High-voltage device and method for testing a high-voltage device

Abstract

The invention relates to a high-voltage device (1), preferably for use as a cable termination, and to a method for testing a high-voltage device (1). The high-voltage device (1) has: an insulating body (20); an inner conductor (10) which is guided through the insulating body (20) in an axial direction; wherein the insulating body (20) comprises a plurality of control inlays (22a to 22g), preferably produced from conductive films, arranged concentrically around the inner conductor (10) for field control; and the insulating body (20) forms an inner cone (21) at one axial end.

Description

[0001] Description

[0002] High-voltage device and method for testing a

[0003] High-voltage device

[0004] Technical area

[0005] The application relates to a high-voltage device, preferably for use as a cable termination, and to a method for testing a high-voltage device.

[0006] State of the art

[0007] At the end of a solid-insulated high-voltage cable, a cable termination is required to connect to an overhead line or switchgear. The cable termination provides a mechanical connection to the cable and also forms an electrically and field-compatible transition to the cable.

[0008] The field distribution is usually controlled by a few large electrodes at ground and high-voltage potential, which can be placed right up to the surface of the insulating body. More recent developments rely on more precise control at the cable termination with numerous conductive inserts, also known as "control inserts," which allow intermediate potentials and thus achieve a uniform field load.

[0009] EP 4 243 229 A1 describes a high-voltage device which can function as a cable termination, comprising an insulating body, an inner conductor and a plurality of control inserts arranged concentrically around the inner conductor for field control.

[0010] The thin control inserts must not extend to the surface of the insulating body, as this could cause excessive field strengths. The challenge is to optimally determine the positions of the control inserts and, through a precisely defined manufacturing process, to ensure that the positions of the control inserts in the finished product meet the design criteria.

[0011] Description of the invention

[0012] An object of the invention is to provide an improved high-voltage device and an improved method for testing a high-voltage device.

[0013] This object is achieved by a high-voltage device having the features of claim 1 and a method having the features of the subordinate method claim. Advantageous further developments follow from the subclaims, the following description of the invention, and the description of preferred embodiments.

[0014] The invention relates to a high-voltage device which is preferably used as a cable end closure, for example for connecting a cable to a line, in particular an overhead line.

[0015] The high-voltage device comprises an insulating body and an inner conductor that extends through the insulating body in an axial direction. In other words, the insulating body surrounds the inner conductor. The inner conductor defines an axial direction and a radial direction. The high-voltage device is preferably constructed axially symmetrically.

[0016] The insulating body contains several control inserts, preferably made of conductive foils, arranged concentrically around the inner conductor for field control. The control inserts preferably extend entirely within the interior of the insulating body, i.e., the control inserts, especially their ends, should not protrude from the surface of the insulating body, as they would otherwise cause high field strengths.

[0017] The insulating body is designed as an inner cone at one axial end. The control inserts extend with their axial ends into the inner cone, thus enabling fine field control in this area.

[0018] The high-voltage device according to the invention has the basic function of a capacitively controlled high-voltage bushing with a receptacle for the cable end in the form of an inner cone. Due to its fine axial and radial control of the electric field, it achieves a very uniform and low load on the surrounding insulating media (e.g., open air, oil, gas, solid) while maintaining compact overall dimensions. The high-voltage device offers a resource-saving and cost-effective design of a dry, for example, resin-impregnated and capacitor-controlled high-voltage bushing. Through optimal field-technical design, the field strength load on the components can be kept as low as possible.

[0019] The axial distance between the axial end of the shortest control insert and the axial end of the longest control insert is referred to as the axial control distance. If the axial ends of the inner control inserts define an imaginary control line, the control distance is the area from the beginning to the end of the imaginary line along the insert ends. A longer control distance generally allows for more effective field control.

