Transformer device, transformer protection and monitoring device and connecting element

Abstract

A transformer device 1 comprises a closed transformer tank 3 filled with an insulating liquid 2, a transformer 4 arranged inside the transformer tank, and a transformer protection and monitoring devic

Description

Transformer device, transformer protection and monitoring device and connecting element The invention relates to a transformer device comprising a closed transformer tank filled with an insulating liquid, a transformer arranged inside the transformer tank and a transformer protection and monitoring device which is arranged on the outside of the transformer tank and is fastened via a sealing connecting unit to the transformer tank in the region of a transformer tank opening. Moreover, the invention relates to a transformer protection and monitoring device, which is designed to monitor the temperature inside a transformer tank, the pressure prevailing in the transformer tank and the filling level of the insulating liquid inside the transformer tank and, in particular, to switch off the transformer if predetermined limit values are exceeded and / or not reached, wherein the transformer protection and monitoring device has a connecting unit, in particular in the form of a sealing flange, which is designed to fasten the transformer protection and monitoring device to a transformer tank. Furthermore, the invention relates to a connecting element. Transformers are known in the state of the art in various designs. They usually comprise at least two coils wound around a common magnetic core and serve to convert an input AC voltage applied to the first coil into an output AC voltage that can be tapped at the second coil. Certain embodiments of transformer devices, also referred to as hermetically sealed transformers, include a closed transformer tank filled with an insulating fluid in which the actual transformer is located. The insulating liquid is used for electrical insulation between the transformer components and for cooling the transformer. It is usually a mineral oil that exhibits good stability at high temperatures and provides good electrical insulation. Alternatively, however, dielectric coolants can also be used, for example. To ensure proper transformer operation, some parameters, in particular the temperature inside the transformer tank, the pressure prevailing in the transformer tank and the level of the insulating liquid inside the transformer tank, should not exceed and / or fall below permissible limit values. Suitable sensors and evaluation units are used to monitor such parameters. For example, transformer protection and monitoring devices are known which are attached to the transformer tank in the area of a transformer tank opening on the top of the transformer tank via a sealing connection unit, usually in the form of a sealing flange, and which are designed to monitor the temperature inside a transformer tank, the pressure prevailing in the transformer tank and the level of the insulating liquid inside the transformer tank and, in particular, to switch off the transformer if predetermined limit values are exceeded and / or not reached. Such transformer protection and monitoring devices are also referred to as transformer protection blocks. Only by way of example, such a protection block is offered under the designation "MCHD" by Albert Maier GmbH, Weil der Stadt. Another parameter that should be checked regularly is the proportion ratio of different gases contained in the insulating liquid. On the basis of these proportion ratios, conclusions can be drawn about operating faults, for example in the form of local temperature increases, discharges in the active part or the like. The determination of the proportion ratios can be carried out at specific time intervals on the basis of an insulating fluid sample taken from the transformer tank. So-called DGA sensors (Dissolved Gas Analysis) are used for automatic determination. The use of such DGA sensors is already widespread in large power transformers. As the size of DGA sensors available on the market decreases, they are also increasingly being used in smaller transformer devices. However, in the case of hermetically sealed transformers, especially those of smaller size, there is still a problem in installing them in accordance with the technical requirements for dimensions and proper function in operation. When installing on the side of the transformer tank, space is very limited due to the large cooling fins usually located there. Positioning the sensor on the top of the transformer tank requires a special device so that the sensor can be installed horizontally as intended. In addition, the space available on the top side is very limited due to the high-voltage bushings and other monitoring equipment usually located there. Moreover, the sensor requires an additional opening in the transformer tank for sampling, which is difficult to achieve in a transformer device already in operation. This makes it difficult to retrofit the DGA sensor. Based on this prior art, it is an object of the present invention to at least partially solve the aforementioned problems . For solving this object the present invention provides a transformer device comprising a closed transformer tank filled with an insulating liquid, a transformer arranged inside the transformer tank and a transformer protection and monitoring device which is arranged on the outside of the transformer tank and is fastened via a sealing connecting unit to the transformer tank in the region of a transformer tank opening, characterized in that a DGA sensor is positioned on the transformer protection and monitoring device, in particular on the connecting unit of the transformer protection and monitoring device, or on an annularly formed connecting element arranged between the connecting unit of the transformer protection and monitoring device and the transformer tank. One advantage of both proposed positions of the DGA sensor on or in the area of the transformer protection and monitoring device is that an arrangement of the DGA sensor does not require any additional installation space. Also, no additional transformer tank opening is required for the DGA sensor, since the transformer tank opening provided for the transformer protection and monitoring device can be used for sampling. Furthermore, the design effort required for the installation of the DGA sensor is very manageable. Preferably, the transformer protection and monitoring device is designed to monitor the temperature inside the transformer tank, the pressure prevailing in the transformer tank and the filling level of the insulating liquid inside the transformer tank and, in particular, to switch off the transformer in the event that predetermined limit values are exceeded and / or not reached. Advantageously, the connecting unit is designed as a sealing flange leading a simple construction. Preferably, the DGA sensor is a semiconductor-based DGA sensor. Such a semiconductor-based DGA sensor is characterized in particular by its small dimensions. According to a first version of the invention the connecting unit of the transformer protection and monitoring device has a connection device designed for connecting a DGA sensor. According to a second version of the invention the transformer protection and monitoring device and the DGA sensor are designed as an integral unit. For solving the above-mentioned object the present invention further provides a transformer protection and monitoring device, which is designed to monitor the temperature inside a transformer tank, the pressure prevailing in the