The invention relates generally to a vertical break disconnect switch for high voltage applications and, more particularly, to an extra high voltage (EHV) vertical break disconnect switch.
In electric power systems, high voltage disconnect switches are employed to isolate transmission lines and high voltage electrical apparatus to permit the inspection or repair of such apparatus or redirect power or other reasons. A common outdoor vertical break disconnect switch drive mechanism includes a post insulator connected to a current carrying blade through a space linkage. Typically, when the switch is opening the insulator is caused to rotate through 100 degrees about its longitudinal axis while the switch blade rotates about its longitudinal axis and then the switch blade is caused to move about a hinge mounted at a proximal end of the blade causing the blade to pivot about its proximal end through about 90 degrees in the vertical direction and thereby provide an air gap across the open switch. The rotating post insulator is solidly connected to an above-mounted single-piece crank shaft. The crank shaft drives a link connecting to the switch blade assembly. High voltage vertical break disconnect switches such as, extra high voltage (EHV) air insulated disconnect switches have comparatively long blades which become heavy under thick ice condition greatly increasing the required power output from the switch's operator putting extra stress on the rotating post insulator. EHV switches are typically rated for handling voltages from 345 kV to 800 kV.
Such high voltage vertical break disconnect switches, including horizontally or vertically mounted high voltage vertical break switches, are characterized by the elongated switch blade when closing, to first swing about a stationary pivot at the proximal end of the blade, in a first switch closing operation and subsequently to rotate about its own axis in a second switch closing operation. A reverse operation of the switch takes place during opening. As such, a horizontally mounted vertical break disconnect switch blade when closing in the first switch closing operation first swings about the stationary pivot from a vertical orientation to a horizontal orientation, where an elongated blade contact portion or tip carried at the distal end of the switch blade comes into first contact with a break jaw stop of a break jaw assembly at an intermediate closing position of the switch. The switch blade then, in the second switch closing operation, rotates about its own longitudinal axis between the parting contact jaws, with the blade tip's side edges forcing the parting contact jaws to spread until desirably full contact with the oppositely disposed break jaws is accomplished in the final closing of the switch. The side edges of the blade contact portion or tip at full contact are typically about horizontal when in full contact with the contact fingers of the break jaws. A basic patent for such a high voltage vertical break switch is disclosed in U.S. Pat. No. 2,521,484, entitled “Electric Switch Whose Blade Swings and Twists”, by Frederick G. Schmidt, issued Sep. 5, 1950. Such a vertical break switch for very high voltage applications is disclosed in Cleaveland/Price Inc. Bulletin DB-06DP-A20, entitled “V2-CA Aluminum Vertical Break Disconnect Switch 500 kV-3000A, which is incorporated herein by reference as though fully set forth. Cleaveland/Price Inc. is the assignee of the present invention.
Such a standard prior art vertical break disconnect switch includes linkage connecting the switch blade driven by a prime mover, such as, an electric motor or geared hand crank assembly rotating a perpendicular cylindrically-shaped insulator that is directly connected to a crank shaft mounted above the rotating insulator. An adjacent non-rotating perpendicular cylindrically-shaped insulator supports a live base assembly that includes the driven linkage connecting to the switch blade which is actuated by the rotating insulator.
It is therefore an object of the present invention to provide a high voltage vertical break disconnect switch such as, an extra high voltage (EHV) vertical break disconnect switch with a compact and economical drive mechanism that places reduced stress on the rotating perpendicular cylindrically-shaped insulator and power transmitting components between the prime mover and the switch crank component compared to prior art switches, particularly when under heavy thick ice conditions when opening or closing.
The object is achieved by the high voltage vertical break disconnect switch of the present invention having an improved drive mechanism for reducing the loads transmitted by the switch's drive components between the switch's operator, i.e., a prime mover such as a motor or geared hand crank assembly, and the switch's crank shaft mounted on top of the perpendicular rotating cylindrically-shaped insulator. This is accomplished by the introduction of a planetary gear reduction assembly into a modified crank shaft of the switch which requires replacing the prior art existing single piece crank shaft with a two-piece crank shaft. The planetary gear reduction assembly of the present invention includes a planetary gear reduction switch drive mechanism having at least one stage. In the case of a high voltage vertical break disconnect switch of the extra high voltage (EHV) type rated for voltages of greater than 500 kV, a two-stage planetary gear reduction switch drive mechanism of the present invention is preferred. In the case of a high voltage vertical break disconnect switch rated for voltages of 345 kV and lower, a single-stage planetary gear reduction switch drive mechanism of the present invention may be utilized. The linkage beyond the crank shaft that moves the blade between the open and closed positions is the same as the prior art standard arrangement for a standard prior art high voltage vertical break disconnect switch.
