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Testing of Transformer Differential Protection
Judas, Jan ; Těžký, Jiří (referee) ; Orságová, Jaroslava (advisor)
My bachelor thesis deals with the protection of a transformer, the main focus of the thesis is the differential protection of a transformer, the principle of its function, stabilization and the operating characteristic. I suggested a way of measuring the operating characteristic of the protection SPAD 346 C (developed) by ABB company. As far as measurement is concerned, I used the testing device TZO3, which was, as well as the tested protection, configurated by a computer, into which the results of single measurements were put. The testing was performed via a kind of a test known as ,,TREND“ test for 3 various configurations of operating characteristic of protection and each measurement was scaled for 2 different ,,TREND“ testings. Two marginal operating characteristics were configurated and the third characteritic was configurated approximately between 2 marginal configurations . An error in the calculations of measurement was shown. Since there were two ,,TREND“ tests of steepness performed, there was a calculation of reaction time of protection conducted/performed as well.. All measured and calculated data were processed to graphs in order to illustrate differences among single measurements. I also provided explanations and calculations of possibilities of elimination of increase of electric current within reaction time of protection at steeper increase of ,,TREND“ test.
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Comparison of Instrument Transformer and Sensor Applications in Feeder Terminal REF 542plus
Hrycík, Tomáš ; Majer, Karol (referee) ; Orságová, Jaroslava (advisor)
The aim of this Master´s thesis is use of instrument transformers and sensors on field of industry protection. We will compare current and voltage transformers, current sensor – based on Rogowski coil, voltage sensor – based on voltage divider. By this measure devices, we can monitoring values of analog quantities in medium voltage switchgear. It is impossible to compare, measure and analyze without this measure devices. There is protection terminal REF542plus, which can compile this values. The REF542plus ability are measuring, monitoring, remote control and protection. First, we will discuss about theory of sensors and convential instrument transformers and analysis of analog signal. We will compare analog input channel on sensor´s analog module and transformer´s analog module. There are few differences between type of analog modules. For analog signal analysis are important frequency filters and Analog/ Digital Convertor (sigma-delta). We will describe functions and options of REF542plus. In practical part of this project, we will test protection functions of protection terminal. First, protection terminal will be connected to sensors. Second protection terminal will be connected to transformers. For testing we chose Earth-fault directional protection and differential protection. We will make only secondary tests. That´s mean, input analog quantities to REF542plus will be simulated by tester. In all we will verify quality of protection. We will focus on lower settings of protection and we will inject protection by low current. Objectives are testing of trip characteristics and measuring of trip time.
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