Wind power plant and wind power plant power cabinet

Abstract

A wind power facility (100) is proposed, the wind power facility having a pod (104) in which an inverter (300) and a grid choke (400) are disposed, the grid choke being coupled to the output of the inverter (300). The grid choke (400) has three choke coils (410) and a yoke (430), wherein the yoke (430) has a lower yoke component (431) and an upper yoke component (432). Each choke coil (410) has a first end side and a second end side (410a, 410b) and a core lamination (411) therebetween. Each choke coil (410) has a first water-cooled unit (440, 441-444), the first water-cooled unit having its first end abutting against the end (411b) of the core lamination (411). The second end of the water-cooled unit (440) serves as a winding contact surface and is designed to be rounded or curved. Each choke coil (410) has at least one additional water-cooling unit, the at least one additional water-cooling unit having a straight first end and a curved or rounded second end as a winding contact surface, wherein the water-cooling unit is disposed between two winding segments.

Description

Technical Field

[0001] This invention relates to a wind power facility and a power control cabinet for the wind power facility. Background Technology

[0002] The wind power facility has an aerodynamic rotor with rotor blades, which is mechanically coupled directly or indirectly to a generator. Therefore, the rotational motion of the aerodynamic rotor puts the generator into rotational motion, thereby generating electrical energy. The generator is coupled to a machine-side choke (machine choke). The machine-side choke is coupled to an inverter and thus positioned between the generator and the inverter. A grid choke (i.e., a grid-side choke) is located at the output of the inverter. The wind power facility is coupled to the power grid via grid output terminals.

[0003] Especially in wind power installations with inverters, grid-side chokes can be placed between the inverter and the power grid. In wind power installations with three-phase systems, chokes are typically used for each phase or a three-phase choke can be used. The three chokes in a three-phase system can be combined into a single three-phase choke. For this purpose, a core assembled from stacked electrical steel plates can be provided. This type of choke generates heat during operation and reaches a critical temperature for use. This can particularly minimize the efficiency and lifespan of the choke.

[0004] Therefore, cooling of the choke on the machine side is essential because the operation of the choke involves significant heat loss. This heat loss occurs both through copper losses in the windings and core losses in the magnetic material, which is the electrical steel sheet that together forms the core laminations. If the generated heat is not effectively dissipated, overheating can occur, which impairs the electrical and mechanical properties of the choke and significantly shortens its lifespan.

[0005] Cooling is particularly challenging in wind power installations because chokes on the machine side can be installed, for example, within the pod of the wind power plant. Space is limited here, and ambient temperatures may already be elevated by waste heat from other components such as generators and converters. Therefore, an effective cooling system must be compact while simultaneously providing high heat dissipation capacity.

[0006] Passive cooling systems, such as natural convection, may be sufficient in some cases; however, careful design of the choke is required to maximize heat radiation. Active cooling systems are needed in applications with high thermal requirements, such as enhanced air cooling or liquid cooling systems using fans. However, these systems must be designed so as not to significantly increase the energy consumption of the wind power facility.

[0007] In addition, the cooling system must withstand the typical mechanical loads and environmental influences of the pod. The intense vibrations and load changes during operation require a robust structural design, while the corrosive environment, especially in the case of offshore equipment, necessitates the use of durable materials and effective seals.

[0008] Finally, uniform heat distribution within the choke on the machine side is crucial to avoid thermal stress and hot spots. This helps improve the choke's reliability and extend its maintenance intervals. Maintenance-friendliness is another important factor, as wind turbine pods are typically difficult to access.

[0009] In the European patent applications that form the basis of priority, the European Patent Office retrieved the following documents: CN 116 052992 A; US 8 837 116 B2; JIANFEN ZHENG et al.: “Research on heat-removal system of wind power generation water-cooling reactor”, Electrical and Control Engineering (ICECE), 2011, IEEE International Conference, September 16, 2011 (2011-09-16), pp. 5413-5416, XP031960661, DOI: 10.1109 / ICECENG.2011.6058049, ISBN:978-1-4244-8162-0; and CN 118 299 151 A. Summary of the Invention

[0010] Therefore, the object of the present invention is to provide a wind energy facility with a machine-side choke and a grid choke, wherein the wind energy equipment can improve the cooling of the machine-side choke and the grid choke in the wind energy facility and reduce power loss.

