EP1911050B1 - Transformer with electrical switch - Google Patents

Description

The invention relates to a transformer (ie an electrical system) with an electrical switch (ie with an electrical component) and a liquid-filled housing of the electrical system, wherein the electrical component disposed in the housing and the electrical component with an insulating and cooling medium is filled.

DE1279833B . DE2515192A and EP0957496A2 reveal transformers with tap changers arranged in the transformer tank. The tap changers each have their own, arranged outside the transformer tank compensating vessel. WO02 / 41336A discloses a transformer in a first oil-filled housing 20 and a busbar and switch assembly in an adjacent, also oil-filled second housing 30. The surge tank 22 of the first housing protrudes into the second housing and the second housing has a balancing vessel 34 disposed outside the housing.

It is known to use a common expansion vessel for a transformer and a switch, but it comes to a mixture of insulating fluids. For this reason, a two-chamber expansion vessel is currently used predominantly.

Such expansion vessels are for example in DE19527763C2 described. Disadvantage of these expansion vessels is the contact of the oil surface with the outside air, which requires the use of so-called dehumidifiers. In these dehumidifiers, the air is passed over a desiccant and thereby dehumidified. The adsorption capacity of the drying agent (hygroscopicity) is used up here and the desiccant has to be renewed regularly. The periodically necessary visual checks and the regular replacement of the desiccant, especially in areas with high humidity, represents a significant cost factor (recommended maintenance intervals: every 3 months).

Furthermore, these dehumidifiers do not offer a reliable seal against the absorption of moisture and oxygen through the insulating liquid, in particular at rapid cooling of the transformer.

In DE10010737A1 a hermetically sealed transformer is described, which provides an expansible radiator for volume compensation. The use of such a radiator to compensate for the volume expansion of the insulating liquid of the switch requires considerable effort and brings problems in the discharge of gases from the switch vessel.

Also known is the use of a nitrogen pad to accommodate the change in volume of the insulating oil. However, a larger volume is required for this and it comes when heated to an overpressure. The pressure within the switch vessel may differ significantly from the pressure of the insulating liquid surrounding the switch.

Furthermore, expansion tanks for transformers are known which use a membrane in the main chamber for separating the insulating liquid from the ambient air. Such is in DE3206368 described. Although these expansion vessels provide a secure conclusion of the insulating liquid from the ambient air, but still need a dehumidifier, which is associated with the disadvantages mentioned above. Furthermore, the contact with the ambient air leads to aging of the membrane and thus causes technical uncertainties.

In DE10224074A1 An arrangement is described for the pipeline leading into the step-electrical component, which uses a labyrinth system to prevent the flow of gases to the expansion vessel. However, this system does not provide a hermetic seal on the electrical component, nor can it fully penetrate gases into the pipeline prevent. Even the complex piping to the oil conservator remains required.

Object of the present invention is to avoid the disadvantages mentioned above and easy to prevent quickly and safely overpressure in the switch of a transformer.

The object is achieved by the features of claim 1. Hereinafter, it is provided that at least one compensation element arranged in the housing is connected to the electrical switch and compensates for volume changes of the insulating and cooling medium within the electrical switch. The arrangement of the compensation element in the liquid-filled housing of the transformer, the pressure in the electrical switch is transferred to the much larger volume of the transformer. Occurring pressure fluctuations within the housing can be compensated with balancing devices.

As a result, with simple means, a pressure equalization between the internal pressure of the electrical component and the surrounding the electrical component liquid-filled housing of the electrical system allows. The invention enables a hermetic conclusion of the electrical component and thus a significant reduction in the aging of the insulating and cooling medium used in the electrical component. The use of the arrangement according to the invention also makes it possible to dispense with dehumidifiers and associated pipelines. Furthermore, the invention solves the problem of gas accumulation in the pipeline to the expansion vessel of hermetically sealed electrical systems.

The volume of the insulating and cooling medium, eg oil, of the electrical component is in relation to the volume of liquid the electrical system very small. This circumstance makes use of the invention by the volume compensation is not made via external expansion vessels, but the volume change of the insulating and cooling medium is transmitted via suitable compensation elements directly to the liquid volume of the electrical system. The compensation then take over the compensation provided for the volume compensation of the electrical system.

