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Transmission Line Switching

Phase-Over-Phase Southern States Disconnect Switches with Interrupter Attachments

One way, two way, and three way phase-over-phase switches are used in transmission lines to isolate and segment the system. These configurations are used in restricted right-of way lines where a substation is too expensive.

Segmenting the system requires switches that can break loop current and drop lines. Traditionally this has been done by switches sharing a single multi gap vacuum interrupter and/or whip. These highly mechanical designs have been unreliable and the cause of multiple outages. They require excessive maintenance and experience; a high number of SAIDI, SAIFI minutes.

Many utilities have switched to independent single gap SFinterrupters for this application. These multiple way switches are simpler to install and adjust, significantly improving the operational reliability. Southern states offers a wide array of disconnect switches which can all be applied to any requested transmission application.

Watch our simulation of an installation video for the ES-1 phase-over-phase transmission line switch with LLS® I interrupter:

  • Single gap SFinterrupters insure disturbance-free switching of lines and loops in transmission lines
  • 1000 operations means long-life performance
  • It can be fit in short phase spacing
  • Simple toggle mechanism has low operating effort
  • Epoxy or silicone covered fiberglass interrupter housing minimizes device’s weight and does not break down or track under the UV rays of the sun
Maximum Voltage Rating72.5kV - 145kV
Continuous Current Rating1200 A, 2000 A
Number of Operations1000
Ambient Temperature Range-40° C to +50° C Standard