EP3580770B1 - Air-cooled dry-type transformer - Google Patents

Description

technical field

The present disclosure relates to methods and devices for cooling dry-type transformers using ring fans, in particular dry-type transformers in non-ventilated housings with forced air cooling inside the housing.

Background of the Invention

Various techniques have been proposed to improve the cooling of dry-type transformers. This includes cooling air channels within the core to improve heat dissipation. In general, an overpressure is generated in the lower part of the housing with a blower, while a negative pressure can be generated in the upper part of the housing by extracting the air. This creates an air flow that flows from the bottom to the top. However, a large amount of air does not flow through the cooling channels of the windings as desired, but rather around the outside of the coils. One of the reasons for this is that the cross-sectional area of the cooling channels within the windings is usually much smaller than the cross-sectional area between the housing wall and the coils.

This can generally be avoided by the following methods: First, the fan can be set up under the coils to blow the air into the cooling ducts. In addition, air baffles can be placed in close proximity to the coils, thereby making the flow resistance of the cooling channels smaller than the flow resistance of the area outside the coils. In this case, blowing the air into the coils requires a relatively powerful fan, with much of the air still flowing around the coils. In addition, so that they are sufficiently effective, the air baffles must be individually adapted to the contours of the coils, which involves a considerable amount of work. Because the air guide plates also generate significant additional resistance, the ventilation system works with a lower overall efficiency. Overall, it is also true that with improved cooling with conventional fans, there is a lot of noise, especially from the rotating blades.

The JP 2015228442 A shows in Fig. 2 (a) and Fig. 5 (a) a plate perforated by individual holes. Against this background, there is a need for the present invention.

Summary of the Invention

The object of the invention is achieved by an air-cooled dry-type transformer according to claim 1, and a method for cooling a dry-type transformer according to claim 7.

The cooling ducts described in this disclosure generally include all types of ducts that, according to aspects and embodiments, can be used or are suitable for conducting cooling air through a dry-type transformer. These can also be channels, for example, which are originally intended or are used for the purpose of dielectric insulation or for monitoring/controlling the field.

Preferably, the dry type transformer includes a housing; and a heat exchanger configured to remove heat from the housing; wherein the flow of cooling air generated by the at least one ring fan, after passing through the cooling duct of the dry-type transformer, hits the heat exchanger and is cooled there.

The method includes providing a ring fan and a dry-type transformer, directing a flow of cooling air from the ring fan at a mating substantially annular opening of a cooling duct of the dry-type transformer.

In a further aspect, the ring fan is proposed for cooling the dry-type transformer, with a directed, essentially ring-shaped cooling air flow of a ring fan being directed onto a matching opening of a cooling channel of the dry-type transformer.

Other features and advantages of the present invention are set out below detailed description of preferred embodiments presented.

Short description of the figures

• Fig. 1 zeigt einen Querschnitt durch einen Trockentransformator gemäß Ausführungsformen, sowie eine Oberansicht des Transformators;
• Fig. 2 zeigt einen Querschnitt durch einen Trockentransformator gemäß weiteren Ausführungsformen;
• Fig. 3 zeigt einen Ring-Ventilator gemäß Ausführungsformen;
• Fig. 4 zeigt einen Querschnitt durch einen Trockentransformator gemäß weiteren Ausführungsformen;
• Fig. 5 zeigt einen Querschnitt durch einen Trockentransformator gemäß weiteren Ausführungsformen;
• Fig. 6 zeigt einen Querschnitt durch ein Kühlsystem für einen Trockentransformator gemäß Ausführungsformen;
• Fig. 7 zeigt eine Draufsicht auf einen Trockentransformator gemäß weiteren Ausführungsformen.