[0011] The objective is achieved by the wind energy facility according to the invention and by the wind energy facility power cabinet according to the invention.

[0012] Therefore, a wind energy facility with a pod is proposed. The pod houses a generator and a choke coil on the machine side. The choke coil on the machine side has at least three choke coils, each with an air cooling device. Each air cooling device has a cooling unit, each with an end, which can be attached to the iron core laminations of the choke coil and can be surrounded by windings at its opposite ends. The choke coil may have iron core laminations, aluminum windings, and an air cooling device. Furthermore, a grid choke coil with a water cooling device is provided in the pod.

[0013] A wind energy facility with a pod is proposed, in which an inverter, a generator, a machine-side choke, and a grid choke are arranged. The machine-side choke is disposed between the generator and the inverter. The machine-side choke has three choke coils. Each choke coil has first and second ends and core laminations therebetween, as well as windings. The core laminations have multiple stacked electrical steel plates and first and second core lamination end sides. Each choke coil of the machine-side choke has an air cooling unit. The air cooling unit has a first air guide channel at the first core lamination end side and a second air guide channel at the second core lamination end side. The grid choke is disposed at the output of the inverter. The grid choke has three choke coils and a yoke. The yoke has a lower yoke component and an upper yoke component. Each choke coil of the grid choke has first and second end sides and core laminations therebetween. Each choke coil of the grid choke has a first water cooling unit, the first water cooling unit having its first end abutting against the end of the core lamination. The second end of the water-cooled unit serves as a winding contact surface and is designed to be rounded or curved. Each choke coil of the power grid choke has at least one additional water-cooled unit, which has a straight first end and a curved or rounded second end that serves as a winding contact surface. The water-cooled unit is disposed between two winding sections.

[0014] Furthermore, improved cooling can reduce the quality of the electrical steel sheet in the yoke laminations without causing the temperature in the choke coil to exceed its limit. This reduced quality of the electrical steel sheet leads to lower costs.

[0015] Therefore, a cost-effective choke can be obtained on the machine side by improving the cooling power.

[0016] Other embodiments of the invention are the subject of the dependent claims. Attached Figure Description

[0017] The advantages and embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0018] Figure 1 A schematic diagram of a wind power facility is shown.

[0019] Figure 2 A schematic circuit diagram showing the power grid circuitry for a wind power facility is provided.

[0020] Figure 3 A schematic cross-sectional view of the choke coil on the machine side is shown.

[0021] Figure 4 The diagram shows a schematic exploded view and a schematic cross-sectional view of the power grid choke coil.

[0022] Figure 5 A schematic cross-sectional view of a power grid choke coil is shown.

[0023] Figures 6A to 6C Different views of the cooling unit are shown.

[0024] Figures 7A to 7C A different view of another cooling unit is shown.

[0025] Figures 8A to 8C A different view of another cooling unit is shown, and

[0026] Figure 9 The power cabinet is shown. Detailed Implementation

[0027] Figure 1 A schematic diagram of a wind power facility is shown. Figure 1 The diagram shows a wind power facility 100 having a tower 102, a pod 104, and an aerodynamic rotor 106. The aerodynamic rotor 106 has three rotor blades 108. The wind power facility 100 also has a fairing 110. The aerodynamic rotor 106 is directly or indirectly coupled to a generator 200 and places the generator in rotational motion. The generator 200 generates energy through rotational motion, which is delivered to an inverter 300. A grid choke 400 may be provided at the output of the inverter. The grid choke 400 may be housed in a power cabinet within the pod. The grid choke 400 may be cooled via a fluid cooling system. Additionally, a machine-side choke 500 is provided.

[0028] Figure 2 A schematic circuit diagram of the power grid circuit for the wind power facility 100 is shown. An aerodynamic rotor 106 with rotor blades 108 is directly or indirectly coupled to a generator 200. The rotational motion of the aerodynamic rotor 106 puts the generator 200 into rotational motion, thereby generating electrical energy. The generator 200 is coupled to a choke 500 on the machine side. The choke 500 on the machine side is coupled to an inverter 300. Therefore, the choke 500 on the machine side is located between the generator 200 and the inverter 300. A grid choke 400 (i.e., the grid-side choke) is provided at the output terminal of the inverter 300. The wind power facility 100 is coupled to the power grid V via a grid output terminal 700.

