AEP installs North America’s first super-sized 800-kV circuit breaker near Piketon, Ohio

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The Don Marquis Substation near Piketon, Ohio, has received North America’s first super-sized 800 kV circuit breaker.

(Story by Stephen J. Ostrander)

PIKETON, Ohio — An AEP substation near Piketon that received the world’s first 765-kilovolt (kV) transmission line in 1969 will make history again this year as North America’s first recipient of a specially designed, super-sized 800-kV circuit breaker.

Assembly of the pioneer circuit breaker began in mid-June at the Don Marquis Substation, which was the destination for the eponymous 765-kV line from the Baker Station, next to Kentucky Power’s Big Sandy Plant, 68 miles away. Once again, the Don Marquis Station will serve as a testing ground for state-of-the-art technology, this time for the latest “dead tank” circuit breaker, which may become the approved circuit breaker for the AEP transmission system.

Long journey to Ohio

The circuit breaker was built in Changwon City, South Korea, by industrial conglomerate Hyosung Corporation. In 2009, Hyosung, HICO America (Hyosung’s affiliate in the U.S.) and AEP entered a joint agreement to design a 800-kV breaker for AEP. When completed, the breaker traveled by ship across the Pacific Ocean, through the Panama Canal to New York, and then by rail to Ohio.

The final mile of the journey involved cranes lifting the unit from a rail car to a flatbed truck. With the assistance of a bulldozer, the truck strained up a steep slope and reached its destination.

Hyosung was first among several Asian manufacturers to build and test a circuit breaker matching AEP Transmission’s latest specifications: 800-kV; interrupting capability for 63,000 amper/pes; 4,000 amps; 300-ohm closing resistor with a 50 mega-joules (MJ) energy rating; plus a two-break interrupter and single mechanism per phase. The breaker passed those tests and additional interruptions at nearly 1100-kV levels at four parameter transient recovery voltage and at full pole.

“To my knowledge, no other 800-kV dead tank circuit breaker with the same ratings has been tested to such severe test levels,” said Michael Skidmore, principal engineer – AEP Transmission.

Circuit breaker heightens reliability  

Location of Don Marquis Station near Piketon, south of Chillicothe, Ohio.

“This circuit breaker meets our specifications and will improve system reliability,” said Skidmore. “We will also have better defense against certain adverse events, such as out of phase voltage closing.”

The breaker mechanism has a significant amount of stored energy and the 50 MJ, 300-ohm resistor better matches the surge impedance of the transmission line while allowing greater capability for more closing events, according to Skidmore.

Don Marquis Station was chosen as the test site because AEP Transmission crews were already at the site for a major upgrade. The improvement included delivery of a “drop-in control module,” a prefabricated control room, and installation of 765-kV mega-switches manufactured by Alstom, based in France, the company updating steam turbines at seven AEP power plants.

“The pre-assembled drop-in control module speeds up our construction, especially for the protection and control phase,” said Jerry Weatherby, project director.

Hyosung consultants from HICO America, based in Greensburg, Pennsylvania, were on hand during construction, which was expected to be finished by the end of summer. The breaker will be energized later this year after AEP Protection and Control inspections and installation of other equipment at the station.

“Ultimately this circuit breaker will become the design standard for AEP, so we want to gain experience using it before full deployment,” said Skidmore.