AT518511B1 - Cable for testing a device under test, test device and method for testing a device under test - Google Patents

Abstract

To test a transformer (2) a cable (20) is used, which connects the transformer (2) with a test device (10). The cable (2) comprises at least two twin lines (23-25). Via a first conductor of a twin line (23-25) in each case a current can be fed into a winding of the transformer. The second line of the twin line (23-25) is used to measure the voltage on the winding.

Description

SUMMARY OF THE INVENTION There is a need for devices and methods that reduce the amount of work involved in testing specimens of power plants and equipment. There is a need for devices and methods with which the establishment of several electrically conductive connections between a test device and a test object is facilitated.

A cable, a test device and a method are specified as defined in the independent claims. The dependent claims define exemplary embodiments.

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Patent Office According to an embodiment, a cable for connecting a test device to a test object is specified. The device under test can in particular be a transformer. The cable comprises a twin line and can in particular comprise at least two twin lines. Each twin line has a first line for carrying a current between the test device and the device under test and a second line for carrying out a voltage measurement during the test.

Through the use of twin lines, the lines for current and voltage, via which test signals can be fed or impressed and / or recorded via the test responses, are mechanically coupled to one another.

The effort for the production of electrically conductive connections for feeding current into a winding and the voltage measurement is reduced. By combining several twin lines in one cable, the effort for connecting the transformer test device is further reduced. The risk that lines that are assigned to different phases of a multiphase transformer, for example, is reduced. The first line has a first line cross section and the second line has a second line cross section that is different from the first line cross section. The first line, which is used for current feed or current measurement, can have a larger line cross section than the second line. According to the invention, the twin line or each of the twin lines each comprises a twin line jacket which has a first cavity in which the first line runs and a second cavity in which the second line runs.

The first cavity and the second cavity can run parallel to one another in a cable sheath.

[0012] The first line and the second line can be welded in parallel. A first section of the twin line jacket surrounding the first line can in each case be attached by welding to a second section of the twin line jacket surrounding the second line.

[0013] The first line and the second line can be twisted lines.

[0014] The first line and the second line can be coaxial lines.

The cable can comprise a cable sheath that surrounds the at least two twin lines over at least a portion of their length. The twin cable sheath is provided separately from the cable sheath and runs inside the cable sheath.

The cable may comprise a support element which is arranged in the cable jacket and extends spaced from the cable jacket along a longitudinal direction of the cable jacket. The support element can be flexible. The support element prevents the cable from being deformed strongly under mechanical stress. Such a load can be caused, for example, by a person stepping on the cable. The individual twin lines and the cable as a whole can be designed in such a way that they do not or only slightly deform under load when a person steps on them.

[0017] The at least two twin lines can rest on the support element.

[0018] Each twin line and the cable as a whole can have a high degree of flexibility.

[0019] Each twin line and the cable as a whole can have a high tensile strength and a high tear resistance.

[0020] Each twin line and the cable as a whole can have a high notch resistance.

[0021] Each twin line and the cable as a whole can have high durability.

The cable can be designed so that it is a cable for outdoor applications. The cable can have a coding to differentiate between different twin lines

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Patent office include. The coding can make it possible to differentiate between the first line and the second line for each twin line. The coding can be a color coding. The coding can include symbols or other marking elements.

The coding can be provided on the end portions of the at least two twin lines emerging from the cable sheath and / or on connectors for connecting the twin lines to windings of the transformer.

The cable may include a connector for connecting the cable to the transformer tester. The connector for connecting the cable to the transformer test device can be set up in such a way that all of the lines carried in the cable can be individually addressed by the transformer test device, for example in order to feed or detect currents in different windings of the transformer independently of one another or to apply voltages to different windings of the Create or record transformers.

The cable may comprise more than two twin lines.

The cable can comprise four twin lines or more than four twin lines.

A test device according to one embodiment comprises a measuring device for recording a test response when testing a test object and a connection for mechanical coupling and electrically conductive connection with a cable which comprises at least two twin lines.

