Mechanical and environmental considerations in transmission line surge arrester applications

Demonstrated long-term electrical reliability of overhead transmission line surge arresters (TLSA) must now be matched by improved mechanical reliability of the installations. The choice of configuration, including externally gapped (EGLA) and non-gapped (NGLA) designs, as well as the mounting arrangements, affects the applied stresses. NGLA suspended from conductors have pendulum frequencies and mass that can affect vibration control measures. Environmental issues such as moisture ingress and external flashover also affect selection of leakage, dry arc and external gap distances. Tests adapted from insulator, mechanical component and substation arrester standards describe some reasonable utility expectations for TLSA mechanical and environmental performance.