On April 25^th, 2023, IEEE (PI)² Austin hosted a Technical Meeting on
“High Voltage Line Component Investigations: 
1 – High Voltage Switch Vacuum Interrupter Component Failure
2 – High Voltage 3WAY GOAB Switch Alternative.”

Nick Choi, Senior Engineer for the Lower Colorado River Authority
Transmission Reliability Engineering department gave an excellent prestation on two recent forensic analyses that they company conducted after failures. The post-mortems on the equipment failure modes in the first instance led the team to work with the manufacture to physically modify the Vacuum switch, improving performance and longevity. In the second instance, the team developed a new switch connection to the transmission lines, which solved the problem.

Investigation of a widespread vacuum switch interrupter component failure experienced on 138-kV vertical air break switch. Failure analysis was conducted with a joint effort of LCRA and the manufacturer. Field testing conducted by LCRA demonstrated 50% loss of the component at 20 operations. Similar results were observed from a HV laboratory test conducted by Turner Electric. IEEE std 1247-2005 section 8.3.1.8 test duty may not be adequate for what utilities need. LCRA mitigated the failure risk through maintenance practice revision, procedure update, and heavy-duty hardware implementation.

 Investigation of inoperable 3WAY GOAB Transmission Switch concerns and LCRA’s new design solution overcoming the challenges. While the popular 3 WAY GOAB Transmission Switches design offered by all major manufacturers may have a flaw that raises switch availability concerns and inoperable problems.