High voltage puffer breaker and a circuit breaker unit comprising such a puffer breaker

Abstract

Gas-insulated high voltage puffer breaker comprising a puffer unit with a movable piston running in a puffer cylinder and delimiting a puffer volume. A piston and a first contact member are attached to a piston stem. A piston and a first contact member are attached to a piston stem. An electric arc is extinguishable in an arcing zone when the first contact member moves from a first position to a second position. The puffer volume is fluidly connected to a gas nozzle by a gas channel such that the puffer volume comprises the gas channel as well as a portion of the puffer cylinder. The gas channel is provided radially outside of the puffer cylinder between a puffer cylinder wall delimiting the puffer cylinder and a wall structure of the puffer unit.

Claims

1. Gas-insulated high voltage puffer breaker, comprising a puffer unit with a piston that is movably arranged in a puffer cylinder such that a puffer volume is delimited, a first contact member being movably arranged relative to a second contact member of the circuit breaker such that a current path is established in a first position where the first contact member is contacting the second contact member and that said current path is interrupted in an arcing zone once the first contact member is moved to a second position where the first contact member is opened from the second contact member, wherein the first contact member is connected to a drive by a piston stem, and a nozzle for circumferentially delimiting the arcing zone of the puffer breaker, wherein the piston and the first contact member are attached to the piston stem, and wherein the puffer volume comprises the gas channel as well as a portion of the puffer cylinder, wherein the gas channel and said portion of the puffer cylinder are fluidly connected to one another by a port such that a gas flowing in a first direction from the portion of the puffer cylinder is redirected via the gas channel in a second direction towards the nozzle once the first contact member is moved from the first position towards the second position, and wherein the gas channel is provided radially outside of the puffer cylinder between a puffer cylinder wall delimiting the puffer cylinder and a wall structure of the puffer unit.

2. The high voltage puffer breaker according to claim 1, wherein the first contact member and the piston stem are movably arranged such that they are movable along a switching axis, in particular along a linear switching axis.

3. The high voltage puffer breaker according to claim 1, wherein the portion of the puffer cylinder is arranged rotationally symmetric with respect to the switching axis, wherein the puffer volume in the portion of the puffer cylinder is delimited radially inwards with respect to the switching axis by the piston stem.

4. The high voltage puffer breaker according to claim 1, wherein the gas channel is arranged in between the puffer cylinder wall and the wall structure of the puffer unit such that a annular radial gap is formed.

5. The high voltage puffer breaker according to claim 1, wherein the gas channel is stationary with respect to the arcing zone.

6. The high voltage puffer breaker according to claim 4, wherein an overall cross section of the annular radial gap is smallest at an end of the gas channel discharging into the nozzle.

7. The high voltage puffer breaker according to claim 1, wherein the port is arranged at a remote first end of the puffer cylinder with respect to the arcing zone.

8. The high voltage puffer breaker according to claim 1, wherein the port is arranged in the puffer cylinder wall extending circumferentially about the portion of the puffer cylinder with respect to the switching axis.

9. The high voltage puffer breaker according to claim 1, wherein the port comprises a plurality of gas outlets leading from the portion of the puffer cylinder to the gas channel.

10. The high voltage puffer breaker according to claim 1, wherein a further volume of the puffer cylinder is located on an opposite side of the piston with regards to the portion of the puffer cylinder and is fluidly connected to an exhaust arranged outside the wall structure of the puffer unit by at least one exhaust port.

11. The high voltage puffer breaker according to claim 1, wherein the piston is dimensioned relative to the portion of the puffer cylinder such that no bodily radial seal element in between the piston and the interior side of the puffer cylinder wall is required.

