Exhaust diffuser for a gas-insulated high voltage circuit breaker

Abstract

A gas exhaust diffuser for a circuit breaker, comprising a first casing extending longitudinally along a principal axis with an open end to allow gas to enter and a closed end, and a second casing coaxial to the first casing, extending along the principal axis, with at least one outlet to allow gas to escape, the closed end of the first casing being arranged in the second casing and the first casing having at least two radial openings near its closed end to provide a fluid communication between the first and second casing. A plurality of incurved elements are positioned radially in the second casing at the at least one radial opening to create a rotation of an entering exhaust flow in a plan perpendicular to the principal axis, thereby generating a substantially helicoidally-shaped exhaust flow path in the second casing.

Claims

1. A gas exhaust diffuser for a circuit breaker, comprising a first casing extending longitudinally along a principal axis with an open end to allow gas to enter and a closed end, and a second casing coaxial to the first casing, extending along the principal axis, with at least one outlet to allow gas to escape, the closed end of the first casing being arranged in the second casing and the first casing having at least two radial openings near its closed end to provide a fluid communication between the first and second casing, wherein the gas exhaust diffuser further comprises a plurality of incurved elements, an incurved element being positioned radially in the second casing at each of the at least two radial openings, the plurality of incurved elements being positioned and configured to create a rotation of an exhaust flow entering in the second casing in a plan perpendicular to the principal axis, thereby generating, in the second casing, an exhaust flow path substantially helicoidal to the principal axis.

2. The gas exhaust diffuser of claim 1, wherein a lateral wall of the second casing extending along the principal axis extends away from the open end of the first casing.

3. The gas exhaust diffuser of claim 2, wherein the lateral wall of the second casing draws near the principal axis as it extends away from the open end of the first casing.

4. The gas exhaust diffuser of claim 1, wherein a lateral wall of the second casing extends along the principal axis in a direction of the open end of the first casing, thereby delimiting an annular passage between the first and second casing.

5. The gas exhaust diffuser of claim 4, wherein the lateral wall of the second casing ends away of a lateral wall of the first casing, thereby forming an annular outlet of the second casing.

6. The gas exhaust diffuser of claim 4, wherein the lateral wall of the second casing meets a lateral wall of the first casing, thereby closing an end of the annular passage.

7. The gas exhaust diffuser of claim 1, wherein the radial openings of the first casing are in a same plan perpendicular to the principal axis.

8. The gas exhaust diffuser of claim 1, wherein the incurved elements are regularly spaced around a circumference of the first casing.

9. The gas exhaust diffuser of claim 1, wherein all the incurved elements are arranged in a clockwise or counter clockwise direction.

10. A high-voltage gas-insulated circuit breaker comprising a tank filled with insulating gas and an interrupter chamber, the interrupter chamber being enclosed in the tank and comprising: an arcing volume; a pair of arcing contacts, at least one being movable between an open and closed position; a blown device for blowing the insulating gas to the arcing volume to extinguish an arc produced during a separation of the arcing contacts, thereby forming hot gas; and a gas exhaust diffuser to exhaust said hot gas, wherein said gas exhaust diffuser includes a first casing extending longitudinally along a principal axis with an open end to allow gas to enter and a closed end, and a second casing coaxial to the first casing, extending along the principal axis, with at least one outlet to allow gas to escape, the closed end of the first casing being arranged in the second casing and the first casing having at least two radial openings near its closed end to provide a fluid communication between the first and second casing, wherein a plurality of incurved elements are positioned radially in the second casing at the at least one radial opening to create a rotation of an entering exhaust flow in a plan perpendicular to the principal axis, thereby generating a substantially helicoidally-shaped exhaust flow path in the second casing.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic sectional side view of a gas exhaust diffuser of a first embodiment according to the invention.

(2) FIG. 2 is a schematic sectional side view of a gas exhaust diffuser of a second embodiment according to the invention.

(3) FIG. 3 is a schematic sectional side view of a gas exhaust diffuser of a third embodiment according to the invention.

(4) FIGS. 4a and 4b are examples of schematic sectional side views of the gas exhaust diffuser as taken generally along line A-A of FIG. 1.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

(5) Now referring to the drawings, wherein like numerals designate like components, FIG. 1 schematically illustrates a gas exhaust diffuser 100 constructed in accordance with the teachings of the invention.

(6) The gas exhaust diffuser 100 includes a first casing 10 extending longitudinally along a principal axis 40, with an open end 11, a closed end 12, a lateral wall 14 extending between the open end 11 and the closed end 12, and radial openings 13 in the side wall 14 near the closed end 12; a second casing 20, extending along the principal axis 40 of the first casing, with a lateral wall 22 and an outlet 21. Incurved elements 30 (for example blades) are positioned at the first casing radial openings 13. The closed end 12 of the first casing has preferably a curved contour configured to deflect and direct the flow towards the radial openings 13.

(7) In the embodiment illustrated in FIG. 1, the lateral wall 22 of the second casing 20 extends away from the open end 11 of the first casing 10 and draws near the principal axis 40 as it extends away from the open end of the first casing. The outlet 21 is centered on the principal axis 40.

