Device for testing an electrical cable

Abstract

The invention relates to a removable test device (6), arranged to test an electrical cable (1) which is arranged so as to form a loop, comprising: - a connector (7) arranged to interconnect a first end (2a) and a second end (2b) of a conductor (2) of the cable; - a deflector (8) arranged around the connector, the deflector being in electrical conductive contact with the first end (2a) and the second end (2b) of the conductor (2) of the cable, such that applying a test voltage (Vt) and / or a test current (It) to the deflector makes it possible to apply the test voltage and / or test current to the conductor (2) of the cable (1).

Description

ELECTRICAL CABLE TESTING DEVICE

[0001] The present invention relates to testing devices for electrical power transmission cables.

[0002] It is particularly applicable, but not exclusively, in the field of electrical cables designed for medium voltage networks (typically between 1 and 52 kV).

[0003] It is known that to test such an electrical cable, a loop can be formed by connecting the two ends of the cable together. Test voltages and currents can then be applied at this connection, and various measurements can then be taken to verify that the cable conforms to its technical specifications.

[0004] To connect the ends of the cable and apply high test voltages and high test currents in the medium voltage cable loop, terminations are usually used.

[0005] However, the use of terminations presents several drawbacks. Terminations are expensive and bulky devices. Furthermore, their installation is time-consuming and their maintenance is complex. The costs of performing these tests are therefore high.

[0006] Furthermore, the structure of these terminations is such that, when test voltages and test currents are applied, the electric field may not be homogeneous at the termination, which could degrade the measurements taken.

[0007] The present invention aims to remedy the aforementioned drawbacks of the prior art.

[0008] To this end, the present invention proposes a removable test device, arranged to test an electrical cable which is positioned to form a loop by bringing together a first end and a second end of the cable, the removable test device comprising: - a fitting arranged to connect a first end and a second end of a cable conductor; - a deflector arranged around the fitting, the deflector being in electrically conductive contact with the first end and the second end of the cable conductor, so that the application of a test voltage and / or a test current on the deflector allows said test voltage and / or said test current to be applied to the cable conductor; - means for fixing the removable test device, arranged to fix the removable test device to the electrical cable and allowing the removable test device to be removed from the cable in order to be installed on another cable.

[0009] The test device is a smaller accessory than a termination, ideal for closing a medium-voltage cable loop at a lower cost. It is quick to install and easy to maintain. The test device allows for the application of high voltages and the flow of high currents without excessive temperature rise. Furthermore, because the test device is removable, it can be easily used on one cable and then, after testing, removed from that cable and installed on another cable to test it. The test device is therefore easily reusable, thus reducing overall testing costs.

[0010] In addition, the deflector helps to prevent the strengthening of the electric field at the connection point.

[0011] A removable test device as previously described is also proposed, in which the fastening means include first fastening means arranged to fix the fitting to the cable conductor at the first end of the cable and the second end of the cable, and second fastening means arranged to fix the deflector to the fitting.

[0012] We also propose a removable test device as previously described, in which the first means of fixing include first screws which extend into a thickness of the fitting and second screws which extend into a thickness of the deflector.

[0013] In addition, a removable test device as previously described is proposed, arranged so that when the removable test device is installed on the cable, the deflector protrudes on both sides of the fitting.

[0014] We also propose a removable test device as previously described, in which the deflector has the shape of a sleeve having a rounded shape at each of its ends.

[0015] We also propose a test system comprising the removable test device as previously described and test means including a voltage generator and a current generator. Brief description of the drawings

[0016] Other aspects and advantages of the invention will become apparent from the following detailed description of particular embodiments, given by way of non-limiting examples, with reference to the accompanying drawings, in which:

[0017] [Fig. 1] Figure 1 schematically represents an electrical cable, arranged to form a loop, and a removable test device according to the present invention, in a particular embodiment. Description of method(s) of implementation

[0018] Referring to Figure 1, electrical cable 1 is a medium-voltage power transmission cable, but it could be any type of power transmission cable. Of course, Figure 1 is a schematic representation of the cable and does not show its actual length.

[0019] Cable 1 comprises at least one conductor 2, here a single conductor 2, an electrically insulating layer 3 which surrounds the conductor 2, and an outer sheath 4 which surrounds the electrically insulating layer 3. Cable 1 could have a different structure: for example, cable 1 could not have an outer sheath, the cable could have other layer(s), insulating or not, etc.

[0020] As can be seen in Figure 1, cable 1 has been arranged so that cable 1 forms a loop. To do this, the first end 1a of cable 1 and the second end 1b of cable 1 have been brought close together.

[0021] The test device 6 allows tests to be performed on the cable 1 while it is in this "loop" configuration. The test device 6 not only allows the first end 1 to be electrically connected to the other end of the cable 1, but also allows the test device 6 to be performed on the cable 1 in a loop configuration. cable 1 and the second end 1b of cable 1, but also to apply a test voltage and / or inject a test current on the cable at this connection.

[0022] Test device 6 includes: - a fitting 7 arranged to connect together a first end 2a and a second end 2b of conductor 2 of cable 1; - a deflector 8 arranged around the fitting 7, the deflector being in electrically conductive contact with the first end 2a and the second end 2b of conductor 2 of the cable, so that the application of a test voltage Vt and / or a test current It on the deflector allows said test voltage and / or said test current to be applied to conductor 2 of cable 1; - means for fixing the removable test device, arranged to fix the removable test device to the electrical cable and allowing the removable test device to be removed from the cable in order to be installed on another cable.

