ARRANGEMENT TO COOL A COIL

Abstract

An arrangement to cool a coil, comprising an enclosure, which at least partially incorporates or houses the coil, and a device to create an airflow to cool the coil, wherein the coil comprises at least one cooling channel to guide the airflow through the windings of the coil and an outer air duct lying radially in the outer circumference area of the coil or lying radially inside below an outer part of the coil, characterized in that an air guidance plate is placed at or near one longitudinal end of the outer air duct and/or of the coil to prevent bypasses of the airflow and/or to block at least partially the airflow through and/or along the outer air duct, achieves the object to cool a coil, especially a coil of a transformer, in an efficient manner using space-saving means.

Claims

1. Arrangement to cool a coil, comprising an enclosure, which at least partially incorporates or houses the coil, and a device to create an airflow to cool the coil, wherein the coil comprises at least one cooling channel to guide the airflow through the windings of the coil and an outer air duct lying radially in the outer circumference area of the coil or lying radially inside below an outer part of the coil, characterized in that an air guidance plate is placed at or near one longitudinal end of the outer air duct and/or of the coil to prevent bypasses of the airflow and/or to block at least partially the airflow through and/or along the outer air duct.

2. Arrangement according to claim 1, characterized in that the air guidance plate is placed at or near to the longitudinal end of the outer air duct and/or of the coil blocking at least partially the airflow through the outer air duct, wherein at this longitudinal end a radially outer part of an insulation is shorter than a radially inner part of the insulation and/or wherein at this longitudinal end a radially outer barrier overhang is shorter than a radially inner barrier overhang.

3. Arrangement according to claim 2, characterized in that the radially outer part of the insulation is shortened relative to the radially inner part of the insulation, wherein the insulation surrounds the at least one cooling channel and wherein the air guidance plate is arranged longitudinally inside with respect to the longitudinal end of the radially inner part.

4. Arrangement according to claim 2, characterized in that at least one first barrier overhang which lies radially outside with respect to the at least one cooling channel is shortened relative to a further barrier overhang which lies radially inside with respect to the first barrier overhang.

5. Arrangement according to claim 1, characterized in that the outer air duct has a width of slit in the range between 30 to 40 mm and wherein a cooling channel lying between two windings has a width of slit in the range between 7 to 10 mm.

6. Arrangement according to claim 1, characterized in that between the air guidance plate and the one longitudinal end of the outer air duct there is a longitudinally oriented air gap having a width in the range between 10 to 30 mm.

7. Arrangement according to claim 2, characterized in that the air guidance plate abuts with one end on the radially inner part of the insulation.

8. Arrangement according to claim 1, characterized in that the air guidance plate is fixed at one end or at one rim on the enclosure and extends with the other end or another rim to the coil.

9. Arrangement according to claim 1, characterized in that the air guidance plate is placed onto the lower part of the high-voltage side of the coil.

10. Arrangement according to claim 1, characterized in that there is at least one air gap between the air guidance plate and the high-voltage side of the coil.

11. Arrangement according to claim 1, characterized in that even a part of the insulation of the lower part of the coil is shortened to place the air guidance plate.

12. Arrangement according to claim 1, characterized in that a barrier overhang of the lower part of the coil is shortened to place the air guidance plate.

13. Transformer, comprising an arrangement according to claim 1.

14. Transformer according to claim 13, which is a dry-type transformer.

15. Transformer according to claim 13, which is part of a train or is used in a rolling stock application.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In the drawings:

[0023] FIG. 1 schematically shows an arrangement according to the state of the art, wherein cooling by an airflow takes place using an air guidance plate, which is placed radially between an enclosure and an outer air duct,

[0024] FIG. 2 schematically shows an arrangement, wherein cooling by an airflow takes place using an air guidance plate between an enclosure and a coil, wherein a part of the insulation has been shortened longitudinally,

[0025] FIG. 3 schematically shows an arrangement, wherein cooling by an airflow takes place using an air guidance plate between an enclosure and a coil, where a large part of the insulation has been shortened longitudinally, and

[0026] FIG. 4 schematically shows a further arrangement, wherein cooling by an airflow takes place using an air guidance plate between an enclosure and a coil, wherein a part of the insulation has been shortened longitudinally with respect to a remaining longer part of the insulation and wherein no radially oriented air gap between the air guidance plate and the longer part of the insulation exists.

DESCRIPTION

[0027] FIG. 1 shows a transformer 1, comprising an arrangement to cool a coil 2 according to the state of the art. The arrangement comprises an enclosure 3, which at least partially incorporates or houses the coil 2 or several coils 2. The arrangement further comprises a device 4 to create an airflow 5 to cool the coil 2. The coil 2 comprises at least one cooling channel 6 to guide the airflow 5 through the windings 7 of the coil 2 and an outer air duct 8 lying radially inside below an outer part 8a of the coil.

[0028] To cool the windings 7 of the coil 2 of the transformer 1, air is guided through the windings 7. Therefore an overpressure is generated by the device 4 or fan at an air inlet area of the enclosure 3 of the transformer 1.

