Lab Services and Grid Reliability, Part 3: DGA, Furan, and Forensics — The Grid’s Most Powerful Diagnostic Tools
In our last post, we looked at real-world examples where lab insights helped utilities catch failures before they escalated. But how do these insights come to life? It starts with the diagnostic tools themselves.
Not all tests are created equal. Some, like dissolved gas analysis (DGA) and furan testing, serve as the grid’s early-warning system. Others, like forensic analysis, help utilities learn from failures to prevent them from happening again. Together, they provide a complete picture of asset health and a foundation for confident decision-making.
Dissolved Gas Analysis: The Gold Standard
When it comes to transformer diagnostics, dissolved gas analysis is the single most powerful tool available.
DGA detects fault gases produced by arcing, overheating, and insulation breakdown inside oil-filled equipment. Even more important than the absolute values are the trends: a sudden spike or steady increase in gases like acetylene can signal problems long before they’re visible in the field.
By flagging early-stage faults, DGA gives utilities the lead time to plan maintenance, coordinate outages, and prevent catastrophic transformer failures. That’s why it’s often called the “gold standard” of transformer testing.
Furan Testing: Seeing Inside Insulation
While DGA focuses on gases in oil, furan testing provides a window into the paper insulation that protects transformer windings. Over time, cellulose insulation degrades, and once it reaches end-of-life, there’s no reversing it.
Furan levels in oil indicate how much insulation has broken down, offering one of the clearest measures of a transformer’s remaining useful life. Utilities use this data to decide whether to extend loading, schedule refurbishment, or replace equipment altogether. In a world where transformer lead times stretch into years, knowing insulation health is critical for planning.
Together, DGA and furan testing act as the grid’s stethoscope, listening for hidden issues before they turn critical.
Supporting Oil and Breaker Tests
While DGA and furan testing often get the most attention, the broader suite of diagnostics, including LTCare (for OLTCs) and Breaker Analysis (DBA) programs ensure no piece of the asset health picture is overlooked.
- Oil quality screen tests (dielectric breakdown voltage, moisture in oil, interfacial tension [ASTM D971], neutralization number [ASTM D974]) reveal whether insulating liquids still meet the demands of load and thermal stress.
- Corrosive sulfur and metals-in-oil analyses detect early chemical attack or contact wear, which may not yet show up in gassing trends.
- Particle count, carbon/particulate testing in OLTCs and oil circuit breakers (both via the LTCare/DBA programs) uncover wear debris, contact erosion, or switching‐induced damage before failure.
Individually, these tests may not carry the weight of DGA or furan analysis, but together they provide the details needed to make informed maintenance decisions across the fleet.
Forensic Analysis: Learning From Failure
Even with the best preventive testing, failures can still happen. When they do, forensic analysis uncovers the root cause.
Labs examine aged paper and pressboard, test tensile strength, and measure degree of polymerization to assess insulation breakdown. Metallurgical analysis reveals cracks, erosion, or poor weld quality. Contaminant analysis identifies foreign particles or byproducts that may have triggered the fault. Cross-sectional imaging exposes thermal damage and wear patterns invisible to the naked eye.
The value of forensic testing isn’t just solving a single failure but applying those lessons across the fleet. Root cause insights inform future strategies, prevent repeat issues, and strengthen warranty and insurance claims.
The Tools That Power Decisions
From gases to furans to forensics, laboratory diagnostics go beyond producing data, they provide the clarity utilities need to act with confidence. Each test adds a different layer of visibility into asset health, and together they form the foundation of proactive, risk-informed asset management.
In the final post in our Lab Services blog series, we’ll look ahead, exploring how the future of grid reliability starts in the lab, from managing AI-driven load growth and EV integration to testing new liquids and next-generation substation equipment.
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