(57) A single-phase ground enclosed load break switch for distribution voltages has a
hermetically sealed cylindrical metal housing (210) of from 2 to 6 inches diameter
which contains an insulating gas under pressure. The switch has a movable contact
assembly to contact a pair of opposed stationary coaxial conductors with the housing.
A rocking bellows (266) at the fulcrum of a crank actuator (264) provides a compact
hermetic seal for the actuator without excessive strain of the bellows. A safety interlock
(302,310,260) with a visual indicator (318,320) locks the contact assembly in case
of a loss of pressure. Excessive pressure in the switch causes the bellows (266) to
be punctured with consequent locking of the contact assembly. The switch is small
enough to be mounted directly on a transformer or placed into a cable, without the
need for a separate enclosure.
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