[0029] By this means an air flow 5 is generated to flow from the inlet towards an outlet and then through a grid into the environment. It is preferred that a large amount of air flows through the cooling channels 6 in the windings 7.

[0030] This is generally achieved by using an air guidance plate 9, which is arranged in close proximity to the coil 2. By this means a flow resistance through the cooling channels 6 becomes smaller than a flow resistance around the coil 2. This principle of the state of the art is schematically shown in FIG. 1.

[0031] This principle involves some drawbacks. In order to ensure an airflow through the cooling channels 6, which is sufficient, an overpressure has to be generated to overcome the resistance in the enclosure 3. This requires a large effort of operation and a device 4 having a high power. Such a device 4 or ventilator implicates a large dimension and therefore lots of space is required for its installation. Further lots of air gets lost while flowing through the outer air duct 8. This reduces the efficiency of cooling.

[0032] To take measures, a sealing 10 is placed onto a coil surface, on which the air guidance plate 9 is placed, so that there is no leak of airflow around the coil surface. FIG. 1 further shows, that the outer part 8a comprises a conductor 11 and that the coil 2 comprises barriers 13 having insulations 12.

[0033] FIGS. 2 and 3 each show a transformer 1′, 1″, comprising an arrangement to cool a coil 2 according to the invention.

[0034] To cool the windings 7 of the coil 2 of the transformer 1, air is guided through the windings 7. Therefore an overpressure is generated by the device 4′ or fan at an air inlet area of the enclosure 3 of the transformer 1. By this means an air flow 5 is generated to flow from the inlet towards an outlet and then optionally through a grid into the environment. It is preferred that a large amount of air flows through the cooling channels 6 in the windings 7.

[0035] An underpressure at an outlet, which may be generated by a fan or an air compressor at the outlet, could also work. This means that the inlet shown in FIGS. 2 and 3 also may be an outlet, which is shown by the arrow in dashed lines. Air can flow from one side to the other side of the coil. This can be reached by an overpressure or an underpressure.

[0036] The arrangement therefore comprises an enclosure 3, which at least partially incorporates or houses at least one coil 2, preferably several coils 2. The arrangement further comprises a device 4′ to create an airflow 5 to cool the coil 2. The coil 2 comprises at least one cooling channel 6 to guide the airflow 5 through the windings 7 of the coil 2 and at least one outer air duct 8 lying radially inside below an outer part 8a of the coil. The outer part 8a may be an outer layer of the coil. The outer part 8a of the coil encircles or surrounds the windings 7.

[0037] At least one air guidance plate 9 is placed at or near one longitudinal end of the outer air duct 8 and of the coil 2 to prevent bypasses of the airflow 5 and to block at least partially the airflow 5 through and along the outer air duct 8. The air guidance plate 9 is fixed at one end or at one rim on the enclosure 3 and extends with the other end or another rim to the coil 2, namely to the longitudinal end of the outer air duct 8.

[0038] The air guidance plate 9 is placed onto the lower part of the high-voltage side of the coil 2. There is a longitudinally oriented air gap 14a between the air guidance plate 9 and the high-voltage side of the coil 2. There is also a radially oriented air gap 14b between the rim of the air guidance plate 9 and the high-voltage side of the coil 2.

[0039] FIG. 2 especially shows that a part of the insulation 15 of the coil 2, which is shown completely and not shortened in FIG. 3, is shortened to place the air guidance plate 9.

[0040] A radially inner part 15a of the insulation 15 is longer than a radially outer part 15b of the insulation 15, wherein the radially outer part 15b is longitudinally shortened with respect to the radially inner part 15a. These parts 15a, 15b or layers are shown in FIG. 4 in detail.

[0041] FIG. 3 especially shows, that a barrier overhang 12 of the coil 2 is shortened to place the air guidance plate 9, wherein the insulation 15 is not shortened.

[0042] The radially inner part 15a of the insulation 15 which can be seen in FIG. 4 is as long as the not shortened radially outer part 15b of the insulation 15, but an radially outer barrier overhang 12 lying between the radially outer part 15b and the radially inner part 15a is shortened relative to at least an radially inner barrier overhang 12, which lies radially inside of the insulation 15.

[0043] The barrier overhangs 12 are also electrical insulations and usually are made of polymers. There are in FIG. 3 three barrier overhangs 12 lying radially inside with respect to the inner part 15a of the insulation 15 and two barrier overhangs 12 lying radially outside with respect to the inner part 15a of the insulation 15.

[0044] The two radially outer barrier overhangs 12 are shortened with respect to the three radially inner barrier overhangs 12, so that the air guidance plate 9 can be arranged very narrow or close to the longitudinal end of the coil 2 or of the outer air duct 8 and can block the outer air duct 8.

[0045] The outer air duct 8 lies between the radially inner part 15a and the radially outer part 15b of the insulation 15. The radially outer barrier overhangs 12 are shortened with respect to the radially inner barrier overhangs 12 on the cold side of the coil 2, which means the lower voltage side of the transformer 1″.

