Patent Application
20120261384
The present invention relates to switchgear interrupters and, more specifically, to voltage sensing at an interrupter.
An interrupter for a switchgear system can include a vacuum interrupter for fault interruption. A vacuum interrupter can be viewed or thought of as a ceramic bottle with two mechanical contacts sealed inside a vacuum. Fault interruptions are performed in the vacuum by the interrupter.
Before and after an interruption is performed it is useful to sense the voltage at the interrupter. Some dielectric switchgear systems provide voltage sensing on one side of an interrupter—either the source side or the load side—but not both. Detecting voltages on both the load side and the source side of an interrupter in a switchgear system when the interrupter is in an open position can be beneficial for some applications such as network reconfiguration and distribution automation. Some embodiments of this invention provide a solid dielectric interrupter with two voltage sensing systems imbedded together inside one module for a single phase application.
In one embodiment, the invention provides an interrupter system for a switchgear. The interrupter system includes a source-side conductor, a load side conductor, and an interrupter. A source-side voltage detector is positioned proximate to the source-side conductor and a load-side voltage detector is positioned proximate to the load-side conductor. An insulating overmold encases both conductors, both voltage detectors, and the interrupter. A controller is coupled to both of the detectors and is configured to detect a source-side voltage and a load-side voltage.
In some embodiments, the voltage detectors include cylindrical voltage screens positioned around each conductor in a coaxial arrangement. The controller senses a capacitance between the voltage screen and the corresponding conductor and determines a voltage based on the sensed capacitance.
In some embodiments, the exterior surface of the overmold is covered with a grounded conductive coating such a metallic paint.
Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings.
Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways.
During operation, a current is applied through the top-side conductor 103, the interrupter 101, and the bottom-side conductor 105. The first voltage screen 107 and the top-side conductor 103 form a capacitor. The capacitance between the first voltage screen 107 and the top-side conductor 103 depends upon the voltage applied to the top-side conductor 103. Therefore, the voltage of the top-side conductor 103 is determined by sensing the capacitance between the top-side conductor 103 and the first voltage screen 107. The calculation of the voltage of the top-side conductor 103 can be performed by a variety of systems such as a controller located proximate to the interrupter system, a remote computer system, or an ASIC.
Similarly, a load-side voltage detector includes a second cylindrical voltage screen 111 positioned around the bottom-side conductor 105. The capacitance between the second voltage screen 111 and the bottom-side conductor 105 is used to determine a voltage of the bottom-side conductor 105. Because voltage sensing systems are arranged proximate to both the top-side conductor 103 and the bottom-side conductor, the system is able to measure a voltage on either side of the interrupter 101 even when the interrupter 101 is in the open position.
The interrupter system illustrated in
The interrupter system 100 illustrated in
As illustrated in
The overmold 117 consists of an insulating material that is applied by a molding process. The exterior of the overmold 117 is covered with a conductive paint on all surfaces except the top-side bushing 119 and the bottom-side bushing 121. The conductive paint is grounded when the interrupter system 100 is in operation. Grounding the conductive paint on the exterior surface of the overmold 117 provides a fixed grounding reference for the voltage screens 107, 111 and prevents the voltage readings from floating.
In other constructions, the overmold 117 is covered in another conductive or semiconducitve material that may not cover as much surface area of the overmold 117. For example, in the construction illustrated in
Thus, the invention provides, among other things, an interrupter system encased in a single insulating overmold capable of measuring voltages on both the source side and the load side whether the interrupter is opened or closed. Various features and advantages of the invention are set forth in the following claims.
