Engineering analysis of electrical effects for the COTP 500 KV transmission line and EBMUD aqueduct corridor

A study was conducted to determine AC electrical interference effects arising in the East Bay Municipal Utility District´s (EBMUD) Mokelumne Aqueducts due to their proximity to the Olinda-Tracy 500 kilovolt (kV) transmission line operated by the Western Area Power Administration (WESTERN). A six-wire gradient control wire mitigation system selected by EBMUD was modeled and evaluated. The study shows that the mitigation system performs satisfactorily under all conditions examined. During steady state conditions, touch voltages are maintained below 15 volts throughout the entire length of the three aqueducts. During fault conditions, touch voltages are maintained below 263 volts, the design limit calculated according to ANSI/IEEE Standard 80. The currents flowing through the isolator/surge protectors do not exceed the ratings of these devices, during steady state and fault conditions