CABLE TESTING DEVICE AND METHOD

Abstract

A cable testing device (6) integrated in high-voltage electrical equipment (3) provided with a main circuit (17), including at least one line connection (4) and one cable outlet (5); at least one control means comprising at least one switch (1a) and/or one disconnecting switch (1b, 1c, 1d). The testing device (6) stands out as it is installed as a first element upstream of the cable outlet (5) and at the same time downstream of the switch (1a) and/or of the disconnecting switch (1b)(1c)(1d), the testing device (6) being independent from the operation of the main circuit (17), such that the switch (1a) and/or the disconnecting switch (1b)(1c)(1d) keep their contacts in an open position during cable testing, the voltage to perform cable testing being injected into the cable outlet (5) through the testing device (6).

Claims

1. Cable testing device integrated in high-voltage electrical equipment provided with a main circuit which comprises: at least one line connection and one cable outlet, at least one control means installed between the line connection and the cable outlet, said control means comprising at least one switch (1a) and/or one disconnecting switch, wherein the cable testing device comprises at least one inlet with at least one contact for the injection of cable testing voltage; wherein said cable testing device is installed as a first element upstream of the cable outlet and at the same time downstream of the switch and/or of the disconnecting switch; and wherein the testing device is independent from the operation of the main circuit, such that the switch and/or the disconnecting switch keep their contacts in an open position during cable testing, the voltage to perform cable testing being injected into the cable outlet through the testing device.

2. Testing device according to claim 1, wherein the inlet comprises at least a first part made of an insulating material incorporating the contact at least partially therein.

3. Testing device according to claim 2, wherein the inlet additionally comprises a second part made of an insulating material, which is concentric to and slides with respect to the at least first part and incorporates the contact at least partially therein.

4. Testing device according to claim 2, wherein the contact is connected with at least one moving contact that moves between a grounded position and an output cable-connected position of the testing device, said moving contact in the output cable-connected position being in electrical contact with a phase of the cable outlet.

5. Testing device according to claim 4, wherein the moving contact in the grounded position of the testing device is in electrical contact with at least one flange which is grounded.

6. Testing device according to claim 5, wherein the moving contact moves integrally with a platform.

7. Testing device according to claim 6, wherein the platform comprises at least one transmission system the actuation thereof causing the movement of the platform and in turn the movement of the moving contact between the grounded position and the output cable-connected position of the testing device.

8. Testing device according to claim 7, wherein the transmission system comprises at least one drive shaft and a lever, such that the actuation of the lever causes the movement of the moving contact.

9. Testing device according to claim 8, wherein the lever comprises at least one projection which is fitted into the at least first part of the testing device in the output cable-connected and grounded positions of the testing device, thus preventing the rotation of the lever.

10. Testing device according to claim 8, wherein the lever comprises on one of its sides at least one through hole which, in the output cable-connected position of the testing device, allows access to the contacts, and comprising on another one of its sides at least one dead wall which, in the grounded position of the testing device, prevents access to the contacts.

11. Testing device according to claim 8, further comprising an interlocking with the disconnecting switch, such that in the grounded position of the testing device, any operation of the disconnecting switch is prevented when at least one cover of the compartment of the testing device or of the compartment of the cable outlet is open.

12. Testing method for testing cables by means of the testing device described in claim 1, comprising the following steps: a) opening the contacts of the switch and/or the disconnecting switch; b) closing the contacts of the disconnecting switch in a grounded position once the absence of voltage in the circuit is verified; c) opening the cover of the compartment of the testing device or of the compartment of the cable outlet, putting the switch and/or disconnecting switch into service being restricted by interlocking; d) actuating the testing device from the grounded position to the output-cable connected position; e) connecting cable testing equipment to the at least one inlet of the testing device; and f) opening the contacts of the disconnecting switch, said disconnecting switch being located in a position of disconnection.

13. Testing method according to claim 12, further comprising the following steps once cable testing has been performed: g) grounding the contacts of the disconnecting switch; h) disconnecting the cable testing equipment from the at least one inlet; i) actuating the testing device from the output cable-connected position to the grounded position; j) closing the cover of the compartment of the testing device (6) or of the compartment of the cables, thus releasing the disconnecting switch; and k) closing the contacts of the switch and/or the disconnecting switch in the position of connection, the electrical equipment thus being operative.