In the case of a high voltage vertical break disconnect switch of the extra high voltage (EHV) type, a two-stage planetary gear reduction switch drive mechanism is installed between the top of the rotating perpendicular cylindrically-shaped insulator to virtually surround in cooperating relationship the two-piece crank shaft, which is operatively attached to the rotating insulator. The two-stage planetary gear reduction switch drive mechanism is mounted in a live base assembly. The two-piece crank shaft has a lower shaft part and an upper shaft part. The lower shaft part of the two-piece crank shaft is solidly connected to the top of the rotating perpendicular cylindrically-shaped insulator, while the upper shaft part of the modified crank shaft is rotatable with respect to the lower shaft part by means of a secondary gear train of the two-stage planetary gear reduction. The top of the lower shaft part of the modified crank shaft operatively engages a sun gear connected as the input gear to a first stage planetary gear set. A first stage planet carrier assembly is rotated by means of the interaction of the input sun gear and a stationary first stage ring gear which is held from rotating by means of stationary insulator side plates of the live base assembly. A second stage sun gear is rigidly connected to the first stage planet carrier and is the input gear for the second stage. A second stage carrier is rotated by the interaction between the second stage sun gear and a second stage ring gear which is held stationary in the same manner as the first stage ring gear. The second stage planet carrier is solidly connected to the upper shaft part of the modified two-piece crank shaft which is the output of the gear train and used to drive the vertical break live base assembly linkage. The upper shaft part of the modified two-piece crank shaft accepts plates that creates a traditional crank component which is used to drive the vertical break linkage.
The standard prior art vertical break switch linkage is driven by the rotating perpendicular cylindrically-shaped insulator that is directly connected to the two-piece crank shaft of the present invention. The live base assembly is held stationary by a non-rotating perpendicular cylindrically-shaped insulator which supports the live base assembly that includes the live base assembly linkage which can be actuated by rotating the rotating insulator.
In the case of a high voltage vertical break disconnect switch rated for system voltages less than 345 kV, a single-stage planetary gear reduction switch drive mechanism is installed between the top of the rotating perpendicular cylindrically-shaped insulator to virtually surround in cooperating relationship the two-piece crank shaft, which is operatively attached to the rotating insulator. The single-stage planetary gear reduction switch drive mechanism is mounted in the live base assembly. The two-piece crank shaft as mentioned has a lower shaft part and an upper shaft part. The lower shaft part of the two-piece crank shaft is solidly connected to the top of the rotating perpendicular cylindrically-shaped insulator, while the upper shaft part of the modified crank shaft is rotatable with respect to the lower shaft part by means of a gear train of the single stage planetary gear reduction switch drive mechanism. The top of the lower shaft part of the modified crank shaft operatively engages a sun gear connected as the input gear to a single stage planetary gear set. A single stage planet carrier assembly is rotated by means of the interaction of the input sun gear and a stationary single stage ring gear which is held from rotating by means of stationary insulator side plates of the live base assembly. The single stage planet carrier is solidly connected to the upper shaft part of the modified two-piece crank shaft which is the output of the gear train and used to drive the vertical break live base assembly linkage. The upper shaft part of the modified two-piece crank shaft accepts plates that creates a traditional crank component which is used to drive the vertical break linkage.
These and other aspects of the present invention will be further understood from the entirety of the description, drawings and claims.
