Air-cooled disconnector provided with cooling slots

Abstract

To provide a high voltage circuit breaker (1) and disconnector (2) for operation in air, extending along an axis (XX'), and comprising an enclosure (3).SOLUTION: A disconnector includes a hollow current-carrying conductor (10, 20, 30) provided in an enclosure and extending along an axis (XX'). The conductor includes at least one lower elongated slot (12a, 22a, 32a) and at least one upper elongated slot (11a, 21a. 31a) extending along the axis, and each of the slots has a width w and a length I opening an air flow cross section. A ratio between an outer diameter surface of the hollow current-carrying conductor (10, 20, 30) and a total air flow cross section of all slots in the same plane perpendicular to the axis (XX') is between 70 and 100.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to the field of air-cooled disconnect switches for generator circuit breakers.

[0002] The generator circuit breaker and its associated disconnector operate in air and are housed in a sealed casing.

[0003] Cooling of such equipment is important because the high currents coming from the power plant generators generate a lot of heat as they pass through the generator circuit breaker and its associated disconnect switches. This heat needs to be efficiently transferred to the outside and the temperature of the live parts needs to be kept within specifications. The following methods are used to enhance the heat transfer: -The heat-carrying fluid moves to the outside while retaining its heat, then cools down and returns to the inside. -The fan blows air inside the case, increasing the heat exchange between the cold case (enclosure) and the hot live components. -Natural convection carries calories from hot live parts to a cooler enclosure through the natural movement of fluids.

[0004] Natural cooling was promoted by the provision of cooling fins and holes. The cooling holes were placed at several locations around the entire circumference of the disconnector. They were elliptical, circular, triangular and rectangular in shape. Such solutions were sized, located and shaped by trial and error. Like other prior art solutions, this method does not consider the 3D effects of air circulation, skin effect, proximity effect and temperature dependent resistivity. By doing so, prior art designs often experience current concentration near the cooling holes or stagnant zones with no air movement, ultimately resulting in undesirable localized hot spots.

[0005] Knowing that higher temperatures lead to higher resistivity, which in turn leads to higher losses and therefore higher temperatures, these hot spots pose a significant risk to the performance of the entire device.

[0006] The maximum nominal current of a piece of equipment is the current that is not leading to a temperature higher than the maximum temperature of the equipment, which is a hot spot. Thus, hot spots limit the nominal current, not the overall design. It is in constructors' clear interest to harden their designs to prevent hot spots.

[0007] Furthermore, prior art designs, which are often found by trial and error, are unreliable because it is not possible to capture all hot spots with a limited amount of temperature sensors.

[0008] In particular, prior art designs do not take into account the effects of air circulation, which may result in local zeros in stagnation regions, and the potential for current concentration at locations near the holes, resulting in higher current densities and additional Joule heating at those locations.

[0009] More efficient solutions are required for both the disconnectors and the housings. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] International Patent Application Publication No. 2023 / 137644A1 Summary of the Invention

[0011] The present invention first relates to the optimization design of the cooling slots of the hollow current-carrying conductor of the air-cooled disconnector.

[0012] The present invention particularly relates to a disconnector for a high voltage circuit breaker, or a high voltage circuit breaker and disconnector, extending along an axis (XX') (or axial direction), said disconnector comprising an enclosure and a hollow current carrying conductor in said enclosure, said conductor comprising at least one lower elongated slot and at least one upper elongated slot extending along said axis.

[0013] Said disconnector can comprise a female part, a tube housing and a moveable tube to connect said female part and said tube housing. Said slots can be provided to any of said parts, for example to only one (for example the tube housing) or to 2 or to all 3 of them.

[0014] The present invention also relates to a method for cooling a disconnector or circuit breaker and disconnector operating in air, extending along an axis (XX'), said disconnector comprising an enclosure and a hollow current carrying conductor in said enclosure, said conductor comprising at least one lower slot and at least one upper slot extending along said axis, a current of, for example, between 10 kA and 30 kA or even up to 50 kA, circulating in said conductor, whereby air is circulating from said at least one lower slot to said at least one upper slot. from said at least one lower slot to said at least one upper slot).

[0015] In a high voltage disconnector (or circuit breaker and disconnector) according to the invention or in a method according to the invention, each of said slot may have a width between 5 mm and 40 mm, for example 8 mm or 10 mm or 20 mm or 30 mm, said width being measured perpendicularly to said axis (XX') or in a plane perpendicular to said axis (XX').