Several lines between the test device and the device under test can be connected to the test device in a simple manner by coupling a connector of the cable to the connection of the test device. In particular, it is not necessary to connect the first and second lines of the twin lines individually to the test device.

The connection can have mutually electrically insulated contact surfaces in order to establish an electrically conductive connection with a first line and a second line of each twin line via the connector of the cable.

The test device can comprise a switch arrangement which comprises a plurality of controllable switches and which can be controlled in order to selectively conductively connect the measuring device and / or a signal source to different twin lines of the cable. The switch arrangement can be set up to selectively connect a plurality of signal sources in a parallel or series connection, in order to provide an increased current or an increased voltage to one or more of the twin lines as a test signal.

The testing device can be a transformer testing device. The test device can comprise an evaluation circuit which is coupled to the measuring device in order to determine a static resistance of a winding of the transformer, a transmission ratio of the transformer, a leakage inductance of the transformer, a leakage reactance of the transformer and / or a power factor of the transformer.

A system according to an embodiment comprises the test device according to an embodiment and a cable according to an embodiment, the cable being connected or connectable to the test device.

The system can include a transformer. The at least two twin lines can be conductively connected to windings of at least two different phases of the transformer.

The test device can be set up to provide test signals to the windings of at least two, in particular at least three different phases of the transformer via the twin lines of the cable and / or to provide test answers from at least two, in particular at least three, via the twin lines of the cable to detect different phases of the transformer.

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Patent Office [0036] A method for testing a test object comprises connecting a test device to the test object with a cable that comprises at least two twin lines.

The at least two twin lines of the cable can be conductively connected with windings of at least two, in particular at least three different phases of the transformer.

[0038] In a transformer test, the test device can detect a test response via the at least two twin lines of the cable. Based on the test response, the test device can determine a static resistance of a winding of the transformer, a transmission ratio of the transformer, a leakage inductance of the transformer, a leakage reactance of the transformer and / or a power factor of the transformer.

In the devices, systems and methods, the device under test can be a transformer, the cable can be a cable for transformer testing and the test device can be a transformer test device.

In the devices, systems and methods, the test device can be a mobile test device, in particular a portable transformer test device.

The cable and the transformer test device can be used to test a multi-phase transformer, for example a three-phase transformer.

Devices, methods and systems according to exemplary embodiments make it possible to efficiently establish several connections between a test device and the test object when testing a test object. The risk of confusing cables is reduced.

BRIEF DESCRIPTION OF THE FIGURES The invention is explained in more detail below with reference to the drawings using preferred embodiments. In the drawings, identical reference numerals designate identical elements.

Figure 1 [0045] Figure 2 [0046] Figure 3 [0047] Figure 4 [0048] Figure 5 shows a system with a cable and a transformer test device according to an embodiment.

shows a cable for testing a device under test, in particular for transformer testing, according to an embodiment.

shows a cross section of the cable according to an embodiment, shows a cross section of the cable according to an embodiment, shows a test device according to an embodiment.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS The present invention is explained in more detail below on the basis of preferred embodiments with reference to the drawings. In the figures, the same reference symbols designate the same or similar elements. The figures are schematic representations of various embodiments of the invention. Elements shown in the figures are not necessarily drawn to scale. Rather, the various elements shown in the figures are reproduced in such a way that their function and purpose can be understood by the skilled person.

In the following, cables, test devices and methods for testing a test object are described in detail. While the exemplary embodiments are described in the context of testing transformers, the exemplary embodiments can also be used for other test objects in power engineering systems.

The transformer that is tested using the cable and the tester can be a transformer for high, medium or low voltage networks. The transformer can be a transformer installed in a power plant or substation. The

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The test device can be a mobile device or can be constructed from several mobile devices in order to allow measurements to be carried out on the installed transformer.

