Below shows a thermal image recorded of an isolating switch supplying an air compressor.
As can be seen in the thermal image below, there is a temperature rise toward the cable terminations on the supply side of the switch. This was due to poor electrical contact at the cable terminations. Note that the isolator cover could not be opened as it was mechanically interlocked.
|Sp1 - Cable temp||40.8°C||19°C|
|Sp2 - Cable reference temp||33.1°C||11°C|
|Dt1 - Temp rise (Sp1 - Sp2)||7.7°C||n/a|
Although the temperature rise was only 7.7°C, the temperature at the cable terminations within the switch were likely to be significantly hotter. Therefore the anomaly was assigned a priority category of Level 2 requiring attention at the earliest opportunity.
The Engineering Team scheduled a shutdown of the compressor to carryout investigative/remedial works. Shortly after shutting the equipment down, the team used their own thermal imaging camera and recorded temperatures inside the isolator in excess of 90°C.
The cables were all re-terminated and the switch mechanism was replaced before re-commissioning the equipment.
The above example shows how important it is to take into consideration possible temperatures at the source of the defect, such that the priority given to remedial works is suitable to prevent damage and unplanned production downtime.
To find out more about the use of thermography for electrical inspections contact us today with your enquiry.