[0016] Preferably, the maximum nominal current is in a range of 10 kA to 50 kA, for example 30 kA, depending on the configuration of the equipment. The current during operation of the power plant may therefore be set from 0 kA to the maximum nominal current.

[0017] The invention concerns the cooling of a hollow disconnector, for example of the type being attached to or beneath a high voltage generator circuit breaker. The disconnector according to an aspect of the invention is operated, insulated and cooled in ambient air. To increase its performance a natural cooling method is implemented, which does not require expensive cooling fans or cooling circuits using cooling liquid.

[0018] Thus, the invention also concerns a method for air cooling a generator circuit breaker's disconnector comprising an inner hollow portion or a hollow conductor, extending along an axis (XX') (or axial direction), comprising circulating air through the at least one bottom slot, then through said hollow portion inside of the disconnector or through said hollow conductor and through the at least one upper slot.

[0019] For example, the present invention relates to a cooling method of a generator circuit breaker's disconnector operating in air, said disconnector comprising an inner hollow portion or a hollow conductor, said method comprising: - circulating cool air through one bottom slot, preferably located at or close to, the lowest possible position of said conductor, then heating up inside the hollow conductor or the hollow live conductor, the hot air leaving at one top slot, preferably located at, or close to, the highest possible position of said conductor; the motor of this natural circulation is the temperature dependency of the air density leading with gravity to an upwards movement of hot air. or circulating cool air through two or more bottom slots, preferably located at, or close to, the lowest possible position of said conductor, then heating up inside the hollow conductor or hollow live conductor, the hot air leaving at two or more top slots, preferably located at, or close to, the highest possible position of said conductor.

[0020] In both cases, the driving force behind natural circulation is the temperature dependence of air density, with gravity causing hot air to move upwards.

[0021] In a device or a method according to the invention, an air cooled disconnector is implemented, comprising a hollow current carrying conductor, extending along an axis (XX') (or axial direction), provided with at least two cooling slots, elongated along said axis or along a direction parallel to said axis, preferably opposed to each other or facing each other, or for example 2 pairs of cooling slots, preferably opposed to each other or facing each other.

[0022] Thus, air can flow from the coldest part at the bottom of the enclosure through the slots on the bottom side of the hollow conductor, heat up inside and become lighter, move out of the enclosure through the slots on the top of the conductor, and then move to the ceiling of the enclosure. At the ceiling of the enclosure, the hot air in the hollow conductor cools and moves to the left and right sides of the enclosure, and finally cools, becomes denser, heavier, and falls to the bottom of the enclosure, where it begins the circular motion again.

[0023] The present invention allows for more efficient natural cooling of conductors while conserving conductive material.

[0024] According to various embodiments of the device or method according to the invention. the slot(s) preferably has / have a long linear shape, each of said slot may have a length between 20 mm and 400 mm, for example 40 mm or 60 mm or 80 mm or 200 mm, said length being measured along, or along a direction or an axis parallel to, said axial direction. and / or any of the slot(s) of the top and / or bottom slot(s) can be divided into several aligned slots to increase the mechanical strength of the hollow conductor. and / or there are 2 slots at the top and 2 at the bottom of the hollow conductor, the spacing between each pair of cooling slots being for example between 10° and 80°, for example 10° or 30° or 70°. and / or said hollow current carrying conductor has an outer diameter of between 30 cm and 200 cm. and / or the number of slots at the top and / or at the bottom of the device is at least equal to 1, or 2, or 3, or 4 or to n (n < 10), for example said conductor comprises at least 1, 2, 3 or more lower slot(s) and a same or a different (for example for mechanical reasons) number of upper slot(s), said lower slot(s) and upper slot(s) preferably facing each other. and / or a heat exchange surface on the outer diameter of the disconnector, e.g. 180.000 mm 2 , the sum of the outer diameter of the hollow current-carrying conductor and the air flow cross section of all the upper slots and all the lower slots, e.g. 2400 mm 2, and / or the ratio between the disconnector's heat exchange surface on the outside diameter, for instance 180.000 mm2, of said hollow current carrying conductor and the sum of air flow cross sections of all upper and all lower slots, for instance 2400 mm2, should preferably be comprised in the range of 70 to 100. Outside this range, cooling slots are less efficient as they either require removing too much of the conductive material (which leads to higher current densities and thus higher Joule losses and in the following higher temperatures) or they are too small (very small slots impede the natural cooling air circulation, resulting in an ineffective cooling and thus in higher temperatures)).