transformer tank and the filling level of the insulating liquid inside the transformer tank and, in particular, to switch off the transformer if predetermined limit values are exceeded and / or not reached, wherein the transformer protection and monitoring device has a connecting unit, in particular in the form of a sealing flange, which is designed to fasten the transformer protection and monitoring device to a transformer tank, characterized in that the connecting unit is provided with a connection device designed for connecting a DGA sensor. Moreover, for solving the above-mentioned object the invention provides a transformer protection and monitoring device, which is designed to monitor the temperature inside a transformer tank, the pressure prevailing in the transformer tank and the filling level of the insulating liquid inside the transformer tank and, in particular, to switch off the transformer if predetermined limit values are exceeded and / or not reached, the transformer protection and monitoring device having a connecting unit, in particular in the form of a sealing flange, which is designed to fasten the transformer protection and monitoring device to a transformer tank, characterized in that the transformer protection and monitoring device has a DGA sensor which is positioned in particular on the connecting unit. Furthermore, for solving the above-mentioned object the invention provides a connecting element which has an annular shape and is designed to be fastened with its underside in a sealing manner to a transformer tank in the region of a transformer tank opening and to receive in a sealing manner on its upper side a connecting unit, designed in particular as a sealing flange, of a transformer protection and monitoring device, a connection device designed for connecting a DGA sensor being provided on the outer circumference of the connecting element. Further advantages and features of the present invention will become apparent from the following description with reference to the accompanying drawing. Therein Figure 1 is a schematic, partially transparent view of a transformer device according to a first embodiment of the present invention, and Figure 2 is a schematic, partially transparent view of a transformer device according to a second embodiment of the present invention. Identical reference numerals hereinafter refer to identical or similarly configured components. Figure 1 shows a transformer device 1 according to a first embodiment of the present invention with a hermetically sealed design. The transformer device 1 comprises a closed transformer tank 3 filled with an insulating liquid 2 provided in this case in the form of oil, a transformer 4 arranged inside the transformer tank 3 and a transformer protection and monitoring device 5 arranged on the outside of the transformer tank 4. The transformer protection and monitoring device 5 is designed to monitor the temperature inside the transformer tank 3, the pressure prevailing in the transformer tank 3 and the filling level of the insulating liquid 2 inside the transformer tank 3 and, in particular, to switch off the transformer 4 if it exceeds and / or falls below predetermined limit values or, if necessary, to change the operating mode in such a way that failure of or damage to the transformer 4 is prevented. For this purpose, the transformer protection and monitoring device 5 comprises suitable sensors and switching devices, not shown in more detail in Figure 1, which are connected to the transformer control system, also not shown. For manual reading and / or setting of the limit values, an insulating liquid level indicator 6, a thermometer 7 which can be set in relation to the limit values and an adjustable pressure switch 8 are provided. In addition, the transformer protection and monitoring device 5 has an insulating liquid sampling valve 9, via which samples of the insulating liquid 2 can be taken from the transformer tank 3 if required. The transformer protection and monitoring device 5 also comprises a sealing connecting unit 10, in this case in the form of a sealing flange, with which it is fastened to the transformer tank 4 in the region of a transformer tank opening 11. On the transformer protection and monitoring device 5, in the embodiment shown on the connection unit 9 of the transformer protection and monitoring device 5, there is a connection device 12 to which a DGA sensor 13 is attached in horizontal alignment, which in this case is a semiconductor-based DGA sensor 13. The connection device 12 is designed in such a way that a fluid connection exists between the transformer tank 3 and the DGA sensor 13, so that the DGA sensor 13 can take insulating fluid samples from the transformer tank 3. Alternatively, the transformer protection and monitoring device 5 and the DGA sensor 11 can also be designed as an integral unit. During operation of the transformer device 1, the temperature inside the transformer tank 3, the pressure prevailing in the transformer tank 3 and the level of the insulating liquid 2 inside the transformer tank 3 are monitored using the transformer protection and monitoring device 5. Furthermore, using the DGA sensor 12, samples of the insulating liquid are taken through the transformer tank opening 10 at regular time intervals and analyzed with respect to proportion ratios of various gases contained in the insulating liquid. In case of exceeding and / or falling below predetermined limit values, which can be set by the user, the corresponding switching devices are actuated in order to switch off the transformer 4 or at least to transfer it into an operating mode which prevents damage to the transformer 4 or even its failure. Figure 2 shows a transformer device 1 according to a further embodiment of the present invention, which differs from the embodiment shown in Figure 1 in that an annular connecting element 14 is positioned between the connecting unit 10 of the transformer protection and monitoring device 5 and the transformer tank 3. The connecting element 14 is designed to be fastened in a sealing manner with its underside to the transformer tank 3 in the region of the transformer tank opening 11 and to receive the connecting unit 10 of the transformer protection and monitoring device 5 in a sealing manner on its upper side. On the outer circumference of the connecting element 12, a connection device 12 designed for connecting a DGA sensor 13 is provided, to which the DGA sensor 13 is attached. The connection device 12 is also designed in such a way that a fluid connection exists between the transformer tank 3 and the DGA sensor 13, so that the DGA sensor 13 can take insulating fluid samples from the transformer tank 3. Although it is not shown here, the transformer tank 3 may have a number of other components, such as cooling fins, in particular arranged circumferentially, and / or high-voltage bushings and / or other monitoring equipment and / or expansion vessels, etc. Although the present invention has been described in detail with reference to the preferred embodiment, it is to be understood that the present invention is not limited by the disclosed examples, and that numerous additional modifications and variations could be made thereto by a person skilled in the art without departing from the scope of the invention. List of reference signs 1 Transformer device 2 Insulating liquid 3 Transformer tank 4 Transformer 5 Transformer protection and monitoring device 6 Insulating liquid level indicator 7 Thermometer 8 Pressure switch 9 Insulating liquid sampling valve 10 Connecting unit 11 Transformer tank opening 12 Connection device 13 DGA sensor 14 Connecting element

