The present invention is directed to electric power systems and, more particularly, to a modular vacuum circuit interrupter with a modular, removable contactor unit containing a modular, removable vacuum bottle unit.
Circuit interrupters have been used for decades at disconnect switches and other types of switches throughout electric power systems. These circuit interrupters typically include contactors, such as butt or penetrating contactors, inside sealed containers housing a high dielectric medium, such as SF6 or a vacuum. While SF6 is a very effective dielectric medium, it is also a very powerful greenhouse gas. There is, therefore, an environmental interest in minimizing the use of SF6 in circuit interrupters. Increasing interest in environmental protection has increased the technical attention paid to vacuum circuit interrupters.
The electric contactors inside vacuum circuit interrupters are designed to conduct electric arcing across the “arc gap” between the contacts when extinguishing electric currents flowing through the contacts. The arcing erodes the contacts over time, eventually requiring replacement of the contacts. Although the contacts themselves are considered to be sacrificial components requiring periodic replacement, the remaining components of the circuit interrupter are rugged and often capable of remaining in use for multiple contactor replacements. The vacuum circuit interrupters may therefore be rebuilt with replacement contacts when the existing set of contacts wears out. This typically requires removing the circuit interrupter from service and taking it to a repair shop, where the contacts are replaced. Because the contacts are enclosed inside a sealed vacuum bottle, the rebuild process requires specialized equipment and there is no practical way to replace the contacts in the field, requiring the entire vacuum circuit interrupter to be taken out of service while the unit is rebuilt.
In addition, as a result of extreme electric field stress imposed over very short distances, vacuum circuit interrupters occasionally fail due to arcing at locations other than across the arc gap between the contacts referred to as “flashover.” For example, a vacuum circuit interrupter can fail by flashover across the vacuum bottle wall, which can destroy the vacuum bottle. As a result, repairing a failed vacuum circuit interrupter sometimes requires more extensive repairs than ordinary contact replacement. The electric power industry therefore has a continuing need for improved vacuum circuit interrupters.
The present invention solves the problem described above through a vacuum circuit interrupter in or for an electric power disconnect switch. The interrupter includes a drive unit having a drive unit housing with a side surface extending in an axial direction from a top end to a bottom end, a drive mechanism positioned within the contactor unit housing with a drive shaft extending axially through the bottom end of the drive unit housing, and an actuator linkage operatively connected to the drive mechanism. The vacuum circuit interrupter also includes a separable contactor unit including a contactor unit housing having a side surface extending in an axial direction from a top end to a bottom end, a baseplate attached to the bottom end, and a vacuum bottle unit positioned within the contactor unit housing. The vacuum bottle unit includes a vacuum container enclosing a contactor with a connecting rod extending through a top end of the vacuum container. The drive shaft of the drive unit is separably connected to the connecting rod of the contactor unit for removing the contactor unit from the drive unit by disconnecting the bottom end of the drive unit from the top end of the contactor unit and rotating the contactor unit with respect to the drive unit to unscrew the connecting rod from the drive shaft. The vacuum bottle unit is then removed from the contactor unit by removing the baseplate from the contactor unit housing and sliding the vacuum bottle unit out the bottom of the contactor unit housing.
The drive unit may also include a lid removably attached to the top end of the drive unit housing for accessing the drive mechanism without further disassembling the drive unit. In addition, the contactor unit housing includes a tapered inner surface and the vacuum bottle unit has a compliant outer surface conforming to the tapered inner surface of the contactor unit housing to form a tight seal while also facilitating sliding the vacuum bottle unit out the bottom end of the contactor unit housing.
It will be understood that specific embodiments may include a variety of features and options in different combinations, as may be desired by different users. Practicing the invention does not require utilization of all, or any particular combination, of these specific features or options. The specific techniques and structures for implementing particular embodiments of the invention and accomplishing the associated advantages will become apparent from the following detailed description of the embodiments and the appended drawings and claims.
The numerous advantages of the invention may be better understood with reference to the accompanying figures in which:
Embodiments of the present invention solve the problem described above through an electric power disconnect switch and associated vacuum circuit interrupter with a modular, removable contactor unit housing a modular, removable vacuum bottle unit. For example, the vacuum circuit interrupter may be mounted on a bracket adjacent to the jaws of a disconnect switch, where the blade of the disconnect switch moves the actuator arm of the vacuum circuit interrupter during operation of the disconnect switch. When the vacuum bottle unit requires replacement, a technician carries a spare contactor unit containing a replacement vacuum bottle unit to the disconnect switch location, where the technician removes and replaces the contactor unit. The vacuum circuit interrupter includes a separable connection between the drive unit housing and the contactor unit housing, which allows the contactor unit to be rotated with respect to the drive unit to unscrew the connecting rod of the contactor unit from the drive shaft of the drive unit. A replacement contactor unit is then installed at the disconnect switch location and the circuit interrupter is returned to service without removing or disassembling the drive unit.