[0025] The air flow cross section of the slot is parallel to XX' of the disconnector.

[0026] Preferably at least one of the slots have rounded ends at the inside of the conductor, which is favorable to the fluid flow along the inside of the conductor. Knowing that the skin effect concentrates the current at the outside of the conductor, such a rounded shape should be implemented preferably only at the inside or inner surface of the conductor where an electrical cross section reduction is of less importance.

[0027] In the axial direction (XX'), one or more (preferably all) of the cooling slots preferably has at least one rounded or oval end, which enables the current to flow smoothly around said rounded or oval shaped end without creating current concentrations. Preferably, the two ends of said one or more, or of all, slot(s) are rounded or oval.

[0028] According to the invention, different sets of slots may be implemented. Parameters like width and / or length and / or shape and / or design, and / or the number of slots and / or the radial distribution of slots can be varied. Depending on the needs, a trade-off is recommended taking into account that, with the introduction of bigger or larger slots. - the electrical current cross section is reduced. the presence of the cooling slots decreases the available current cross section and raises the current density in the remaining conductor leading to higher joule losses and consequently a higher temperature. -Natural convection gets more powerful as the air can travel more easily through wider bottom and top slot(s). the pressure drop for wider slots or openings is lower and a higher mass flow of cold air can go into the hollow disconnector and cool it consequently more efficiently from the inside. [Brief description of the drawings]

[0029] [Figure 1] 1 shows an example of a generator circuit breaker equipped with a disconnecting switch to which the present invention can be applied. [Diagram 2] 1 shows an example of a generator circuit breaker equipped with a disconnecting switch to which the present invention can be applied. [Diagram 3] 1 shows an example of a disconnector with different parts according to the invention; [Figure 4] 4A and 4B show embodiments of the invention including a double slot and a triple slot. [Figure 5A] 1 shows a simplified model of a disconnect in accordance with the present invention, consisting of one slot at the bottom and one slot at the top. [Figure 5B] 1 shows a simplified model of a disconnect in accordance with the present invention, consisting of one slot at the bottom and one slot at the top. [Figure 5C] 5A and 5B show the results of calculations of the simplified model, and FIG. 5C shows the temperature map. [Figure 5D] 5A and 5B show the calculation results of the simplified model, and FIG. 5D shows the cooling air velocity map. [Figure 5E] 5A and 5B show the results of calculations of the simplified model, and FIG. 5E shows the current density map of a device according to the present invention. [Figure 6A] 1 shows a simplified model of one embodiment of a disconnector according to the present invention, with three slots at the bottom and three slots at the top. [Figure 6B] 1 shows a simplified model of one embodiment of a disconnector according to the present invention, with three slots at the bottom and three slots at the top. [Figure 6C] 6A and 6B show the results of calculations of the simplified model, and FIG. 6C shows the temperature map of a device according to the invention. [Figure 6D] 6A and 6B show the calculation results of the simplified model, and FIG. 6D shows the cooling air velocity map. [Figure 6E] Calculation results for the simplified model shown in 6A and 6B are shown, and FIG. 6E shows the current density map. [Figure 7A] The results (in terms of temperature rise) for different slot widths w (measured at the radial cross section of the disconnector) are shown for a configuration with one upper and one lower slot. [Figure 7B] The results (temperature rise) are shown for different numbers of upper and lower slots. [Figure 7C] The effect (temperature rise) of varying the angle between the slots (measured at the radial cross section of the disconnector) is shown. [Figure 8] FIG. 2 is a radial cross-section of the disconnect showing the preferred shape of the single upper slot and the single lower slot. [Figure 9] FIG. 1 is a radial cross-section of the disconnect showing the preferred shape of the design including two upper slots and two lower slots. [Figure 10A] 1 shows a top or bottom view of a preferred shape of one or more upper slots. [Figure 10B] 1 shows a top or bottom view of a preferred shape of one or more upper slots. [Figure 10C] 1 shows a top or bottom view of a preferred shape of one or more upper slots. [Figure 10D] 1 shows a top or bottom view of a preferred shape of one or more upper slots. [Figure 10E] 1 shows a top or bottom view of a preferred shape of one or more upper slots. [Figure 11] 1 illustrates natural cooling flow through a disconnector according to an embodiment of the present invention, which is composed of upper and lower slots oriented relative to the vertical direction. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] The structure of an apparatus to which the present invention can be applied is shown in FIG. 1 and FIG.