[0029] Figure 3A schematic cross-sectional view of the choke coil on the machine side is shown. The choke coil 500 on the machine side has first and second ends 501, 502, two connecting rails 510, 520, a core lamination 530, a winding 540, and a cooling element 550. The core lamination 530 has first and second end sides 531, 532. Air guide channels 551, 552 are respectively provided at the first and second end sides 531, 532, through which cooling air is guided. The second air guide channel 552 and the second connecting rail 520 are connected to the second end side 532. The winding 540 is provided around the core lamination 530, around the air guide channels 551, 552, and around the second connecting rail 510. Therefore, the winding 540 has four distinct regions: a first region 541 on the first end side 531 of the core lamination 530, a second region 542 on the longitudinal side of the core lamination 530, a third section 534 between the two connecting rails 510 and 520, and a fourth section 544 on the second longitudinal side of the core lamination 530. Thus, the winding 540 surrounds the core lamination 530, the air guide channel 550, and the second connecting rail 520.

[0030] The first air guide channel 551 is attached to one side of the first end side 531 and is wound with a first winding area on its opposite side.

[0031] The second air guide channel 552 is located between the second end side 532 and the second connecting rail 520.

[0032] Therefore, the choke on the machine side is equipped with an air cooling device, which dissipates the heat loss generated in the core laminations and windings.

[0033] The cooling system has at least one fan that generates an airflow that can flow through an air passage, thereby cooling the air passage. This cooling of the air passage then similarly cools the core laminations and windings.

[0034] The choke on the machine side may have a yoke, which has an upper yoke component and a lower yoke component without a cooling element. Thus, cooling of the yoke occurs only through air guide channels that abut against the core laminations.

[0035] Figure 4 A schematic partially exploded view and a schematic cross-sectional view of the power grid choke are shown.

[0036] Figure 5A schematic cross-sectional view of a power grid choke is shown. The power grid choke 400 has at least one choke coil 410 and a yoke 430. The choke coil has first and second end sides 410a, 410b, and the yoke has a lower yoke part 431 and an upper yoke part 432. Furthermore, each choke coil 410 is equipped with two connecting rails 420. The choke coil 410 has a core lamination 411 and multiple electrical steel plates, windings 412, and a water cooling device 440. The core laminations have first and second ends 411a, 411b. The water cooling devices 440 of the respective choke coils 410 can be connected via water pipes 445. Each choke coil 410 has a core lamination 411 and multiple windings 412. The windings 412 are wound around the core lamination 411. Additionally, connecting rails 420 are provided, which are also wound at least partially around the windings 412.

[0037] Furthermore, the water cooling device 440 is provided with, for example, four water cooling units 441, 442, 443, and 444. Cooling units 441-444 are located at the end sides 410a and 410b of the choke coil 410. The core lamination 411 has first and second ends 411a and 411b and two longitudinal sides 411c and 411d. The longitudinal sides 411c and 411d are winding contact surfaces that are not cooled by the water cooling units. Thus, a choke coil with a smaller structural size can be achieved.

[0038] A first water-cooling unit 443 is provided at the end 411a of the first core lamination. A connecting rail 420 is connected in the direction of the end side 410a and is wound around the connecting rail by a first winding section 412a. A second water-cooling unit 444 is connected to the first winding section 412a. The water-cooling unit 444 has first and second ends 444a and 444b. The first end 444a is connected to the first winding section 412a. The second end 444b is surrounded by the second winding section 412b. The second end 444b is rounded.

[0039] The third water-cooling unit 441 is connected to the second end 411b of the iron core lamination 411. The third water-cooling unit has first and second ends 441a and 441b. The first end 441a is connected to the second end 411b of the iron core lamination and can optionally be designed straight. The second end 441b is opposite to the first end 441a and can be designed to be at least partially rounded.

[0040] The third winding section 412c is connected to the second end 441b. The fourth water-cooling unit 442 is connected to the third winding section 412c. The water-cooling unit 442 has first and second ends 442a and 442b. The second end 442b may be rounded. A fourth winding section 412d may be provided at the second end 442b.