Description

DESCRIPTION OF THE DRAWINGS

[0049] To complement the description that is being made and for the purpose of aiding to better understand the features of the invention according to a preferred practical embodiment thereof, a set of drawings is attached as an integral part of said description in which the following is depicted with an illustrative and non-limiting character:

[0050] FIG. 1A shows a perspective view of the cable testing device of the invention according to a first preferred embodiment, said testing device being depicted in a grounded position.

[0051] FIG. 1B shows a perspective view of the testing device in an output cable-connected position.

[0052] FIG. 2 shows a front view of the cable testing device of FIG. 1B.

[0053] FIG. 3 shows a plan view of the cable testing device.

[0054] FIG. 4 shows another perspective view of the testing device where its grounding flanges are shown.

[0055] FIG. 5 shows a perspective view of the testing device according to a second preferred embodiment in which the cable testing equipment is connected through at least one conductor.

[0056] FIG. 6 shows a single-line diagram of electrical equipment incorporating the cable testing device of the invention.

[0057] FIG. 7 shows a general perspective view of electrical equipment in which the testing device of the invention is incorporated.

[0058] FIG. 8 shows a perspective view of the testing device according to the second preferred embodiment in which the cable testing equipment is connected through at least one point of contact.

PREFERRED EMBODIMENT OF THE INVENTION

[0059] Several preferred embodiments are described below in relation to the aforementioned drawings without it limiting or reducing the scope of protection of the present invention.

[0060] According to a possible practical embodiment of the invention, the drawings show a cable testing device (6) which is incorporated in high-voltage electrical equipment (3) also known as switchgear. The testing device (6) object of the invention is a passive element, i.e., during normal operation of the electrical equipment (3) said testing device (6) is kept inactive (it is kept in a grounded position), whereas the control means of the main circuit (17) (the switch (1a) and/or the disconnecting switch (1b, 1c, 1d)), schematically shown in FIG. 6, are active (a current circulates through same). In contrast, during cable testing the control means (1a, 1b, 1c, 1d) are kept inactive (their contacts are kept in an open or grounded position). In summary, the testing device (6) of the invention is a device independent from the operation of the main circuit (17), i.e., it is not linked with the control means (1a, 1b, 1c, 1d) when the electrical equipment (3) is in service, and in turn the control means (1a, 1b, 1c, 1d) are also not linked with the testing device (6) during cable testing.

[0061] As shown in FIG. 6, the testing device (6) of the invention is installed together with the elements of the main circuit (17) of the electrical equipment (3) between at least one line connection (4) and at least one cable outlet (5), specifically as a first element upstream of the at least one cable outlet (5) and at the same time downstream of at least one control means (1a, 1b, 1c, 1d), such as a switch (1a) and/or a disconnecting switch (1b, 1c, 1d), for example.

[0062] According to a first preferred embodiment shown in FIGS. 1 to 4, the testing device (6) comprises at least one inlet (7) with at least one contact (2) where the cable testing equipment (24) is connected, and through which the voltage to perform the test is applied. Likewise, the inlet (7) of the testing device (6) comprises at least a first part (16) made of an insulating material which incorporates the contact (2) for the connection of the cable testing equipment (24) at least partially therein.

[0063] In a second preferred embodiment of the invention shown in FIGS. 5 and 8, the possibility of the inlet of the testing device (6) being able to comprise a second part (18) made of an insulating material which is concentric to and slides with respect to the first part (16) and incorporates the contact (2) for the connection of the cable testing equipment (24) at least partially therein either through at least one conductor (25) or through at least one point of contact (26) is contemplated. This sliding second part (18) made of an insulating material provides greater dielectric distance.

[0064] In both possible embodiments, the testing device (6) of the invention comprises at least one moving contact (8), shown in FIGS. 1B, 2, 4, 5 and 8, which is electrically connected with the contact (2) for the connection of the cable testing equipment (24). This moving contact (8) moves integrally with a platform (10) and on the inside of the electrical equipment (3), depicted in FIG. 4, between a grounded position and an output cable-connected position. In the grounded position of the testing device (6), the moving contact (8) is grounded through a flange (15), shown in FIG. 4, whereas in the output cable-connected position of the testing device (6), the moving contact (8) is electrically connected with at least one phase (9) of the cable outlet (5) and insulated from ground.