[0031] It comprises a generator circuit breaker 1 (connectable via braids 4 to a busbar which itself can be connected to a generator) and a disconnector 2 (connectable via blades 4 to a busbar which itself can be connected to a transformer, e.g. a step-up transformer), both extending along an axis XX'. The outer diameter of the tube housing 30 of the disconnector depends on the rated current and varies, for example, between 30 cm and 200 cm.

[0032] Both the generator circuit breaker 1 and the disconnect switch 2 may be supported by insulators 5 which separate the central live components from a grounded casing or enclosure 6 .

[0033] The disconnector 2 can include three main parts as shown in Figure 2. This hollow air-cooled insulating disconnector has an outside diameter (outer diameter of the tube housing 30) of, for example, 30 cm to 200 cm depending on its performance. This disconnector includes a female part 10, which is completely and preferably permanently connected to the generator circuit breaker 1, a moveable tube 20, and a tube housing 30. Usually, both parts 10, 30 have approximately the same outside diameter. The moveable tube 20 can connect the generator and the transformer by axial movement along the axis (XX'). In other words, the hollow moveable tube 20 opens and closes the contact with the other fixed side 30 (tube housing). The whole device can also include an earth switch, a generator starting switch, current and voltage transformers, surge arresters, which are not shown in the figure. The device is housed in a casing or enclosure 3 filled with air. The casing 3 does not allow air exchange with the outside atmosphere 6, it protects the current carrying parts (busbars, blades, circuit breakers, disconnectors) from the environment, keeps the magnetic field inside, and protects the current carrying parts from unwanted grounding.

[0034] The disconnectors can carry currents from 10kA to 30kA or even 50kA (nominal current). The nominal current is the maximum current that can flow through the device. Currents greater than the nominal current can cause overheating and destroy the device. In operation, the current through the circuit breakers and disconnectors can vary from 0kA to the nominal current, for example 30kA.

[0035] According to one embodiment of the disconnector according to the invention shown in figures 3A and 3B, one or more cooling slots 11a, 21a, 31a are arranged on the upper side (top) of the disconnector and one or more cooling slots 12a, 22a, 32a are arranged on the lower side (bottom) of the disconnector, more precisely in at least one of the disconnector parts 10, 20, 30 as explained above. As can be seen in figure 3A, such cooling slots can be present in all three parts 10, 20, 30.

[0036] The remainder of this description will focus on slots located in the tube housing 30, but is equally applicable to slots that may be located in the other components 10,20.

[0037] Preferably, the cooling slots 32 a at the bottom of the component 30 are next to the insulator 5 .

[0038] Each slot preferably extends along (or parallel to) the axis XX'. The effect of such slots will be explained below. In this application, the "top" (or "upper side") and "bottom" (or "lower side") of a conductor must be understood with reference to the direction of gravity g (illustrated in Figures 1 and 11).

[0039] 3B shows a cross section of the tube housing 30. Due to the presence of the insulator 5, the lower slot 32a and the upper slot 31a are slightly offset from each other.

[0040] Figures 4A and 4B show a device according to the invention, which includes two bottom and two top slots (Figure 4A) and three bottom and three top slots (Figure 4B). The angle α is the angular spacing between the parallel slots, measured in a plane perpendicular to the axis XX' (or in a radial cross section of the disconnect).

[0041] In view of the various computer simulations carried out for the disconnector according to the invention and presented below, a simplified model was used. For the embodiment of the disconnector 2 and its casing 3, a simplified model was used as shown in Figures 5A and 5B, in which a ring or hollow tube corresponding to the hollow tube housing 30 of the disconnector is placed in a frame (having a thickness te of, for example, 12 mm) corresponding to the casing 3. In all simulations, symmetrical boundary conditions were chosen.

[0042] Simulation results of the model of the embodiment of Figures 5A and 5B are shown in Figures 5C, 5D (including temperature and velocity scales in both Figures 5C and 5D) and 5E. Figure 5C shows the temperature distribution, Figure 5D shows the wind speed distribution and Figure 5E shows the current density near the slot (current density is higher closer to the slot). The simulated model consists of one cooling slot 31a at the top of the disconnector and one cooling slot 32a at the bottom of the disconnector.

