Modeling of partial discharge (PD) for solid insulation with void and building a hardware setup to measure partial discharge

In high voltage (HV) electrical power systems; varieties of materials (solid, liquid and gaseous) are used for insulation purpose to protect the early failure in High Voltage power equipment. Most of insulating materials are not perfect in all respect and contain some impurities. The presence of air bubble is one of such impurities in insulating materials which is highly undesirable. Insulation of the HV power equipment gradually degrades due to cumulative effect of electrical, chemical and thermal stress and aging. Due to the high voltage stress the weak zone inside the insulator causes the partial discharge (PD).This deteriorates the insulator. In this paper, an electrical circuit model of solid insulator with void is used to study the PD activity leading to breakdown inside the insulator. Among the models (namely capacitive model and induced charge concept model), the capacitive model is adopted in present work. The simulink capacitive model implemented, effectively demonstrates the partial discharge process. The model is used to study and demonstrate effect of permittivity of cavity/impurity and breakdown inception voltage level of the impurity. HV Laboratory experiments with ‘melinex’ insulation paper and pre-breakdown currents are measured; as the insulation did not puncture up to 12 KV (Highest voltage in the present work). Breakdown voltage with ‘Garlam’ insulation sheet with and without void (Sandwiched between ‘Garlam’ sheet and low voltage electrode) showed the time dependency. This is to infer that, breakdown due to activity in the void resulted into early breakdown with higher applied voltages (above the PD inception voltage levels for the void).these experiments effectively demonstrates the effect of partial discharge due to void.