[0020] Preferably, the control insert closest to the inner conductor in the radial direction has the shortest distance from the outer surface of the inner cone compared to the other control inserts. The control insert closest to the inner conductor (adjacent) at high-voltage potential, also referred to herein as the "high-voltage insert", defines the position of the start of control and is preferably positioned so that the distance to the insulating material surface (outer surface) of the inner cone is as minimal as possible. This achieves maximum shielding of the areas below the high-voltage insert, which may contain sharp-edged metal parts or air gaps. For the same reason, the high-voltage insert preferably projects beyond the start of the cone, i.e. in this case the high-voltage insert extends in the axial direction beyond the start of the inner cone.

[0021] Preferably, the control inserts comprise a group of inner control inserts, wherein the distance between the axial ends of the inner control inserts and the outer surface of the inner cone increases from the inside to the outside, as seen in the radial direction. In this way, the potential reduction is optimized in the axial and radial directions.

[0022] If the axial ends of the inner control inserts define an imaginary control line, this preferably forms a control angle a > 0 with an inner cone line which is defined by the outer surface of the inner cone in longitudinal section.

[0023] The length of the control path and / or the control angle, along with the number of control elements, are selected depending on the operating and test voltage values ​​so that the potential reduction in the axial and radial directions results in the lowest possible field strength loads. The respective electrode geometry and position, particularly on the cable connector side, are also taken into account in the design and can lead to individual adaptation.

[0024] Preferably, the insulating body has, adjacent to the inner cone, a hollow cylindrical section, viewed in the radial direction, which extends the insulating body in the axial direction relative to the axial end of the inner cone. The hollow cylindrical section thus protrudes outward, for example, in the direction of a cable connector to be connected.

[0025] Preferably, a control insert, which is the last control insert in the radial direction of the insulating body, extends axially into the protruding section. The control insert extending into the protruding section is at ground potential. By extending the last control insert in this way, in particular beyond the control path, the field loading is limited to the area below the control insert between the high-voltage device and a plug part. This has the advantage that a shielded transition is created and there is no significant field loading outside the plug-in area.

[0026] The insulating body preferably comprises hardened resin, for example in the form of resin-impregnated insulating layers. After impregnation with the resin (for example an epoxy resin), such an insulating body is dimensionally stable and forms a relatively hard block. The insulating layers can comprise paper or fleece and can be wound concentrically or spirally around the inner conductor to form a winding body. In this way, the high-voltage bushing can be manufactured particularly simply and cost-effectively. Furthermore, a particularly uniform arrangement of the insulating layers in the insulating body can be ensured. The high-voltage device designed in this way is particularly low-maintenance.

[0027] The above-mentioned object is further achieved by a method for testing a high-voltage device. The method comprises: producing a high-voltage device comprising an insulating body and an inner conductor that is guided through the insulating body in an axial direction, wherein a plurality of control inserts arranged concentrically around the inner conductor are provided in the insulating body for field control; and testing a position of at least one of the control inserts by means of an ultrasonic measurement, which is carried out by means of a testing device with an ultrasonic sensor.

[0028] The ultrasonic testing concept allows for quality assurance during the production of the high-voltage device and / or conclusions regarding any positional changes during the manufacturing process and / or the creation of a control element profile to verify functionality. Ultrasonic testing for reliable determination of the control element position(s) eliminates the need for a preliminary test of the high-voltage device with the cable connected. A single test of the high-voltage device after production is sufficient to enable direct assembly at the installation site.

[0029] Preferably, the testing device is based on the measuring principle of a pulse-echo method and / or a through-transmission method, whereby the position of the control inserts can be determined reliably.

[0030] The ultrasonic measurement can be carried out using a contact and / or immersion technique.

[0031] To improve the measurement accuracy, the test device is preferably adjusted to the sound speed of the material(s) of the insulating body before the ultrasonic measurement.

[0032] Preferably, the ultrasonic measurement is carried out along the entire control path in order to subject the high-voltage device to a quality test as comprehensively as possible.

[0033] The test concept is not limited to an insulating body with an inner cone, but is also applicable to insulating bodies of other geometries, including in particular insulating bodies with an outer cone.

