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Master thesis Testing of Directional Earth Fault Protections Using the Experimentally Obtained Fault Records deals with the protective functions of earth fault protections during earth faults in compensated medium voltage distribution network and their testing options. At the beginning of the thesis we charakterize operation of medium voltage distribution system in general. We begin with definition and characteristics of earth fault and its compartmentalization by the type of the fault, size of the transition resistance and duration. We also mention grounding methods of node winding transformer on medium voltage distribution network and we describe the most common of them in detail, i.e. network grouded through the arc suppression coil and its operation with automatic switching auxiliary resistor. In this part of the thesis we discuss the localization of the earth fault using passive static methods in compensated systems, which include wattmetric, admittance and conductance method. In next section we deal with the fault records stored in COMTRADE file format, its structure and all elements of its configuration and data file. We create and describe an example of converting ADF file format, recorded by Yokogawa oscilloscope fault recorder, into COMTRADE file format using Microsoft Excel program and M-File created in the MATLAB program. In the practical part we introduce workspace devices and software, which includes secondary testing equipment OMICRON CMC 256plus and its software OMICRON Test Universe with Advance Transplay test module, we further describe multifunctional earth fault protection RYo from PROTECTION & CONSULTING, s. r. o. and machine terminal REM 543 from ABB and their protective functions. The last part describes the actual testing of parallel connected earth fault protection with COMTRADE fault records by Advance Transplay test module in the OMICRON Test Universe. In the conclusion we describe evaluation of the suitability of each protective functions of earth fault protection in a variety of sizes the transition resistance at the earth fault location.

The thesis deals with the proposal, implementation and evaluation of test for fault condition indicators. Thesis focusing on earth fault indicators based on admittance principles. These indicators must be able to evaluate earth faults in compensated, compensated with auxiliary resistor, unearthed and high-resistance earthed networks. The proposed tests verify the current and voltage measurement errors in inputs including monitored characteristic variables such as conductance and susceptance. The proposed test are applied to a selected ample of the fault indicator. As part of the tests, the indicator is subjected to secondary test using the Omicron CMC256plus tester as well as test on fault records that have been converted to COMTRADE for this purpose. The last series of tests carried out uses the physical model of the medium voltage system, where the tested equipment is subjected to fault states in the compensated whit auxiliary resistor system and isolated system. Furthermore, part of the thesis is research of new methods of earth fault detection, including their principles and function description. Also included in the thesis is an overview of manufacturers of indicators, or protection, who are involved in the production of earth fault protection.

The thesis deals with wattmetric and conductance principle of faulted feeder detection in medium voltage compensated distribution networks. These principles are analysed and tested with particular emphasis on high impedance earth faults. The first part of testing utilizes data about state of the system with earth fault, which was determined by designed static model of earth fault. The testing in the second part utilizes real records of high impedance earth faults. In both parts the wattmetric and conductance protections was presented on protective relays ABB REF 615, ABB REM 543 and Protection&Consulting RYo by means of unit OMICRON CMC 256plus. As a major result of performed tests are records of detection of particular earth faults. Based on these records it could be concluded, that functionality of protections is substantially dependent on magnitude of zero sequence voltage. Furthermore the wattmetric protections are dependent on fault resistance as well.