Gassing Transformers Require Continuous Monitoring - Vaisala Published: Nov 28, 2016 Press Releases Leading industrial measurement provider collaborates with Fingrid to demonstrate that real-time data is critical in assessing the health of assets with a track record of faults Vaisala, a global leader in environmental and industrial measurement, has demonstrated the role of online monitoring in keeping tabs on developing gas trends in a transformer and assessing the efficacy of repairs. As part of a study conducted alongside Fingrid, Finland's national transmission system operator, Vaisala deployed its Optimus online Dissolved Gas Analysis (DGA) device to monitor the removal of dissolved gases from a 400 MVA transformer. The study demonstrates that, for transformers with a fault history, online measurement of dissolved gas levels is crucial, even after repair and maintenance work. Managing a Recurring Problem Once significant levels of fault-generated gases are detected in its oil, a transformer must be taken offline and have its fault diagnosed. Often, the transformer oil is also treated during or after the actual repair of the fault. This process is known as degassing. When the gases are removed from the oil, a new baseline reference is formed to detect any increasing gas trends in the future; this in turn is essential to reveal internal thermal activity or fault, which generates gases. It is difficult to achieve full removal of all dissolved gases, meaning that gas levels may begin to rise again shortly after degassing, even without any fault being involved. As a result, online DGA monitoring is required, since a transformer continues in operation after the fault has been repaired. In conjunction with Fingrid, Vaisala equipped a 400 MVA power transformer in Finland with a multi-gas Optimus DGA monitor prototype, which remained in place before, during and after scheduled degassing work. The monitor tracked changes in dissolved gas levels in real time, demonstrating how, even after the transformer in question had undergone repair and initial degassing, an underlying thermal issue remained. Thus, utilizing a multi-gas monitoring device is essential also going forward, to monitor this transformer continuously and with enough accuracy and good repeatability to illustrate gas trends consistently. Vaisala and Fingrid Present at Euro TechCon The full findings of this collaboration are set to be presented by Senja Leivo, a Senior Industry Expert at Vaisala, and Juha Mertanen, an Adviser at Fingrid, in a paper entitled 'Transformer Fault Detection and Repair Followed by Degassing Monitored with Online DGA' on Wednesday, November 30th at Euro TechCon 2016 in Bristol, UK. The conference brings together leading HV engineers and maintenance experts to discuss new ideas, technologies and case studies relevant to the industry. "When it comes to transformer maintenance, there really is no such thing as a quick fix," commented Senja Leivo. "As transformer fleets continue to operate past their designed life span, online DGA monitoring is essential if internal faults are to be detected and addressed promptly and efficiently. It also provides an invaluable 'health check' following repairs and other service actions, demonstrating exactly how effective this work has been in targeting the root causes of gas build-up." For more information Katri Ahlgren, Communications Manager, Vaisala +358-40-3502557 [email protected] About Vaisala Vaisala is a global leader in environmental and industrial measurement. Building on 80 years of experience, Vaisala provides observations for a better world. Our instruments and systems are used in over 150 countries in demanding industries, including airports, pharmaceuticals, and power generation. Vaisala sensors are used in the harshest places on earth - arctic, maritime, and tropical environments - and even on Mars. Headquartered in Finland, Vaisala employs approximately 1,600 professionals worldwide and is listed on the NASDAQ Helsinki stock exchange. www.vaisala.com www.twitter.com/VaisalaGroup For power generation and transmission industry, Vaisala provides unique measurement equipment for online monitoring of transformer insulation oil. Our reliable solutions support in planning and optimizing the preventive maintenance of power transformers, and thus help to extend their lifetime and reduce the risk of unexpected and costly outages.