12. The high voltage puffer breaker according to claim 1, wherein an annular groove is arranged on an interior side of the puffer cylinder wall adjacent to the port such that a diameter of the interior side of the puffer cylinder is larger than an outer diameter of the piston, wherein the annular groove starts at about an axial position reached by a trailing end of the piston when the first contact member is approaching the second position in an operating state of the puffer breaker, and wherein the annular groove extends in the direction of the switching axis over a distance being larger than a thickness of the piston at the inside wall of the puffer cylinder, and wherein the annular groove is dimensioned such that gas from the portion of the puffer cylinder is allowed to escape to the exhaust via said annular groove to a rear side of the piston along an escape path when the first contact member is approaching the second position.

13. The high voltage puffer breaker according to claim 1, wherein an electromagnetic repulsive force can be produced by the Thomson coil drive for moving the piston stem.

14. The high voltage puffer breaker according to claim 1, wherein at least one of the piston and the first contact member are at least partially integrated into the piston stem.

15. The high voltage puffer breaker according to claim 1, wherein the puffer unit is arranged in a gas-tight enclosure, and in that the drive is connected to the piston stem by a pull rod, wherein the drive and the pull rod are located in the same gas-tight enclosure as the puffer unit, too.

16. A breaker unit comprising a vacuum interrupter that is electrically connected in series to a high-voltage puffer breaker comprising: a puffer unit with a piston that is movably arranged in a puffer cylinder such that a puffer volume is delimited, a first contact member being movably arranged relative to a second contact member of the circuit breaker such that a current path is established in a first position where the first contact member is contacting the second contact member and that said current path is interrupted in an arcing zone once the first contact member is moved to a second position where the first contact member is opened from the second contact member, wherein the first contact member is connected to a drive by a piston stem, and a nozzle for circumferentially delimiting the arcing zone of the puffer breaker, wherein the puffer volume is fluidly connected to the nozzle by a gas channel, wherein the piston and the first contact member are attached to the piston stem, and wherein the puffer volume comprises the gas channel as well as a portion of the puffer cylinder, wherein the gas channel and said portion of the puffer cylinder are fluidly connected to one another by a port such that a gas flowing in a first direction from the portion of the puffer cylinder is redirected via the gas channel in a second direction towards the nozzle once the first contact member is moved from the first position towards the second position, and wherein the gas channel is provided radially outside of the puffer cylinder between a puffer cylinder wall delimiting the puffer cylinder and a wall structure of the puffer unit.

17. The circuit breaker unit, according to claim 16, wherein the vacuum interrupter comprises a further drive, wherein a further electromagnetic repulsive force can be produced by said further drive for moving a movable contact member of the vacuum interrupter.

18. The circuit breaker unit, according to claim 16, wherein the movable contact member of the vacuum interrupter can be moved by the same drive as the first contact member of the puffer breaker.

19. A combination, comprising: a HVDC system and a circuit breaker unit comprising a vacuum interrupter that is electrically connected in series to a high-voltage puffer breaker comprising: a puffer unit with a piston that is movably arranged in a puffer cylinder such that a puffer volume is delimited, a first contact member being movably arranged relative to a second contact member of the circuit breaker such that a current path is established in a first position where the first contact member is contacting the second contact member and that said current path is interrupted in an arcing zone once the first contact member is moved to a second position where the first contact member is opened from the second contact member, wherein the first contact member is connected to a drive by a piston stem, and a nozzle for circumferentially delimiting the arcing zone of the puffer breaker, wherein the puffer volume is fluidly connected to the nozzle by a gas channel, wherein the piston and the first contact member are attached to the piston stem, and wherein the puffer volume comprises the gas channel as well as a portion of the puffer cylinder, wherein the gas channel and said portion of the puffer cylinder are fluidly connected to one another by a port such that a gas flowing in a first direction from the portion of the puffer cylinder is redirected via the gas channel in a second direction towards the nozzle once the first contact member is moved from the first position towards the second position, and wherein the gas channel is provided radially outside of the puffer cylinder between a puffer cylinder wall delimiting the puffer cylinder and a wall structure of the puffer unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The description makes reference to the annexed drawings, which are schematically showing in

(2) FIG. 1 a schematic longitudinal section through a first embodiment of the puffer breaker, where a first contact member is in its first position;