Claims

1. Transformer device (1) comprising a closed transformer tank (3) filled with an insulating liquid (2), a transformer (4) arranged inside the transformer tank (3) and a transformer protection and monitoring device (5) which is arranged on the outside of the transformer tank (3) and is fastened via a sealing connecting unit (10) to the transformer tank (3) in the region of a transformer tank opening (11), characterized in that a DGA sensor (13) is positioned on the transformer protection and monitoring device (5), in particular on the connecting unit (10) of the transformer protection and monitoring device (5), or on an annularly formed connecting element (14) arranged between the connecting unit (10) of the transformer protection and monitoring device (5) and the transformer tank (3).

2. Transformer device (1) according to claim 1, characterized in that the transformer protection and monitoring device (5) is designed to monitor the temperature inside the transformer tank (3), the pressure prevailing in the transformer tank (3) and the filling level of the insulating liquid (2) inside the transformer tank (3) and, in particular, to switch off the transformer (4) in the event that predetermined limit values are exceeded and / or not reached.

3. Transformer device (1) according to claim 1 or 2, characterized in that the connecting unit (10) is designed as a sealing flange.

4. Transformer device (1) according to one of the preceding claims, characterized in that the DGA sensor (13) is a semiconductor-based DGA sensor.

5. Transformer device (1) according to one of thepreceding claims, characterized in that the connecting unit (10) of the transformer protection and monitoring device (5) has a connection device (12) designed for connecting a DGA sensor (13).

6. Transformer device (1) according to one of claims 1 to 4, characterized in that the transformer protection and monitoring device (5) and the DGA sensor (13) are designed as an integral unit.

7. Transformer protection and monitoring device (5), which is designed to monitor the temperature inside a transformer tank (3), the pressure prevailing in the transformer tank (3) and the filling level of the insulating liquid (2) inside the transformer tank (3) and, in particular, to switch off the transformer (4) if predetermined limit values are exceeded and / or not reached, wherein the transformer protection and monitoring device (5) has a connecting unit (10), in particular in the form of a sealing flange, which is designed to fasten the transformer protection and monitoring device (5) to a transformer tank (3), characterized in that the connecting unit (10) is provided with a connection device (12) designed for connecting a DGA sensor (13).

8. Transformer protection and monitoring device (5), which is designed to monitor the temperature inside a transformer tank (3), the pressure prevailing in the transformer tank (3) and the filling level of theinsulating liquid (2) inside the transformer tank (3) and, in particular, to switch off the transformer (4) if predetermined limit values are exceeded and / or not reached, the transformer protection and monitoring device (5) having a connecting unit (10), in particular in the form of a sealing flange, which is designed to fasten the transformer protection and monitoring device (5) to a transformer tank (3), characterized in that the transformer protection and monitoring device (5) has a DGA sensor (13) which is positioned in particular on the connecting unit (10).

9. Connecting element (14) which has an annular shape and is designed to be fastened with its underside in a sealing manner to a transformer tank (3) in the region of a transformer tank opening (11) and to receive in a sealing manner on its upper side a connecting unit (10), designed in particular as a sealing flange, of a transformer protection and monitoring device (5), a connection device (12) designed for connecting a DGA sensor (13) being provided on the outer circumference of the connecting element (14).

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