A PROTECTION CIRCUIT FOR POTENTIAL TRANSFORMERS

摘要

The subject of the invention is a protection circuit for potential transformers, finding application in the attenuation of ferroresonant oscillations occurring in potential transformers in a high voltage network. The system according to the invention features is characterized that the damping resistor (2) and the thermal protection element (3) having a form of a PTC thermistor are connected into the circuit of the open-delta arranged auxiliary windings of the three single phase potential transformers by means of a an electronic switching element or a circuitry (4) of a threshold switching characteristic so that exceeding the threshold voltage at the terminals of the open-delta arranged auxiliary windings of the three single phase potential transformers turns the switching element or the circuitry (4) into its conductive state.