(3) FIG. 2 a schematic longitudinal section through a first embodiment of the puffer breaker of FIG. 1, wherein the first contact member is in an intermediate position between the first position and a second position;

(4) FIG. 3 a schematic longitudinal section through a first embodiment of the puffer breaker of FIG. 1, wherein the first contact member has just reached its second position;

(5) FIG. 4 a schematic longitudinal section through a second embodiment of the puffer breaker similar to FIG. 2, wherein the first contact member is in the same intermediate position between the first position and a second position;

(6) FIG. 5 a schematic longitudinal section through a second embodiment of the puffer breaker of FIG. 4, wherein the first contact member has just reached its second position; and

(7) FIG. 6 an embodiment of a drive for driving a piston unit via a pull rod by means of an electromagnetic repulsive force.

(8) In the drawings identical parts, currents and voltages are designated by identical reference characters.

WAYS OF WORKING THE INVENTION

(9) In FIG. 1 a first embodiment of the puffer breaker 1, where a first contact member 2 is in its first position. Said gas-insulated high voltage puffer breaker 1 has a puffer unit 3 with a piston 4 that is movably arranged in a puffer cylinder 5 such that a puffer volume 6 is delimited. The first contact member 2 is movably arranged relative to a tulip-shaped second contact member 7 such that a current path is established. The power connection of the second contact member 7 has not been illustrated in FIG. 1 and following as it is known to the skilled reader. The first contact member 2 is connected to a drive 8 by a piston stem 9 and a pull rod 10 in order to form a gearless and rigid mechanical chain along switching axis 11.

(10) The puffer unit 3 comprises a nozzle 12 for laterally delimiting an arcing zone 13 of the puffer breaker 1 in that it extends about the switching axis 11.

(11) The puffer volume 6 is fluidly connected to the nozzle 12 and the arcing zone 13 by a gas channel 14. Said gas channel has an annular cross-section when seen in the direction of the switching axis 11.

(12) The piston 4 and the first contact member 2 are attached to the piston stem 9. The puffer volume 6 comprises the volume of the gas channel 14 as well as a portion 15 of the puffer cylinder 5, wherein the gas channel 14 and said cylinder portion 15 are fluidly connected to one another by a port 16 such that a gas flowing in a first direction from the portion 15 of the puffer cylinder is redirected via the gas channel 14 in a second direction towards the nozzle 12 once the first contact member 2 is moved from the first position towards the second position.

(13) The port 16 is arranged at a remote first end 20 of the puffer volume or puffer cylinder with respect to the interruption zone/arcing zone 13. The port 16 comprises a plurality of gas outlets leading from the portion 15 of the puffer cylinder 5 to the gas channel 14.

(14) The gas channel 14 is provided radially outside of the puffer cylinder 5 between a cylindrical puffer cylinder wall 17 delimiting the puffer cylinder and a wall structure 18 of the puffer unit 3. The puffer cylinder wall 17 is a structural element of the puffer breaker and not to be confused with an inner surface of the puffer cylinder wall 17 addressed in more detail later on.

(15) The puffer unit 3, the drive 8 and the pull rod 10 are arranged in a common gas-tight enclosure 19 shown in a very simplified manner in FIG. 1 and subsequent figures.

(16) FIG. 2 shows the puffer breaker 1 of FIG. 1 but where the first contact member 2 is in an intermediate position between the first position and a second position. Compared to FIG. 1 the piston stem 9 with the first contact member 2 and the piston 4 are drawn further to the left in FIG. 2. At this intermediate position the gas pressure at the gas channel outlet to the nozzle is maximal and an electric arc 23 extending in between the tip ends of the first contact member 2 and the second contact member 7 is about to be extinguished by a gas flow 24 emerging into the arcing zone 13 from the gas channel 14. The gas channel has an annular shape when discharging into the nozzle 12. Said gas flow 24 is caused by the movement of the puffer piston 4 squeezing the gas out of the portion 15 of the puffer cylinder 5 through the gas channel 14. In the arcing zone the gas flow 24 causes a stagnation point 25 indicated by a bullet point and two radial interruption areas at an axial interruption point 26, 27 indicated by a cross-mark each. Gas movements in the gas channel 14 and in the portion 15 of the puffer cylinder 5 are indicated by dashed arrows.

