EP2346052A1 - Housing for an electric machine - Google Patents

Abstract

The housing (18) has a cooling system (20), cooling channels through which cooling fluid flows, and vertical channels (26, 28) for cooling medium e.g. gaseous medium, which flows around an electric machine (10), where the housing accommodates the electric machine and the cooling system and forms hermetic encapsulation. A part of one of the cooling channels rest on a surface of windings (19) of the electric machine. The cooling channels are formed by individual pipes and by a corrugated structure made of metal, plastic, corrugated sheet or corrugated glass.

Description

The invention relates to a housing for an electrical machine, in particular for an electrical power transformer, for example a dry-type transformer, within which cooling channels are provided, through which cooling fluid flows.

Conventionally, the cooling of designed as power transformers electrical machines in dry construction by discharging the heat generated during operation in the dry transformer directly to the environment.

In electric machines or in those with high power, which are designed as a compact designed power transformers, it may be necessary to consider in addition to the cooling by convection addition cooling measures.

Thus, in current housing concepts special cooling channels for the cooling of a compact designed power transformer are provided, the cooling predominantly by means of free convection, that is, by natural cooling takes place. At higher transformer power, however, this may no longer be sufficient, so that the design of the housing is adapted or provide an additional separate cooling system with forced cooling.

Similarly, according to recent concepts for trained as a dry-type transformers power transformers is also to surround the dry-type transformer with a housing which allows improved cooling of the transformer by targeted flow around its windings with cooling fluid, for example, with air-air coolers or air Water cooler is cooled.

From the DE 19812243 is an enclosure for a dry transformer whose elements and their arrangement, characterized in that the enclosure can be flowed through all around by ambient air, which cools and humidifies when flowing through a constantly or load-dependent moistened with water outer wettable shell and the cooled humidified air is guided so that it constantly cools the illuminated by the high-voltage windings solid surfaces and enters from below into the cooling channels of the individual transformer legs and sucked out at the exit from the cooling channels and carried away.

This known cooling principle is based on the fact that the main components of air, nitrogen and oxygen, very poor heat transfer and heat radiation are practically permeable. In contrast, a number of gases, especially carbon dioxide and water vapor, absorb radiant heat and emit it.

Also, a high proportion of water vapor in the unsaturated state in the cooling air of a transformer would thus improve the heat capacity of the same. It is also known that water has a very high heat of vaporization. It is at normal pressure about 627 Wh / kg, so that the use of water in principle promises a good heat absorption, by providing the cooling of the transformer enriches certain air with water and this evaporates due to the heat absorbed by the transformer and thus deprives her of heat.

The disadvantage here is that for the regular addition of water to the air, a preferably closed cooling system is required, so as to limit the consumption of water.

On the other hand, when developing transformer boxes with forced cooling, the respective cooling system must be redesigned and installed for each transformer. In this case, the possibility of natural cooling is lost by convection, that is, such transformers can then be cooled only forced.

Up to a certain housing size, natural cooling inside and outside the housing under constant ambient conditions is sufficient to dissipate a certain power dissipation. However, in order to be able to dissipate an excessive power dissipation beyond the same housing or to ensure compensation for an increased ambient temperature, further measures for cooling are required.

Based on this prior art, it is an object of the invention to provide a housing for an electrical machine, which allows both a natural and a forced, that is forced, cooling of the transformer, depending on the transformer power loss.

This object is achieved by the characterizing features of claim 1. Accordingly, a housing is provided, in which the electric machine is arranged completely and the cooling system and having vertically arranged channels for a cooling medium, which flows around the electric machine, wherein both the electrical machine as well as the cooling system receiving housing at least partially forms a hermetic encapsulation.

One possibility here is to integrate one or more housing modules in the side walls, which include fans for the internal circulation improvement, another possibility is the attachment of a module, which includes external fans and improves the external circulation. Both measures can be considered both individually and in combination.

According to a preferred embodiment of the invention, it is provided that the channels for the cooling fluid in each case bear against the surface of the windings of the electric machine. Here, the arrangement of the cooling channels is provided so that on the one hand the required electrical insulation thickness is not exceeded and on the other hand a sufficient surface contact is ensured for the best possible heat transfer.

According to an advantageous embodiment of the invention, it is provided that the cooling fluid is gaseous. According to a particular embodiment of the invention, however, it can be provided that a liquid cooling medium is used.

