High-voltage equipment is exposed to electrical, mechanical and thermal stresses as well as environmental conditions that can act to accelerate the deterioration of insulation, and hence electrical integrity, eventually leading to failure. Detection and measurement of partial discharge (PD) phenomena, a symptom of insulation deterioration, can provide early warning.

Non-invasive condition based surveys are performed to evaluate partial discharge levels for insulators, arresters, instrument transformers (CTs, VTs, CVTs), cable terminations, circuit breakers and transformers.  Internal and external insulation defects are identified with surveying equipment that combines techniques to detect PD, including dissolved gas analysis (DGA), acoustic emissions (EA) and radio frequency (RFI) to locate the fault.

Well-established as an on-line, non-invasive, early-stage assessment technique, RFI scanning can quickly and accurately document problem areas before they may begin generating heat and be detected with thermography.

Equipment identified as having above normal RFI levels can then be investigated in greater detail using more focused on-line (partial discharge, infrared, acoustic, ultrasonic, UV, etc.) and off-line testing techniques.