Discloses a high-voltage circuit breaker comprising a control device at high potential operable to produce separation of the usual contacts of the breaker, an operator at ground potential for operating the control device, and a linkage mechanically connecting the operator and the control device. The linkage comprises a releasable coupling at a location of substantially line potential that is releasable to allow the control device to be operated independently of the operator. Latch means normally prevents coupling-release but is operable in response to predetermined electrical conditions to release the coupling and allow high-speed operation of the control device before the operator operates.