Gas-insulated switchgear apparatus

A gas-insulated switchgear apparatus comprising:

• (a) three-phase gas-insulated main buses extending substantially along a straight path;
• (b) line feeder switching units corresponding to the three phases respectively, said line feeder switching units being arranged to extend in a horizontal direction orthogonal with respect to the axial direction of said gas-insulated main buses and connected at one end thereof to said gas-insulated main buses respectively;
• (c) three entry gantries of respectively different heights for anchoring three-phase AC power transmission lines while maintaining a required vertical open-air insulation distance between said power transmission lines, each of said entry gantries including a pair of entry towers disposed opposite to each other on a line parallel with the axial direction of said gas-insulated main buses, and an auxiliary incoming line anchored between said entry towers, said entry gantries being spaced apart from each other by a predetermined open-air insulation distance in said horizontal direction and disposed in such a relation that a taller one of said entry tower pairs is located at a position remoter than that of the next adjacent one in the incoming direction of said power transmission lines;
• (d) bushings connected to the other end of said three-phase line feeder switching units respectively, each of said bushings being connected with the corresponding entry gantry of the same phase while being spaced apart from the next adjacent one by a predetermined open-air insulation distance in said horizontal direction;
• (e) means for anchoring said power transmission lines to said entry gantries in such a relation that the higher one of said power transmission lines is anchored to the taller one of said entry tower pairs;
• and
• (f) incoming lines electrically connecting said power transmission lines of the three phases to the external terminals of said bushings of the corresponding phases through said auxiliary incoming lines respectively.

A gas-insulated switchgear apparatus comprising:

• (a) a phase-separating structure of three-phase units spaced from each other in a horizontal direction, each of said units including a gas-insulated main bus of one of the three phases extending substantially along a straight path, a line feeder switching unit of the same phase extending in said horizontal direction orthogonal with respect to the axial direction of said gas-insulated main bus and connected at one end thereof to said gas-insulated main bus, and a bushing of the same phase connected to the other end of said line feeder switching unit;
• (b) three entry gantries erected adjacent to said bushings of the corresponding phases respectively and extending substantially in parallel with the axial direction of said gas-insulated main buses, said entry gantries of the three phases having heights progressively increased in a direction away from the incoming direction of power transmission lines;
• (c) means for anchoring said power transmission lines of the three phases to said entry gantries of the corresponding phases respectively in such a relation that a higher one of said power transmission lines is anchored to a taller one of said entry gantries;
• and
• (d) incoming lines electrically connecting said power transmission lines of the three phases to the external terminals of said bushings of the corresponding phases respectively.