A Basic Guide to Thermography Method Of Inspecting Electrical Equipment

Thermography

Thermography is a method of inspecting electrical and mechanical equipment by obtaining heat distribution pictures. This inspection method is based on the fact that most components in a system show an increase in temperature when malfunctioning.

The increase in temperature in an electrical circuit could be due to loose connections or a worn bearing in the case of mechanical equipment. By observing the heat patterns in operational system components, faults can be located and their seriousness evaluated.

Modern Thermal Imagers are portable with easily operated controls.

As physical contact with the system is not required, inspections can be made under full operational conditions resulting in no loss of production or downtime.

The thermography inspection tool is a device designed for plant condition monitoring, preventative maintenance and process monitoring applications. Potential applications include inspection of electrical equipment, mechanical equipment and refractory lined structures.

Measurement of Temperature using Infrared Methods

When using a Thermal Imager it is helpful to have a basic knowledge of infrared theory. An object when heated radiates electromagnetic energy. The amount of energy is related to the object’s temperature.

The Thermal Imager can determine the temperature of the object without physical contact by measuring the emitted energy.

Electromagnetic Spectrum

The energy from a heated object is radiated at different levels across the electromagnetic spectrum. In most industrial applications it is the energy radiated at infrared wavelengths which is used to determine the object’s temperature.

There are various forms of radiated energy in the electromagnetic spectrum including X-rays, Ultra Violet, Infrared and Radio.

The human eye responds to visible light in the range 0.4 to 0.75 microns. The vast majority of infrared temperature measurement is made in the range 0.2 to 20 microns.

Although emissions are mostly unable to be detected by a standard camera the Thermal Imager can focus this energy via an optical system on to a detector in a similar way to visible light.