Insulation Coordination

This section describes the voltages and overvoltages that impact a transmission line, such as switching and lightning surges. It discusses the changes in the insulation stress and withstand characteristics due to compaction of overhead power lines, highlighting the differences in the insulation design between AC and DC overhead power lines and proposing some mitigation measures, like the placement of surge arrester devices. The AC system overvoltage stresses are the input of the insulation coordination study for the design of clearances and of the insulator chain of the AC overhead power lines. On the other hand, for DC lines these designs are usually determined by the pollution performance requirements. Note this is not a complete description of the insulation coordination process but describes the voltages and overvoltages that impact a compact transmission line.