A switch assembly that is part of a transformer in an underground residential power distribution circuit and that provides fault isolation and restoration. The switch assembly includes first and second switching devices each having an outer housing, a transformer interface electrically coupled to the transformer, a connector interface electrically coupled to a first connector and a first vacuum interrupter having a fixed contact and a movable contact, where the fixed contact is electrically coupled to the connector interface and the movable contact is electrically coupled to the transformer interface. A control board controls the first and second switching devices, where the control board is responsive to voltage signals from capacitors in the first and second switching devices.

A method for isolating a fault in an underground power distribution network. The network includes a power line, a plurality of transformers electrically coupled to and positioned along the power line, a first recloser connected to one end of the power line and a second recloser connected to an opposite end of the power line, where each transformer includes an upstream switching device and a downstream switching device, and where power is provided to both ends of the power line through the first and second reclosers and one of the switching devices is a normally open switching device. The method includes detecting overcurrent by some of the switching devices, detecting loss of voltage by some of the switching devices and sending clear to close messages to some of the switching devices to open and close certain ones of the switching devices to isolate the fault.

A transformer assembly including a transformer that is part of an underground residential power distribution circuit and that provides fault isolation and restoration. The transformer assembly includes an enclosure enclosing a primary winding and a secondary winding. The transformer assembly also includes first and second switching devices mounted to a panel of the enclosure, where each switching device includes an outer housing, a transformer interface electrically coupled to the primary winding, a connector interface electrically coupled to a first connector and a vacuum interrupter having a fixed contact and a movable contact. The fixed contact is electrically coupled to the connector interface or the transformer interface and the movable terminal is electrically coupled to the other connector interface or the transformer interface.

A method for isolating a fault in an underground power distribution network. The network includes a power line, a plurality of transformers electrically coupled to and positioned along the power line, a first end switch connected to one end of the power line and a second end switch connected to an opposite end of the power line, where each transformer includes an upstream switching device and a downstream switching device, and where source power is provided to both ends of the power line through the first and second end switches and one of the switching devices is a normally open switching device. The method includes detecting overcurrent in the network from the fault, opening certain ones of the switching devices in response thereto, detecting loss of voltage as a result of the open switching devices and opening or closing certain ones of the switching devices to isolate the fault.

A triggered vacuum gap (TVG) device that has application as a closing switch for synchronized closing in distribution and transmission power systems. The TVG device controllably sustains a current arc in the device through initial current zeros created by power system transients and, thereby, prevents premature interruption of the closing operation. The TVG device includes main electrodes defining a vacuum gap therebetween and a triggering electrode providing a triggering gap between one main electrode and the triggering electrode. The TVG device also includes a triggering circuit having a high voltage impulse source that supplies a fast rising impulse voltage to the one main electrode and the triggering electrode for creation of a plasma to provide an initial breakdown of the triggering gap and a low voltage unidirectional current source that supplies current to the one main electrode and the triggering electrode once the first triggering gap breakdown has occurred.

A triggered vacuum gap (TVG) device that has application as a closing switch for synchronized closing in distribution and transmission power systems. The TVG device controllably sustains a current arc in the device through initial current zeros created by power system transients and, thereby, prevents premature interruption of the closing operation. The TVG device includes main electrodes defining a vacuum gap therebetween and a triggering electrode providing a triggering gap between one main electrode and the triggering electrode. The TVG device also includes a triggering circuit having a high voltage impulse source that supplies a fast rising impulse voltage to the one main electrode and the triggering electrode for creation of a plasma to provide an initial breakdown of the triggering gap and a low voltage unidirectional current source that supplies current to the one main electrode and the triggering electrode once the first triggering gap breakdown has occurred.

Disconnect switches include a housing, a fixed main contact in the housing, a movable main contact in the housing in cooperating alignment with the fixed main contact, a first actuator coupled to the movable main contact, and a second actuator coupled to the housing. The second actuator is configured to apply a motive force to the housing that is in a direction opposing a motive force applied by the first actuator to the movable main contact.

Disconnect switches include a housing, a fixed main contact in the housing, a movable main contact in the housing in cooperating alignment with the fixed main contact, a first actuator coupled to the movable main contact, and a second actuator coupled to the housing. The second actuator is configured to apply a motive force to the housing that is in a direction opposing a motive force applied by the first actuator to the movable main contact.

A medium voltage switching pole includes: a fixed contact of a vacuum interrupter; a movable contact of the vacuum interrupter; a piston; at least one electrical contact; a first terminal; and a second terminal. The fixed contact is fixedly connected to the first terminal. The movable contact is fixedly connected to the piston. The piston moves within the second terminal along an axis. The at least one electrical contact makes an electrical connection between the piston and the second terminal. An outer surface of the piston and an inner surface of the second terminal are arranged such that: when in an open configuration the fixed contact and movable contact are separated, at least one first radial line perpendicular to the axis extends through locations of the at least one electrical contact, and a first distance along the at least one first radial line extends from the outer surface.

A switch including a first electrical terminal, the first electrical terminal including a blade pivotable between an open position and a closed position, and a rod extending from the first electrical terminal parallel to the blade. The switch further includes a second electrical terminal configured to receive the blade when in the closed position, the second electrical terminal including a vacuum interrupter, wherein the vacuum interrupter engages the rod when in the closed position. Rotating the first electrical terminal in a first direction causes the blade to disengage from the second electrical terminal at a first point, and further rotating the first electrical terminal in the first direction causes the rod to disengage from the vacuum interrupter at a second point.