Exhaust of hot gases resulting from an arc event in an electric switchgear

1 . An Electric-electric switchgear, comprising:

a switchgear housing;

a switching device arranged in the switchgear housing;

an inner housing arranged within the switchgear housing and surrounding the switching device, wherein the inner housing is pneumatically connected to an exhaust channel,

wherein the exhaust channel passes through or connects to an opening in a housing wall of the switchgear housing,

wherein the exhaust channel comprises a narrowing and exhaust channel inlet holes, which are arranged at the narrowing and which are provided to supply air from outside of the inner housing into the interior of the exhaust channel, and

wherein the electric switchgear is configured such that, in use, a main air flow through the exhaust channel caused by an arc event in the switchgear housing causes a local underpressure at the narrowing based on Bernoulli's principle and air to be sucked into the exhaust channel through the exhaust channel inlet holes and support the burn of unburned gases in the exhaust channel.

2 . The electric switchgear as claimed claim 1 , wherein

a) the exhaust channel is fully arranged within the switchgear housing, and the inlet holes are arranged within the switchgear housing as well or

b) the exhaust channel is fully arranged out of the switchgear housing, and the inlet holes are arranged out of the switchgear housing as well or

c) the exhaust channel is arranged partly within the switchgear housing and partly out of the switchgear housing, and the inlet holes are arranged within the switchgear housing or

d) the exhaust channel is arranged partly within the switchgear housing and partly out of the switchgear housing, and the inlet holes are arranged out of the switchgear housing.

3 . The electric switchgear as claimed in claim 2 , wherein

A) the exhaust channel is directly located at or comprises a housing wall of the switchgear housing, wherein the inlet holes directly lead out of the switchgear housing or

B) the exhaust channel is spaced from a housing wall of the switchgear housing, wherein the inlet holes connect to the interior of the switchgear housing or

C) the exhaust channel is spaced from a housing wall of the switchgear housing, wherein the inlet holes are connected to at least one supply tube or supply channel, which leads out of the switchgear housing.

4 . The electric switchgear as claimed in claim 3 , wherein

the exhaust channel has surrounding channel walls and

the narrowing is formed by one or more of the channel walls, which in cross sectional view

i) has a triangular surface facing the interior of the exhaust channel, wherein the exhaust channel inlet holes are arranged in the triangular surface, or

ii) has a trapezoid surface facing the interior of the exhaust channel, wherein the exhaust channel inlet holes are arranged in the trapezoid surface, or

iii) has a curved surface facing the interior of the exhaust channel, wherein the exhaust channel inlet holes are arranged in the curved surface.

5 . The electric switchgear as claimed in claim 3 , wherein

the exhaust channel has surrounding channel walls,

the narrowing is embodied by a profile part attached to the inner side of the channel wall,

the channel wall comprises secondary holes,

the profile part comprises the exhaust channel inlet holes arranged at the narrowing and

both the secondary holes and the exhaust channel inlet holes connect to a space formed between the channel wall and the profile part.

6 . The electric switchgear as claimed in claim 5 , wherein the profile part

i) has a triangular surface facing the interior of the exhaust channel, wherein the exhaust channel inlet holes are arranged in the triangular surface, or

ii) has a trapezoid surface facing the interior of the exhaust channel, wherein the exhaust channel inlet holes are arranged in the trapezoid surface, or

iii) has a curved surface facing the interior of the exhaust channel, wherein the exhaust channel inlet holes are arranged in the curved surface.

7 . The electric switchgear as claimed in claim 6 , wherein the exhaust channel inlet holes are arranged after the narrowing seen in flow direction of a gas expanding in the inner housing.

8 . The electric switchgear as claimed in claim 6 , wherein the exhaust channel inlet holes are arranged at the narrowest point of the narrowing.

9 . The electric switchgear as claimed in claim 8 , wherein a cooling structure or element, which is arranged after the exhaust channel inlet holes seen in flow direction of a gas expanding in the inner housing.

10 . The electric switchgear as claimed in claim 9 , wherein a cooling structure or element, which is arranged after the narrowing seen in flow direction of a gas expanding in the inner housing.

11 . The electric switchgear as claimed in claim 10 , wherein one or more check valves, which allow a gas flow into the exhaust channel through the exhaust channel inlet holes and block a gas flow out of the exhaust channel through the exhaust channel inlet holes.

12 . The electric switchgear as claimed in claim 1 , wherein an electrical connection with a nominal short circuit power of >50 MVA.

13 . The electric switchgear as claimed in claim 1 , further comprising:

a cooling structure arranged over the narrowing, wherein in use, hot gases generated by burning of the unburned gases in the exhaust channel are cooled by the ceramic cooling structure.