Power Arc on Insulator Strings: Testing Procedures and Design of Guard Devices for HV Transmission Lines

The power arc behavior on HV insulator strings is studied with regard to both the testing procedures and the design of guard devices. More precisely, the paper discusses the problems of firing the arc with an impulse or a fuse wire and the importance of the symmetry conditions of the supply and the return circuit in order to obtain reproducible and representative tests. The consequences of such testing procedures in the design of HV transmission lines are shown in some typical cases, that is, for vertical and for V- insulator strings.