Gas-insulated high or medium voltage circuit breaker

1. A gas-insulated high or medium voltage circuit breaker comprising:

a first arcing contact and a second arcing contact, wherein at least one of the first and second arcing contacts is axially movable including a first and a second state of motion along a switching axis, wherein during a breaking operation, an arc between the first arcing contact and the second arcing contact is formed in an arcing region;

a nozzle including a channel directed to the arcing region, for blowing an arc-extinguishing gas to the arcing region during the breaking operation;

a diffuser adjacent to the nozzle, for transporting the gas from the arcing region to a region downstream of the diffuser;

a buffer volume directly downstream of the diffuser, and

an enclosure substantially surrounding the buffer volume circumferentially, wherein the enclosure comprises:

an inner enclosure portion and a coaxially arranged outer enclosure portion, wherein at least one of the inner enclosure portion and the outer enclosure portion is movable relative to the other one; and

a first aperture provided on a surface of the inner enclosure portion and a second aperture provided on a surface of the outer enclosure portion, such that a through opening is provided through the enclosure, wherein

in the first state of motion during the breaking operation the through opening corresponding to the first aperture is blocked, as to prevent the gas from being released from the buffer volume to a volume outside of the enclosure; and

in the second state of motion, the first aperture and the second aperture overlap one another, such that an overlap of the first aperture and the second aperture provides the through opening for the gas to be partially released from the buffer volume to the volume outside of the enclosure.

2. The gas-insulated high or medium voltage circuit breaker according to claim 1 , wherein the inner enclosure portion and the outer enclosure portion of the enclosure are cylindrically shaped.

3. The gas-insulated high or medium voltage circuit breaker-according to claim 1 , wherein the inner enclosure portion and the outer enclosure portion of the enclosure are electrically conductive metal pipes.

4. The gas-insulated high or medium voltage circuit breaker according to claim 1 , wherein the enclosure is at a same electrical potential as the second arcing contact.

5. The gas-insulated high or medium voltage circuit breaker according to claim 1 , wherein at least part of the enclosure is formed as a portion of a nominal current path.

6. The gas-insulated high or medium voltage circuit breaker according to claim 1 , further comprising a guiding element adjacent to the second aperture of the outer enclosure portion radially outside to guide the gas that is released in an axial direction away from an axial position of the arcing region.

7. The gas-insulated high or medium voltage circuit breaker according to claim 1 , wherein during the breaking operation the through opening in the second state of motion is established at a zero crossing of an electrical current during an arcing time.

8. The gas-insulated high or medium voltage circuit breaker according to claim 1 , wherein the first state of motion corresponds to a start of the breaking operation, wherein the first arcing contact and the second arcing contact start to move apart along the switching axis.

9. The gas-insulated high or medium voltage circuit breaker according to claim 1 , wherein one of the inner enclosure portion and the outer enclosure portion is stationary and a respective other one is movable together with the second arcing contact.

10. The gas-insulated high or medium voltage circuit breaker according to claim 1 , wherein in the second state of motion the overlap of the first aperture and the second aperture is formed at an axial position located along an length axis extending between a front portion of the diffuser and an axial end portion of the second arcing contact.

11. The gas-insulated high or medium voltage circuit breaker according to claim 1 , wherein the gas-insulated high or medium circuit breaker is adapted to interrupt medium to high-voltages of 12 kV or more; and/or wherein the gas-insulated high or medium voltage circuit breaker is one of a puffer-type circuit breaker, a self-blast circuit breaker, or a combination thereof.

12. A method of operating the gas-insulated high or medium voltage circuit breaker, the method comprising:

breaking an electric current with the high or medium voltage circuit breaker according to claim 1 .

13. The method of operating the gas-insulated high or medium voltage circuit breaker according to claim 12 , wherein breaking the electric current comprises:

separating the first arcing contact and the second arcing contact by moving at least one of the first and second arcing contact along the switching axis to initiate the breaking operation; and

moving, during the breaking operation, at least one of the inner enclosure portion and the outer enclosure portion relatively to each other along the switching axis, such that in the second state of motion the first aperture and the second aperture overlap and provide the through opening for the arc-extinguishing gas to be partially released from the buffer volume to the volume outside of the enclosure, wherein the through opening is established at a zero crossing of the electrical current during an arcing time.

14. The gas-insulated high or medium voltage circuit breaker according to claim 1 , wherein the circuit breaker is the gas-insulated circuit breaker adapted to interrupt medium to high-voltages of 52 kV or more.

15. The gas-insulated high or medium voltage circuit breaker according to claim 1 , wherein the circuit breaker is the gas-insulated circuit breaker adapted to interrupt medium to high-voltages of more than 72 kV.

16. The gas-insulated high or medium voltage circuit breaker according to claim 1 , wherein the circuit breaker is the gas-insulated circuit breaker adapted to interrupt medium to high-voltages of 145 kV or more.