[0043] Another simplified model of a disconnector 2 according to an embodiment of the present invention is shown in Figures 6A and 6B, which comprises three cooling slots 31a, 31b and 31c on the upper side of the disconnector and three cooling slots 32a, 32b and 32c on the lower side of the disconnector. Figure 6C shows the temperature distribution especially near the slots, Figure 6D shows the wind speed distribution and Figure 6E shows the current density near the upper and lower slots.

[0044] Whatever the number of upper cooling slots 31a, 31b, 31c and the number of lower cooling slots 32a, 32b, 32c, their locations may be an optimal tradeoff. The presence of the slots 31a-31c and 32a-32c reduces the cross-sectional area of ​​the current (which leads to a higher current density and therefore a higher Joule effect around the slots, generating more heat). - more efficient natural cooling by convection. However, the cooler the conductor 30 is, the more heat is taken away and transported, resulting in heating of the housing 3. - Better cooling means the gas will carry heat closer to the enclosure, which can cause it to heat up. -Also, there is a possibility that the chassis will heat up due to the greater amount of Joule heat generated near the cooling slots and the greater amount of heat dissipated.

[0045] A disconnector according to the invention may, for example, comprise: There is only one cooling slot 31a at the top of the disconnector and two cooling slots 32a, 32b at the bottom. The upper part of the disconnector has two cooling slots 31a, 31b, while the lower part has only one cooling slot 32a. There is only one cooling slot 31a at the top of the disconnector and only one cooling slot 32a at the bottom (shown in Figures 5A and 5B). The disconnector has three cooling slots 31a, 31b, 31c in the upper part and three cooling slots 32a, 32b, 32c in the lower part (Figures 4B, 6A, 6B). -There are several upper cooling slots and several lower cooling slots, the number of upper and lower cooling slots may or may not be the same, for example, for mechanical reasons, it is possible to have two slots at the top (each slot is e.g. 10 mm wide) and three slots at the bottom (each slot is e.g. 6.67 mm wide)

[0046] The slot according to the invention saves 1% to 3% of conductive material (see the bottom of each of Figures 7A, 7B to 7C, commented below) and lightens the conductor 30 (or the corresponding part of the disconnector).

[0047] More generally, each slot may have a width w (see FIG. 5E) measured perpendicular to the axis (XX') (see FIG. 7A) of between 0.2 cm and 4 cm, for example 1 cm.

[0048] The ratio of the outer diameter surface of said hollow current carrying conductor 30 to the added slot cross section, which is width w x length l x total number of slots (31a, 32a) (see FIG. 5E), is preferably between 70 and 100, more preferably between 80 and 90. The total number of slots (31a and 32a) (see FIG. 5E) is preferably between 70 and 100, more preferably between 80 and 90, and even more preferably equal to or close to 85. For optimum results, ratios outside the range of 70 to 100 are not preferred (higher temperature rise occurs when the ratio is in the range of 70 to 100).

[0049] Best results are obtained if the surface area of ​​all lower slots through which the air flows is equal or similar (within a range of +10%, preferably +5%) to the surface area of ​​all upper slots through which the air flows.

[0050] In other words, if the sum of all air passing cross sections is called A and the external heat transfer surface of the slotted conductor is called B, then the ratio B / A is preferably in the range of 70 to 100.

[0051] As is clear from the above, the invention also covers a solution in which a single slot is made at the top and a single slot is made at the bottom of the conductor in front of the top slot. However, tests have shown that this solution with only two single slots can lead to too much current concentration around the slots, if said single slots are too large, leading to increased Joule losses and increased temperatures. Therefore, an alternative exists. An embodiment comprising two slots made at the top and two slots made at the bottom of the conductor, preferably before the top slots (see Figures 4A, 9A and 9B). An embodiment comprising three slots made at the top and three slots made at the bottom of the conductor, preferably before the top slots (see Figures 4B, 6A, 6B).

[0052] According to one aspect of the invention, air flows by convection from the bottom of the casing through the bottom slots 32a, upward through the conductors, and then through the top slots 31a. The invention provides efficient natural cooling of the conductors while saving materials. However, attention must also be paid to the temperature of the casing, since it will be heated by the heat carried by the air flow.

[0053] Although only one phase has been described above, the present application finds application to three phase circuit breakers / circuit breakers, each having a structure according to the invention.

