Stay Ahead of Transformer Failures | Expert Insights

Dissolved Gas Analysis (DGA) analysers are crucial for monitoring the health of transformers. They detect gases in the insulating oil that indicate potential problems. In a recent conversation with Tim Miller from Megger, he explained the importance of watching certain gas levels. Specifically, acetylene levels between 3-5 ppm are a serious warning sign of arcing or severe overheating and need immediate attention. Recognising these gas signatures is key for timely maintenance and ensuring that transformers operate reliably.

1. DGA analyzers are used to monitor the condition of transformers and gases dissolved in oil. They are a key diagnostic tool. What types of transformer faults (e.g., overheating, partial discharges, arcing) are most likely to be detected first through continuous DGA monitoring, and what order of magnitude of early warning can this give the operator?   

   "Dissolved Gas Analysis is inherently a slower means of detecting transformer problems than monitoring partial discharge or bushing condition in real time because gases generated by faults take time (hours typically) to migrate through the oil to the monitor and be measured.  This slower response does not mean that DGA monitoring does not provide value since the identities and quantities of gases generated provide information on the type of faults the transformer is experiencing.  Acetylene, ethylene, and methane are so called ‘hot metal gases’ and are indicative of faults in the windings or connections to the windings.  Carbon monoxide and carbon dioxide are generated by thermal decomposition of paper insulation.  Lower energy faults caused by gas bubbles or dielectric breakdown of oil generate hydrogen.  Acetylene is the most critical of the gases since it is caused by high temperature faults or arcs and concentrations as low as 3-5 ppm in the transformer are a clear predictor of imminent transformer failure.  Properly installed, maintained, and alarmed/networked DGA monitors provide transformer owners with information that can warn of imminent problems, prioritize maintenance activities, and indicate remaining life."
   
    

2. How can your product, the Insulogix online system, help utility companies increase their operational efficiency? How does InsuLogix differ technically and operationally from other online DGA solutions (e.g., in terms of detectable gases, sensitivity, environmental resistance, IT integration)?

   "Megger currently manufactures and sells the InsuLogix G2 incipient fault monitor that measures hydrogen, acetylene and moisture with limits of detection of 25, 0.5, and 2 ppm, respectively.  The InsuLogix G2 uniquely uses a tunable laser diode spectrometer to measure acetylene and moisture providing among the lowest acetylene sensitivity of any available monitor and comparable to the detection limit of offline lab measurements using gas chromatography.  Competitive incipient alarm monitors measure only total combustible gases and moisture, hydrogen and moisture, or hydrogen, carbon monoxide, and moisture.  None of the competitive monitors measures acetylene which can only be measured by much more (2-3X) expensive, complex, and complicated to install diagnostic multi-gas monitors.  Any DGA monitoring system is only effective if it is installed on a significant portion of a utiliy’s transformer fleet, connected to the utility’s network with appropriate alarms, functions over the life of the transformer, and properly maintained.  Fleet coverage is a strong function of the total (purchase, installation, and operating) costs.  The InsuLogix G2 excels here in that its cost is comparable to many single gas or total combustible gas monitors, requires no regular maintenance and has an expected lifetime of ten years."
   
    

3. In the era of digitalization, how does InsuLogix work with asset management systems, and how do you combine DGA data with other sources (e.g., temperature monitoring, PD, historical oil tests) for a holistic condition assessment?   

   "The InsuLogix G2 supports Modbus, DNP3, and ICE 61850 communication protocols.  Its software is stored internally and its settings, log files, and data can be accessed via an ethernet connection to a laptop with standard internet browsing software e.g. Microsoft Edge or Google Chrome or a Megger supplied cellular modem (Remote Communication Box).  The monitor is equipped with four user defineable analogue output signals (DC voltages or 4-20 mA)  that can be tied to the owner’s SCADA network.  It also has 8 signal relays and 4 power relays that can be set to trigger based on the monitor’s or the transformer’s conditions.  The InsuLogix G2 does not have input channels that can be tied to temperatures, loads, or other transformer parameters; however, this is planned in the next generation product."
   
    

4. How does InsuLogix approach the issue of data compatibility and standardization (e.g., DGA formats, diagnostic models)—are there any industry interoperability initiatives you are involved in?   

   "The InsuLogix G2 is a two-gas incipient fault monitor and therefore cannot provide diagnostic detail such as Duval Triangle or key gas ratios that a multi-gas monitor provides; however, its capability to measure and trend hydrogen and acetylene positions it to offer transformer heatlh information that no other monitor in its price range provides..  Megger will launch its InsuLogix G7 multi-gas monitor in 2026 that will offer full diagnostic DGA information and incorporate 5 additional (3 4-20 mA and 2 temperature) sensor inputs.  In addition to this launch, Megger is working to combine its partial discharge monitoring capability contained in the ICMObserver with the InsuLogix G7 in order to offer transformer owners complete asset health information."