(8) In the embodiments illustrated in FIG. 2 and FIG. 3, the lateral wall 22 of the second casing 20 extends along the principal axis 40 in a direction of the open end 11 of the first casing 10. The second casing 20 covers the first casing 10, thereby delimiting an annular passage 23 between the wall 14 of the first casing 10 and the wall 22 of the second casing 20.

(9) In the embodiment illustrated in FIG. 2, the lateral wall 22 of the second casing 20 ends to an open end, as the lateral wall 22 ends away of the lateral wall 14 of the first casing 10. The outlet 21 of the second casing 20 is an annular outlet 24 in this embodiment.

(10) In the embodiment illustrated in FIG. 3, the lateral wall 22 of the second casing 20 meets the lateral wall of the first casing 10. In this embodiment, the second casing 20 comprises side outlets, for example two or four outlets.

(11) The embodiments illustrated in FIGS. 1, 2 and 3 allow for three possibilities for the direction of the gas flowing out of the gas exhaust diffuser: a first common exhaust stage in the first casing 10 wherein the gas flow follows a direction parallel to the longitudinal direction of the first casing and a second exhaust stage, wherein the gas flow is helicoidally-shaped and directed towards the tank end of the circuit breaker (in FIG. 1), towards the interrupter gap (in FIG. 2) and radially outwards towards the tank lateral side (in FIG. 3).

(12) In the embodiment of FIG. 1, the direction of gas flow in the second casing is such that the distance between the end of the interrupter chamber and the tank end can be minimized (compared to the prior art exhaust diffusers wherein the exhaust flow is ejected from the exhaust diffusers towards the tank end, for example, in the configurations described in the Patent Application JP 2003 217411 and in the Patent Application JPH09231885), since the exhaust direction is not primarily in the interrupter longitudinal direction.

(13) In the embodiment of FIG. 2, the gas exits from the second casing 20 through an annular outlet 24 on a recessed surface with respect to the wall of the second casing. This recessed area is subjected to lower electric field intensity than those elements of the interrupter chamber with larger radial dimensions. It presents the advantage of using the space between the second casing 20 and the interrupter gap. In addition, the helicoidal direction of the gas flow in the second casing 20 is such that it minimizes the reach of the exhaust gas as it exits the second casing, thereby reducing the required length of the interrupting unit. In other words, in this configuration, the gas flow is forced along a curling path which increases the effectiveness of the exhaust containment volume. In addition, the speed of the flow in the longitudinal direction is reduced. Distance between the outlet and the interrupter gap can consequently be shortened.

(14) In the embodiment of FIG. 3, the gas exhaust is also directed towards the gap between the second casing 20 and the tank. There are two or four outlets radially located near the closed end of the second casing. This configuration presents the advantage of allowing the second casing 20 to extend closer to the interrupter gap and venting radially in the space between the casing 20 and the tank.

(15) In a gas-insulated circuit breaker, hot gases are generated in the arcing area of an interrupter chamber between the arcing contacts and flow in both directions of the arcing contacts, but flow mostly in the pin direction along the direction of the longitudinal axis of the interrupter chamber. That is the reason why the open end of the first casing is to be mounted along the longitudinal axis of the interrupter chamber, so that the hot gas flow pursues its longitudinal path in the first casing 10 (the direction of the flow is symbolized by arrows F) until it is deflected by the closed end 11 of the first casing 10 and directed to the radial openings 13 and the incurved elements 30. The incurved elements, by their configuration (shape) and position, introduce a rotation of the gas flow. This motion is very efficient in pushing the hot gases and mixing them with cold gases pockets in the interrupter chamber of the circuit breaker. When the hot gas is forced to flow in a helicoidal path, a more efficient use of the available containment volume is obtained. This allows for better mixing of the hot exhaust with cool gas and improved cooling without requiring a very long path for the gas flow.

(16) FIG. 4a and FIG. 4b illustrate two possible configurations for the location of the incurved elements for inducing rotation of the hot gas flow in the second casing. The incurved elements may be placed in a clockwise direction (FIG. 4a) to induce a clockwise rotation of the flow, or in a counterclockwise direction to induce a counterclockwise rotation of the flow (FIG. 4b).

(17) It will be appreciated by those of ordinary skill in the art that the exemplary gas exhaust diffusers described therein can be embodied in various specific forms without departing from the essential characteristics thereof. The presently disclosed embodiments are considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the appended claims, rather than the foregoing description, and all changes that come within the meaning and range of equivalence thereof are intended to be embraced.

LIST OF REFERENCE NUMERALS

(18) 10 First casing 11 Open end of the first casing 12 Closed end of the first casing 13 Radial opening of the first casing 14 Lateral wall of the first casing 20 Second casing 21 Outlet of the second casing 22 Lateral wall of the second casing 23 Annular passage of the second casing 24 Annular outlet of the second casing 30 Incurved element 40 Principal axis 100 Gas exhaust diffuser F Direction of the hot gas flow