Infrared Thermography for Electrical Systems
A Thermographic Survey or Infrared Scan assists in finding areas of high heat or thermal radiation caused by loose connections, overloaded circuits, or defective equipment. The increase in heat signature or hot spot can be indication of failing electrical equipment and can be investigated to reduce the likelihood of an electrical fault causing an outage and costly down time. Infrared scan may be part of a preventative maintenance program or performed during the electrical commissioning phase of a project.
The Standard for Maintenance Testing Specifications for Electrical Power Equipment & Systems (NETA-MTS 2019) recommends a Thermographic Survey be performed every 12 months. This work involves the removal of dead-front panels covers or the use of infrared windows to view installed equipment and conductors. Electrical equipment is then loaded to its maximum or approximately 40% of its rating at a minimum, and an infrared camera is used to take pictures which capture a thermographic image and surface temperatures. Temperatures differences based on comparisons between similar components under similar loading, and temperature difference base on comparisons between component and ambient air, can then be evaluated. NETA MTS Table 100.8 provides suggested actions based on temperature rise.
A thermographic survey report will be issued detailing discrepancies and includes equipment photographs, thermographic images, load conditions at time of inspection, recordings of temperature values at equipment surfaces of concern, and recommendations for repair.
This work should be performed by qualified persons who have been trained to perform the work at a safe distance using the appropriate personal protective equipment (PPE). Important safety concerns must be observed since this work involves scanning energized electrical equipment when protective panel covers have been removed and enclosures are opened.