Patent Application
20230197375
The present disclosure relates generally to a scissor link for linking an actuator to a control lever and, more particularly, to a scissor link for linking a magnetically latched actuator to a manual control lever to manually open the switch.
An electrical power distribution network, often referred to as an electrical grid, typically includes power generation plants each having power generators, such as gas turbines, nuclear reactors, coal-fired generators, hydro-electric dams, etc. The power plants provide power at a variety of medium voltages that are then stepped up by transformers to a high voltage AC signal to be connected to high voltage transmission lines that deliver electrical power to substations typically located within a community, where the voltage is stepped down to a medium voltage for distribution. The substations provide the medium voltage power to three-phase feeders including three single-phase feeder lines that carry the same current but are 120° apart in phase. A number of three-phase and single-phase lateral lines are tapped off of the feeder that provide the medium voltage to various distribution transformers, where the voltage is stepped down to a low voltage and is provided to loads, such as homes, businesses, etc.
Periodically, faults occur in the distribution network as a result of various things, such as animals touching the lines, lightning strikes, tree branches falling on the lines, vehicle collisions with utility poles, etc. Faults may create a short-circuit that increases the load on the network, which may cause the current flow from the substation to significantly increase, for example, many times above the normal current, along the fault path. This amount of current causes the electrical lines to significantly heat up and possibly melt, and also could cause mechanical damage to various components in the substation and in the network. Power distribution networks of the type referred to above often include switching devices, breakers, reclosers, interrupters, etc. that control the flow of power throughout the network and may be used to isolate faults within a faulted section of the network.
As part of its power distribution network, many utilities employ underground single-phase lateral circuits that feed residential and commercial customers. Often times these circuits are configured in a loop and fed from both ends, where an open location, typically at a transformer, is used in the circuit to isolate the two power sources. Although providing underground power cables protects circuits from faults created by things like storms and vegetation growth, underground cables still may break or otherwise fail as a result of corrosion and other things.
For a residential loop circuit of the type referred to above having two power sources, it is usually possible to reconfigure the open location in the circuit so that loads that are affected by a failed cable are fed by the other source and service to all of the loads is maintained. However, known processes for identifying the location of a cable failure and the subsequent reconfiguration of the open location often result in long power restoration times because workers are required to physically go to the transformers to test for power and then reconfigure the transformers to change the open location.
It has been proposed to provide bushing well interrupter devices employing vacuum interrupters and magnetic actuators in the existing transformers for these types of loop circuits that provide automatic protection, isolation and restoration of underground residential cable loops and methods to switch cable segments without handling cable elbows. These bushing well interrupter devices often have limited clearances to allow them to be installed in the existing transformers. The bushing well interrupter devices need to have a mechanical system for opening the vacuum interrupter that can be used by a local service person to overcome the actuator/spring forces if needed. Various types of links are known that coupled the actuator to a manual control lever. These links must open the vacuum interrupter, but cannot be used to close the vacuum interrupter or interfere with the normal closing of the vacuum interrupter, thus complicating the overall bushing well interrupter device design. In addition, the move toward smaller packaging of the bushing well interrupter devices is making the manual-open link a more difficult design challenge.
The following discussion discloses and describes a switch assembly that includes an outer housing having a cover at one end, a switch provided within the housing at an end opposite to the cover, and a drive rod coupled to the switch at one end. The switch assembly also includes an actuator assembly operable to magnetically latch the switch in a closed position, where the actuator assembly includes a cup member coupled to the drive rod opposite to the switch and an opening spring positioned within the cup member and being held in compression when the switch is latched closed, and where the cup member includes a central opening. The switch assembly further includes a scissor link having a first leg and a second leg pivotally attached at a pivot point, where one end of the first and second legs extend into the central opening and are rigidly attached to the cup member and an opposite end of the first and second legs extend through the cover, and where pulling the link away from the actuator assembly breaks the magnetic latch and moves the drive rod to open the switch.
Additional features of the disclosure will become apparent from the following description and appended claims, taken in conjunction with the accompanying drawings.
The following discussion of the embodiments of the disclosure directed to a scissor link for linking a magnetically latched actuator that magnetically opens and closes a switch to a manual control lever so as to manually open the switch is merely exemplary in nature, and is in no way intended to limit the invention or its applications or uses.
The bushing well interrupter device 22 also includes an actuator assembly 90 that controls the drive rod 84 to open and close the vacuum interrupter 66.
The actuator assembly 90 also includes a scissor link 150 having a pair of scissor legs 152 and 154 that pivot relative to each other on a pivot pin 156.
The legs 152 and 154 are pivoted closed (opposite to
A cam 210 including adjacent tabs 212 is rotated when the lever 48 is raised. This causes the tabs 212 to engage the tabs 164 and 180, which causes the link 150 to pull on the cup member 110 with the bias of the opening spring 126. This breaks the latch of the permanent magnets 106 and allows the vacuum interrupter 66 to open under the force of the opening spring 126. Lowering the lever 48 rotates the cam 210 back to a home position, but does not cause the link 150 to be engaged. Movement of the link 150 in the cylinder 196 causes the rod 190 to ride in the helical groove, which causes the indicator unit 194 to rotate. When the unit 194 rotates the red sections 200 move out from under the windows 204 and the green sections 200 move under the windows 204 to provide an indication that the bushing well interrupter device 22 is open.
The foregoing discussion discloses and describes merely exemplary embodiments of the present disclosure. One skilled in the art will readily recognize from such discussion and from the accompanying drawings and claims that various changes, modifications and variations can be made therein without departing from the spirit and scope of the disclosure as defined in the following claims.
This application claims the benefit of priority from the U.S. Provisional Application No. 63/293,039, filed on Dec. 22, 2021, the disclosure of which is hereby expressly incorporated herein by reference for all purposes.
| Number | Date | Country | |
|---|---|---|---|
| 63293039 | Dec 2021 | US |