[0054] The present invention may find application, for example, in circuit breakers carrying very high nominal currents (eg 10 kA and 50 kA) and / or voltages in the range 10 kV to 40 kV.

[0055] Next, another embodiment of the present invention will be described with reference to FIGS. 8A to 11. - Figures 8A and 8B show radial cross sections of a disconnector in a configuration with one upper slot and one lower slot. Figure 8A shows an enlargement of the upper slot 31a and the rounded edge 34a of the inner surface 33 of the hollow conductor 30. Figure 8B shows an enlargement of the lower slot 32a and the rounded edge 35a of said inner surface 33 of the hollow conductor 30. The arrows in these figures indicate the flow of fluid along said inner surface 33. Since the skin effect concentrates the current on the outside of the conductor, the optimization of the shape for a smoother fluid flow is preferably only performed on the inside of the conductor, where the reduction of the electrical cross section is less important. - Figures 9A and 9B show radial sections of a disconnector in a configuration with two upper slots 31a and 31b and two lower slots 32a and 32b. Figure 9A shows an enlarged view of the upper slots 31a, 31b and the rounded edges 34a, 34b on the inside of the hollow conductor 33. The inside allows the fluid flow to move smoothly around the corners with low pressure loss. Figure 9B shows an enlarged view of the lower slots 32a, 32b and the rounded edges 35a, 35b on the inside of the hollow conductor 30. The slots thus direct the cooling air to the hot conductor surface. The same effect as described above is obtained in favoring the flow of the fluid along the surface 33. Preferably, the rounded edges 35a, 35b are made only on the side 33 along which the fluid should flow. The rounded edges 35a, 35b have a diffuser effect which reduces pressure loss and therefore facilitates the passage of air through the slots. - Figures 10A-10E show several cooling slot configurations according to embodiments of the invention, where all slots 31a-31c have rounded ends 36. All figures show the disconnector from the top of the housing, but similar configurations can be applied to the bottom slots 32a-32c. Figure 10A (respectively 10C or 10D) shows one (respectively two or three) slots 31a (respectively 31a and 31b, or 31a, 31b and 31c) arranged symmetrically from a vertical plane constituting the axis XX' of the hollow tube, Figure 10E shows a configuration with two double slots 31a, 31b, a single slot 31c, and Figure 10F shows a configuration with two double slots 31a, 31b, a single slot 31c, and another double slot 31d, 31e. In all configurations, the rounded ends 36 allow a smooth current path without local current concentrations. As shown in FIG. 10B, a single cooling slot can also be divided into two or more aligned cooling slots that can have rounded and / or elliptical ends 36 with the same beneficial effect on temperature rise. For mechanical stability reasons, one or more of the upper and lower slots 31a1, 31a2 (see FIG. 10B) can be divided into two, three or more (e.g. ten) axially aligned slots, as in the example shown in FIG. 10B. In this example, the slots are aligned but divided into two slots. A small bridge of conductive material between them considerably increases the strength and stiffness of the entire conductor structure.

[0056] The invention implements natural convection of natural fluids that move from hot live components to the cold enclosure, carrying away calories. For high permanent currents, for example in the range of 10-30 kA, natural cooling is sufficient to keep the temperature of the live components below the limit. No extra cooling means like fans or heat pipes are needed. By improving and optimizing the natural convection, the equipment can be cooled more efficiently and the same product can be used for even higher nominal currents without extra investments.

[0057] The present invention relates to optimized cooling of special equipment of circuit breakers and disconnectors for air insulated generators placed in an enclosure. A detailed analysis of the location, shape and dimensions of the cooling slots has allowed a significant improvement in performance while saving conductive material.

[0058] The inventors of the present invention have simulated different configurations and arrived at different features of the cooling slots to reduce the temperature rise while saving conductive material. These features are the design and / or location and / or shape and / or width and / or length of the cooling slots.

[0059] In devices containing only one slot at the top and one slot at the bottom, the two slots are preferably opposite each other, as shown in Figures 5A and 5B. In configurations containing more than one slot at the top and / or more than one slot at the bottom, a symmetrical design is preferred, see for example Figures 4A and 4B. The angle shown in Figures 4A and 4B should be kept between 10° and 80° (see results in Figure 7C).

