Not only are more testing methodologies listed in the new maintenance and diagnostics charts, but also included are new annexes developed to complement the guide regarding these new additions: Only general information about FRA and DFR was included in annexes F and G because when C57.152 was close to being published, other working groups were developing specific guidelines for the advanced diagnostic techniques of SFRA and DFR. The C57 standards already contained other transformer-related guidelines administered and supervised by the IEEE Transformer Committee (Figure 1). Test Equipment Required. This allows acquisition of sufficient data to estimate moisture content in the solid insulation and conductivity of the liquid insulation. Transformer Testing and Maintenance Standards . An excitation ac signal is applied to one electrode in a wide range of frequencies — typically from 1kHz down to 1mHz — and current is measured. The work was led by Jane Verner (Chair), Loren Wagenaar (Vice Chair), Kipp Yule (Secretary), and supported by many members of IEEE who dedicated long hours in revisions and contributions to the new guide. As it checks the quality of material used and the procedure of transformer manufacturing hence provide us details of life of transformer, the transformer behaviour on different faults. Annex A covers the measurement lead connections. Transformer manufacturers and field operators have always benefitted when new technologies are applied during design, manufacturing, commissioning, and operational processes that improve the quality and reliability of electrical apparatuses.

To prove that the transformer meets customer’s specifications and design expectations, the transformer has to go through different testing procedures in manufacturer premises. The different institutions working worldwide to provide best practices and guidelines rely on the knowledge and experience of transformermanufacturers, academics, researchers, fieldusers, and instrument manufacturers whowork together for the best interests ofthe technical community. By Zia Salami, Ph.D., CDM Smith, Charlotte, N.C.; Lilly Vang, CDM Smith, Raleigh, N.C.; and Adrian Hendels, CDM Smith, Boca Raton, Fla. NEMA ST-20: Dry-Type Transformers for General Applications. A comparative analysis shows the following methodologies were added to the new guide: IEEE C57.152 (Chapter 5) also considered the importance of providing a maintenance chart where the end user could select the testing practices recommended (REC), as-needed (AN), and optional (OPT) for different stages during the service life of the transformer: commissioning, in-service, after protection trip due to system fault, or after protection trip due to internal fault. ON-SITE TRANSFORMER TESTING AND DIAGNOSTICS SITE ACCEPTANCE TEST To ensure that a transformer is operational safe to be connected to the power grid, a Site Acceptance Test can be performed by STS. One way is by following the activities of national and international regulatory institutions that focus their resources on keeping up with the latest technological developments for design, construction, operation, testing, maintenance, and even post-mortem investigations of power and distribution transformers. Original article published in NETA Winter Journal 2015 Transformer testing standards update - NETA '16, We use cookies to provide you with a better experience. On subsequent attempts to generate the transformer signature, replicating the high-frequency band is almost impossible.

Transformer testing has developed considerably over the past years. Once the transformer has passed the FAT, it is ready for shipment to a new site, where a testing crew will commission the unit before energization. Transformers are tested for overvoltages by exciting the secondary of the transformer from a high frequency a.c. source (100 to 400 Hz) to about twice the rated voltage.This reduces the core saturation and also limits the charging current necessary in large, travelling wave technique similar to that for cables.


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