According to a further preferred embodiment of the invention, the cooling channels for guiding the cooling fluid of individual tubes are formed, which are each arranged around the respective winding of the transformer.

Instead of cooling tubes, the cooling channels can also be formed by a wave-shaped or box-shaped structure, which preferably consists of metal, but optionally also of plastic, for example of corrugated metal or corrugated glass, which is arranged around the respective winding of the transformer.

In addition, that is, for improved dissipation of operationally caused in the coil wind heat, cooling channels can also be arranged in the coil windings through which the heat generated in the interior of the coil winding is conducted to the outside and there by the cooling medium flowing through the cooling channels arranged in the housing is picked up and taken away.

A further preferred embodiment of the invention provides that the cooling fluid circulates under the influence of natural convection and flows around the electric machine.

In an advantageous improvement of the invention may further be provided that at least one conveying device is provided for the cooling fluid, which for the Forcibly circulation of the cooling fluid to the flow around the electric machine and recording their heat provides.

According to a preferred embodiment of the invention, at least one fan is provided as a conveying device for the cooling fluid, wherein advantageously the at least one fan is arranged on the upper side of the housing receiving the electric machine with the cooling system. This has the advantage that a fan arranged here can derive controlled from the heat originating from the transformer, which rises and collects here.

If necessary, the cooling system according to the invention can be improved by at least one fan is arranged laterally on the receiving the electrical machine with the cooling system housing.

Finally, it can also be provided that at least one fan is arranged on the underside of the electrical machine with the cooling system housing receiving.

In an advantageous embodiment of the invention, the cooling system according to the invention, be characterized in that it has at least one structure which is similar to a plate heat exchanger and provides sufficient internal circulation and an external circulation of the cooling fluid.

By the vertically mounted cooling tubes or by means of the corrugated structure, a heat transfer geometry is created, which is similar, for example, the geometry of a plate heat exchanger. Both internal (outside of the cooling channels) and external circulation (inside the cooling channels) around the housing are achieved. This circulation of air can be forced or natural flow.

It is particularly advantageous that is made possible by the arrangement of the electric machine, the at least one conveyor for the cooling fluid and the at least one plate heat exchanger similar structure in the surrounding common housing a modular design.

In principle, the invention can also be regarded as an inner and an outer cooling circuit, wherein the inner cooling circuit comprises the region around the coil windings, which is preferably shielded from the outer region laterally by a flow barrier. Within this area bounded by the flow barriers, the cooling medium is selectively conveyed upwards or downwards, where it comes into direct contact with the cooling medium of the outer area and transfers the heat to it.

The outer region of the cooling circuit comprises the region bounded in each case by the outer wall of the housing and the flow barriers and the heat exchanger provided according to the invention in the roof region or laterally and optionally in the bottom region.

In particular, it proves to be advantageous for the cooling system that the arrangement formed by the electric machine, the at least one conveying device for the cooling fluid and the at least one plate heat exchanger can be modularly expanded in the surrounding housing. For this purpose, the individual components are designed as modules whose dimensions are coordinated so that a simple change can be done easily and without much effort.

For the purpose of forced cooling fans are provided, which, as already mentioned, can be mounted below, laterally or in the upper region of the housing. The fans can be designed as axial fans and thereby be modularly mounted on the roof, with a corresponding roof construction or serving for attachment scaffolding is optionally provided.

The cooling of hot areas, for example the roof, is thereby improved, since the roof ventilators continue to suck in cooling air from the surroundings at the transformer housing bottom at the so-called "coking medium inlet". The exit of the cooling air takes place advantageously above. Furthermore, further fans, for example centrifugal fans, may be mounted laterally on the housing. These then ensure that the heated air is sucked in at the coil top edge and is returned between the cooling tubes or the corrugated structure and a vertical air guide plate. In this case, the lateral fans are preferably also mounted in a scaffold to ensure the modularity of the concept.

These and other advantageous embodiments and improvements of the invention are the subject of the dependent claims.

Reference to an embodiment of the invention shown in the accompanying drawings, the invention, advantageous embodiments and improvements of the invention and particular advantages of the invention will be explained and described in detail.