As described in more detail below, a cable is used according to embodiments, which has one or more twin lines to connect the tester to the transformer. In the transformer test, a first line of the twin line can carry a current, which can be, for example, a test signal to be impressed or a test response to be evaluated. In the transformer test, a second line of the twin line can be connected to a voltage source for applying a voltage as a test signal or to a voltage measuring device. The first line thus serves to carry a current during the transformer test, the second line, for example, to measure a voltage.

The test device has a connection which is set up for coupling with such a cable.

In the test device and the cable can be used to automatically determine different parameters of the transformer. For example, transformation ratios of the transformer can be determined automatically. Other parameters such as static or dynamic resistances or a leakage reactance and / or a leakage inductance of the transformer or a power factor of the transformer can also be determined. For this purpose, the test device can in each case feed a current as a test signal into a winding of the transformer via the first line of a twin line and record the voltage as a test response via the second line of the twin line and the second line of another twin line of the cable.

Figure 1 shows a system 1 according to an embodiment. A test device 10 for determining a parameter of a transformer 2 is connected via a cable 20 to one winding or a plurality of windings of the transformer 2.

The cable 20 has a first section 21, in which a plurality of twin lines 2325 are guided within a cable jacket of the cable. At one end of the cable jacket, the twin lines 23-25 emerge from the end of the cable jacket. Each of the twin lines 23-25 may be divided into a section at its end into its two individual lines, the first line and the second line of the corresponding twin line. In the transformer test, the twin lines 23-25 can be connected to the device under test via connectors, for example via bushing insulators 3-5.

[0057] The twin lines 23-25 each have a first line and a second line. The first line can be designed such that it can be used to feed a current as a test signal into a winding of the transformer during the transformer test. The second line can be designed such that the test device 10 detects the voltage across the winding as a test response via the second line and, for example, the second line of a further twin line.

The first line and the second line can each have cross-sectional areas that ensure sufficiently low resistances for the feeding of the current and the voltage detection during the transformer test. The first line and the second line can each have a cross-sectional area of at least 1 mm ² . The first line and the second line can also have different cross-sectional areas. The cross-sectional area of the first line of each twin line can be larger than the cross-sectional area of the second line of the same twin line.

The test device 10 has a connection for coupling to a connector of the cable 20. The test device 20 is set up to feed current into the first line of a twin line 23-25 during the transformer test. A voltmeter or other voltage measuring device of the test device 10 can be connected to the second line of this twin line in order to record a test response.

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Patent Office [0060] Figure 2 is a side view of a cable 20 according to an embodiment. In section 21, a plurality of twin lines 23-25 run within the cable sheath 27. Each of the twin lines 23-25 can have a twin line sheath that surrounds the first and second lines of the twin line 23-25.

The twin line jacket of one or more twin lines 23-25 can rest on an inside of the jacket 27.

A connector 22 of the cable 20 is set up for coupling to a connection of the test device 10. At an end of the jacket opposite the connector 22, the twin lines 23-25 emerge from the jacket. The twin lines 23-25 can initially be continued so that the first and second lines are continued together. In an end region, the first line 31 and the second line 32 of the twin line 23-25 can each be separated from one another. At the ends of the first and second lines 31, 32, connectors 33, 34 are provided for connection to the test specimen.

In order to prevent the sheath 27 from being deformed under load, for example by the weight of a person standing on the sheath 27, at least one support element can run in addition to the twin lines in the sheath 27, as shown in FIG. 4 is described in more detail.

The cable 20 and the individual twin lines 23-25 can be designed such that they have high flexibility, high tensile strength, high tensile strength, high notch strength and high durability.

The ends of the first and second lines of all twin lines 23-25 can be coded differently. Color coding or another marking can be used for coding. The coding can be such that the first and second lines of a twin line 23-25 can be distinguished in each case. The coding can be such that the coding can be used to determine which of a plurality of twin lines 23-25 the corresponding end with the connector 33, 34 belongs to, and that the coding can also be used to determine whether the connector 31, 32 is a first Line for feeding the current or a second line for voltage measurement belongs.

