The premise behind predictive reliability approaches is the ability to identify points of risk on the grid that allow mitigation of problems before the outage occurs. While equipment data from the manufacturer, years in the field, and other variables can be helpful, actual field conditions are the best indicator of a future failure.
Most utilities employ visual inspection and IR assessments to identify at risk conditions, but according to Dr. Stephen Sebo, Professor Emeritus at The Ohio State University High Voltage Laboratory, partial discharge RF emissions are the most indicative sign of overhead equipment in a deterorated state and at risk for failure.
How Effective are Visual Inspections?
Visual inspections are required for a variety of reasons beyond detecting equipment problems. Veteran utility field and reliability professionals will tell you that 80%-90% of at-risk equipment that is either arcing, or emitting heat cannot be seen under normal conditions. At best, only 10-20% of overhead equipment problems can be detected visually.
What % of Failing Equipment will IR Assessments Find?
IR cameras are very effective at identifying late stage failure on some overhead components, however, it’s estimated that only about 10% of all equipment will exhibit “heat” conditions prior to failure. Furthermore, with an IR camera, a heavy line load is required for the heat signature to be visible. If surveys are done with light load on the lines, even the most troublesome equipment will not be identified as problematic.
RF Partial Discharge Emissions Indicate Predictive Risk from Early Stage Deterioration Through Eventual Failure
The equpment failure process chart below shows why RF partial discharges in the form of equipment arcing, leaking, or tracking are the single most indicative predictive condition for deterioriating equipment that has begun to fail.
As this chart shows, the ability for both early and late stage problem detection is critical for a predicitve reliability program. Exacter's patented technology is unique in ability to identify these conditions.
Exacter Technology is a Scalable Means to Identify RF Emissions Across Thousands of Miles in a Matter of Weeks
Both IR and visual inspections require stopping at each pole and assessing each piece of equipment on the pole which can be a time consuming process. In contrast, an Exacter assessment uses technology mounted in vehicles or on aircraft that perform accurate RF emission condition assessments while driving or flying at typical speeds. An Exacter Assessment will find one failure signature emission every 5-10 miles. As part of the process, field locating teams using ultrasonic technology pinpoint the precise component on the asset emitting the partial discharge.
If your utility is moving away from run-to-failure approaches and toward predictive reliability program, having a means to detect RF partial discharge emissions will be absolutely critical. A program without evaluating this condition would be significantly incomplete.
This table shows the root causes for Lightning Arrester failure and if those causes can be detected visually, with heat or with rf emissions. As you can see rf emissions identify almost all root causes for equiopment failure.