[0034] In the case of testing a high-voltage device according to one of the embodiments described above, the features, technical effects, advantages and embodiments described with reference to the high-voltage device apply analogously to the method.

[0035] Further advantages and features of the present invention will become apparent from the following description of preferred embodiments. The features described therein can be implemented alone or in combination with one or more of the features set forth above, provided the features do not contradict one another. The following description of preferred embodiments is made with reference to the accompanying drawings.

[0036] Short description of the figure

[0037] Preferred further embodiments of the invention are explained in more detail by the following description of the figure. It shows:

[0038] Figure 1 shows schematically a longitudinal section through a high-voltage device with an inner conductor, an insulating body and several control inserts arranged therein.

[0039] Detailed description of preferred embodiments

[0040] Preferred embodiments are described below with reference to Figure 1.

[0041] Figure 1 schematically shows a longitudinal section through a high-voltage device 1 with an inner conductor 10 and an insulating body 20 surrounding the inner conductor 10. The high-voltage device 1 is axially symmetrical, with Figure 1 showing only one "half" of the insulating body 20. The high-voltage device 1 can be used as a cable termination for a high-voltage cable.

[0042] The insulating body 20 comprises an inner cone 21 designed to receive a complementary end of a cable connector (not shown in Figure 1) or the like. The inner cone 21 is delimited by a lateral surface 21a, the longitudinal section of which defines an inner cone line.

[0043] Control inserts 22a to 22g extend concentrically around the inner conductor 10 inside the insulating body 20. The control inserts 22a to 22g extend with their axial ends into the inner cone 21 and enable fine field control in this area. The control inserts 22a to 22g are preferably made of conductive foils.

[0044] The insulating body 20 preferably comprises cured resin. According to one embodiment of the invention, the insulating body 20 comprises resin-impregnated insulating layers. After impregnation with the resin (e.g. an epoxy resin), such an insulating body 20 is dimensionally stable and forms a relatively hard block. The insulating layers can comprise paper or fleece and can be wound concentrically or spirally around the inner conductor 10 to form a winding body. In this way, the high-voltage bushing 1 can be manufactured particularly simply and cost-effectively. Furthermore, a particularly uniform arrangement of the insulating layers in the insulating body 20 can be ensured. The high-voltage device 1 configured in this way is particularly low-maintenance.

[0045] Although Figure 1 depicts control insert 22g as the shortest and 22a as the longest, it is possible that control inserts 22a to 22g extend even further to the left and are also graduated there, so that, for example, in a complete representation, control insert 22b may be the shortest. In this description, the terms "shortest," "longest," etc., in the context of the control inserts, refer to the representation in Figure 1.

[0046] The axial distance between the axial end of the shortest control insert 22g and the axial end of the longest control insert 22a is referred to as the axial control path S. If, as in the exemplary embodiment of Figure 1, the axial ends of the inner control inserts 22b to 22g define an imaginary control line 24, the area from the beginning to the end of the imaginary line 24 along the insert ends is referred to as the control path S. A longer control path S generally allows for more effective field control.

[0047] The closest (neighbouring) to the inner conductor 10

[0048] Control insert 22g on high voltage potential, also referred to herein as "high voltage insert", defines the position of the control start and is positioned so that the minimum possible distance a minto the insulating surface of the inner cone 21. This ensures maximum shielding of the areas below the high-voltage insert 22g, which may contain sharp-edged metal parts or air gaps.

[0049] Preferably, the high-voltage insert 22g projects beyond the beginning of the cone, i.e. in this case the high-voltage insert 22g extends in the axial direction beyond the beginning of the inner cone.

[0050] The ends of the control inserts 22a to 22g should not protrude from the surface of the insulating body 20, since otherwise they would cause high field strengths.

