Patent ID: 12211635

DESCRIPTION

FIG.1shows a transformer1, comprising an arrangement to cool a coil2according to the state of the art. The arrangement comprises an enclosure3, which at least partially incorporates or houses the coil2or several coils2. The arrangement further comprises a device4to create an airflow5to cool the coil2. The coil2comprises at least one cooling channel6to guide the airflow5through the windings7of the coil2and an outer air duct8lying radially inside below an outer part8aof the coil.

To cool the windings7of the coil2of the transformer1, air is guided through the windings7. Therefore an overpressure is generated by the device4or fan at an air inlet area of the enclosure3of the transformer1.

By this means an air flow5is 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 channels6in the windings7.

This is generally achieved by using an air guidance plate9, which is arranged in close proximity to the coil2. By this means a flow resistance through the cooling channels6becomes smaller than a flow resistance around the coil2. This principle of the state of the art is schematically shown inFIG.1.

This principle involves some drawbacks. In order to ensure an airflow through the cooling channels6, which is sufficient, an overpressure has to be generated to overcome the resistance in the enclosure3. This requires a large effort of operation and a device4having a high power. Such a device4or 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 duct8. This reduces the efficiency of cooling.

To take measures, a sealing10is placed onto a coil surface, on which the air guidance plate9is placed, so that there is no leak of airflow around the coil surface.FIG.1further shows, that the outer part8acomprises a conductor11and that the coil2comprises barriers13having insulations12.

FIGS.2and3each show a transformer1′,1″, comprising an arrangement to cool a coil2according to the invention.

To cool the windings7of the coil2of the transformer1, air is guided through the windings7. Therefore an overpressure is generated by the device4′ or fan at an air inlet area of the enclosure3of the transformer1. By this means an air flow5is 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 channels6in the windings7.

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 inFIGS.2and3also 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.

The arrangement therefore comprises an enclosure3, which at least partially incorporates or houses at least one coil2, preferably several coils2. The arrangement further comprises a device4′ to create an airflow5to cool the coil2. The coil2comprises at least one cooling channel6to guide the airflow5through the windings7of the coil2and at least one outer air duct8lying radially inside below an outer part8aof the coil. The outer part8amay be an outer layer of the coil. The outer part8aof the coil encircles or surrounds the windings7.

At least one air guidance plate9is placed at or near one longitudinal end of the outer air duct8and of the coil2to prevent bypasses of the airflow5and to block at least partially the airflow5through and along the outer air duct8. The air guidance plate9is fixed at one end or at one rim on the enclosure3and extends with the other end or another rim to the coil2, namely to the longitudinal end of the outer air duct8.

The air guidance plate9is placed onto the lower part of the high-voltage side of the coil2. There is a longitudinally oriented air gap14abetween the air guidance plate9and the high-voltage side of the coil2. There is also a radially oriented air gap14bbetween the rim of the air guidance plate9and the high-voltage side of the coil2.

FIG.2especially shows that a part of the insulation15of the coil2, which is shown completely and not shortened inFIG.3, is shortened to place the air guidance plate9.

A radially inner part15aof the insulation15is longer than a radially outer part15bof the insulation15, wherein the radially outer part15bis longitudinally shortened with respect to the radially inner part15a. These parts15a,15bor layers are shown inFIG.4in detail.

FIG.3especially shows, that a barrier overhang12of the coil2is shortened to place the air guidance plate9, wherein the insulation15is not shortened.

The radially inner part15aof the insulation15which can be seen inFIG.4is as long as the not shortened radially outer part15bof the insulation15, but an radially outer barrier overhang12lying between the radially outer part15band the radially inner part15ais shortened relative to at least an radially inner barrier overhang12, which lies radially inside of the insulation15.

The barrier overhangs12are also electrical insulations and usually are made of polymers. There are inFIG.3three barrier overhangs12lying radially inside with respect to the inner part15aof the insulation15and two barrier overhangs12lying radially outside with respect to the inner part15aof the insulation15.

The two radially outer barrier overhangs12are shortened with respect to the three radially inner barrier overhangs12, so that the air guidance plate9can be arranged very narrow or close to the longitudinal end of the coil2or of the outer air duct8and can block the outer air duct8.

The outer air duct8lies between the radially inner part15aand the radially outer part15bof the insulation15. The radially outer barrier overhangs12are shortened with respect to the radially inner barrier overhangs12on the cold side of the coil2, which means the lower voltage side of the transformer1″.

