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Gas-insulated high-voltage switching device

IP.com Disclosure Number: IPCOM000245633D
Publication Date: 2016-Mar-23

Publishing Venue

The IP.com Prior Art Database

Related People

YE Xiangyang: AUTHOR [+12]

Abstract

The gas-insulated high-voltage switching device comprises an arcing contact which is aligned along an axis (A) and which is designed as a contact tulip (21) with resilient contact fingers (25) and with a nozzle throat (26). The contact tulip (21) is connected to a hollow contact carrier (22). The contact tulip (21) and the contact carrier (22) enclose an axially aligned exhaust gas channel for passing a gas flow from an arcing zone to an expansion room. A diffuser (70) of the exhaust gas channel joins the nozzle throat (26) downstream and comprises a circular flow cross-section which increases continuously between the nozzle throat (26) and an end of the diffuser (70) that is positioned downstream. In order to keep the switching device small-sized and to allow a high number of short current interruptions: the diffuser (70) comprises a main portion (71), which starts at a minimum flow cross-section (A26) of the contact tulip (21), an exit portion (72) and a transition zone (73), in which the flow cross-section of the main portion (71) turns into the flow cross-section of the exit portion (72) and in which the flow cross-section of the exit portion (72) has a faster increase than the flow cross-section of the main portion (71), the length (l71) of the main portion (71) is at least three times the radius of the minimum flow cross-section (A26), and the flow cross-section (A73) of the diffuser (70) in the transition zone (73) is at least 1.4 and at most 2.2 times the minimum flow cross-section (A26).

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Page 01 of 18

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CH-15023

Gas-insulated high-voltage switching device

TECHNICAL FIELD

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The invention relates to a gas-insulated high-voltage switching device according to the first part of claim 1. The switching device is typically configured as a circuit breaker and comprises an arcing contact which is aligned along an axis and which is designed as a contact tulip with resilient contact fingers and with a nozzle throat. The contact tulip is connected to a hollow contact carrier. The contact tulip and the

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contact carrier enclose an axially aligned exhaust gas channel for passing a gas flow from an arcing zone to an expansion room. A diffuser of the exhaust gas channel joins the nozzle throat downstream and comprises a circular flow cross- section which increases continuously between the nozzle throat and an end of the diffuser that is positioned downstream. Such a gas-insulated high-voltage circuit 15

breaker is operated with rated voltages between 10 kV and 1200 kV, typically between 30 kV and 550 kV, and comprises a current-breaking capacity up to 80 kA.

The breaking of a short current with the afore-defined switching device causes a powerful switching arc which burns in an arcing zone between the contact tulip

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and a second arcing contact and which generates hot arcing gas with temperatures up to approximately 20 000 K. Pressurized hot arcing gas expands downstream the nozzle throat inside the diffuser and causes a significant erosion of the contact tulip. Typically used contact tulips withstand only a limited number of short current interruptions. Additional short current interruption processes reduce

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the thickness of the contact fingers and lead to lower stiffness of the contact fingers. A resulting higher contact resistance impedes the commutation of the short current from a main current circuit to a current circuit comprising the contact tulip and the second arcing contact. Furthermore, additional current breaking processes can even detach the contact fingers from the contact tulip and thus can 30

reduce the dielectric properties of the switching device dramatically.


Page 02 of 18

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CH-15023

PRIOR ART

Embodiments of the switching device according to the first part of claim 1 are described in EP 1 831 906 B1 and in US 4,774,388. These embodiments comprise a contact tulip with resilient contact fingers which form a flexible nozzle throat and with a diffuser which joins the nozzle throat downstream. The flow cross-section of

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the diffuser increases continuously between the nozzle throat and an end of the diffuser which is positioned downstream.

The embodiments according to US 4,4774,388 comprise a metallic sleeve which forms a section of the diffuser and which protects the contact fingers against the erosion effect of powerful switching arcs. Furthermore IP.com number 000240181

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describes a switching unit in which a sleeve of an insulating material, like PTFE, protects the inside of a contact tulip against erosion during arcing...