The cable 20 can be configured such that the twin lines run within the cable jacket 27 over a first length 41. The cable 20 can be configured in such a way that the first and second lines 31, 32 of the twin lines 23-25 are continued together over a second length 42 starting from the end of the cable sheath 27. The cable 20 can be configured such that the first and second lines 31, 32 of the twin lines 23-25 are separated from one another by a third length 43 starting from the end of the cable sheath 27. The cable 20 can be designed such that the second length 42 is greater than the third length 43. The cable 20 can be configured such that the first length 41 is greater than the second length 42.

Figure 3 shows a cross section of a cable 20 according to an embodiment. The cross section is shown for a point of the cable 20 at which the cable sheath 27 surrounds the twin line. The cable 20 comprises two twin lines 23, 24. The cable 20 can also have more than two twin lines, for example three twin lines.

[0068] A first twin line 23 has a first conductor 51 and a second conductor 52. The first conductor 51 and the second conductor 52 can have different diameters and different cross-sectional areas. In other configurations, the cross-sectional areas of the first conductor 51 and the second conductor 52 can be the same.

The first twin line 23 has a twin line jacket 53 which surrounds the first conductor 51 and the second conductor 52. The twin line sheath 53 can be formed in such a way that a sheath of the first conductor 51 and a sheath of the second conductor 52 are welded in order to form a twin line 23 welded in parallel.

The twin line jacket 53 forms a first elongated cavity in which the

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Patent Office extends first conductor 51, and a second elongated cavity in which the second conductor 52 extends. The first cavity and the second cavity can extend parallel to one another at least within the cable sheath 27.

A second twin line 24 has a first conductor 54, a second conductor 55 and a twin line jacket 56 which, apart from a coding which may be provided for distinguishing twin lines, can be configured identically to the first twin line 23. Different twin lines 23, 24 can also have different configurations from one another.

When using the cable, a current can be impressed into a winding of the transformer via the first conductors 51, 54. A voltage across the winding can be detected as a test response via the second conductors 52, 55.

Figure 4 shows a cross section of a cable 20 according to an embodiment. The cross section is shown for a point of the cable 20 at which the cable sheath 27 surrounds the twin lines. The cable 20 comprises four twin lines 23-26. The cable 20 can also have more than four twin lines. The twin lines 23-26 can be constructed as described with reference to FIG. 3.

The cable 20 comprises a support element 28. The support element 28 can extend over part or the entire length of the jacket 27 within the cavity defined by the jacket 27. The twin lines 23-26 can rest on the support element 28. In a state of the cable 20 in which the cable 20 is not loaded with pressure from outside, the twin lines 23-26 can rest against the support element 28 and the inside of the jacket 27 or be slightly spaced therefrom. In this way, the stability of the cable 20 can be increased.

While FIG. 3 and FIG. 4 show twin lines welded in parallel or other twin lines with parallel first and second lines 51, 52, other twin lines can also be used. For example, twisted or coaxial lines can be used.

The cable 20, but also each of the twin lines 23-26 can have a high degree of flexibility in each of the exemplary embodiments described.

The cable 20 according to exemplary embodiments can offer advantages in terms of weight and production costs in addition to advantages when carrying out the testing of the transformer. For example, the assembly effort can be reduced and / or material can be saved.

By stripping over a total length, which corresponds to the sum of the second length 42 and third length 43 shown in Figure 2, a sufficiently flexible usability for testing different transformers can be achieved, while reducing the risk that there are different lines confuse with each other. The total length over which the twin lines are stripped, i.e. the sum of the second length 42 and third length 43 shown in FIG. 2 can be 3 m or more than 3 m. The total length over which the twin lines are stripped, i.e. the sum of the second length 42 and third length 43 shown in FIG. 2 can be 4.5 m or more than 4.5 m.

FIG. 5 is a schematic illustration of a test device 10 which is set up to be connected to a transformer for a transformer test via a cable which comprises one or more twin lines. The transformer can in particular be a multi-winding transformer.

