Type GO 1940 Type GM 1942 2,500 MVA Type GW 1952 3,500 MVA 15,000 Gallons Oil 7,000 Gallons Oil 3,900 Gallons Oil A "factor of four" figures in recent 230-kv circuit-breaker design -ratings have increased by four, oil has decreased by almost four. figure 18. A quantity of oil control by design. (Used courtesy of the authors.) figure 19. A typical live tank OCB. (File photo of a 220-kV, 3,500 MVA circuit breaker manufactured by CKD Stalingrad Works, used by permission of the authors.) 96 ieee power & energy magazine may/june 2018