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Circuit breaker with contact shield movable by a pressure differential of the insulating gas

IP.com Disclosure Number: IPCOM000240151D
Publication Date: 2015-Jan-07
Document File: 4 page(s) / 47K

Publishing Venue

The IP.com Prior Art Database

Abstract

This movement of the shield 52b is effected by exposing the shield 52b to a pressure differential. Namely, during the opening switching operation, the gas on the right-hand side of the shield 52b is compressed, so that the pressure on the right-hand side is higher than on the left-hand side of the shield 52b, as indicated by “p↑” and “p↓”, respectively, in Fig. b. This gas pressure differential is caused by the compression of the volume right of the shield 52b, due to the movement of the nozzle system 30. Namely, the nozzle system 30 is connected to the second arcing contact (tulip, not shown in Figs. a and b), and by retracting it to the left the volume behind (right of) the shield 52b is diminished. This pressure differential moves the shield 52b toward the other contact 60 until a limit position relative to the shield holder 52a defined by a stop (see Fig. b) is reached. Thereby the connection springs are charged. In the fully open position, after equalization of the gas pressure on both electrode sides, the connection springs will bring the electrode back to its more retracted normal position (same position relative to the shield holder 52a as shown in Fig. a)

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Circuit breaker with contact shield movable by a pressure differential of the insulating gas

Authors: J. Kostovic, T. Sutherland, and Xiangyang Ye, all of ABB Switzerland Ltd.

TECHNICAL FIELD

The present disclosure in general relates to circuit breakers and is especially applicable to high voltage circuit breakers. In particular, the present disclosure relates to a gas insulated type circuit breaker having a pair of arcing contact members, a pair of nominal contact members and a contact shield that is movable by a pressure differential of the insulating gas.

BACKGROUND OF THE DISCLOSURE

High voltage (HV, herein defined as voltages of 72,5 kV or more) circuit breakers often interrupt electrical current by the separation of two arcing contact members - a first arcing contact member and a second arcing contact member - from one another. After the separation of the two arcing contact members, the electrical current continues to flow between them and is carried by an arc between the two contacts. For interrupting the current, the arc must be extinguished and re-ignition must be suppressed. In gas insulated type circuit breakers, the arc is extinguished using a dielectric gas such as SF6. The dielectric gas also reduces the risk of re-ignition and dielectric breakdown.

However, especially at higher voltages (e.g. 380 kV or more), there is a need for further reducing the risk of dielectric breakdown in various configurations of the circuit breaker. This risk can be reduced by increasing the distance between elements with different voltages within the circuit breaker. Such an increased distance, however, is not always possible or desired, e.g., if a compact design is important.

SUMMARY

According to the present disclosure, circuit breaker with high dielectric strength with a compact design is enabled without any additional complications imposed on the drive mechanism.

The circuit breaker comprises a housing defining a gas volume for a dielectric insulation gas; a first arcing contact member and a second arcing contact member, wherein the first arcing contact member and the second arcing contact member are movable relative to each other along an axis; a first nominal contact member and a second nominal contact member, wherein the first nominal contact member and the second nominal contact member are movable relative to each other along the axis; and a first contact shielding arrangement for electrically shielding the first arcing contact member and/or the first nominal contact member.

One or both sides of the circuit breaker may also include contact shielding electrodes each of which may be moved together with (or in a different manner than) the nominal contacts or may be stationary.

"Movable relative to each other" means that at least one of the respective contacts is movable, but also includes the case of double motion. Thus, during a switching operation the contact shielding electrode on the drive opposite side can be moved by the...