[0041] The winding coil 410 has first and second end sides 410a, 410b and first and second longitudinal sides 410c, 410d. The cooling unit 443 has first and second ends 443a, 443b. The first end 443a abuts against the first end 441a of the lamination assembly 411. The second end 443b abuts against the rail 420. Therefore, the first water-cooled unit 443 extends between the first end 441a of the core lamination 411 and one of the two busbars 420. The first end 441a is the core lamination contact surface. The second end 443b is the busbar contact surface. A first winding section 412a is provided between the busbar 420 and the second cooling unit 444. The second cooling unit 444 has first and second ends 444a, 444b. The first end 444a can be designed substantially straight. The second end 444b is configured as a winding contact surface and is at least partially rounded or curved. The design of the second side 444b increases the winding contact surface, thereby achieving improved heat transfer. Due to the rounded design, the winding can be wound more effectively around the second cooling unit and, in particular, around the second end 444b of the cooling unit.

[0042] Figures 6A to 6C Different views of the cooling unit are shown.

[0043] Figures 7A to 7C A different view of another cooling unit is shown.

[0044] Figures 8A to 8C A different view of another cooling unit is shown. Figures 6A to 8C The diagram illustrates three different implementations of the water-cooling unit. According to... Figures 6A to 8C The difference in the water-cooled unit lies in the design of its second end, and especially in the design of the bending of the second end, i.e., the winding contact surface.

[0045] The cooling unit 441 has first and second sides 441a and 441b. Optionally, the first side 441a can be designed straight, and the second side 441b can be designed curved or rounded. Figures 6A to 8C The image shows different cooling units with different rounded corners.

[0046] The cooling unit 441 has at least two through holes 441c through which coolant can flow.

[0047] The cooling unit 441 can be made of metal. In particular, the cooling unit can be milled from a single piece, wherein through holes must subsequently be provided accordingly. Alternatively, the cooling unit can be made from a sheet metal having tubes 441c.

[0048] The radius of the bending of the cooling unit can be, for example, 8-12 mm, especially 10 mm, or the bending can have multiple bending segments, such as bending of 8-15 mm, especially 12 mm, and bending of 40-60 mm, especially 50 mm.

[0049] With improved cooling via the power grid choke coil, electrical steel sheets of reduced quality can be used for the core laminations. No improvement in quality is necessary because the cooling system is sufficient to dissipate enough heat from the core laminations.

[0050] In the prior art, electrical steel sheet 2 can be used, for example. However, with the construction according to the invention, electrical steel sheet 1 of lower quality can be used because the construction according to the invention ensures improved cooling power. Electrical steel sheet 2 is, for example, the Power Core from ThyssenKrupp Steel Corporation. M250-35A. Electrical steel sheet 1, for example, is the powercore from ThyssenKrupp Steel Company, conforming to DIN EN 10303 with the reference quality NO27-14. traction 027-140Y420.

[0051] In Table 1

[0052] 50Hz 0.93W / Kg 1.12W / Kg 200Hz 5.15W / Kg 5.99W / Kg 400HZ 13.29 W / kg 16.91 W / kg 1000Hz 52.89 W / kg 72.36 W / kg

[0053] The choke coil has an iron core lamination, an aluminum winding, and a water cooling device, which may have, for example, four units. First and second connecting rails for the two terminals of the choke coil are wound in the winding. A first cooling unit is provided between the connecting rails and the iron core lamination. A second cooling unit is provided at the other end of the iron core lamination, i.e., at the end side, and the second cooling unit has at least a partially rounded or bent end. A third cooling unit is provided on one side of the busbar, and the third cooling unit is designed to be at least partially rounded or bent at its free end. The second cooling unit can be wound by means of the winding. A fourth cooling unit can be provided at the winding, and the fourth cooling unit can also be at least partially wound by means of the winding. The fourth cooling unit has at least a partially rounded end.

[0054] The rounded or curved ends of the cooling unit, wound with aluminum windings and flattened, allow for better heat transfer from the cooling unit to the windings. This, in particular, avoids air gaps between the cooling unit and the aluminum windings. This improved heat transfer enhances the overall cooling system.

[0055] According to the present invention, the heat dissipation of the power grid choke is improved by designing the water-cooling unit at least partially bent or rounded at one end. This allows the windings to be better positioned around the water-cooling unit, thereby improving the winding of the windings around the water-cooling unit. In particular, this reduces air bubbles, improving heat conduction from the cooling unit to the outside via the windings. The released heat can be absorbed by the water-cooling unit as close as possible to the windings.

