Background. Ferroresonance occupies a special place among the phenomena that negatively affect the operation of equipment in isolated-neutral networks. This problem is relevant not only for the networks of Russia, but also for a number of European countries. However, to date there are no patterns and parameters of the network elements (electromagnetic voltage transformers (VT) and total network capacitance), that could sufficiently establish the potential occurrence of ferroresonance phenomena. In addition, there is the problem of experimental validation of anti-resonance properties of VT by manufacturers within independent laboratories. Thus, there is a task to study ferroresonance phenomena based on a full-scale physical model of an isolated-neutral network that allows us to evaluate the conditions of this kind of processes, using real electromagnetic VT produced by modern manufacturers.
Materials and methods. The method of the study that can most adequately reflect the nature of the processes and the order of the values to be studied within the scope of the research is physical modelling based on the test-bed for modelling 6–10 kV networks.
Results. The authors have studied quantitative parameters of phase currents and voltages of VT primary winding, as well as arc currents and triple voltage of zero sequence from the terminals of open delta in case of ferroresonance phenomena in the network. Oscillograms have been obtained, that demonstrate the nature of the change of the values of the indicated currents and voltages during the initiation of ferroresonance processes. Evaluation of the application of different methods for ferroresonance prevention in isolated-neutral networks is given.
Conclusions. The obtained results make it possible to draw conclusions about the quantitative characteristics of the network parameters at which ferroresonance processes occur, as well as on the effectiveness of a number of measures to prevent ferroresonance in 6–10 kV isolated-neutral networks.