A 230-Kv 10,000-Megavolt-Ampere Steel-Clad Impulse Breaker - Another Rating in a Line of High-Capacity High-Voltage Breakers [includes discussion]

This paper describes a further step in the development of a line of high-voltage high-capacity steel-clad impulse oil circuit breakers to fulfill the industry requirements for increased interrupting ratings at 138 kv, 161 kv, 230 kv, and 330 kv. The 230-kv 10,000-megavolt-ampere breaker introduced in this paper follows the design concepts formulated for the initial step and offers the same excellent operating characteristics associated with the impulse oil-blast principle of interruption. A new tank configuration results in an oil reduction of 40 per cent over the 230-kv conventional round tank breaker while doubling the short-circuit interrupting rating of that design. It further minimizes ground shock disturbance during the interruption of heavy-duty fault currents and allows overall tank heights to be reduced to such an extent that it is now possible to ship 230-kv breakers with all three poles factory-assembled and welded to a unit base. Complete electrical, interrupting, and mechanical design tests demonstrated that the breaker meets all industry standards with ample margins of safety. Tests at the Switchgear Development Laboratory included both fault duty interruptions and the switching of line charging currents. These tests have fully proved the adequacy of the design and indicate that higher interrupting ratings could be obtained, with modifications.