Circuit breaker

Abstract

The invention relates to a circuit breaker (1). The circuit breaker (1) comprises two interrupter units (3, 5) each having an electrical interrupter switch (25, 35), an electrical parallel connection of a closing resistor (15) and an electrical bypass switch (17) connected electrically in series with the interrupter switches (25, 35), and a mechanical linkage (19) which is movable by a drive mechanism (13) between a closing state in which it closes the interrupter switches (25, 35) and the bypass switch (17), and an opening state in which it opens the interrupter switches (25, 35) and the bypass switch (17). The mechanical linkage (19) is designed in such a way that the interrupter switches (25, 35) close before the bypass switch (17) closes, and the interrupter switches (25, 35) open before the bypass switch (17) opens. The closing resistor (15) is placed within a metallic resistor housing (49).

Description

[0001] 2024PF00416

[0002] 1

[0003] Description

[0004] Circuit Breaker

[0005] The invention relates to a circuit breaker.

[0006] In particular, the invention relates to a high voltage circuit breaker. High voltage circuit breakers controlling long transmission lines are provided with resistors which are connected into a circuit before the circuit breaker main interrupter contacts are closed. The interrupter units of the circuit breakers are designed to make and break operating and fault currents whereas the contacts introducing resistors into the circuit are designed only to make the resistor currents. Circuit breakers used on extra high voltage systems like 420 kV and more use multi-break designs, that is several interrupters which are connected in series.

[0007] Typically, a circuit breaker with two interrupter units (normally referred as "double interrupter unit breaker" design) is used for system voltages above 362 kV. In this arrangement, each of the interrupter units is equipped with a closing resistor assembly. The resistor assemblies are arranged such that the resistor contacts are closed before the main interrupter contacts of the interrupter units by about a half cycle of a power frequency. Furthermore, the resistor contacts should also open first during an opening operation so that main interrupter contacts interrupt the current. These requirements lead to complicated mechanical linkages and assemblies of resistors close to the interrupters.

[0008] In the existing design of circuit breakers, the closing resistors are arranged in such a way that they can prevent switching over voltages by damping the system travelling waves. Each interrupter unit has one closing resistor fixed in parallel to the main interrupter contact. Hence, for each pole of a circuit breaker of the double interrupter unit2024PF00416

[0009] 2

[0010] breaker design there are four contacts to be operated. In live tank designs, the interrupter units along with the closing resistors are usually placed at elevated height.

[0011] It is an object of the present invention to provide a circuit breaker, in particular for high voltages, with an improved closing resistor assembly.

[0012] According to the invention the object is solved by a circuit breaker with the features of claim 1.

[0013] Advantageous embodiments of the invention are the subject of the dependent claims.

[0014] A circuit breaker according to the invention comprises

[0015] - two interrupter units each of which has an electrical interrupter switch,

[0016] - an electrical parallel connection of a closing resistor and an electrical bypass switch, and

[0017] - a mechanical linkage linking the interrupter switches and the bypass switch to a drive mechanism in such a way that the mechanical linkage is movable by the drive mechanism between a closing state in which it closes the interrupter switches and the bypass switch, and an opening state in which it opens the interrupter switches and the bypass switch, wherein - the parallel connection of the closing resistor and the bypass switch is connected electrically in series with the interrupter switches,

[0018] - the mechanical linkage is designed in such a way that the interrupter switches close before the bypass switch closes, and the interrupter switches open before the bypass switch opens, and

[0019] - the closing resistor is placed within a metallic resistor housing. For instance, the resistor housing is made of aluminum or steel.

[0020] Hence, a circuit breaker according to the invention comprises two interrupter units but only one closing resistor.2024PF00416

[0021] Furthermore, an electrical parallel connection of the closing resistor and an electrical bypass switch is connected electrically in series with the interrupter switches of the interrupter units. This allows one to use the closing resistor for both interrupter units. This reduces the number of closing resistors as compared to standard designs comprising one closing resistor for each interrupter unit which is connected in parallel to the interrupter switch of the interrupter unit. Furthermore, only one bypass switch is needed for the closing resistor in place of two switches (one for each closing resistor) needed in the standard design. All this reduces advantageously both the amount of material and the space required for the closing resistor assembly, the costs of the circuit breaker as well as the assembly time needed for circuit breaker. Furthermore, the mechanical energy required for operating the switches of the circuit breaker is reduced due to the reduced number and mass of switches which additionally increases the reliability of the circuit breaker. In addition, the mass of the closing resistor assembly is reduced as compared to the standard design which reduces mechanical stability problems and improves the seismic withstand capability of the circuit breaker, especially when the interrupter units und the closing resistor have to be arranged at an elevated height.