Other features and advantages of the present invention will become apparent to those skilled in the art from the detailed description taken in conjunction with the attached figures. show:

• 1 12 shows a cross-section through a dry-type transformer according to embodiments, as well as a top view of the transformer;
• 2 shows a cross section through a dry type transformer according to further embodiments;
• 3 12 shows a ring fan according to embodiments;
• 4 shows a cross section through a dry type transformer according to further embodiments;
• figure 5 shows a cross section through a dry type transformer according to further embodiments;
• 6 12 shows a cross-section through a cooling system for a dry-type transformer according to embodiments;
• 7 12 shows a plan view of a dry-type transformer according to further embodiments.

Detailed description

In general, embodiments of the invention relate to dry-type transformers that are cooled with at least one electrically driven ring fan. A ring fan as used in this disclosure includes an annular housing from which an annular flow of air emanates in the axial direction of the ring. In the center of the housing is a central opening through which, in exemplary embodiments, one leg of the transformer core passes or is located. In general, in this disclosure, the term "ring fan" is to be considered as corresponding to the previous definition, thereby including the variants described below. A ring fan can have a ring-shaped housing as a stator, with a likewise ring-shaped runner in it, on which blades are attached, which are visible to the outside like in a conventional fan. In another, here In the form used, the ring fan can be a bladeless fan in exemplary embodiments. A bladeless fan blows the air out of a ring without directly involving rotating rotor blades, or they are typically encapsulated in a separate housing. The air is drawn in by an internally installed rotor in the base or on the side of the bladeless fan through holes in it, and guided into a circumferential cavity of a ring. The air is then accelerated through a slit, which is preferably provided on an inner side of the ring.

This results in an air jet that is shaped according to the geometry of the ring. To channel the direction of the air jet, the jet is blown over a slope shaped somewhat like an airfoil. At the same time, the surrounding air can be sucked in as a secondary flow, which increases the overall air flow from the fan.

Various measures ensure that a large part of the ventilated air is blown directly through the cooling ducts of the dry-type transformer and does not flow past the outside of the coils/windings. In the following, it is generally assumed that the core of the transformer is vertical in relation to the earth's surface. This is favorable in terms of flow technology, since the air flow generated by the fan is supported or intensified by the convection of the heated air. In exemplary embodiments, however, the core can also have other orientations, for example horizontally to the earth's surface, so that the cooling air flow also flows horizontally. In the following, however, it is consistently assumed that cores or legs are positioned vertically, as is customary in technical terms.

Exemplary embodiments relate in particular to the following cases: The transformer is typically cooled by an air flow directed from below upwards, which is generated by a ring or bladeless fan arranged in the lower region of the windings or directly under the windings. Alternatively, the bottom-up air flow can be generated by a ring or bladeless fan located in the top portion of the coils. After all, the airflow can flow through both the lower and the upper area of the windings arranged ring or bladeless fans can be created, i.e. by a combination of the above two cases. If the windings are separated from each other in the vertical direction, ie along the longitudinal axis of the core, a fan can also be installed (in addition to the variants described above, or individually) between the upper coil or winding and the lower coil or winding. For three separate windings on three legs of a three-phase dry-type transformer, the above variants can be made individually for each leg, or a single fan can be used with a ring, where the ring is not round but elongated and all three windings are on the covering three legs.

Embodiments have the following advantages over conventional ventilation techniques with conventional fans. On the one hand, the air baffle plates described at the beginning and their holding device or connections can be omitted completely. In addition, in embodiments, for example through a heat exchanger, cooled air can be routed directly to the fan through a pipe and then blown into the cooling channels. This avoids unnecessary heat exchange between the cooling air and the environment outside the windings. Therefore, the cooled air in the inlet duct to the ringless fan stays cool. A large part of the air accelerated by the fan flows directly into and through the cooling channels in the windings, while at the same time this is achieved with little or reduced structural effort. In addition, the bladeless fans in particular operate with a low noise level due to the absence of open rotating blades as in a conventional fan or blower.