[0023] Fitting 7 has a general cylindrical shape with axis X, and conductor 2 of cable 1 extends into the fitting along axis X.

[0024] The deflector 8 is arranged around the fitting 7. The deflector 8 also has a general cylindrical shape with axis X, and the fitting 7 extends into the deflector 8 along the axis X.

[0025] The deflector 8 is in the form of a sleeve with a rounded shape at each end. The length of the deflector 8, that is, its dimension along the X-axis, is greater than the length of the fitting 7. In other words, the deflector 8 extends beyond the fitting 7 on both sides.

[0026] Fitting 7 and deflector 8 are both made with one or more electrically conductive materials - for example, metallic. As we have seen, the deflector 8 is in electrically conductive contact with conductor 2 of cable 1 at its first end 2a (corresponding to the first end 1a of cable 1) and its second end 2b (corresponding to the second end 1b of cable 1). The electrical contact is made via the fitting 7.

[0027] To carry out the tests on the cable, test means 10 are brought near the test device 6, for example a voltage generator 10a and a current generator 10b.

[0028] The voltage generator 10a is directly connected to the deflector 8 to apply the test voltage Vt to conductor 2, and the current generator 10b is connected to the deflector 8 to inject the test current It into conductor 2.

[0029] The effect of the deflector 8 is to prevent the amplification of the electric field at the connection 7 during these tests. As a non-limiting example, this is useful when measuring partial discharges, as the deflector prevents the presence of electrical signals at the connection 7 that would distort the measurement. The deflector 8 therefore fulfills a dual function: providing electrical access to the conductor 2 of cable 1 for testing, and homogenizing the electric field at the connection between the ends of cable 1. We will now examine how the test device 6 is installed on cable 1.

[0030] The means for fixing the removable test device 6, enabling it to be fixed to the cable 1, include first means for fixing the fitting 7 to the conductor 2 of the cable 1 at the first end 1a of the cable 1 and the second end 1b of the cable 1, and second means for fixing the deflector 8 to the fitting 7. The means for fixing also enable the device 6 to be assembled.

[0031] The first means of fixing include first screws 11 which extend into a thickness of the fitting 7 and second screws 12 which extend into a thickness of the deflector 8.

[0032] Thus, to install the test device 6, one end 1a, 1b of cable 1 is first passed through the deflector 8, which is then slightly removed from said end. The two ends 2a, 2b of conductor 2 are inserted into the fitting 7, on either side of it. The two ends 2a, 2b of conductor 2 are brought into contact with each other. The fitting 7 is then fixed to the conductor 2 by means of the first screws 11, which are positioned on either side of the first end 2a of conductor 2 and the second end 2b of conductor 2. The first screws 11, which extend into the thickness of the fitting 7, come into contact with conductor 2 to tighten and fix the fitting 7 to conductor 2.

[0033] Then, the deflector 8 is positioned around the fitting 7 and the second screws 12, which extend into the thickness of the deflector 8, come into contact with the fitting 7 to tighten and fix the deflector 8 to the fitting 7.

[0034] The installation of test device 6 is therefore very simple and quick. Test device 6 can be easily removed from the cable and used to perform tests on another cable. Since the same test device can be used to test different cables, there is no need to have many test devices, making these tests inexpensive to perform.

[0035] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0036] Fitting 7 and deflector 8 could have different shapes. Fitting 7 and deflector 8 could each consist of several parts, or they could form a single piece. Fitting 7 and deflector 8 could be assembled in different ways.

Claims

Demands 1. Removable test device (6), arranged to test an electrical cable (1) which is arranged to form a loop by bringing together a first end (1a) and a second end (1b) of the cable, the removable test device comprising: - a fitting (7) arranged to connect together a first end (2a) and a second end (2b) of a conductor (2) of the cable; - a deflector (8) arranged around the fitting, the deflector being in electrically conductive contact with the first end (2a) and the second end (2b) of the conductor (2) of the cable, so that the application of a test voltage (Vt) and / or a test current (It) on the deflector allows said test voltage and / or said test current to be applied to the conductor (2) of the cable (1); - means for fixing (11, 12) the removable test device, arranged to fix the removable test device to the electrical cable and to allow the removable test device to be removed from the cable in order to be installed on another cable.

2. Removable test device according to claim 1, wherein the fastening means comprise first fastening means (11) arranged to fix the fitting (7) to the conductor (2) of the cable at the first end of the cable and the second end of the cable, and second fastening means (12) arranged to fix the deflector (8) on the fitting (7).

3. Removable test device according to claim 2, wherein the first fastening means comprise first screws (11) which extend into a thickness of the fitting (7) and second screws (12) which extend into a thickness of the deflector (8).

4. Removable test device according to any one of the preceding claims, arranged so that when the removable test device is installed on the cable, the deflector (8) protrudes on either side of the fitting (7).

5. Removable test device according to any one of the preceding claims, wherein the deflector (8) has the shape of a sleeve having a rounded shape at each of its ends.

6. Test system comprising the removable test device (6) according to any one of the preceding claims and test means comprising a voltage generator (1 Oa) and a current generator (10b).

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