The removed contactor unit is typically taken to a repair shop for inspection and repair. With the contactor unit separated from the drive unit, a baseplate is removed from the contactor unit housing allowing the vacuum bottle unit located inside the contactor unit housing to be removed intact. A complete replacement vacuum bottle unit is then installed and the rebuilt contactor unit returned to service. The removed vacuum bottle unit can then be inspected and repaired or discarded, as appropriate, in view of the condition of the vacuum bottle unit.
The vacuum bottle unit includes an insulation jacket surrounding a vacuum bottle wall reducing the likelihood of potentially damaging flashover across the vacuum bottle wall. The insulation jacket is compliant allowing it to conform to the tapered inner surface of the contactor unit housing to make a tight seal and facilitate removal of the vacuum bottle unit from the contactor unit housing. The drive unit of the vacuum circuit interrupter also includes a removable lid allowing access to the drive mechanism and associated linkage inside the drive unit housing at the disconnect switch location without removing or further disassembling the circuit interrupter.
Reference will now be made in detail to embodiments of the invention. In general, the same or similar reference numerals are used in the drawings and the description to refer to the same or like parts or steps. The drawings are in simplified form and are not to precise scale unless specifically indicated. The word “couple” and similar terms do not necessarily denote direct and immediate connections, but also include connections through intermediate elements or devices. Certain descriptors, such “first” and “second”, “top and bottom”, “upper” and “lower”, or “inner” and “outer” may be employed to differentiate structures from each other. These descriptors are utilized as a matter of descriptive convenience and are not employed to implicitly limit the invention to any particular position or orientation.
To do so, the vacuum circuit interrupter 20 includes an actuator arm 18 that comes into contact with, and is lifted by, a roller 19 attached to the blade 15 as the blade moves from the closed position to the open position. The roller 19 forms an electrical connection with the actuator arm 18 diverting the electric current through the vacuum circuit interrupter 20 once the blade 15 separates from the jaws 16. This prevents arcing between the blade 15 and the jaws 16, instead extinguishing the electric current inside the vacuum circuit interrupter 20 where controlled arcing occurs between the contacts inside the vacuum bottle unit located inside the circuit interrupter. It should be noted that
The contactor unit 33 includes a contactor unit housing 34 with a side surface 36 that extends from a top end 35 to a bottom flange 37 with a bottom end 38, which is covered by a removable base plate 39. A removable vacuum bottle unit 40 located inside the contactor unit housing 34 includes a connecting rod 41 and a compliant outer surface 42 of a jacket fabricated from a flexible high dielectric insulator material, such as rubber, silicon, neoprene, polyester, polyethylene, various laminates, or a similar material. The contactor unit housing 34 includes a tapered inner surface 43 that makes a tight seal with the compliant outer surface 42 of the vacuum bottle unit 40 and facilitates removal of the vacuum bottle unit from the contactor unit housing. The bottom flange 37 includes holes for receiving bolts that connect the contactor unit housing 34 to a support surface, in this example the bracket 17 shown in
As is well known in the electric power industry, the drive mechanism 30 may be a toggle mechanism, a cam mechanism, or any other suitable type of motive mechanism for extending and retracting the drive shaft 31 at the speed desired for circuit interruption. The drive unit housing 22 and the contactor unit housing 34 are fabricated from a non-conductive electric insulation material, such as fiberglass, and may be covered by the familiar weather-shed “bells” often seen on high voltage insulators. The actuator linkage 26 is a spring tensioned mechanism that translates movement of the actuator arm to movement of the drive mechanism and may include latches and other features well known in the industry. The contactors inside the vacuum bottle unit 40 may, for example, be butt contactors or penetration contactors. The embodiments of the present invention are not dependent on these conventional features of the drive unit 21 or the contactor unit 33, which will not be described in greater detail.
This view also shows the desiccant valve 29 in the removable lid 28 of the of the drive unit 21. The desiccant valve 29 includes a hydrophobic filter, such as a polytetrafluoroethylene (PTFE) membrane, which results in dehumidified ambient air 70 inside the drive unit housing 22. Reducing the moisture content of the medium inside the housing helps to reduce corrosion and avoid condensation, which can cause flashover inside the housing. In this embodiment, the dehumidified ambient air 70 also communicates into the top portion of the interior of the contactor housing 34 above the vacuum container 63. The tight seal between the insulation jacket 62 and the inner surface 43 of the contactor unit housing prevents the dehumidified air 70 from entering into this area, further reducing the likelihood of potentially damaging flashover between the vacuum container 63 and other structures.
As shown in
Although particular aspects of representative embodiments have been shown and described in detail, it will be apparent to those skills that the invention is not limited to those precise embodiments, and that various modifications and variations can be made to the explicitly described embodiments without departing from the scope or spirit of the invention. The following clams are therefore intended to cover modifications and variations of the representative embodiments provided they come within the scope of the appended claims and their equivalents.