The testing device 10 can be a testing device that has a housing 11. The test device can be mobile, in particular portable. The test device can also consist of several separate devices.

The test device 10 has a connection 18 for coupling to a cable 20, which comprises at least two twin lines. The connection 18 can have contact surfaces

AT 518 511 B1 2018-10-15 Austrian patent office, which are arranged to electrically contact the first and second lines of the different twin lines 23-26 individually. The connection 18 can be set up for mechanical coupling to the connector 22 of the cable.

The testing device 10 may include a switch arrangement 14. The switch arrangement 14 has a plurality of controllable switches, which can be relays or power transistors. Direct or alternating currents, which are generated by a source 15, can optionally be supplied to the first conductors of different twin lines via the switch arrangement 14. For example, a control and evaluation circuit 12 can control the switch arrangement 14 in such a way that the source 15 feeds a current via the first conductor of the first twin line 23 and the first conductor of the second twin line 24 into the winding of a phase of the transformer and the voltage measuring device 16 via the second conductor of the first twin line 23 and the second conductor of the second twin line 24 detects a voltage across the winding. The control and evaluation circuit 12 can control the switch arrangement 14 in such a way that the source 15 feeds a current via the first conductor of the third twin line 25 and the first conductor of the fourth twin line 26 into the winding of another phase of the transformer and the voltage measuring device 16 via the second conductor of the third twin line 25 and the second conductor of the fourth twin line 26 detects a voltage across the winding.

The switch arrangement 14 can also be set up to connect a plurality of sources of the test device 10 in parallel in order to provide the resulting current as a test signal. The resulting current can optionally be provided to the windings of different phases of the transformer, wherein the control and evaluation circuit 12 controls the switch arrangement 14 in order to feed the current provided by several sources into a winding of the transformer via the first conductor of a twin line.

[0084] The control and evaluation circuit 12 can evaluate the test response, for example the detected voltage of the winding of the transformer. From the amplitude and optionally also the phase position of the detected voltage in response to the current impressed as a test signal, the control and evaluation circuit 12 can determine a static resistance of one winding or several windings of the transformer, a dynamic resistance of one winding or several windings of the transformer, a transmission ratio of the transformer, a leakage inductance of the transformer, a leakage reactance of the transformer and / or a power factor of the transformer. The control and evaluation circuit 12 can comprise at least one integrated circuit which can carry out the corresponding processing steps.

[0085] While exemplary embodiments have been described in detail with reference to the figures, alternative or additional features can be used in further exemplary embodiments. For example, while certain measurements such as the determination of transmission ratios, resistances, leakage reactances and / or leakage inductances of multiphase transformers have been described by way of example, the cable and the test device according to exemplary embodiments can also be used to test other test objects or to determine other parameters.

While the cable and the test device can be used to test a transformer that can be installed in a power plant or substation of a power supply network, the device and the method according to exemplary embodiments can also be used with smaller transformers.

Cables, test devices, methods and systems according to exemplary embodiments allow a test specimen to be tested, and the amount of cabling required for the test can be reduced.

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Claims (25)