[0051] The insulating body 20 of the high-voltage device 1 according to the present exemplary embodiment has, in addition to the inner cone 21, a protruding or hollow-cylindrical section 23 which has a hollow-cylindrical shape and extends the insulating body outwards, i.e. towards the cable connector or the like. The control insert 22a at earth potential located therein, which is the last control insert in the radial direction of the insulating body 20, extends in the axial direction into the protruding section 23. By extending the last control insert 22a beyond the control path S in this way, the field loading is limited to the area below the control insert 22a between the high-voltage device 1 (= high-voltage bushing) and a connector part or the like. This has the advantage that a shielded transition is created and there is no significant field loading outside the plug-in area.

[0052] The ends of the control inserts 22b to 22g in the inner cone 21, which are also referred to herein as "inner control inserts" (all control inserts except the radially outer control insert 22a at ground potential), define an imaginary control line 24, which forms a control angle a > 0 with the outer surface 21a (= inner cone line in longitudinal section). In other words, the distance between the ends of the inner control inserts 22b to 22g and the outer surface 21a, i.e. the insulating material surface, increases from the inside to the outside, viewed in the radial direction.

[0053] The length of the control path S and / or the control angle a, together with the number of control inserts 22a to 22g, are selected depending on the operating and test voltage values ​​so that the potential reduction in the axial and radial directions results in the lowest possible field strength loads. The respective electrode geometry and position on the cable connector side are also taken into account in the design and can lead to individual adaptation. The permissible field strengths depend on the application and material.

[0054] The field distribution influenced by the control inserts 22a to 22g differs depending on whether an AC voltage or a DC voltage is applied.

[0055] The determination of the position of the control inserts 22a to 22g for the manufacturing process, for example the winding process, of the insulating body 20 is preferably carried out taking into account the thermal shrinkage and expansion effects during the manufacturing process.

[0056] The high-voltage device 1 described above offers a particularly compact, lightweight, and thus resource-saving and cost-effective design of a dry, e.g., resin-impregnated and capacitor-controlled high-voltage bushing, particularly as a cable termination. Through optimal field-technical design, the field strength load on the components can be kept as low as possible.

[0057] A check of the positions of the control inserts 22a to 22g, in particular their end positions, along the surface of the finished insulating body 20 is carried out by means of a testing device 50 comprising an ultrasonic sensor 51.

[0058] The function of the testing device 50 can be based on different measuring principles, including, for example, the pulse-echo method with one or more, in particular two, ultrasonic sensors 51 in an angular arrangement and / or the through-transmission method. The test can be performed using both contact and immersion techniques, with the ultrasonic sensor 51 being able to be moved manually or automatically.

[0059] The ultrasonic test is preferably calibrated in advance to the sound velocity of the material(s) of the insulating body 20. The use of spacers, which also allow complete or partial angle compensation of the cone slope, is also feasible. The measurement can be performed along the entire control section S; in some cases, a check of the position of individual, critical control inserts 22a to 22g may be sufficient as a routine test. The test can be performed several times at circumferentially offset locations.

[0060] By computationally evaluating (manually or automatically) the transit times of the ultrasonic signals, taking into account the ultrasonic sensor position(s) during the measurement data acquisition, the radial position (depth) and axial position of the control inserts 22a to 22g or their ends can be clearly determined. The computational evaluation is preferably carried out by means of an evaluation device 52, which is in communication with the at least one ultrasonic sensor 51.

[0061] The test concept presented above allows quality assurance during production of the high-voltage device 1, conclusions to be drawn about possible position changes during the manufacturing process and / or the creation of a control insert profile to demonstrate functionality. The test concept is not restricted to an insulating body 20 with an inner cone 21 as shown above, but is also applicable to insulating bodies of other geometries, including in particular insulating bodies 20 with an outer cone. The reliable determination of the control insert position(s) using the test concept presented above makes a preliminary test of the high-voltage device 1 with the connected cable superfluous. An individual test of the high-voltage device 1 after production is sufficient to enable direct assembly at the place of use.

[0062] Where applicable, all individual features shown in the embodiments can be combined and / or exchanged with one another without departing from the scope of the invention.