[0065] As shown in FIGS. 1A, 1B, 4, 5 and 8, the moving contact (8) of the testing device (6) moves integrally with a platform (10) which comprises at least one transmission system, such that the actuation of said transmission system causes the movement of the platform (10) and in turn the movement of the moving contact (8) between the grounded position and output cable-connected position of the testing device (6). The transmission system comprises at least one drive shaft (13) and at least one lever (14). Therefore, the movement of the moving contact (8) of the testing device (6) is produced by means of actuating said lever (14). Although it has been envisaged in the preferred embodiment of the invention that the actuation of the lever (14) is manual, said actuation can also be motorized.

[0066] As a safety measure, as can be seen in FIGS. 3-5 and 8, the lever (14) comprises at least one projection (19) which is fitted into the first parts (16) of the testing device (6) in the output cable-connected and grounded positions of the testing device, thus preventing the rotation of the lever (14) when cable testing is being performed or when the electrical equipment (3) is in service or in normal operation. Likewise, the lever (14) comprises on one of its sides at least one through hole (20), shown in FIGS. 1A, 1B and 2, which in the output cable-connected position of the testing device (6), reflected in FIG. 1B, allows access to the contacts (2), and comprises on another one of its sides at least one dead wall (21) which, in the grounded position of the testing device (6) depicted in FIG. 1A, prevents access to said contacts (2).

[0067] FIG. 6 shows a single-line diagram of an electrical equipment (3) wherein the testing device (6) comprises an interlocking (22) with the disconnecting switch (1b, 1c, 1d), such that in the grounded position of the testing device (6) all operations of the disconnecting switch (1b, 1c, 1d) are prevented when at least one cover (23) of the compartment of the testing device (6) or of the compartment of the cable outlet (5), see FIG. 7, is open.

[0068] The cable testing method using to that end the testing device (6) comprises several steps both for performing the test and for putting the electrical equipment (3) back in service after having performed said cable testing.

[0069] To perform cable testing, in a first step the contacts of the switch (la) and/or the disconnecting switch (1b, 1c, 1d) are opened, the main circuit (17) thus being inactive, i.e., without any power supply. In a second step, the contacts of the disconnecting switch (1b, 1c, 1d) are closed in a grounded position, such that all elements located downstream of said disconnecting switch (1b, 1c, 1d) are grounded. In a third step, the cover (23) of the compartment of the testing device (6) or of the compartment of the cable outlet (5) is opened, putting the switch (1a) and/or the disconnecting switch (1b, 1c, 1d) into service being restricted by interlocking in a safe position. In a fourth step, the testing device (6) is operated from the grounded position to the output cable-connected position, the moving contact (8) being in electrical connection with at least one phase (9) of the cable outlet (5) in this last position. In a fifth step, a cable testing equipment (24) is connected to the inlets (7) of the testing device (6), and finally in a sixth step the contacts of the disconnecting switch (1b, 1c, 1d) are opened, said disconnecting switch (1b, 1c, 1d) being in a position of disconnection and the facility is ready for cable testing.

[0070] Once cable testing is performed, the following steps are carried out to put the electrical equipment (3) back in service. In a first step, the contacts of the disconnecting switch (1b, 1c, 1d) are grounded, in a second step the cable testing equipment (24) is disconnected from the inlets (7), in a third step the testing device (6) is operated from the output cable-connected position to the grounded position, the moving contact (8) being in electrical connection with the grounding flange (15) of the testing device (6), in a fourth step the cover (23) of the compartment of the testing device (6) or of the compartment of the cables is closed, thus releasing the disconnecting switch (1b, 1c, 1d), and finally in a fifth step the contacts of the switch (1a) and/or the disconnecting switch (1b, 1c, 1d) are closed in the position of connection, the electrical equipment (3) thus being operative.

[0071] The electrical equipment (3) can comprise a switch (1a) and/or a disconnecting switch (1b, 1c, 1d), the switch (1a) being able to be a cut-off switch or a circuit breaker, and the disconnecting switch (1b, 1c, 1d) being able to be a disconnecting switch (1b), a disconnecting grounding switch (1c) or a disconnecting switch/disconnecting grounding switch (1d).