voltage transformer

One of the problems in the electrical network with isolated (compensated) neutral is the selective determination of the damaged element in a single-phase earth fault. For selective and reliable operation of protections against single-phase earth faults in networks with isolated (compensated) neutral, in addition to the zero-sequence current, information on phase voltages and zero-sequence voltage of the electrical network is required. Many transformer substations do not have traditional electromagnetic voltage transformers.

The object of research is the choice of the optimal technical solution to prevent the development or the long existence of ferroresonance processes in electrical distribution grids of 6-35 kV, which are operated in isolated neutral mode. A lot of factors such as the grounding mode of a grid neutral, its capacitive current of a short circuit to the ground, the type and number of voltage transformers (VT) etc. influence on the probability of occurrence and duration of ferroresonance processes.

A criterion of adequate modeling of equal parameters of windings and their parts is the equal quantities of consumed active and reactive power by a physical original and its mathematical model. A necessity of alternate measurements of parameters during a physical experiment has been proved so now it allows declining measurements errors. A model of a voltage transformer “NOM-10” (Single-phase Oil Transformer-10) has been synthesized for the first time.