Improvements in or relating to power circuit breakers

TLDR: Oerlik and Schinen as discussed by the authors described a liquid break switch with a movable contact and a differential piston that can be closed by applying the chamber pressure to the other side of the differential piston.

Abstract: 1,223,291 Liquid break switches MASCHINENFABRIK OERLIKON 6 March, 1968 [17 March, 1967], No 10785/68 Heading HlN In a small volume liquid break switch the arc chamber 6 contains a liquid, eg oil, permanently under pressure and a movable contact 9 is movable to the closed position by applying the chamber pressure to the other side of a differential piston 18 The chamber 6 is connected to a pump 3 by way of an accumulator 4; a cylinder space 19 can also be connected by a valve 5 so as to apply chamber pressure to the piston; the other side of the piston extends into the arc chamber and thus always experiences the pressure To open the contacts valve member 5a is rotated so as to connect space 19 with a low pressure reservoir 12 surrounding the arc chamber 6 In modifications (Figs 2, 3, not shown) valves are fitted to permit release of excess pressures produced in the arc chamber due to arcing