[0063] Reference symbol list

[0064] 1 high-voltage device

[0065] 10 inner conductors

[0066] 20 I insulating body

[0067] 21 inner cone

[0068] 21a Shell surface

[0069] 22a . . . 22g Tax deposit

[0070] 23 Hollow cylindrical section

[0071] 24 tax line

[0072] 50 test fixture

[0073] 51 Ultrasonic sensor

[0074] 52 Evaluation device

[0075] S control path a min Minimum distance of the high-voltage insert a control angle

Claims

Patent claims 1. High-voltage device (1), preferably for use as a cable end closure, comprising: an insulating body (20); an inner conductor (10) which is guided through the insulating body (20) in an axial direction; wherein the insulating body (20) comprises a plurality of control inserts (22a to 22g) arranged concentrically around the inner conductor (10), preferably made of conductive foils, for field control; and the insulating body (20) forms an inner cone (21) at one axial end.

2. High-voltage device (1) according to claim 1, characterized in that the control insert (22g) closest to the inner conductor (10) in the radial direction has the smallest distance to the outer surface (21a) of the inner cone (21) compared to the other control inserts (22a to 22f).

3. High-voltage device (1) according to claim 2, characterized in that the control inserts (22a to 22g) comprise a group of inner control inserts (22b to 22g), wherein the distance between the axial ends of the inner control inserts (22b to 22g) and the outer surface (21a) of the inner cone (21) increases from the inside to the outside, viewed in the radial direction.

4. High-voltage device (1) according to claim 3, characterized in that the axial ends of the inner control inserts (22b to 22g) define an imaginary control line (24) which forms a control angle a > 0 with an inner cone line which is defined by the lateral surface (21a) of the inner cone (21) in longitudinal section.

5. High-voltage device (1) according to one of the preceding claims, characterized in that the inner conductor (10) nearest control insert in radial direction (22g) extends in the axial direction beyond the beginning of the inner cone (21).

6. High-voltage device (1) according to one of the preceding claims, characterized in that the insulating body (20) has, following the inner cone (21), seen in the radial direction, a hollow cylindrical section (23) which extends the insulating body (20) in the axial direction.

7. High-voltage device (1) according to claim 6, characterized in that a control insert (22a), which is the last control insert in the radial direction of the insulating body (20), extends in the axial direction into the projecting portion (23).

8. High-voltage device (1) according to one of the preceding claims, characterized in that the insulating body (20) comprises cured resin in the form of resin-impregnated insulating layers which are wound concentrically or spirally around the inner conductor (10) to form a winding body, wherein the insulating layers preferably comprise paper or fleece.

9. A method for testing a high-voltage device (1), the method comprising: Producing a high-voltage device (1) comprising an insulating body (20) and an inner conductor (10) which is guided through the insulating body (20) in an axial direction, wherein a plurality of control inserts (22a to 22g) arranged concentrically around the inner conductor (10) are provided in the insulating body (20) for field control; and Checking a position of at least one of the control inserts (22a to 22g) by means of an ultrasonic measurement which is carried out by means of a testing device (50) with an ultrasonic sensor (51).

10. The method according to claim 9, characterized in that the testing device (50) is based on the measuring principle of a pulse-echo method and / or a through-transmission method.

11. Method according to claim 9 or 10, characterized in that the ultrasonic measurement is carried out using a contact and / or immersion technique.

12. Method according to one of claims 9 to 11, characterized in that before the ultrasonic measurement, an adjustment of the testing device (50) is carried out to the speed of sound of one or more materials of the insulating body (20).

13. Method according to one of claims 9 to 12, characterized in that the ultrasonic measurement is carried out along the entire control section (S), defined by the axial distance between the axial end of a shortest control insert (22g) and the axial end of a longest control insert (22a).

14. Method according to one of claims 9 to 13, characterized in that the insulating body (20) of the high-voltage device (1) forms an inner cone (21) or outer cone at one axial end.

15. Method according to claim 14, characterized in that the high-voltage device (1) is a high-voltage device (1) according to one of claims 2 to 7.

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