[0022] In an embodiment of the invention the circuit breaker comprises a tank which is placed between the interrupter units and houses the mechanical linkage, and on top of which the resistor housing is placed. In particular, this allows to arrange the closing resistor in-line with the center of gravity of the circuit breaker which further improves the mechanical stability and the seismic withstand capability of the circuit breaker.

[0023] In a further embodiment of the invention the tank is placed on top of an insulator column. This realizes the arrangement of the interrupter units and the closing resistor at an2024PF00416

[0024] elevated height, which is often needed for live tank designs, for instance.

[0025] In a further embodiment of the invention the drive mechanism comprises a mechanic, electric or hydrodynamic drive unit and a connecting member which connects the drive unit and the mechanical linkage. For instance, the connecting member may run through the insulator column. This allows one to operate the switches of the circuit breaker by means of a drive unit which is spaced apart from the mechanical linkage.

[0026] In a further embodiment of the invention the mechanical linkage comprises a lever mechanism connecting the connecting member to the interrupter switches and the bypass switch. A lever mechanism allows one to realize a simple and robust mechanical connection of the switches to the drive mechanism.

[0027] In a further embodiment of the invention the closing resistor comprises at least one stack of resistor discs. This allows one to adapt the closing resistor to respective requirements by choosing an appropriate number of resistor discs.

[0028] In a further embodiment of the invention each interrupter switch comprises a fixed interrupter contact, and a movable interrupter contact which is movable by means of the mechanical linkage between a first position in which it contacts the fixed interrupter contact and a second position in which it is separated from the fixed interrupter contact. This allows one to operate each interrupter switch by moving the movable interrupter contact of the switch.

[0029] In a further embodiment of the invention the bypass switch comprises a fixed bypass contact, and a movable bypass contact which is movable by means of the mechanical linkage between a first position in which it contacts the fixed bypass contact and a second position in which it is separated from the fixed bypass contact. For instance, the fixed bypass contact and the movable bypass contact are arranged2024PF00416

[0030] vertically with respect to each other, and the movable bypass contact is movable vertically relative to the fixed bypass contact. This allows one to operate the bypass switch by moving the movable contact vertically relative to the fixed bypass contact.

[0031] The properties, features and advantages of this invention, as well as the way in which these are achieved, become clearer and are understood better in conjunction with the description hereunder of embodiments, which are explained in more detail with reference to the drawings, in which

[0032] FIG 1 shows schematically an embodiment of a circuit breaker according to the invention,

[0033] FIG 2 shows a first switching state of switches of a circuit breaker according to the invention,

[0034] FIG 3 shows a second switching state of switches of a circuit breaker according to the invention,

[0035] FIG 4 shows a third switching state of switches of a circuit breaker according to the invention,

[0036] FIG 5 shows a fourth switching state of switches of a circuit breaker according to the invention.

[0037] Corresponding parts are designated with the same reference signs in the figures.

[0038] Figure 1 ( FIG 1 ) shows schematically an embodiment of a circuit breaker 1 according to the invention. The circuit breaker 1 comprises a first interrupter unit 3, a second interrupter unit 5, a tank 7, an insulator column 9, a base unit 11, a drive mechanism 13, a closing resistor 15, a bypass switch 17, and a mechanical linkage 19.2024PF00416

[0039] 6

[0040] The first interrupter unit 3 comprises an electrically insulating first interrupter housing 21, a first contact terminal 23, and a first interrupter switch 25. The first interrupter switch 25 is placed within the first interrupter housing 21 and comprises a first fixed interrupter contact 27 and a first movable interrupter contact 29. The first movable interrupter contact 29 is movable by means of the mechanical linkage 19 between a first position in which it contacts the first fixed interrupter contact 27, and a second position in which it is separated from the first fixed interrupter contact 27. The first contact terminal 23 is placed at an end of the first interrupter housing 21 and connected electrically to the first fixed interrupter contact 27.

