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Since the first years in the market, the Bushing Monitor proved itself as a solid and reliable product, and its first major case of success came in its second year of operation (2004). After that, many others consolidate the BM as an efficient equipment – not all these cases became public, but some of them, listed below, show how the sensor has been a case of success.
SS MIGUEL (SDG&E)
Installed in 2003 at SE Miguel, of San Diego Gas & Electric (SDG&E) – USA, in order to increment the safety in the operation of two single-phase auto-transformers benches, the Bushing Monitor soon achieved its objective.
At the end of 2004, the Bushing Monitor (BM) sent an alert of high capacity to one of the bushings, thus avoiding a possible failure thereof, fact proven with the conduction of offline measurements. Allowing the early identification of the failure, the BM helped preventing a large blackout in the west coast of the United States.
To read more details on this case, click here.
SERRA DA MESA (FURNAS)
At the Serra da Mesa Plant, uncertainties related to a specific family of bushings led to the need of reducing the interval between measurements from 6 years to only 3 months, increasing substantially the costs with maintenance and unavailability of the system.
The alternative to overcome the challenges of a time-based maintenance is the online monitoring of the capacitance and delta tangent of the bushings, which allows that these measurements occur continuously and during the conventional operation of the equipment. Thus, the BM bushing monitoring system was installed in November/2005.
The suspicions in relation to the family of bushings were confirmed during the operation of the monitoring system, which sent an alarm due to a large elevation of the capacitance in the bushing. Even more serious, a high trend of increase of capacitance was also verified, which led to the quick disconnection of the bench.
Offline measurements of the capacitance and quantity of gases present in the bushing attested the veracity of the alarm sent by the BM.
To know more about this successful case, click here.
SS MESQUITA (CEMIG)
CEMIG has also chosen the Treetech’s bushing monitoring system in 2005 for a family of bushings that arose uncertainties at SE Mesquita, in the city of Santana do Paraíso, Minas Gerais.
In this case, the uncertainties were not identified at a first instance. In 2011, however, the Bushing Monitor indicated trend alarms of High Capacitance and High Delta Tangent in one of the bushings. According to the BM diagnosis, these indicators achieved levels above the normal within two months.
The increasing trend of the Capacitance and Delta Tangent continued as it was foreseen until the day prior to its disconnection, when the monitoring system indicated a sudden progression of the delta tangent. From this record, an emergency disconnection was authorized to assess the bushing’s condition.
The results obtained through online monitoring were confirmed by the tests conducted directly on the bushing, which had to be changed. A later analysis of the bushing oil proved the loss of its insulation capacity and Cemig’s judgment in deciding for the disconnection of the transformer.
A technical article elaborated from this case was presented at the 22nd National Seminar on Electrical Power Production and Transmission (“XXII Seminário Nacional de Produção e Transmissão de Energia Elétrica”). To access the article, click here.
UHE ITÁ (ENGIE)
In 2014, more than ten years after being released, the BM continued proving its efficiency, this time at UHE Itá, of Engie, where it was installed in 2011. At site, the Bushing Monitor detected high levels of capacitance and delta tangent, factors that indicated the deterioration of the insulation capacity of the bushing, causing engineers to remove the transformer from the operation.
With the bushing disconnected, a series of tests was carried out to confirm the problem. These tests indicated high levels of combustible gases: Hydrogen (H2), Methane (CH4), Ethylene (C2H4), Ethane (C2H6) and Acetylene (C2H2) – corroborating the diagnosis indicated in real time by the Bushing Monitor.
To know more about this case, click here.
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