(17) As can be seen in FIG. 2 a portion of the gas flow 24 emerging of the nozzle 12 is directed partly towards the exhaust 29 and partly towards a further volume 28 of the puffer cylinder 5. Said further volume 28 is located on an opposite side of the piston 4 with respect to the portion 15 of the puffer volume 5 and is fluidly connected to an exhaust 29 arranged outside the wall structure 18 of the puffer unit 3 by at least one exhaust port 30. In this embodiment the least one exhaust port 30 comprises a plurality of sleeve-like exhaust ports that are evenly distributed in the circumferential direction with respect to the switching axis 11 at an opposite end 31 of the puffer cylinder 5 proximal to the arcing zone 13. Since the gas may move freely through the exhaust ports 30 if needed the direction of the gas flow at the exhaust ports 30 is indicated by double-headed arrows.

(18) In FIG. 3 the piston stem 9 with the first contact member 2 and the piston 4 are drawn again further to the left compared to 2 before the piston is brought to a halt. In this stage the first contact member 2 has just reached its second position. The arc interruption process has been concluded at the intermediate position of the first contact member 2 as shown in FIG. 2. FIG. 3 discloses that the dead volume consist of a disc-shaped remainder of the portion 5 of the puffer cylinder 15 and the gas channel 14.

(19) While the minimal play in between the shell surface of the piston 4 and the interior side 34 of the puffer cylinder 5 allows for a sufficient sealing function during the fast acceleration of the puffer volume 6 against the further volume 28 even without providing conventional sealing gaskets the formation of a gas cushion in the terminal stage of the movement of the piston 4 may lead to an undesired amount of a back travel movement of the piston 4 towards its initial position shown in FIG. 1. The larger the acceleration the larger the back travel of the piston 4 becomes an issue because a movement of the piston to the right inevitably brings the first contact member 2 closer to the fixed second contact member 7. This is undesired as it promotes re-arcing which has to be avoided. Thus a good embodiment for preventing back travel of the piston is explained hereinafter.

(20) A second embodiment of a puffer breaker 100 is described below with reference to FIGS. 4 and 5. Since the second embodiment of a puffer breaker 100 is similar to the first embodiment of a puffer breaker 1 described before, same or functionally identical elements are given the same reference numerals as in FIGS. 1 to 3. Below the focus is put on indicating the differences of the second embodiment of a puffer breaker 100 compared to the first embodiment of a puffer breaker 1.

(21) The difference of the second embodiment 100 resides in the shape of the puffer unit 3 at the first end 20, especially the shape of an interior side 34 of the puffer cylinder 5 proximate to the port 16 comprising again a plurality of gas outlets leading from the portion 15 of the puffer cylinder 5 to the gas channel 14. An annular groove 35 (also referred to a radial widening) is arranged on an interior side 34 of the puffer cylinder wall 17 proximate to the port 16 such that a diameter 36 of the locally widened interior side 34 of the puffer cylinder 5 is larger than an outer diameter of the piston 4. Said annular groove 35 starts at about an axial position reached by a trailing end of the piston at the moment of current interruption in an operating state of the puffer breaker. In other words, the annular groove starts at about an axial position the trailing end 37 of the puffer piston 4 reaches when the first contact member 2 is approaching the second position. At that moment in time the arc interruption process in the arcing zone is concluded and having a maximal gas pressure at the nozzle is not required at that moment of interruption process any longer. Thus FIG. 4 corresponds functionally exactly to the situation of the interruption process explained with reference to FIG. 2. The position on the piston stem 9, the first contact member 2 and the piston 4 in FIG. 5 is the very same as shown and described in FIG. 3.

