Electrical

Thermographic surveys of electrical equipment will identify problems caused by current/resistance relationships. Hot spots in an electrical circuit will be generated as a result of loose, oxidised or corroded connections, or malfunction of equipment itself. The plant which can be surveyed may consist of the following, transformers, sub-station switch gear, bus bars, overhead power lines, electrical control panels, local isolators,  motor connections, thyristor packs – and the list continues. The heat generated at the point of increased resistance is conducted away by the adjacent conductor and air. When this occurs, the thermogram will show a hot area at the connection and a gradual reduction in temperature as the distance from the connection increases.

Mechanical

This normally involves rotating equipment where excessive heat can be generated from friction caused by faulty bearings, inadequate lubrication, misalignment, normal wear and tear, belt drives, gearboxes, compressors, pump, motors, compressed air leaks.

Thermographic surveys in mechanical inspection save time by pinpointing the problem area rather than the cause of the overheating. Other inspection methods, such as vibration analysis can then be used to find the root cause of the problem.

With some electromechanical components, thermography is the only inspection technique needed to determine if maintenance or repair is necessary.

Insulating Material

Thermographic surveys of refractory and other insulation material are based on the assumption that if a uniform temperature exists inside a vessel, then the exterior surface temperature is a direct function of heat conduction through the insulation and external walls.

Localised moisture in the insulation or uneven wear in the refractory can be identified and located by the thermogram as a hot spot because of the uneven heat conductance from the vessel’s interior to its outside surface.

The survey may be carried out on batch and continuous furnaces, heat treatment furnaces, ovens, dryers, kilns, boilers, ladle, hot storage tanks and incinerators.