FIGS.2and3each show a transformer1′,1″, comprising an arrangement according to the invention. The transformer1′,1″ is a dry-type transformer. The Transformer1′,1″ is part of a train or is used in a rolling stock application.

FIG.4as well shows a transformer1′″, comprising an arrangement according to the invention. The transformer1′″ is a dry-type transformer. The Transformer1′″ is part of a train or is used in a rolling stock application.

FIG.4again shows, that the air guidance plate9is placed at or near to the longitudinal end of the outer air duct8and of the coil2blocking at least partially the airflow5through the outer air duct8, wherein at this longitudinal end a radially outer part15bof the insulation15is shorter than the radially inner part15aof the insulation15. As well, at this longitudinal end a radially outer barrier overhang12is shorter than a radially inner barrier overhang12.

The radially outer part15bof the insulation15is shortened relative to the radially inner part15aof the insulation15, wherein the insulation15surrounds the cooling channels6and wherein the air guidance plate9is arranged longitudinally inside with respect to the longitudinal end of the radially inner part15a.

At least one first barrier overhang12, which lies radially outside with respect to the cooling channels6is shortened relative to a further barrier overhang12, which lies radially inside with respect to the first barrier overhang12.

The outer air duct8has a width of slit in the range between 30 to 40 mm and a cooling channel6lying between two windings7,7a,7bhas a width of slit in the range between 7 to 10 mm.

Between the air guidance plate9and the longitudinal end of the outer air duct8there is a longitudinally oriented air gap14ahaving a width in the range between 10 to 30 mm. The air guidance plate9abuts with one end on the radially inner part15aof the insulation15without any radially oriented air gap.

FIG.4in principle shows the arrangement ofFIG.2, with the addition that no radially oriented air gap14bexists and wherein the air guidance plate9abuts on the radially inner part15aof the insulation15, which is longer than the radially outer part15bof the insulation15. The insulation15is made of silicone.

The radially inner part15aof the insulation15is about 40 mm to 100 mm longer than the radially outer part15bof the insulation15, wherein the radially outer part15bis longitudinally shortened with respect to the radially inner part15a. These parts15a,15bare a kind of layers of an insulation15or insulation arrangement.

The air guidance plate9also abuts on the enclosure3so that no radially oriented gap exists at all. The longitudinally oriented air gap14ahas a width in longitudinal direction of about 20 mm.

The air guidance plate9is placed on the cold side of an active part of the transformers1′,1″,1′″ shown here, wherein said active part comprises the coil2and the core16. All windings7surround this core16.

The cold side means the lower voltage side of the active part of the transformer1′,1″, l′″. The increase of voltage from right to left side is shown inFIG.4by the long arrow at the top ofFIG.4. This increase of voltage in direction of the arrow is also given with respect toFIGS.2and3.

The device4′ or ventilator shown here can be placed on any side of this active part. The device4′ or ventilator can suck and/or blow air to create the air flow5.

The heat sources of the described active part are the core16, at least an LV-part7aand HV-parts7b. LV means low voltage and HV means high voltage. LV-part7aand HV-parts7bare windings7.

The LV-part7aor HV-parts7beach may comprise several parts, which are separated by cooling channels6.

A cooling channel6may have a width in radial direction of 7 to 10 mm. The outer air duct8may have a width in radial direction of 30 to 40 mm.

It is required that most of the cooling air flows though the LV-parts7aand HV-parts7b. The outermost air duct8or air ducts between an outer part8aand those HV-parts7bis a big gap, which allows a lot of air to go through.

Therefore, this big gap reduces the cooling effect for the LV-part7aand the HV-parts7b. The invention is to block this big air gap between an outer part8aand HV-parts7b.

Reference numbers1, 1′, 1″Transformer2Coil of 1, 1′3Enclosure of 1, 1′First line voltage supply toconsumers of electricity4, 4′Device or fan5Airflow6Cooling channel of 77Windings of 27aLV-part7bHV-part8Outer air duct of 28aOuter part of 29Air guidance plate10Sealing11Conductor of 812Barrier overhang13Barrier14aAir gap, longitudinally oriented14bAir gap, radially oriented15Insulation of 815aRadially inner part of 1515bRadially outer part of 1516Core of 2