[0056] Each water-cooled unit has a winding contact surface, which can be increased by designing the second end, i.e., rounding or bending the second end. This increases heat transfer between the winding and the cooling body.

[0057] By placing the cooling unit at the end face of the choke coil and by using a rounded or bent design for the winding contact surface of the cooling unit, the cooling power can be increased, making it possible to abandon the cooling of the yoke.

[0058] Furthermore, improved cooling can reduce the quality of the electrical steel sheet used in the core laminations without causing the temperature in the choke coil to exceed its limit. This reduced quality of the electrical steel sheet leads to lower costs.

[0059] This allows for the acquisition of cost-effective grid chokes by improving cooling power.

[0060] By omitting the yoke cooling, the electrical power used to operate the yoke cooling can be saved.

[0061] Figure 9 The power cabinet is shown. The power cabinet 600 can be set in... Figure 1 The power cabinet 600 can be designed as a frame 610. The power cabinet 600 has a grid choke (grid-side choke) 400 and a machine-side choke 500 stacked vertically within the frame 610. Here, the grid choke 400 can be positioned below the machine-side choke 500. Through the improved cooling of the grid choke 400 described above, the cooling device for the upper machine-side choke 500 can be smaller or designed with reduced power, because even when the machine-side choke is not operating, the lower grid choke generates less heat, which causes the machine-side choke to heat up. Since the thermal conditions in the pod are altered by using the aforementioned grid choke, these factors can be considered when designing the machine-side choke.

[0062] Therefore, when designing the choke on the machine side, the design of the power grid choke and other heat-generating components in the pod must be taken into account.

[0063] When considering the cooling efficiency of the choke coil on the machine side, the power of the fan used for air cooling must also be taken into account. The power loss of air cooling can be between 1kW and 2kW (e.g., 1.65kW). The temperature inside the coil can, for example, be <100°C.