For a better understanding of the invention reference may be made to the accompanying drawings exemplary of the invention, in which:
With reference to
A line-terminal connection 20 and a stationary break-jaw contact assembly 22 are attached to the top 15 of the stationary first post perpendicular cylindrically-shaped insulator 13a. The break-jaw contact assembly 22 may have U-shaped break-jaws, not shown in the drawings. An elongated movable switch-blade assembly 24 makes electrical contact with the stationary break-jaw contact assembly 22, when the switch 10 is closed. The elongated movable switch-blade assembly 24 includes an elongated switch blade 26 which is pivotally mounted at its proximal end 30 to a hinge assembly 28, for electrically opening and closing the high voltage vertical break disconnect switch 10. The general details of this arrangement are apparent by reference to
As shown in
The hinge assembly 28 is provided with a blade hinge pivot point, which may be hinge shaft 38; the hinge assembly 28 in electrically conductive relationship with the elongated switch blade 26. The switch-blade 26 is operatively attached at its proximal end 30 to the hinge shaft 38 which blade hinge pivot point is used for rotating the blade 26 to the open position as shown in
Regarding the operation of the switch 10 during closing, the movement of the rotatable third post perpendicular cylindrically-shaped insulator 14 initially causes the one piece crank shaft 50 and the elongated movable switch-blade assembly 24 to rotate about the hinge axis 44, through a predetermined angle ‘A’—from a vertical orientation to a horizontal orientation as shown in
The horizontal vertical break switch 10 of prior art as described thus far is conventional and well known in the industry. As shown in
In this embodiment, a second stage sun gear 92 is rigidly connected to the first stage planet carrier 90 and is driven by the first stage planetary gear set 82. The second stage sun gear 92 is the input gear for the second stage planetary gear set 78. The second stage planetary gear set 78 is turned by the interaction or engagement of the second stage sun gear 92, i.e., the input gear, and a stationary second stage ring gear 96 which is held stationary in the same manner as the first stage ring gear 86. Within the center of the second stage planetary gear set 78 is a second stage planet carrier 94 configured to carry the second stage planetary gear set 78. The upper shaft part 76 of the two-piece crank shaft assembly 72 is solidly connected to the second stage planet carrier 94 and is the output of the two-stage planetary gear reduction switch drive mechanism 70. The upper shaft part 76 is part of the second stage planetary gear set 78 and is the gear reduction output.
The lower shaft part 74 of the two-piece crank shaft assembly 72 is operably connected to the first stage sun gear 80 by cross pin 100. As the lower shaft part 74 of the two-piece crank shaft assembly 72 is caused to rotate by perpendicular cylindrically-shaped insulator 14 connected to the prime mover 36 the first stage sun gear 80 actuates first stage planetary gear set 82 of the two-stage planetary gear reduction switch drive mechanism 70.
This embodiment of the two-stage planetary gear reduction switch drive mechanism 70 with an associated two-piece crank shaft assembly 72 provides for the rotatable third post insulator 14 and the lower shaft part 74 of the two-piece crank shaft assembly 72 to rotate multiple times while the upper shaft part 76 of the two-piece crank shaft assembly 72 rotates about 180 degrees. This particular arrangement has a 9:1 gear reduction. The rotatable third post insulator 14 rotates about 4.5 times to rotate the crank assembly 40 through 0.5 rotations, thus providing reduced stress on the rotating perpendicular cylindrically-shaped insulator 14 and power transmitting components between prime mover 36 and the switch crank component compared to prior art switches, particularly under heavy thick ice conditions when opening or closing.
In a second embodiment of the invention, applicable to the case of a high voltage vertical break disconnect switch 10 rated for voltages of 345 kV and lower, a single-stage planetary gear reduction switch drive mechanism 98 of the present invention may be utilized as shown in
Within the center of the single stage planetary gear set 78 is a single stage planet carrier 90 configured to carry the single stage planetary gear set 78. The upper shaft part 76 of the two-piece crank shaft assembly 72 is solidly connected to the single stage planet carrier 90 and is the output of the single-stage planetary gear reduction switch drive mechanism 98. The upper shaft part 76 is part of the single stage planetary gear set 78 and is the gear reduction output.
As the lower shaft part 74 of the two-piece crank shaft assembly 72 is caused to rotate by insulator 14 connected to the prime mover 36, the single stage sun gear 80 actuates the single stage planetary gear set 78 of the single-stage planetary gear reduction switch drive mechanism 98.
This embodiment of the single-stage planetary gear reduction switch drive mechanism 98 with an associated two-piece crank shaft assembly 72 provides for the rotatable third post insulator 14 and the lower shaft part 74 of the two piece crank shaft assembly 72 to rotate multiple times while the upper shaft part 76 of the two piece crank shaft assembly 72 rotates about 180 degrees. This particular arrangement has a 3:1 gear reduction. The rotatable third post insulator 14 rotates about 1.5 times to rotate the crank assembly 40 through 0.5 rotations, thus providing reduced stress on the rotating insulator 14 and power transmitting components between prime mover 36 and the switch crank component compared to prior art switches, particularly under heavy thick ice conditions when opening or closing.
Of course variations from the foregoing embodiments are possible without departing from the scope of the invention.
This application claims the benefit of U.S. Provisional Patent Application No. 63/114,167 filed Nov. 16, 2020, which is incorporated herein by reference in its entirety.
Number | Date | Country | |
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63114167 | Nov 2020 | US |