[0041] The second interrupter unit 5 comprises an electrically insulating second interrupter housing 31, a second contact terminal 33, and a second interrupter switch 35. The second interrupter switch 35 is placed within the second interrupter housing 31 and comprises a second fixed interrupter contact 37 and a second movable interrupter contact 39. The second movable interrupter contact 39 is movable by means of the mechanical linkage 19 between a first position in which it contacts the second fixed interrupter contact 37, and a second position in which it is separated from the second fixed interrupter contact 37. The second contact terminal 33 is placed at an end of the second interrupter housing 31 and connected electrically to the second fixed interrupter contact 37.

[0042] The tank 7 is placed on top of the insulator column 9 and between the interrupter housings 21, 31. The tank 7 houses the mechanical linkage 19 and the bypass switch 17.

[0043] The bypass switch 17 comprises a fixed bypass contact 41 and a movable bypass contact 43. The movable bypass contact 43 is movable by means of the mechanical linkage 19 between a first position in which it contacts the fixed bypass contact 41, and a second position in which it is separated from the fixed2024PF00416

[0044] 7

[0045] bypass contact 41. The fixed bypass contact 41 is connected electrically to the second movable interrupter contact 39. The movable bypass contact 43 is connected electrically to the first movable interrupter contact 29. The fixed bypass contact 41 and the movable bypass contact 43 are arranged vertically with respect to each other, and the movable bypass contact 43 is movable vertically relative to the fixed bypass contact 41, as indicated by the double arrow in figure 1.

[0046] The closing resistor 15 comprises two stacks 45, 46 of resistor discs 47 which are placed within a metallic resistor housing 49 mounted on top of the tank 7. A first end 53 of a first stack 45 is connected electrically to the first movable interrupter contact 29. A second end 54 of the first stack 45 is connected electrically to a first end 55 of a second stack 46. A second end 56 of the second stack 46 is connected electrically to the second movable interrupter contact 39.

[0047] Hence, an electrical parallel connection of the closing resistor 15 and the bypass switch 17 is connected electrically in series with the interrupter switches 25, 35.

[0048] The insulator column 9 is mounted on top of the base unit 11. The drive mechanism 13 comprises a mechanic, electric or hydrodynamic drive unit 57 and a connecting member 59 which connects the drive unit 57 and the mechanical linkage 19. The drive unit 57 is placed within a drive housing 61 mounted to a side of the base unit 11. The connecting member 59 comprises a rodlike member running from the base unit 11 through the insulator column 9 to the mechanical linkage 19.

[0049] The mechanical linkage 19 links the interrupter switches 25, 35 and the bypass switch 17 to the drive mechanism 13 in such a way that the mechanical linkage 19 is movable by the drive mechanism 13 between a closing state in which the interrupter switches 25, 35 and the bypass switch 17 are closed, and an opening state in which the interrupter switches 25, 35 and the bypass switch 17 are open. For instance, the mechanical2024PF00416

[0050] 8

[0051] linkage 19 may comprise a lever mechanism interacting with the movable interrupter contacts 29, 39 of the interrupter switches 25, 35 and with the movable bypass contact 43 of the bypass switch 17.

[0052] Furthermore, the mechanical linkage 19 is designed in such a way that the interrupter switches 25, 35 close before the bypass switch 17 closes, and the interrupter switches 25, 35 open before the bypass switch 17 opens. This is explained by means of figures 2 to 5 which show various switching states of the switches 17, 25, 35, respectively.

[0053] Figure 2 ( FIG 2 ) shows the opening state in which the interrupter switches 25, 35 and the bypass switch 17 are open, respectively. In this state no electrical current flows between the first terminal 23 and the second terminal 33.

[0054] Figure 3 ( FIG 3 ) shows a first intermediate state when the mechanical linkage 19 moves from the opening state shown in figure 2 to the closing state shown in figure 4. In this intermediate state the interrupter switches 25, 35 are closed whereas the bypass switch 17 is still open. An electrical current now flows between the first terminal 23 and the second terminal 33 through the closing resistor 15. The flow of the current is indicated in figure 3 by arrows. The bypass switch 17 will close later than the interrupter switches 25, 35. For instance, the bypass switch 17 may close later by about half a period of an alternating voltage driving the electrical current. So, when the frequency of the alternating voltage is 50 Hz, the bypass switch 17 may close about 10 ms after the interrupter switches 25, 35 close.

[0055] Figure 4 ( FIG 4 ) shows the closing state in which the interrupter switches 25, 35 and the bypass switch 17 are closed, respectively. In this state the main electrical current flows between the first terminal 23 and the second terminal 33 through the bypass switch 17, as is indicated in2024PF00416

[0056] 9

[0057] figure 4 by arrows. Only a negligible electrical current flows through the closing resistor 15.

