leads to a telltale pattern.

Interpreting emissivity in thermal images

The emissivity depends on the viewing angle, surface condition, spectral wavelength, and temperature. Almost all nonmetallic materials are efficient radiation of energy. Infrared cameras have the capacity to change the emissivity settings. The user of the camera can make adjustments to get closer to the surface temperature. Keep in mind, that if the emissivity is less than 0.60, you cannot obtain an accurate temperature reading; there are also other factors that can affect the temperature reading.

Inaccurate temperature can be a sign of trouble ahead. Prevent the danger from happening by checking equipment temperature meticulously. With Fluke thermal cameras you can detect issues before they become problems. Designed for everyday use, in the toughest industrial environments, Fluke offers infrared cameras for a wide range of applications. Reach us through for more information on thermal cameras or visit

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