The use of further compensation devices for the insulating and / or coolant, such as oil conservator, Dehnradiatoren, compensators or gas cushion, is required only in special cases, since the volume required for the electrical component is almost always significantly less than 1% of the volume of the electrical system ,

It is also advantageous that the housing is hermetically sealed and at least one compensating device connected to the housing serves to receive an overpressure in the housing. Furthermore, the compensation element is integrated in the electrical component.

Preferably, the compensation element is connected via a pipe to the electrical component. The opening of the pipeline is positioned in the lower region of the electrical component in order to prevent any gases from entering the pipeline.

An outlet and / or a shut-off and / or a drain valve is integrated into the electrical component, which open or close when exceeding or falling below specified pressures.

Preferably, the compensation element consists at least partially of electrically conductive material and thus serves as a shield. Furthermore, the compensation element is designed as an elastic membrane. In addition, the compensation element consists of metallic compensators and / or bellows.

In an advantageous embodiment, the compensation element is provided with a spring element to produce a predetermined pressure difference between the housing and the electrical component. The compensation element is protected from pressure waves by at least one pressure wave damper.

The pressure wave damper is arranged in the supply line to the compensation element by means of a cross-sectional reduction.

The housing wall of the electrical component preferably serves partially or completely as a compensation element.

The electrical component is an electrical switch and the electrical system is a transformer.

Preferably, the arrangement according to the invention is designed so that the electrical component is equipped with at least one device for collecting and discharging gases which form.

The electrical system is equipped with devices for detecting the level of the liquid and / or the insulating and cooling medium and / or for detecting pressures.

Advantageously, the electrical component with an additional body for receiving a small amount of additional Insulating and cooling medium equipped to replace the loss of insulating and cooling medium resulting from decomposition by switching operations and / or heating of the contact resistors.

The deformations caused by the change in volume on the compensation element serve to evaluate and / or display the existing insulating and cooling medium.

The embodiment of the invention arranged Kompensationslements is possible both as a metallic compensator, bladder accumulator, foil bag, plastic membrane or rubber compensator.

In an advantageous embodiment of the invention, the problem of gas accumulation in the pipeline to the expansion vessel is achieved in that the pipeline for the removal of the gases is separated from the connecting line between the electrical component and the compensation element. As a result, malfunctions are avoided by gas cushion in the connection to the expansion vessel in hermetically sealed electrical systems. In addition, this design allows the provision of a special gas collection chamber, by which a too frequent response of the pressure relief valve and the associated often associated additional oil loss is avoided.

In a further embodiment, the electrical component is provided in the upper region with an additional volume for receiving a certain amount of additional insulating and cooling medium in order to replace the loss of the insulating and cooling medium resulting from decomposition by switching operations and / or heating of the switching resistors.

The gases produced by the decomposition of the insulating and cooling medium rise upwards and accumulate in this additional space. The significantly larger gas volume leads to an overpressure in the electrical component. If the pressure in the electrical component exceeds a predetermined limit value, the pressure relief valve which is closed during normal operation opens and produces a pressure relief with the atmosphere surrounding the electrical component. The inventive design of the compensation elements can be a complete completion of the insulating and cooling medium of the electrical component of the atmosphere / ambient air without limiting the oil expansion reach. The insulating and cooling medium in the electrical component can be liquid or gaseous.

The absorption of moisture and oxygen by the insulating and cooling medium is prevented. An influence on the electrical breakdown strength of the insulating and cooling medium by moisture is avoided and aging significantly reduced.

The outer expansion tank, the dehumidifier and the associated piping can be omitted. The regular check of the condition of the desiccant in the dehumidifier can be saved and there are cost savings due to the elimination of the costly regular replacement of the desiccant. Pollution and disposal problems caused by spent desiccants are avoided.

The compensation elements do not come into contact with the external atmosphere, so that the corrosion of metal compensators under moisture as well as the aging of plastic membranes of the compensation elements under the influence of moisture, oxygen and ozone is avoided. This will be significantly reduces the requirements for the compensation elements used.

Advantageously, the electrical component according to the invention is equipped with a gas discharge valve. This may conveniently be carried out or controlled so that it responds to a small gas pressure, but not in concern of the insulating and cooling medium. As a result, a constant pumping of the gases is possible. To protect against overpressure is a pressure valve and / or a conventional large-scale pressure relief valve.

