Transmission Line Insulation Design at High Altitude

The Public Service Company of Colorado plans to initiate 345-kV transmission at altitudes of 1250 to 3680 m. Compared to sea-level designs, the increase in the required tower strike distance has been predicted at about 50% for altitudes of 3600 m [1]. However, by use of surge arresters at station entrances and preinsertion resistors in the circuit breakers, the tower insulation design is comparable to present lower altitude designs.