A new mathematical model for flashover voltages of polluted porcelain insulators

In the present work, flashover behaviour of polluted ceramic insulators is investigated by means of experimental tests and a mathematical model. As a first step, experiments were conducted in two phases. In the first phase arc voltage-arc current behaviour were studied for scintillations on the underside of polluted insulator for different Equivalent Salt Deposit Densities and arc currents. These experimental results were then used to determine the arc constants A and n of Ayrton´s arc voltage gradient equation. In the second phase, critical current (current just before flashover) and flashover voltages were obtained experimentally for three different types of disc insulators. Based on the experimental results, a new generalized mathematical model was developed for the flashover voltage of polluted insulators. The mathematical model includes geometrical parameters of the insulator, pollution severity, critical arc length, pressure, humidity and arc constants. The model was also verified with the experimental and theoretical results of other researchers and the agreement is good.