[0060] As shown in FIG. 11, the slots, in this example two lower slots and two upper slots, are preferably arranged in different orientations to obtain better results. The lower slots 32a and 32b are preferably diverging from each other (from the outside to the inside of the conductor 30) and are oriented to direct the cool cooling air flow towards or along the hot inner disconnector surface 33. The cool air passing through the slots has a significant kinetic energy, which is used for efficient heat exchange with the inner surface of the disconnector. The slots may be oriented towards the inner surface at an angle β comprised between 5 degrees and 30 degrees with respect to the vertical. The upper slots 31a and 31b are preferably convergent towards each other (from the inside towards the outside of the conductor 30) and are oriented in such a way that the heated airflow faces as little resistance as possible when leaving the hollow inner part of the disconnector. The slots are therefore oriented in a direction in which the airflow has to rotate the least. The slots can be oriented towards the inner surface at an angle β comprised in the range of 5 to 30° with respect to the vertical.

[0061] Figures 7A-7C show the temperature rise for different design parameters and / or different devices (having different diameters), different slot widths, and / or different numbers of slots, and / or different angles between adjacent slots. The top of Figure 7A shows the maximum temperature rise for devices having the same diameter and shape. The maximum temperature rise is shown at the top of each figure and varies between 70.3 Kelvin and 72.9 Kelvin.

[0062] The first device (left, temperature rise 72.9 Kelvin) has no slots, the others have one slot on the top and one on the bottom, and the widths of said slots vary from 5mm, 10mm, 15mm, 20mm, 30mm, 40mm (from left to right).

[0063] The bottom part of Figure 7A shows the material consumption of the same devices arranged in the same order as the top part of Figure 7A, starting on the left with a device without slots (100% material). By incorporating or adding wider slots, less conductive material is consumed.

[0064] The top part of Figure 7B shows the maximum temperature rise for different numbers of slots, identical device diameters, and identical airflow cross-sectional areas (except for device 1, which has no slots and therefore zero cross-sectional area). The maximum temperature rise is shown at the top of each figure and varies between 69.8 Kelvin and 72.9 Kelvin.

[0065] The first device (on the left, max temp rise 72.9 Kelvin) has no slots, the device to the right has one slot on the top and one slot on the bottom (max temp rise 70.3 Kelvin, each slot is 20mm wide), the device to the right of that has two slots on the top and two slots on the bottom (max temp rise 70.0 Kelvin, each slot is 10mm wide), and the last device on the right has three slots on the top and three slots on the bottom (max temp rise 69.8 Kelvin, each slot is 6.7mm wide).

[0066] The bottom part of Figure 7B shows the material consumption of the same devices arranged in the same order as the top part of Figure 7B, starting from the left with the device without the slot (100% material), the other three devices consume the same amount of aluminum (98.6%), and the outer diameter is the same for all four devices.

[0067] The top part of Figure 7C shows the maximum temperature rise for devices of the same diameter with varying angle α between adjacent slots. The maximum temperature rise is shown at the top of each figure and varies between 69.8 Kelvin and 72.9 Kelvin.

[0068] The first device (left, with a maximum temperature rise of 72.9 Kelvin) has no slots. The other devices have two slots on the top and two on the bottom, spaced at angles of 10° (devices with a maximum temperature rise of 70.0 Kelvin), 20° (devices with a maximum temperature rise of 69.8 Kelvin), 30° (devices with a maximum temperature rise of 69.9 Kelvin), 40° (devices with a maximum temperature rise of 69.8 Kelvin), 60° (devices with a maximum temperature rise of 69.9 Kelvin), 80° (devices with a maximum temperature rise of 70.2 Kelvin), and 100° (devices with a maximum temperature rise of 70.7 Kelvin).

[0069] Preferably, the angle α between adjacent slots is between 20° and 60°.

[0070] The bottom of Figure 7C shows the material consumption for the same devices arranged in the same order as the top of Figure 7C, starting from the left with the device without the slot (100% material) and the other devices consuming the same amount of aluminum (98.6%).

[0071] 7A-7C show that the present invention reduces the temperature rise by over 4%, from 72.9 Kelvin to 69.8 Kelvin, while saving 1.4% of conductive material. The estimated 4% reduction in heating (due to the presence of the slot) allows the rated current to be increased by about 4%, while still limiting the temperature rise to 75 Kelvin. For example, a device with a maximum current of 20 kA (without slots) can be used up to 20.8 kA with the cooling slots of the present invention.

[0072] By limiting the maximum temperature rise of the conductor to below 75 Kelvin, cooling fans that must be installed around the conductor can be eliminated.

