FIELD: physics.
SUBSTANCE: present group of inventions relates to the protection of electrical power systems and more specifically to a method of measuring, analysing and differentiating signals for determining leakage and/or fault currents in electrical devices powered by such systems. The method includes digital sampling of a current or group of currents in an electrical power system using sufficient bandwidth in the said sampling to reconstruct the amplitude and phase of a synthesised electric frequency and its harmonics and a fundamental carrier frequency of switching electronics and modulation sidebands, real-time analysis of signals from multiple transducers or measurement points to provide fault diagnostic and location information in insulated neutral supply networks. The method includes the identification of frequency components of currents in electrical power systems. The invention also discloses methods of detecting ground faults and leakage of high-frequency currents, particularly, although not exclusively, in supply networks with an insulated neutral (I-T) and/or limited ground fault and, particularly, in supply networks in hazardous areas, such as mines. The invention also relates to a method of improving relay reliability when determining ground leakage, particularly when the relay operates together with switching electronics. The invention also relates to a method of interpreting broadband measurement signals to detect potential hazards which might occur due to the operation of switching electronics, instead of rejecting signals such as noise, in order to simplify analysis. The protective device is capable of detecting direct current signals and higher frequency relating to the normal and abnormal operation of the power switching electronics connected as a load to the electrical power system, wherein ground leakage currents are analysed in order to turn on protective equipment.
EFFECT: achieving high accuracy of measuring and analysing signals of electrical power systems which include switching electronics, and improving protection methods thereof.
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