In a further particular embodiment, the compensation element is provided with a spring element in order to achieve a predetermined pressure difference between the two insulating fluids.

The speed of the necessary volume compensation when heated depends on the time constants of the electrical system and the electrical component as well as the operating conditions, but is always quite slow. In order to keep away surge-like volume changes (generation of large quantities of gas due to decomposition of the insulating and cooling medium) from the compensation element in the event of an error, the attachment of pressure dampers in the pipeline to the compensation element is advantageous.

At the same time a gas discharge is slightly obstructing and delaying guidance of the gases to provide a pressure relief valve or other pressure reducing device.

In a special embodiment, the compensation element is equipped with a volume limitation in one or both directions. As a result, for example, in the electrical Component a smaller pressure play than in the main boiler of the electrical system can be realized. This limitation is also possible by a stroke limitation of the compensation elements and a multi-part compensation element with chambers of different spring constant.

FIG. 1

schematische Seitenansicht der elektrischen Anlage mit erfindungsgemäßem elektrischen Bauteil innerhalb des Gehäuses;

FIG. 2

schematische Seitenansicht der elektrischen Anlage mit erfindungsgemäßem elektrischen Bauteil am Gehäusedeckel;

FIG. 3

schematische Draufsicht auf die elektrischen Anlage mit am Gehäusedeckel angeordneten elektrischen Bauteil;

FIG. 4

schematische Draufsicht auf die elektrischen Anlage mit am Gehäusedeckel angeordneten elektrischen Bauteil;

FIG. 5

schematische Seitenansicht der elektrischen Anlage mit erfindungsgemäßem elektrischen Bauteil und Flansch am Gehäusedeckel;

FIG. 6a,..,6d

schematische Seitenansichten des elektrischen Bauteils mit unterschiedlichen Kompensationselementen;

FIG. 7a,..,7d

schematische Seitenansichten des elektrischen Bauteils mit unterschiedlichen Kompensationselementen mit negativer Kompensation;

FIG. 8

schematische Seitenansicht des elektrischen Bauteils mit zusätzlichen Volumenkörpern.

Further advantageous embodiments are described in the subclaims. The invention will be explained by way of example with reference to the drawings. The drawings show:

FIG. 1

schematic side view of the electrical system with inventive electrical component within the housing;

FIG. 2

schematic side view of the electrical system with inventive electrical component on the housing cover;

FIG. 3

schematic plan view of the electrical system with the housing cover arranged electrical component;

FIG. 4

schematic plan view of the electrical system with the housing cover arranged electrical component;

FIG. 5

schematic side view of the electrical system with inventive electrical component and flange on the housing cover;

FIG. 6a .. 6d

schematic side views of the electrical component with different compensation elements;

FIG. 7a, .., 7d

schematic side views of the electrical component with different compensation elements with negative compensation;

FIG. 8th

schematic side view of the electrical component with additional solids.

The figure FIG. 1 shows an electrical component 1, which is arranged in the housing 2 of the electrical system 3. In the housing 2 is an active part of the electrical system 3 as a transformer with at least one winding. The space inside the housing 2 is filled with a liquid 5.

According to the invention, the volume compensation of the insulating and cooling medium 4 via a compensation element 6, which is connected via a pipe 8 to the interior of the electrical component 1. When heating the insulating and cooling medium 4 in the electrical component 1, there is a thermal expansion and thus an increase in the volume. Since the housing wall 9 of the electrical component 1 hermetically seals it, the insulating and cooling medium flows via the pipeline 8 to the compensation element 6. By stretching this compensation element 6, pressure equalization takes place between the insulating and cooling medium 4 of the electrical component 1 and the liquid 5 of the electrical system 3. The change in volume of the insulating and cooling medium 4 of the electrical component 1 is passed on to the liquid 5 of the housing 2. In the housing 2 of the electrical system 3, the volume change to the existing expansion vessel 7a or to other volume compensation devices 7b for the liquid 5 eg: Dehnradiatoren, passed. Expansion tanks are in particular oil conservator, Dehnradiatoren, compensators or body with gas cushion.

To avoid accumulation of gas in the pipeline to the expansion vessel 7a, the channel for the removal of the gases from the connecting line between the electrical component and the compensation element 6 is disconnected. The connection to the electrical component 1 takes place via a pipeline 8 which leads at least so deeply into the electrical component 1 that the entry of gases into this pipeline 8 is precluded.

