Thermal Imaging Inspection
A method of finding abnormally hot places by scanning the connection points of an energised and loaded system with an infrared camera. It lets a whole panel be scanned in a few minutes without touching the circuit at all. The assessment is made by looking not at absolute temperature but at the difference between similar points.
The strength of the method is that it is comparative. If one of three similar connections carrying the same current is markedly hotter than the others, there is extra resistance there. Absolute temperature, by contrast, is misleading on its own because it varies with ambient temperature, load and ventilation.
- Precondition: the scan is done while the system runs at its real load. A connection that heats up is invisible in an idle system.
- Emissivity: bright metal surfaces give misleadingly low values in the infrared. Correct the camera's emissivity setting for the surface or use a matte reference tape.
- Safety: because the measurement is made on an energised system, work from a suitable distance and with protective equipment while the panel cover is open.
- Records: the points found are recorded with photographs; this gives a basis for comparison at the next maintenance.
Crane panels, DC driver supply busbars and battery terminal connections are the priority points in a scan. Every finding must be verified by a voltage drop measurement after the power has been switched off.
Context in which this term is used: Installation, redundancy and field continuity