1 12 shows an air-cooled dry-type transformer 1 according to embodiments in cross section. This comprises a core 10 with a leg 11 and a winding body 14 arranged around the core 10 or around the leg 11. The winding body 14 can have a plurality of windings or winding parts. A cooling channel 25 is located between an inner part 15 of the winding body 14 and an outer part 20 of the winding body 14. This has two openings 40, 42 at its two ends, typically at the bottom and at the top when the core 10 or leg 11 is vertical 25 has a substantially annular cross-section. At the bottom part of 1 A top plan view is shown with the ring 32 shown in black. The dry-type transformer 1 can also have several legs 11, for example two or three.

A ring fan 30a arranged under the dry-type transformer 1 comprises a ring 32 and a blower 34 (see also 3 ). The blower 34 is configured to draw in air from the environment (eg, in embodiments, the air may be supplied through a tube) and blow the air out of a slot 33 in the ring 32 in a directed manner along a longitudinal axis of the ring 32 . A flow of cooling air 35 is generated in the process. The ring fan 30 is dimensioned and arranged in such a way that it generates an annular flow of cooling air 35 which geometrically matches the dimensions of the cooling channel 25 .

The cooling air flow 35 essentially corresponds in its cross-sectional profile and in its dimensions to the cross-sectional profile and the dimensions of one of the openings 40, 42, i.e. typically also the dimensions of the cooling air duct 25. The cooling duct 25 typically has an inner cooling duct diameter d1 and an outer cooling duct -Diameter d2 on. These are essentially identical to the inner air flow diameter dks1 and the outer air flow diameter dks2 of the cooling air flow 31.

In 2 an exemplary embodiment is shown in which a ring fan 30b is arranged above the winding body 14 . That is, the cooling air flow 35 is generated by sucking the air out of the cooling air duct 25 .

In 3 1 shows an exemplary, non-limiting example of a ring fan 30, 30a, 30b in the form of a bladeless fan. The flow of cooling air 35 blown out of the slot 33 in the ring 32 is represented symbolically by arrows. In addition, the supply of the cooling air to the blower 34 is shown on the right-hand side. In exemplary embodiments, the flow of cooling air is routed through a pipe or duct to the fan 34 .

In 4 Another embodiment is shown, in which the ring or bladeless fan is not arranged on or around the core 10 as in the other examples, but is arranged outside and above the dry-type transformer 1 and the core 10 is. In this case, the fan can be attached, for example, to the top or ceiling of a housing, i.e. without direct contact with the transformer 1 itself.

In figure 5 is a dry-type transformer 1 shown according to embodiments, which is a combination of the variants from the 1 and 2 represents. In addition, the windings on the core or legs are divided here, so that another ring or bladeless fan 30c is arranged between the winding segments 70, 75. That is, the fan 30c is arranged between two winding segments 70, 75 arranged separately in the longitudinal direction of the core 10. For one of the winding segments 70 he works in the blowing mode, for the other winding segment 75 in the suction mode. In other embodiments, only the center ringless fan 30c may be used with such a transformer configuration.

6 shows a transformer cooling system 100, with a dry transformer 1 according to one of the embodiments described above. The dry-type transformer 1 is located in a (substantially or completely closed) housing 50. The cooling air of the cooling air flow 35 is guided into a heat exchanger 60 after passing through the cooling duct 25. This is used to dissipate the waste heat from the housing 100, for example to the ambient air, or to a cooling circuit with a fluid such as water.

After passing through the cooling channel 25 of the dry transformer 1, the cooling air flow 35 heated by the dry-type transformer 1 is thus guided into the heat exchanger 60 and cooled there. The cooled air flow is then drawn back through the blower 34 of the (or more) ring or bladeless fan 30a via a tube 36 . This creates a closed cooling air circuit.

7 shows from below a dry-type transformer 1 with three legs 11, such as a three-phase transformer. In this case, only one bladeless fan 30d is used, the ring 32b of which is designed to be elongated or elongated in order to cover all three winding bodies 14. Alternatively, one or more separate fans can also be provided for each leg 11 or winding body 14, such as in the example 1 and figure 5 described.