Forming gases rise upwards and are led via a further pipeline to a monitoring device. If the amount of gas is too large, gas is released via a valve 19.

In the illustrated embodiment, 6 unused spaces within the housing 2, for example, below the electrical component 1 used to accommodate the compensation element.

In the figure FIG. 2 the direct arrangement of the compensation element 6 is shown on the upper cover of the housing 2. This embodiment requires only short pipes 8 for connection to the compensation element 6. In this arrangement, the optimal use of the most square shape of the housing 2 and round windings of the electrical system 3 and the shape of the electrical component 1 resulting spaces for the arrangement the compensation element 6 within the housing 2 possible.

The figure FIG. 3 shows a plan view of the electrical system 3 with an attachment of the compensation element 6 under the cover of the housing 2 of the electrical system 3. Here, the space within the housing 2 by taking advantage of itself through round windings of the transformer as electrical system 3 and the electrical component 1 devoted space optimally used. The figure FIG. 4 shows a similar arrangement as FIG. 3 in which a slide 13 in the line between the electrical component 1 and the compensation element 6 is replaced by a three-way valve 14, to which an additional pipe 15 is provided for establishing a direct connection in the housing 2. Through this, a direct pressure equalization, for example when filling or evacuating the housing 2, are produced. This would give the same possibilities as when using a traditional two-chamber expansion vessel.

The in the figure FIG. 5 illustrated embodiment of the invention shows the compensation element 6 with a flange 16 which is larger than the compensation element 6 and mounted directly under the lid of the housing 2. This arrangement allows, if necessary, an uncomplicated control and the replacement of the compensation element 6. Between the compensation element 6 and the electrical component 1, an intermediate wall 25 is arranged.

Furthermore, the invention includes an electrical component 1, in which a compensation element 6 is attached directly to the electrical component 1. Here, too, the volume compensation takes place by transferring the change in volume of the insulating and cooling medium 4 of the electrical component 1 via compensation elements 6 on the housing 2. By this arrangement according to the invention the compensation element 6 becomes part of the electrical component 1. Additional external Modules omitted and lead to a simplification of the entire electrical system. 3

This embodiment will be explained in more detail with reference to the following figures.

The FIG. 6a shows an inventive designed electrical component 1 with a compensation element 6, which is mounted directly on the switch as an electrical component 1. This compensation element 6 leads to a direct compensation of the internal pressure in the electrical component 1 with the pressure within the housing 2 of the electrical system 3. Forming gases rise upwards and are guided via the pipe 17 to a monitoring device 18.

The FIGS. 6c and 6d show arrangements and embodiments of the compensation elements 6, which allow the use thereof as Abschirmelektroden. For this purpose, metallic compensators are suitable due to their relatively large radii and the necessary diameter for the compensation.

In Figure 7a an embodiment is shown which uses a negative compensation element 6. In this embodiment, the compensation element 6 is not stretched when heated, but the increase in the volume of the insulating and cooling medium 4 of the electrical component 1 is achieved by compressing the compensation element 6 and pushing liquid 5 into the housing 2.

In this variant, the compensation element 6 can be easily mechanically protected by the housing wall 9 of the electrical component 1 or cylindrical support body.

figure FIG. 7c shows the equipment of the compensation element 6 with a spring element 20 in order to achieve a predetermined pressure difference between the two insulating fluids. This makes it possible, for example, to ensure protection against the penetration of the soiled by switching insulating and cooling medium 4 of the electrical component 1 in the event of leakage.

characters FIG. 7b and 7d show an electrical component 1, in which the compensation element 6 includes a negative compensator and the targeted adjustment of a pressure difference between the insulating and cooling medium 4 of the electrical component 1 and the liquid 5 of the housing 2 of the electrical system 3 via a force acting on the compensation element 6 additional adjustment force can be generated. In the exemplary embodiment, this force is generated by the weight of a weighting body 21 and / or by a spring element. This weighting body 21 can advantageously be formed as an electrode.

figure FIG. 8th shows an electrical component 1, which is provided in the upper region of the electrical component 1 with an additional volume body 22 for receiving a suitable amount of additional insulating and cooling medium 4 to the resulting in decomposition, for example by heating the switching resistors, loss of insulating and Coolant 4 to replace. The resulting gas during decomposition rises and collects in this additional space of the volume body 22. Due to the significantly larger gas volume, there is an overpressure in the electrical component 1. If the pressure in the electrical component 1 exceeds a predetermined limit value, the opening during the normal operation closed gas outlet 11c and creates a pressure relief with the surrounding atmosphere. advantageously, controls a controller 23 that a response of the gas outlet 11c only occurs when gas is present in the head region of the electrical component 1.