[0064] List of reference numerals

[0065] 100 wind power facilities

[0066] 102 Tower

[0067] 104 pods

[0068] 106 rotor

[0069] 108 rotor blades

[0070] 110 fairing

[0071] 200 generator

[0072] 300 inverter

[0073] 400 power grid choke

[0074] 410 choke coil

[0075] 410a First End Side

[0076] 410b second end side

[0077] 410c First longitudinal side

[0078] 410d Second Longitudinal Side

[0079] 411 iron core lamination

[0080] 411a First end

[0081] 411b Second end

[0082] 412 winding

[0083] 412a First Winding Section

[0084] 412b Second Winding Section

[0085] 412c third winding section

[0086] 412d fourth winding section

[0087] 420 connecting rail

[0088] 430 yoke

[0089] 431 lower yoke component

[0090] 432 yoke components

[0091] 440 water cooling unit

[0092] 441 Water-cooled Unit

[0093] 441a First end

[0094] 441b Second End

[0095] 441c through hole

[0096] 442 water-cooled unit

[0097] 442a First end

[0098] 442b Second End

[0099] 443 Water-cooled Unit

[0100] 443a First end

[0101] 443b Second End

[0102] 444 water-cooled unit

[0103] 444a First end

[0104] 444b second end

[0105] 445 water pipe

[0106] Choke on the 500 machine side

[0107] 501 First End

[0108] 502 Second End

[0109] 503 electrical steel plate

[0110] 510 First Connecting Rail

[0111] 520 Second Connecting Rail

[0112] 530 iron core lamination

[0113] 531 First End Side

[0114] 532 Second End Side

[0115] 540 winding

[0116] 541 First Winding Section

[0117] 542 Second Winding Section

[0118] 543 Third Winding Section

[0119] 544 Fourth Winding Section

[0120] 550 Air Guidance Unit

[0121] 551 First Air Guidance Channel

[0122] 552 Second Air Guidance Channel

Claims

1. A wind energy facility (100), said wind energy facility having A pod (104) is provided with an inverter (300), a generator (200), and a machine-side choke (500), wherein the machine-side choke (500) is disposed between the generator (200) and the inverter (300). The machine-side choke coil (500) has three choke coils, each of which has first and second ends (501, 502), core laminations (530) therebetween, and windings (540). The core lamination (530) has multiple electrical steel plates (503) stacked on top of each other and first and second core lamination end sides (531, 532). Each choke coil of the machine-side choke coil (500) has an air cooling unit (550). The air guiding unit (550) has a first air guiding channel (551) at the first iron core lamination end side (531) and a second air guiding channel (552) at the second iron core lamination end side (532). The wind power facility also has A grid choke (400) is coupled to the output terminal of the inverter (300). The power grid choke (400) has three choke coils (410) and a yoke (430), wherein the yoke (430) has a lower yoke component (431) and an upper yoke component (432). Each choke coil (410) has first and second end sides (410a, 410b) and core laminations (411) therebetween. Each choke coil (410) has a first water-cooling unit (440, 441-444), the first water-cooling unit having its first end abutting against the end (411b) of the core lamination (411), wherein the second end of the water-cooling unit (440) serves as a winding contact surface and is designed to be rounded or bent. Each choke coil (410) has at least one additional water-cooling unit, the at least one additional water-cooling unit having a straight first end and a curved or rounded second end as a winding contact surface, wherein the water-cooling unit is disposed between two winding segments.

2. The wind energy facility (100) according to claim 1, further comprising: First and second connecting rails (510, 520). The second connecting rail (520) is located on one side of the second air guide channel (552).

3. The wind energy facility (100) according to claim 1 or 2, wherein The winding (540) has a first winding region (541) at the first air guide channel (551), a second winding region (542) on the longitudinal side of the core lamination (530), a third winding region (543) between the first and second connecting rails (510, 520), and a fourth winding region (544) on the longitudinal side of the core lamination (530).

4. The wind energy facility (100) according to claim 1, wherein The water-cooling units (440, 441-444) each have two water guiding sections (441c), which are suitable for containing the cooling medium of the water-cooling device.

5. The wind energy facility (100) according to claim 1 or 4, wherein the wind energy facility further comprises A first water-cooling unit (443) is located between the end of the first core lamination (411a) and the busbar (420), the first water-cooling unit having first and second ends (443a, 443b). The second water-cooling unit (444) has a straight first end and a rounded or curved second end (444b), the second end serving as a winding contact surface. The first winding section (412a) is abutted between the busbar (412) and the second water-cooling unit (444), wherein the first end (444a) of the second water-cooling unit (444) is abutted at the first winding section (412a). The second winding segment (412b) is wound around the second end (444b) of the second water-cooling unit (444), such that the winding (412b) rests against the winding contact surface of the second water-cooling unit (444). A third water-cooling unit (441) has first and second ends (441a, 441b), the second end serving as a winding contact surface, wherein the first end (441a) abuts against the second end (441b) of the core lamination and is designed to be straight. The second end (441b) of the third water-cooling unit (441) is designed to be curved or rounded, and is a winding contact surface. A third winding segment (412c) is wound around the second end (441b), such that the winding is in contact with the winding contact surface. A fourth water-cooling unit (442) has first and second ends (442a, 442b), wherein the first end (442a) is designed to be straight and abuts against the third winding section (412c). The second end (442b) of the fourth water-cooling unit (442) is designed to be rounded or curved, and is a winding contact surface. A fourth winding segment (412d) is wound around the second end (442b) such that the winding is in contact with the winding contact surface.

6. A wind energy facility power cabinet, wherein the wind energy facility power cabinet has A power grid choke with three choke coils (410) and a yoke (430), wherein the yoke (430) has a lower yoke part (431) and an upper yoke part (432). The power grid choke (400) is located in the first position. Each choke coil (410) has first and second end sides (410a, 410b) and core laminations (411) therebetween. Each choke coil (410) has a first water-cooling unit (440, 441-444), the first water-cooling unit having its first end abutting against the end (411b) of the core lamination (411), wherein the second end of the water-cooling unit (440) serves as a winding contact surface and is designed to be rounded or bent. Each choke coil (410) has at least one additional water-cooling unit, which has a straight first end and a curved or rounded second end that serves as a winding contact surface, wherein the water-cooling unit is disposed between two winding segments. The machine-side choke (500) has... Three choke coils, Each of the choke coils has first and second ends (501, 502) and a core lamination (530) therebetween. Each of the choke coils has a first air guide channel, the first air guide channel having its first end abutting against the first end side (531) of the core lamination (530). The second end of the first air guiding channel rests against the connecting rail. The second end of the second air guide channel is surrounded by the winding section. The choke (500) on the machine side is disposed in a second position, which is above the first position.

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