Fig. 1

eine schematische Darstellung eines dreiphasigen Leistungstransformators in einer stirnseitigen Schnittansicht;

Fig. 2

eine Seitenansicht des Transformators gemäß Fig. 1,

Fig. 3

eine Draufsicht auf einen Transformator gemäß Fig. 1 und

Fig. 4

eine ausschnittweise Vergrößerung der Einzelheit "X" in Fig. 3

Show it:

Fig. 1

a schematic representation of a three-phase power transformer in a front sectional view;

Fig. 2

a side view of the transformer according to Fig. 1 .

Fig. 3

a plan view of a transformer according to Fig. 1 and

Fig. 4

a partial enlargement of the detail "X" in Fig. 3

In Fig. 1 is a schematic representation of a three-phase power transformer 10 according to the invention in a sectional view of the front side of the transformer 12 with upper yoke 14 and lower yoke 16 and the surrounding housing 18 reproduced, the cross-section through the transformer 12 receiving housing 18 immediately behind the frontal housing wall is done.

Furthermore, the cooling device 20 according to the invention for the transformer 12 can be seen from this sectional view. The cooling device 20 has two recognizable in this representation, laterally arranged respectively on the side walls 22 of the housing 20 conveying means for the cooling medium and both sides of the windings 19 arranged cooling channels 24, 26, 28, which are each shielded by a flow guide 30 against each other, each of which covers the entire height of the winding 19 and up or down a gap 34 releases, through which circulates the cooling medium.

As the cooling medium, air is provided in the example shown here, which flows around in the housing 18, the heat-emitting transformer 12 and thereby absorbs its heat and promotes heat sink.

The mentioned, each arranged on the side walls 22 of the housing 18 conveying means for the cooling medium are part of the cooling device 20 and preferably designed as a radial fan, which promote the cooling medium in the first between the outer wall 22 of the housing 18 and a flow guide 30 arranged cooling channels 24 down. There, the cooling stream mixed with cooling medium, which flows through near-bottom openings 32, and flows through second, also between the outer wall 22 and the flow baffle 30 disposed flow channels 26 back up.

As in particular from in Fig. 4 shown detail enlargement of the detail "X" can be seen, the first and second cooling channels 24 and 26 are arranged alternately side by side, so that along the longitudinal side of the relevant electric machine 10, a uniform temperature profile as a heat sink for the cooling of the electric machine 10 results.

In addition, cooling medium passes through a gap 34 in a space laterally adjacent to the lower yoke 16 at the bottom of the housing 18. From there, the cooling flow is reflected upward and flows in a separated by the flow baffle 30 from the cooling channels 24, 26 further cooling channel 28 again above.

This upward flow of the cooling medium is assisted by at least one further cooling fan 20, not shown here, arranged in the so-called roof part 36 of the housing 18, which delivers the now heated cooling medium to the outside (arrows).

Fig. 2 shows a side view of the in Fig. 1 illustrated transformer 10 which is arranged in a housing 18 together with the cooling device 20. The cooling device includes except in Fig. 1 illustrated conveying means 24 and inlet openings 32 for the cooling medium and first and second cooling channels 26, 28 and arranged in the roof area 36 of the transformer 10 according to the invention further conveying means 38 for cooling medium, which is indicated here in the side view and plate heat exchangers 40, which ensure optimum cooling by dissipating the waste heat.

At both ends of the housing 18 each junction boxes 42 are arranged for the electrical connection of the transformer 10.

In Fig. 3 Finally, in a sectional view, a plan view of the transformer 10 is shown, which shows the transformer 12 and the surrounding housing 18 with the cooling channels 24, 26, 28 arranged therein. For this purpose, the roof area 36 of the transformer 10 is removed.

The first and second cooling channels 24, 26, which are arranged side by side on both sides of the three windings 19 of the transformer 12 parallel to the axis of their longitudinal axis, consist of individually shaped channels with a rectangular cross-section. They are made of a correspondingly profiled flat material, preferably light metal because of the low thermal conductivity or plastic profile, box-shaped, on both sides of the windings immediately adjacent to each of the already mentioned Strömungsleitprofil 30 is provided, which the first and second cooling channels 24, 26 of the other Cooling channels 28 separates.

From the in Fig. 4 shown detail enlargement of the detail "X" can be seen that the first and second cooling channels 24 and 26 are arranged alternately side by side, so that along the longitudinal side of the electric machine 10 a uniform temperature profile as a heat sink for the cooling of the electric machine 10 results.

