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eng Silicon carbide varistors
Galvin, Dr. Tom; Coll, Dominic
Transformers Magazine Vol. 9, No. SE1, 2022
Current transformers are used to monitor large currents within power grids and power stations, producing a current in the device’s secondary winding that is proportional to the current flowing in its primary winding. Varistors are used to protect current transformers by preventing an open circuit condition if the secondary is disconnected, which can cause high voltages and arcing. Silicon carbide varistors are a superior solution for protecting current transformers due to their ability to limit voltages even in sustained high ambient temperatur...
Hrčak ID: 277836


eng Single-phase exciting current components extraction
Borges, Roberto
Transformers Magazine Vol. 9, No. SE1, 2022
Introduced in 2017, the extraction of exciting current components opens the door for a further enhancement of electromagnetic circuits’ diagnostics. Traditionally, analysis of single-phase exciting current and loss data relies on total current, loss and power factor. For some transformers, the prominence of the capacitive current component masks the behaviour of the inductive component, yielding to uncertainties of the diagnostic criteria. The method allows the separation of the essential constituents of the total measured current and the repo...
Hrčak ID: 277840


hrv Detekcija i kompenzacija zasićenja strujnog transformatora zasnovana na trenutnim proračunima gustoće toka
eng Current Transformers' Saturation Detection and Compensation Based on Instantaneous Flux Density Calculations
Ramezani, Nabiollah; Fallahi, Alireza; Ahmadi, Iraj
Automatika Vol. 57, No. 4, 2016
Jedan od najvećih problema zaštite elektroenergetskog sustava je zasićenje strujnih transformatora i nemogućnost zaštitnih releja da to prepoznaju i komenziraju. U ovom radu prikazan je pristup identifikaciji zasićenja strujnog transformatora zasnovan na trenutnim proračunima gustoće toka. Također, za kompenzaciju zasićenja koristi se izračunata struja magnetizacije. U predloženom algoritmu, trenutna gustoća toka i struja magnetizacije izračunati su korištenjem Jiles-Atherton metode. Korištenjem gustoće toka koljena predložen je kriterij za ide...
Hrčak ID: 196274


eng A dry type HV insulation system for extreme environments
Middleton, Robert; Euvrard, Eric
Transformers Magazine Vol. 6, No. 2, 2019
The aim of this article is to make readers aware of a dry type, paperless insulation technology that offers a safer and cost-effective alternative to traditional oil-filled current transformers. The design concepts and advantages of this unique HV dry type current transformer technology have been delivering verifiable improvements to the power grid over the past 20 years from 35 kV to 600 kV. The example of the implementation of this technology in Canada is a good case in point. Multiple evolutions of the technology have been continuously expan...
Hrčak ID: 218841


eng HV instrument transformer condition assessment
Robalino, Diego
Transformers Magazine Vol. 6, No. 5, 2019
This article discusses the application of dielectric frequency response for the analysis of the insulation in MV, HV and EHV instrument transformers. Overall condition assessment of instrument transformers should not be limited to the analysis of the electro-magnetic circuit; it must also include a reliable method to analyse the insulation of instrument transformers.
Hrčak ID: 228366


eng Advanced online electrical testing in real time aided by electromagnetic signature analysis (EMSA) and artificial intelligence (AI) technology
Ladroga, Richard K.
Transformers Magazine Vol. 9, No. SE2, 2022
The electrical power grid and the apparatus are often subject to online monitoring in order to log data for further analysis in the case of an error or failure. Several levels of maintenance testing and maintenance generations are discussed in the article. Nowadays, they are often using electromagnetic signature analysis technology. The most advanced preventive maintenance and testing paradigm incorporates Artificial Intelligence into the analysis.
Hrčak ID: 286643


eng Temperature reduction in turrets - part I
Magdaleno-Adame, Salvador
Transformers Magazine Vol. 9, No. 2, 2022
This article presents the identification process of high temperatures in low voltage (LV) turrets of a single-phase generator step-up (GSU) transformer which is equipped with non-magnetic stainless steel (SS) inserts in the turrets. High temperatures are detected in the SS insert regions of the LV turrets utilizing thermography cameras and temperature labels. The presence of high temperature in the LV turrets generated issues in the transformer as the crystallization of the turret gasket seals and the presence of transformer oil leaks. To figur...
Hrčak ID: 275181


eng Detection and reduction of high current turrets of GSU transformers - Part II
Magdaleno-Adame, Salvador
Transformers Magazine Vol. 9, No. SE1, 2022
This article is the continuation of the paper: “Detection and reduction of high temperature in high current turrets of generator step-up (GSU) transformers – Part I” published in the April 2022 issue of “Transformers Magazine”, where the author demonstrated that the heating issue in the low voltage (LV) turrets of a 90 MVA GSU transformer is produced by the low carbon steel employed in the LV turret structure and by the presence of short non-magnetic stainless steel (SS) inserts located in the turrets which were manufactured by the original tra...
Hrčak ID: 277839