[0058] Figure 5 ( FIG 5 ) shows a second intermediate state when the mechanical linkage 19 moves from the closing state shown in figure 4 to the opening state shown in figure 2. In this intermediate state the interrupter switches 25, 35 are open whereas the bypass switch 17 is still closed. No electrical current flows between the first terminal 23 and the second terminal 33. The bypass switch 17 will open later than the interrupter switches 25, 35. Similarly as when closing the switches 17, 25, 35, the bypass switch 17 may open later by about half a period of the alternating voltage.

[0059] Although the invention has been illustrated and described in detail by preferred embodiments, the invention is not limited by the examples disclosed and other variations may be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims

2024PF0041610Patent Claims1. Circuit breaker ( 1 ), comprising- two interrupter units ( 3, 5 ) each of which has an electrical interrupter switch ( 25, 35 ),- an electrical parallel connection of a closingresistor ( 15 ) and an electrical bypass switch ( 17 ), and - a mechanical linkage ( 19 ) linking the interrupter switches ( 25, 35 ) and the bypass switch ( 17 ) to a drive mechanism ( 13 ) in such a way that the mechanical linkage ( 19 ) is movable by the drive mechanism ( 13 ) between a closing state in which it closes the interrupter switches ( 25, 35 ) and the bypass switch ( 17 ), and an opening state in which it opens the interrupter switches ( 25, 35 ) and the bypass switch ( 17 ), wherein- the parallel connection of the closing resistor ( 15 ) and the bypass switch ( 17 ) is connected electrically in series with the interrupter switches ( 25, 35 ),- the mechanical linkage ( 19 ) is designed in such a way that the interrupter switches ( 25, 35 ) close before the bypass switch ( 17 ) closes, and the interrupter switches ( 25, 35 ) open before the bypass switch ( 17 ) opens, and- the closing resistor ( 15 ) is placed within a metallic resistor housing ( 49 ).

2. Circuit breaker ( 1 ) according to claim 1, wherein the resistor housing ( 49 ) is made of aluminum or steel.

3. Circuit breaker ( 1 ) according to claim 1 or 2 comprising a tank ( 7 ) which is placed between the interrupter units ( 3, 5 ) and houses the mechanical linkage ( 19 ), and on top of which the resistor housing ( 49 ) is placed.

4. Circuit breaker ( 1 ) according to claim 3, wherein the tank ( 7 ) is placed on top of an insulator column ( 9 ).

5. Circuit breaker ( 1 ) according to any one of the preceding claims, wherein the drive mechanism ( 13 ) comprises a2024PF0041611mechanic, electric or hydrodynamic drive unit ( 57 ) and a connecting member ( 59 ) which connects the drive unit (57) and the mechanical linkage (19).

6. Circuit breaker ( 1 ) according to claims 4 and 5, wherein the connecting member ( 59 ) runs through the insulator column ( 9 ).

7. Circuit breaker ( 1 ) according to any one of the preceding claims, wherein the mechanical linkage ( 19 ) comprises a lever mechanism connecting the connecting member ( 59 ) to the interrupter switches ( 25, 35 ) and the bypas s switch ( 17 ).

8. Circuit breaker ( 1 ) according to any one of the preceding claims, wherein the closing res istor ( 15 ) comprises at least one stack (45, 46) of resistor discs (47).

9. Circuit breaker ( 1 ) according to any one of the preceding claims, wherein each interrupter switch ( 25, 35 ) comprises a fixed interrupter contact ( 27, 37 ), and a movable interrupter contact ( 29, 39 ) which is movable by means of the mechanical linkage ( 19 ) between a first position in which it contacts the fixed interrupter contact ( 27, 37 ) and a second position in which it is separated from the fixed interrupter contact (27, 37).

10. Circuit breaker ( 1 ) according to any one of the preceding claims, wherein the bypass switch (17) comprises a fixed bypass contact (41), and a movable bypass contact (43) which is movable by means of the mechanical linkage (19) between a first position in which it contacts the fixed bypass contact (41) and a second position in which it is separated from the fixed bypass contact (41).

11. Circuit breaker ( 1 ) according to claim 10, wherein the fixed bypass contact (41) and the movable bypass contact (43) are arranged vertically with respect to each other, and the2024PF0041612movable bypas s contact ( 43 ) is movable vertically relative to the fixed bypas s contact ( 41 ).

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