The protection against pressure waves takes over the pressure relief valve 24. The subsequent flow of the insulating and cooling medium 4 from the upper part of the electrical component 1 and the discharge of the resulting gas allow a substantial freedom from maintenance of the electrical component 1 with a small size, complete completion of the insulating and cooling medium 4 from the atmosphere and without the need of an external oil conservator. Furthermore, vacuum switching cells 26 are arranged in the electrical component 1.

Claims (17)

1. Transformer (3) having a housing (2), filled with a liquid (5), an electrical switch (1) being arranged in the housing (2) and the electrical switch (1) being filled with an insulating and cooling medium (4), and also the electrical switch (1) being tightly sealed by a housing wall (9),
   characterized in that
   at least one compensation element (6) arranged in the housing (2) is connected to the electrical switch (1) and compensates for volume changes in the insulating and cooling medium (4).
2. Transformer (3) according to Claim 1,
   characterized in that
   the housing (2) is hermetically sealed and at least one compensating apparatus (7a) connected to the housing (2) is used to absorb an excess pressure in the housing (2).
3. Transformer (3) according to one of Claims 1 and 2,
   characterized in that
   the compensation element (6) is integrated in the electrical switch (1).
4. Transformer (3) according to one of Claims 1 to 3,
   characterized in that
   the compensation element (6) is connected to the electrical switch (1) via a conduit (8).
5. Transformer (3) according to Claim 4,
   characterized in that an opening in the conduit (8) is positioned in the lower region of the electrical switch (1) in order to prevent any gases present from entering the conduit (8).
6. Transformer (3) according to one of Claims 4 and 5,
   characterized in that
   a passage valve and/or a shutoff valve and/or a drain valve (19) is integrated in the electrical switch (1) and opens or closes when set pressures are exceeded or undershot.
7. Transformer (3) according to one of Claims 1 to 6,
   characterized in that
   the compensation element (6) at least partly comprises electrically conductive material and is used as a shield.
8. Transformer (3) according to one of Claims 1 to 7,
   characterized in that
   the compensation element (6) is in the form of an elastic diaphragm.
9. Transformer (3) according to one of Claims 1 to 8,
   characterized in that
   the compensation element (6) comprises metal compensators and/or bellows.
10. Transformer (3) according to one of Claims 1 to 9,
    characterized in that
    the compensation element (6) is provided with a spring element in order to produce a predetermined pressure difference between the housing (2) and the electrical switch (1).
11. Transformer (3) according to one of Claims 1 to 10,
    characterized in that
    the compensation element (6) is protected from pressure waves by at least one pressure wave attenuator (10).
12. Transformer (3) according to Claim 11,
    characterized in that
    the pressure wave attenuator (10) is arranged in the supply line to the compensation element (6) by means of a reduction in cross section.
13. Transformer (3) according to one of Claims 1 to 12,
    characterized in that
    the housing wall (9) of the electrical switch (1) is used partly or completely as a compensation element (6).
14. Transformer (3) according to one of Claims 1 to 13,
    characterized in that
    the electrical switch (1) is equipped with at least one apparatus (11a) for collecting and draining gases which are produced.
15. Transformer (3) according to Claim 15,
    characterized in that
    the transformer (3) is equipped with apparatuses for detecting the filling level of the liquid (5) and/or of the insulating and cooling medium (4) and/or for detecting pressures.
16. Transformer (3) according to one of Claims 14 and 15,
    characterized in that
    the electrical switch (1) is equipped with a supplementary body for holding a small quantity of an additional insulating and cooling medium (4) in order to replace the loss of insulating and cooling medium (4) which arises in the event of decomposition as a result of switching processes and/or heating of the transition resistors.
17. Transformer (3) according to one of Claims 14 to 16,
    characterized in that
    the deformation caused on the compensation element (6) by the volume alteration is measured and is used for evaluating and/or indicating the insulating and cooling medium (4) which is present.

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