(22) The annular groove 35 extends in the direction of the switching axis 11 over a distance 38 that is larger than a thickness 39 of the piston 4 proximate to the interior side 34 of the puffer cylinder 5. The annular groove 35 is dimensioned such that gas from the portion 5 of the puffer cylinder 6 at the leading end 40 of the puffer piston 4 is allowed to escape to the exhaust 29 via said annular groove 35 to a trailing end 37, i.e. the side of the piston 4 along an annular escape path 41 when the first contact member is approaching the second position. That way the energy of the gas trapped in the dead volume 6 can escape easily because an overall gas resistance in the escape path 41 is designed such that it is smaller than an overall gas resistance in the gas channel 14 at this position of the piston 4 in an operating state of the puffer breaker 100. As a result the pressure in the whole dead volume 6 can be released faster due to the additional outflow cross-section formed by the annular groove 35.

(23) As a result the back travel of the piston in the puffer cylinder can be prevented or at lowered to a minimum such that the risk of a re-arcing can be avoided.

(24) Compared to the first embodiment 1 the diameter of the wall structure 18 of the puffer unit 3 of the second embodiment 100 has been widened for ensuring that the smallest cross-section of the gas channel 14 is still at the nozzle 12 and not at a constriction caused by the radially outwardly bulge of the puffer cylinder wall 17.

(25) FIG. 6 illustrates an embodiment of a drive 8 for driving a piston unit of a puffer unit 3 via the pull rod 10 by means of an electromagnetic repulsive force caused by the drive 8. FIG. 6 shows a portion of the pull rod 10 and a schematic close-up of the drives shown in FIGS. 1-5. In said FIGS. 1-5 the pull rod 10 has been drawn to have different lengths depending to their position relative to the switching axis. Since the drive chain of the embodiments of the present application are linear and rigid the length of the pull rod will not vary and remain constant instead. Thus the simplification in FIGS. 1-5 shall be excused.

(26) FIG. 6 shows a longitudinal cross-section through an electromagnetic repulsive drive 8 also known as Thomson coil drive. Said drive 8 has a piston chamber 45 with a drive piston 46 shown in a position corresponding to the position the first contact member has in its first position. The drive piston 46 is connected to the pull rod 10.

(27) The electromagnetic repulsive drive 8 has a first drive coil 47 and a second drive coil 48. Once the first drive coil 47 is activated the drive piston 46 is accelerated very quick and moved to the left causing the first contact member 2 of the puffer unit 3 to leave its first position and to move to its second position. A bistable suspension or the like (not shown in FIG. 6) may assist the drive piston 46 in remaining at two predefined static positions only.

(28) The second drive coil 48 is activated for moving the drive piston 46 and thus the first contact member 2 back to its initial first position. The drive piston 46 is shown in its initial first piston in FIG. 6 whereas the contour when in its second position is indicated by dashed lines proximate to the second drive coil.

LIST OF REFERENCE NUMERALS

(29) 1, 100 Puffer breaker 2 First contact member 3 Puffer unit 4 Piston 5 Puffer cylinder 6 Puffer volume 7 Second contact member 8 drive 9 piston stem 10 pull rod 11 switching axis 12 gas nozzle 13 arcing zone 14 gas channel 15 portion of the puffer cylinder 16 port 17 puffer cylinder wall 18 wall structure 19 gas tight enclosure 20 first end of the puffer volume/puffer cylinder 23 electric arc 24 gas flow 25 stagnation point 26 axial interruption point 27 axial interruption point 28 further volume 29 exhaust 30 exhaust port 31 opposite end of puffer cylinder 34 interior wall side of puffer cylinder wall 17 35 annular groove 36 diameter of the interior wall at the groove 35 37 trailing end of the puffer piston (when opening) 38 distance 39 thickness of piston 40 leading end of the puffer piston (when opening) 41 escape path 45 piston chamber 46 drive piston 47 first drive coil 48 second drive coil