[0073] The present invention allows for device optimization and reduction of maximum or hot spot temperatures allowing for higher nominal currents without increasing the conductive cross-sectional area. [Explanation of symbols]

[0074] 1: Generator circuit breaker 2: Disconnector 3: Casing / housing 5: Insulator 6: Housing 10: Female part 11a, 21a, 31a, 31b, 31c: Upper cooling slot 12a, 22a, 32a, 32b, 32c: Lower cooling slot 20: Moving tube 30: Tube housing 31d, 31e: Double slot 33: Inner surface 34a, 34b, 35a, 35b: Edge 36: End g: Gravity direction XX': Axis α: Angle

Claims

1. A high voltage circuit breaker and disconnector for operation in air, extending along an axis (XX'), comprising a housing (3), the disconnector comprising a hollow current carrying conductor (10, 20, 30) disposed within the housing and extending along the axis (XX'), the conductor comprising at least one lower elongated slot (12a, 22a, 32a) and at least one upper elongated slot (11a, 21a, 31a) extending along the axis, each of the slots having a width w and a length l, the product of l and w giving an air flow cross section of the slot, the ratio between the outer diameter surface of the hollow current carrying conductor (10, 20, 30) and the sum of the air flow cross sections of all the slots being between 70 and 100.

2. the conductor includes at least one, two, three or more lower slots (12b, 22b, 32b) and an equal or different number of upper slots (11a, 21a, 31a), the lower slots and the upper slots preferably facing each other; And / or at least one of the upper and lower slots is divided into a plurality of alignment slots (31a1, 31a2).

3. two or more lower slots (12a, 12b, 22a, 22b, 32a, 32b) and two or more upper slots (11a, 11b, 21a, 21b, 31a, 31b); Each of the upper slots (11a, 21a, 31a) is spaced apart from the adjacent slots (11b, 21b, 31b) by an angle between 20° and 60°; and / or each slot of the lower slots (12a, 22a, 32b) is spaced apart from an adjacent slot (12b, 22b, 32b) by an angle between 20° and 60°.

4. The upper slots (11a, 21a, 31a) are spaced apart by an angle of 10°; and / or the plurality of slots of the lower slots (12a, 22a, 32a) are spaced apart by an angle of 10 degrees.

5. The high voltage circuit breaker and interrupter of claim 1, wherein the width of each slot (11a-11c, 12a-12c, 21a-21c, 22a-22c, 31a-31c, 32a-32c) is between 5mm and 40mm.

6. 2. The high voltage circuit breaker and interrupter of claim 1, wherein a surface of the one or more lower slots through which air enters the hollow conductor (12a, 22a, 32a) is the same or similar to within 5% of a surface of the one or more upper slots through which air exits the hollow conductor (11a, 21a, 31a).

7. 2. The high voltage circuit breaker and interrupter of claim 1, wherein the hollow current carrying conductor has an outside diameter between 30 cm and 200 cm.

8. 2. The high voltage circuit breaker and interrupter of claim 1, wherein the slot is oriented on an inner surface (33) of the interrupter.

9. 2. The high voltage circuit breaker and interrupter of claim 1, wherein at least one of the slots has at least one rounded edge (34a, 35a, 34b, 35b) on the inside of the hollow conductor in a curvilinear direction from the axis XX'.

10. 2. The high voltage circuit breaker and interrupter of claim 1, wherein at least one of the slots has at least one rounded or elliptical edge (36) on the inside of the hollow conductor in a direction parallel to the axis XX'.

11. 2. The high voltage circuit breaker and interrupter of claim 1, wherein the housing (6) is filled with air.

12. The high voltage circuit breaker and interrupter of claim 1, wherein the one or more lower slots and / or upper slots are oriented at an angle of between 5 and 30 degrees on the inner surface (33).

13. 13. A three phase breaker / disconnector, each phase comprising a high voltage circuit breaker and disconnector according to any preceding claim.

14. 14. A method for cooling circuit breakers and disconnectors according to any one of claims 1 to 13, operating in air and carrying a current of 10 kA to 50 kA inclusive through a conductor, whereby air flows from the at least one lower slot to the at least one upper slot.

15. 15. The method according to claim 14, wherein air circulates from the at least one lower slot (12a, 22a, 32a) to the inner surface (33) of the conductor and then to the at least one upper slot (11a, 21a, 31a) driven by natural convection.

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