Summary

In 2020 our U.S. partner, Exacter Inc, began working with a Colorado utility company after it experienced an average of 10 pole fires each year within a 320 km area of its distribution grid. Following a 5-week assessment, Exacter identified 65 issues with active components which the utility promptly replaced. Subsequently, the utility experienced ZERO pole fires for the next 24 months.

Following an investigation, Exacter determined that a combination of natural factors and contamination from jet fuel was the cause of the high number of pole fires. To help mitigate these risks in the future, Exacter provided suggestions to the utility including washing of the active components and an Exacter-conducted inspection every two years.

Background

Pole fires are an expensive and dangerous result of long-term current leakage from deteriorated equipment. Studies show that pole age, climate, wet-to-dry weather transition periods, and as little as 4 mA of current flow can combine to cause spontaneous combustion.

Our US Partner, Exacter Inc, (working closely with a Colorado utility) was asked to study and recommend a mitigation strategy in a particularly vexing case.

Problem

For 10 years, the Colorado utility experienced between 8 and 12 pole fires a year. The fires were contained to an area covering 320 km. The area statistics were:

• 6,000 medium voltage power poles.
• 30,000 pieces of electrical equipment.
• An average of 10 fires per year.
• Typical recovery costs to the utility of AUD 50K per fire event.

Exacter completed a 5-week analysis of the grid using its mobile survey technology. This technology can detect, discriminate, and locate specific RF emission signatures that indicate deteriorated equipment that can lead to circuit failures. The detection methodology as well as the failure signature library have been refined through the assessment of 20 million pieces of infrastructure over 17 years.

Deteriorated equipment can include cracked or damaged insulators, punctured lightning arresters, arcing transformers, loose pole line hardware, damaged line splices, and equipment surface contamination. These conditions can result in flashovers (or mechanical failures) and power outages. Many conditions are accompanied by higher-than-normal leakage currents that, over time, can result in spontaneous wood pole ignition.

Pole fires can be costly and often devastating with embers from pole ignition leading to brush or ground fires. There’s also the risk of outages and danger to employees and the public.

Results of Mitigation Strategy

Exacter technology located 65 deteriorated components in the study area, which the utility replaced. Visual inspection of the equipment led investigators to believe the cause of the RF emission was related to air contamination from nearby airfields and heavy, low-level air traffic.
Statistics resulting from the pole fire mitigation were:

• 0.7% of the medium voltage power poles had deteriorated equipment.
• 0.2% of all electrical equipment was in a deteriorated state that could contribute to a pole fire.
• No pole fires occurred in the 24 months following the predictive maintenance program.
• $0 were expended by the utility to recover from pole fire events following the program.

The success of this strategy for pole fire reduction is easily deployed and has an immediate average payback of less than 6 months. However, avoiding a bushfire is a community win.

If you are interested in having Grid Analytics demonstrate the Exacter solution to assess your electricity grid infrastructure to mitigate/eliminate pole fire risk, please contact us at bud@gridanalytics.com.au or call on +61 427 009 752.