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Efficient mixing for multicomponent mixtures in the heating volume of gas-insulated switchgear

IP.com Disclosure Number: IPCOM000252652D
Publication Date: 2018-Jan-31
Document File: 24 page(s) / 1M

Publishing Venue

The IP.com Prior Art Database

Related People

ABB Switzerland Ltd.: OWNER [+4]

Abstract

A switching chamber filled with a dielectric insulating medium comprises a first arcing contact (3) and a mating second arcing contact (4), an insulating main nozzle (2), an insulating auxiliary nozzle (8), an arcing volume (5), a heating volume (6) and a channel (7) connecting the arcing volume (5) with the heating volume (6). At least one separating element (9a; 10) is provided inside the heating volume (6), being adapted to separate the heating volume (6) into a first and a second partial heating volume (6a, 6b) in such a way that dielectric insulating medium flows from the arcing volume (5) through the channel (7) first into the first partial heating volume (6a) and subsequently into the second partial heating volume (6b).

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This is the abbreviated version, containing approximately 8% of the total text.

CH-15085

1 / 22

Switching chamber and electrical switching device

Technical field

5

The invention relates to the field of medium

and high voltage switching technologies and concerns a

switching chamber for an electrical switching device as

well as such an electrical switching device according to

the independent claims, particularly for use as an 10

earthing device, a fast-acting earthing device, a circuit

breaker, a generator circuit breaker, a switch disconnec-

tor, a combined disconnector and earthing switch, or a

load break switch in power transmission and distribution

systems.15

Background

Electrical switching devices are well known

in the field of medium and high voltage switching 20

applications. They are e.g. used for interrupting a

current when an electrical fault occurs. As an example

for an electrical switching device, circuit breakers have

the task of opening contacts and keeping them far apart

from one another in order to avoid a current flow, even 25

in the case of electrical faults. For the purposes of

this disclosure the term medium voltage refers to

voltages from 1 kV to 72.5 kV and the term high voltage

refers to voltages higher than 72.5 kV.

During the opening process of the electrical 30

switching device an electric arc forms between arcing

contacts of the device in an area called arcing volume.

The electric arc is conductive and still carries electric

current even after the opening of the arcing contacts. In

order to interrupt the current, the electrical switching 35

devices contain a dielectrically inert fluid used as a

dielectric insulating medium and for quenching the

CH-15085

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electric arc as fast as possible. Quenching the electric

arc means extracting as much energy as possible from it.

Consequently, a part of the fluid located in the area

where the electric arc is generated is considerably

heated up in a very short period of time and causes 5

ablation of nozzle material. Due to the thus generated

gas volume expansion this part of the fluid builds up a

high pressure and is ejected from the area of the

electric arc (arcing volume) into a heating volume, where

it mixes with cold fluid present therein. At or near 10

current zero and flow reversal occurs. If the mixing in

the heating chamber is not thorough enough, still too hot

fluid is blown back into the arcing volume and dielectric

failures can occur during current interruption. In other

cases late restrikes can be caused by the same effect. 15

A problem with late return of hot fluid is the weakening

of dielectric withstand between the arcing contacts at

recovery voltage levels.

Thus, the colder the fluid streaming back

into the arcing volume is, the more effectively the 20

electric arc can be blown off. By keeping the fluid

temperature comparatively low, it is possible to use

alternative types of fluids other than SF6. As known,

alternative arc extinguishing and insulating gas mixtures

(dielectric insulation medium) useful in high or medium 25

voltage switchin...

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