Mitigating lightning outages on 138 kv transmission lines

Transmission systems are required to provide high levels of reliability to maintain and to increase the marginal return on the electric service provided. There are several means of improving the lightning performance of transmission lines. Improvement costs range from extraordinarily expensive to very moderate. A comparison of different means of improving lightning performance (increasing insulator string length, adding an overhead ground wire, installing arresters, making grounding improvements) is provided. The costs and benefits to the customer of improved lightning performance are described. A low cost means of improving line performance has been applied for several years with excellent results.