claims A cable for connecting a test device (10) to a test object (2), in particular to a transformer, comprising: at least two twin lines (23-26), each having a first line (51, 54) for carrying a current between the test device (10) and the test object when testing the test object (2) and a second line (52, 55) for Carrying out a voltage measurement when testing the test specimen (2), the first line (51, 54) having a first line cross section and the second line (52, 55) having a second line cross section different from the first line cross section, characterized in that at least one Twin line has a twin line jacket (53, 56) which has a first cavity in which the first line (51, 54) is arranged and a second cavity in which the second line (52, 55) is arranged. 2. The cable of claim 1, wherein the first cavity and the second cavity are parallel to each other. 3. Cable according to one of claims 1 to 2, wherein the first line (51, 54) and the second line (52, 55) form a parallel welded twin line (23-26). 4. The cable of claim 1, wherein the first line (51, 54) and the second line (52, 55) are twisted together lines. 5. The cable of claim 1, wherein the first line (51,54) and the second line (52, 55) are coaxial lines. 6. Cable according to one of the preceding claims, comprising a cable sheath (27) which surrounds the at least two twin lines (23-26) over at least a portion of their length (41). 7. Cable according to claim 6, comprising a support element (28) which is arranged in the cable sheath (27) and extends spaced from the cable sheath (27) along a longitudinal direction of the cable sheath (27). 8. Cable according to claim 7, wherein the at least two twin lines (23-26) abut the support element (28). 9.14 AT 518 511 B1 2018-10-15 Austrian Patent Office 9. Cable according to one of claims 6 to 8, comprising a coding for differentiating different twin lines (23-26). 10/14 AT 518 511 B1 2018-10-15 Austrian Patent Office 10. Cable according to claim 9, wherein the coding on the cable sheath (27) end portions of the at least two twin lines (23-26) and / or on connectors (33, 34) for connecting the twin lines (23-26) with windings Transformer (2) is provided. 11. Cable according to one of the preceding claims, comprising a connector (22) for connecting the cable to the test device (10). 12. Cable according to one of the preceding claims, wherein the cable (20) comprises more than two twin lines (23-26). 13. Cable according to one of the preceding claims, wherein the cable (20) comprises four twin lines (23-26). 14. Cable according to one of the preceding claims, wherein the cable (20) is a cable for a transformer test, and wherein the at least two twin lines (23-26) are set up for connection to windings of a multiphase transformer. 15. Test device comprising a measuring device (16) for recording a test response when testing a test specimen (2), and a connection (18) for mechanical coupling and electrically conductive connection with a cable (20) which connects at least two twin lines (23- 26) includes. 16. Test device according to claim 15, wherein the connection has mutually electrically insulated contact surfaces in order to produce an electrically conductive connection with a first line (51, 54) and a second line (52, 55) of each twin line (23-26). 17. Test device according to claim 15 or claim 16, comprising a switch arrangement (40) which comprises a plurality of controllable switches and which can be controlled to selectively connect the measuring device (16) and / or a test signal source (15) with different twin lines (23-26 ) to connect the cable (20) in a conductive manner. 18. Test device according to one of claims 15 to 17, wherein the test device (10) is a transformer test device (10). 19. Testing device according to claim 18, comprising an evaluation circuit (12), which is coupled to the measuring device (16), around a static resistance of at least one winding of the transformer (2), a dynamic resistance of at least one winding of the transformer (2) Determine transmission ratio of the transformer (2), a leakage inductance of the transformer (2), a leakage reactance of the transformer (2) and / or a power factor of the transformer (2). 20. A system comprising the test device (10) according to one of claims 15 to 19 and a cable (20) according to one of claims 1 to 14, which is connected or connectable to the test device (10). 21. System according to claim 20, comprising a transformer (2), wherein the at least two twin lines (23-26) are conductively connected to windings of at least two different phases of the transformer (2). 22. A method for testing a test object (2), in particular a transformer (2), comprising: Connecting a test device (10) to the test object (2) with a cable (20) according to one of claims 1 to 14. 23. The method according to claim 22, wherein the at least two twin lines (23-26) of the cable (20) are conductively connected to windings of at least two different phases of a transformer (2). 24. The method of claim 22 or claim 23, wherein the device under test (2) is a transformer (2), and wherein the test device (10) during the transformer test, a test response via the at least two twin lines (23-26) of the cable (20) detects and based on the test response a static resistance of at least one winding of the transformer (20), a transformation ratio of the transformer (20), a leakage inductance of the transformer (20), a leakage reactance of the transformer (20) and / or a power factor of the transformer (20 ) determined. 25. The method according to any one of claims 22 to 24, wherein the first line (51, 54) of a twin line (23-26) is connected to a current source (15) of the test device (10) and wherein the second line (52, 55) the twin line (23-26) is connected to a voltage measuring device (16) of the test device (10).