These first and second cooling channels 26, 27 may preferably be formed by a correspondingly shaped box profile, which is used uniformly in the bounded by the outer wall 22 and the cooling baffle 30 space.

In general, the present cooling concept according to the invention can be regarded as a two-circuit system with an internal circuit in which, for example, an air flow through radial fan 38 is supported. In this case, cooling medium flows between the aforementioned, for example by the wave or box profile formed cooling channels, and between the housing wall and Strömungsluftleitplatte. The heat is transferred to the outer "cycle".

The outer cooling circuit is based on the fact that a vertical flow of the cooling medium supported by roof ventilator, for example axial fan 40, is generated by sucking cool air in the bottom area and from there flowing upwards in the provided cooling channels. Here, the cool air absorbs the heat from the inner cooling circuit and releases it to the outside.

Preferably, the coils of the transformer for use in the housing according to the invention are provided with internal cooling channels so as to better dissipate the power losses.

LIST OF REFERENCE NUMBERS

10

Transformer)

12

transformer

14

upper yoke

16

lower yoke

18

casing

19

winding

20

Cooling device, cooling system

22

outer wall

24

first cooling channel

26

second cooling channel

28

another cooling channel

30

flow guide

32

lower housing opening (for example for air supply)

34

Gap range, for e.g. Ausblaß the already cooled inner air

36

roof

38

Conveyor, e.g. Radialge-blower

40

Plate heat exchanger (with conveyor, eg axial fan)

42

Connection box 10

Claims (15)

Housing for an electrical machine (10), in particular for an electric power transformer (12), for example a dry-type transformer, wherein cooling channels (24, 26, 28) are provided inside the housing (18), through which cooling fluid flows,
characterized in that
in the housing (18) both the electric machine (10) and a cooling system (20) are arranged, wherein vertically arranged first and second channels (26, 28) are provided for the cooling medium, which flows around the electric machine (12), wherein the electrical machine (10) and the cooling system (20) receiving the housing (18) at least partially forms a hermetic encapsulation. Housing for an electric machine according to claim 1, characterized in that at least a part of the channels (28) for the cooling fluid in each case bears against the surface of the windings (19) of the electric machine (12). Housing for an electric machine according to claim 1 or 2, characterized in that the cooling fluid is gaseous. Housing for an electrical machine according to one of the preceding claims, characterized in that the cooling channels (24, 26) are formed by individual tubes. Housing for an electrical machine according to one of claims 1 to 3, characterized in that the cooling channels (24, 26) are formed by a wave-shaped structure made of metal or plastic, for example corrugated sheet or corrugated glass. Housing for an electrical machine according to one of the preceding claims, characterized in that the cooling fluid circulates under the influence of natural convection and the electric machine (12) flows around. Housing for an electrical machine according to one of claims 1 to 5, characterized in that at least one conveying device for the cooling fluid is provided, which causes the forced circulation of the cooling fluid to flow around the electric machine (12) and receiving their heat. Housing for an electric machine according to claim 7, characterized in that at least one fan (38) is provided as a conveying device for the cooling fluid. Housing for an electric machine according to claim 7 or 8, characterized in that the at least one conveying device for the cooling medium is provided as a fan (38) in the roof area (36) of the electric machine (12) with the cooling system (20) receiving Housing (18) is arranged. Housing for an electrical machine according to one of claims 7 or 8, characterized in that at least one fan is arranged laterally on which the electrical machine (12) with the cooling system (20) receiving the housing (18). Housing for an electrical machine according to one of the preceding claims 7 to 10, characterized in that at least one fan on the underside of the electric machine (12) with the cooling system (20) receiving the housing (18) is arranged. Housing for an electric machine according to one of the preceding claims, characterized in that at least one plate heat exchanger is provided, which has an inner circulation and an outer circulation of the cooling fluid. Housing for an electric machine according to claim 12, characterized in that at least one plate heat exchanger above the windings (19) of the electric machine (12) is arranged. Housing for an electrical machine according to one of the preceding claims,
characterized in that the electrical machine (12), the at least one conveyor for the cooling fluid and the at least one plate heat exchanger receiving housing (18) is modular and allows a modular design. Cooling system according to claim 14, characterized in that the by the electric machine (12), the at least one conveyor for the cooling fluid and the at least one plate heat exchanger formed arrangement receiving housing (18) is modularly expandable.

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