[0046] FIGS. 2 and 3 each show a transformer 1′, 1″, comprising an arrangement according to the invention. The transformer 1′, 1″ is a dry-type transformer. The Transformer 1′, 1″ is part of a train or is used in a rolling stock application.

[0047] FIG. 4 as well shows a transformer 1′″, comprising an arrangement according to the invention. The transformer 1′″ is a dry-type transformer. The Transformer 1′″ is part of a train or is used in a rolling stock application.

[0048] FIG. 4 again shows, that the air guidance plate 9 is placed at or near to the longitudinal end of the outer air duct 8 and of the coil 2 blocking at least partially the airflow 5 through the outer air duct 8, wherein at this longitudinal end a radially outer part 15b of the insulation 15 is shorter than the radially inner part 15a of the insulation 15. As well, at this longitudinal end a radially outer barrier overhang 12 is shorter than a radially inner barrier overhang 12.

[0049] The radially outer part 15b of the insulation 15 is shortened relative to the radially inner part 15a of the insulation 15, wherein the insulation 15 surrounds the cooling channels 6 and wherein the air guidance plate 9 is arranged longitudinally inside with respect to the longitudinal end of the radially inner part 15a.

[0050] At least one first barrier overhang 12, which lies radially outside with respect to the cooling channels 6 is shortened relative to a further barrier overhang 12, which lies radially inside with respect to the first barrier overhang 12.

[0051] The outer air duct 8 has a width of slit in the range between 30 to 40 mm and a cooling channel 6 lying between two windings 7, 7a, 7b has a width of slit in the range between 7 to 10 mm.

[0052] Between the air guidance plate 9 and the longitudinal end of the outer air duct 8 there is a longitudinally oriented air gap 14a having a width in the range between 10 to 30 mm. The air guidance plate 9 abuts with one end on the radially inner part 15a of the insulation 15 without any radially oriented air gap.

[0053] FIG. 4 in principle shows the arrangement of FIG. 2, with the addition that no radially oriented air gap 14b exists and wherein the air guidance plate 9 abuts on the radially inner part 15a of the insulation 15, which is longer than the radially outer part 15b of the insulation 15. The insulation 15 is made of silicone.

[0054] The radially inner part 15a of the insulation 15 is about 40 mm to 100 mm longer than the radially outer part 15b of the insulation 15, wherein the radially outer part 15b is longitudinally shortened with respect to the radially inner part 15a. These parts 15a, 15b are a kind of layers of an insulation 15 or insulation arrangement.

[0055] The air guidance plate 9 also abuts on the enclosure 3 so that no radially oriented gap exists at all. The longitudinally oriented air gap 14a has a width in longitudinal direction of about 20 mm.

[0056] The air guidance plate 9 is placed on the cold side of an active part of the transformers 1′, 1″, 1′″ shown here, wherein said active part comprises the coil 2 and the core 16. All windings 7 surround this core 16.

[0057] The cold side means the lower voltage side of the active part of the transformer 1′, 1″, l′″. The increase of voltage from right to left side is shown in FIG. 4 by the long arrow at the top of FIG. 4. This increase of voltage in direction of the arrow is also given with respect to FIGS. 2 and 3.

[0058] The device 4′ or ventilator shown here can be placed on any side of this active part. The device 4′ or ventilator can suck and/or blow air to create the air flow 5.

[0059] The heat sources of the described active part are the core 16, at least an LV-part 7a and HV-parts 7b. LV means low voltage and HV means high voltage. LV-part 7a and HV-parts 7b are windings 7.

[0060] The LV-part 7a or HV-parts 7b each may comprise several parts, which are separated by cooling channels 6.

[0061] A cooling channel 6 may have a width in radial direction of 7 to 10 mm. The outer air duct 8 may have a width in radial direction of 30 to 40 mm.

[0062] It is required that most of the cooling air flows though the LV-parts 7a and HV-parts 7b. The outermost air duct 8 or air ducts between an outer part 8a and those HV-parts 7b is a big gap, which allows a lot of air to go through.

[0063] Therefore, this big gap reduces the cooling effect for the LV-part 7a and the HV-parts 7b. The invention is to block this big air gap between an outer part 8a and HV-parts 7b.

TABLE-US-00001 Reference numbers 1, 1′, 1″ Transformer 2 Coil of 1, 1′ 3 Enclosure of 1, 1′First line voltage supply to consumers of electricity 4, 4′ Device or fan 5 Airflow 6 Cooling channel of 7 7 Windings of 2  7a LV-part  7b HV-part 8 Outer air duct of 2  8a Outer part of 2 9 Air guidance plate 10  Sealing 11  Conductor of 8 12  Barrier overhang 13  Barrier 14a Air gap, longitudinally oriented 14b Air gap, radially oriented 15  Insulation of 8 15a Radially inner part of 15 15b Radially outer part of 15 16  Core of 2