Application of Magnetic Materials in Inductive Sensors for Partial Discharge Activity Monitoring

The measurement and monitoring of partial discharge activity is one of the commonly used methods to determine the status of insulation system in high voltage power devices.For such monitoring there are various methods involving direct galvanic coupled measurement, acoustic method, or measurement by inductive method.Inductive measurement of partial discharges uses inductive sensors, which sense the partial discharge pulses occurring in high voltage circuit.The sensitivity of such sensors depends on their design, construction, and materials used for sensor core.The choice of magnetic material is very important to achieve optimal values of sensor sensitivity.We have constructed experimental sensors using different magnetic materials and different construction.In our experiments we have selected two magnetic material types: magnetic material based on Fe-Ni (permalloy) and magnetic material based on MO•Fe2O3.We were able to examine the optimal construction type and magnetic material of sensor core for these sensors.The minimum acceptable sensitivity of the sensors was determined by equivalent measuring sensitivity when using direct galvanic method.