Navigating the Modern Substation: The Evolution of Bushing Technology and Monitoring
In the high-stakes environment of power distribution, the transformer stands as the most critical and expensive asset in the substation. Yet, as industry veterans know, a transformer is only as reliable as its weakest link. Often, that link is the bushing. As global electricity demand surges and the grid undergoes a rapid digital transformation, the way utilities manage, monitor, and specify bushings is shifting from traditional maintenance to sophisticated, data-driven strategies.
Decoding the Acronyms: OIP, RIP, and RIS
Randy Williams, a renowned expert in bushing technology representing the Asplundh Infrastructure Group (AIG), notes the longevity and evolution of these components “condenser bushings, OIP, have been around for 100 years now,” Williams explains. While OIP remains prevalent, Resin-Impregnated Paper (RIP) and the newer Resin-Impregnated Synthetic (RIS) offer distinct advantages, particularly regarding moisture resistance. Williams highlights that “the synthetic doesn’t take on the moisture,” making RIS a more forgiving option for utilities that may not always store components in ideal conditions.
However, the choice between these technologies is not merely a matter of performance but also of manufacturing constraints. Thomas Linn, Global Director Services at Qualitrol, points out the differences in production. “Production, for example, of RIP bushing, I am talking about the 420 kV oil air bushing… will take you to four to five weeks, if you are being fast… if you do a RIS bushing, RIS bushing is three, four days instead,” Linn observes. This disparity in lead times becomes a critical factor in an era where supply chains are increasingly strained.
The Reliability Gap: Why Bushings Fail
The urgency for better monitoring is driven by a sobering statistic: bushings are frequently the root cause of catastrophic transformer failures. Linn, highlights the impact of these components on overall grid health. He notes that “20 % of transformer failures tie back to bushings,” and further adds that “Bushing’s typically have a lifespan of half the lifespan
of a transformer”.
Understanding why these failures occur is paramount for any maintenance team. While the bushing often takes the blame when porcelain is found scattered across a yard, the root cause is frequently external. Williams, who has participated in thousands of failure investigations, identifies common culprits. “Typically, heat and connections are the problem, the failure,” Williams states. He explains that hotspots at connections can lead to gasket failure, which then allows for “moisture ingress, and the moisture attacks the condenser, and then you have that failure”.
From Periodic Checks to Continuous Monitoring
To combat these failures, utilities are moving away from once-a-year manual inspections toward continuous monitoring. This transition is characterized by two distinct approaches.
Brad Bowness, CIO with Systems With Intelligence describes these strategies, noting that “One is more strategic, which is looking at a condition-based maintenance strategy… the other bucket of customers is the targeted asset-centric”.
Strategic utilities leverage various technologies— including Dissolved Gas Analysis (DGA), thermal monitors, and bushing monitors—to create a comprehensive “health index” for their assets. For those focused on specific high-value or problematic assets, targeted investments in monitoring provide a safety net for aging equipment. Bowness emphasizes the value of non-intrusive solutions in this space. “We have a solution that doesn’t need to be intrusively impactful… it is an externally mounted camera and sensor that does both visual and thermal Monitoring on a continuous basis,” he explains.
Thomas Linn argues that a modern health index must look beyond simple electrical parameters. “When I look for an asset health index for a bushing… I would also consider the condition of the gas insulated switch gears, so to say, how often they get switched,” Linn suggests. He believes that factors like transients from switching operations and environmental contamination on silicone insulators must be integrated to provide a truly meaningful assessment of asset health.
The Role of AI and Big Data
The future of bushing management is inextricably linked to Artificial Intelligence (AI) and Big Data. While the industry has discussed the “promise” of big data for decades, the necessary computational power and analytical tools have finally arrived.
Linn sees significant potential for AI in improving the stability of online monitoring data. “I think we could do more in terms of AI and learning algorithms in terms of getting us more improving there the long-term stability also from the providing of the trending for bushing data,” he says. This is particularly important because online measurements can be sensitive to environmental influences and magnetic fields.
Brad Bowness echoes this sentiment, focusing on the practical application of computer vision. “We really think there’s an opportunity to leverage visual inspection, to reduce the amount of manual visual inspection that’s taking place,” he notes. By using AI to proactively identify issues like cracks or lightning strikes, utilities can stay ahead of the maintenance curve.
Procurement and the Supply Chain Crisis
In the current market, simply deciding on the best technology is not enough; utilities must also navigate extreme lead times and manufacturing limitations. For many, the choice of bushing is dictated by what is available.
Williams points out that the industry cannot simply abandon older technologies overnight. “The manufacturing capacity is not there if you wanted to switch anyway,” Williams warns, noting that OIP still accounts for roughly 80% of the business. This reality makes the adherence to standards even more critical for future-proofing. “I think the first thing you have to tell someone when they are specifying their bushings is specify per the IEEE standards first,” Williams advises. Adhering to these standards ensures that when a bushing eventually needs replacement, a compatible unit will actually fit the existing transformer.
The Human Element: Making Power “Sexy”
Beyond the technical and logistical challenges lies a more fundamental issue: the industry’s aging workforce. As experienced experts retire, there is a pressing need to attract a new generation of engineers and data scientists.
Linn highlights this challenge with a call to action. “We have to make our industry a little bit sexier,” Linn asserts. He suggests that by embracing new technologies like AI and digital twins, the power sector can become more attractive to young talent who want to work at the cutting edge of technology while contributing to the vital goal of grid reliability.
Conclusion
The humble bushing, once a “set and forget” component, has become a focal point of substation modernization. Whether through the adoption of RIS technology, the implementation of continuous thermal monitoring, or the application of AI-driven analytics, the goal remains the same: ensuring the heart of the grid keeps beating. As Bowness summarizes, the focus must be on “getting more insight on those assets, getting more life out of those assets, and helping to keep up with the electricity demand with a high level of reliability”.
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This article was originally published in the February 2026 issue of the Advanced Diagnostics & Analytics magazine.
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