In general, the ring or bladeless fans 30, 30a, 30b, 30c described here can be used according to exemplary embodiments for cooling all types of dry-type transformers. The ring 32a of the bladeless fan, which is elongate or elongate here, can also assume shapes other than circular, e.g. elliptical, square or rectangular.

Claims (7)

1. An air-cooled dry-type transformer (1) comprising

   a core (10) which comprises a limb (11),

   a winding body (14) which is arranged around the limb (11),

   a cooling channel (25) which extends in the direction of the longitudinal axis of the winding body (14) and is arranged between an inner part (15) of the winding body (14) and an outer part (20) of the winding body (14), wherein the cooling channel (25) has at its two ends substantially ring-shaped openings (40, 42) and has a substantially ring-like cross section with a round, oval or polygonal basic shape;

   at least one ring fan (30, 30a, 30b, 30c) which comprises a ring (32) and a blower (34), wherein the blower (34) is configured to suck in air, and to blow the air out of the ring (32) in a manner directed along a longitudinal axis of the ring (32), wherein an air stream (31) is produced; wherein the ring fan (30, 30a, 30b, 30c) is dimensioned and arranged in such a way that the air stream (31) produces a cooling-air stream (35) in the cooling channel (25),

   characterized by

   a first ring fan (30a) which is configured in such a way that it blows air into the cooling channel (25) through a first one of the openings (40, 42), and a second ring fan (30b) which is configured in such a way that it sucks air out of the cooling channel (25) through a second one of the openings (40, 42), and/or

   characterized in that the ring has a slot which is configured in such a way that the air can be blown out in a manner directed along a longitudinal axis of the ring (32) through the slot (33) in the ring (32).
2. Dry-type transformer (1) according to Claim 1, wherein, in terms of its cross-sectional profile, the air stream (31) corresponds substantially to the cross-sectional profile of at least one of the openings (40, 42) of the cooling channel (25).
3. Dry-type transformer (1) according to Claim 1 or 2, wherein the cooling channel (25) has an inner cooling-channel diameter d1 and an outer cooling-channel diameter d2, which are substantially identical to the inner air-stream diameter dks1 and the outer air-stream diameter dks2 of the air stream (31).
4. Dry-type transformer according to one of the preceding claims, comprising at least one further ring fan (30c) which is arranged on the limb (11) between two winding-body segments (70, 75), arranged in a manner separated in the longitudinal direction of the limb (11) and having in each case an inner part (15, 15a) of the winding-body segment (70, 75) and an outer part (20, 20a) of the winding-body segment (70, 75), and which operates in blowing mode for one of the winding-body segments (70, 75) and in sucking mode for the other winding-body segment (70, 75).
5. Dry-type transformer (1) according to one of the preceding claims, said dry-type transformer (1) being a three-phase transformer and comprising three limbs (11) with three winding bodies (14) in each case according to one of the preceding claims, wherein either:

   - a ring fan (30, 30a, 30b, 30c) is attached to each limb (11) of the transformer, or

   - provision is made of a common ring fan (30d) whose elongate ring (32a) extends over all three winding bodies (14) and blows air in each case into the cooling channels (25) of the individual winding bodies (14).
6. Transformer cooling system (100) comprising:

   a. a dry-type transformer (1) according to one of the preceding claims; and

   b. a housing (50) for the dry-type transformer (1); and

   c. a heat exchanger (60) which is designed for removal of heat from the housing such that, after passing through the cooling channel (25) of the dry-type transformer (1), the cooling-air stream (35) produced by the at least one ring fan (30, 30a, 30b, 30c) impinges on the heat exchanger (60) and is cooled there.
7. Method for cooling a dry-type transformer (1) according to one of the preceding claims, comprising:

   - providing the dry-type transformer (1),

   - directing the cooling-air stream (31) of the at least one ring fan to the substantially ring-shaped opening (40, 42) of the cooling channel (25) of the dry-type transformer (1), wherein the substantially ring-shaped opening has been adapted to the geometry of the cooling channel.

Images