ARRANGEMENT FOR EARTHING A DC INTERMEDIATE LINK

Abstract

An arrangement for earthing a DC intermediate link connected to a converter on board a track-bound vehicle is configured to be permanently arranged on board the vehicle and comprises two conducting members (23, 24) permanently connected to a pole each of a DC intermediate link and to a first contact member (29, 30) each movably arranged with respect to second contact members (35, 36) permanently connected to a chassis part of the vehicle connected to earth. A handle (34) is connected to the first or second contact members while being electrically insulated with respect thereto to be manually operated for moving the contact members connected thereto between a position of not earthing and a position of earthing the DC intermediate link.

Claims

1. An arrangement for earthing a DC intermediate link (12, 13) connected to a converter (6, 7, 14, 15) on board a track-bound vehicle (1), configured to be permanently arranged on board a track-bound vehicle and comprising: two conducting members (23, 24) configured to have one end (25, 26) permanently connected to a pole (8-11) of a DC intermediate link and the other end (27, 28) connected to a first contact member (29, 30) configured to be movably arranged with respect to second contact members (35, 36) permanently connected to a chassis part of the vehicle connected to earth, in which the first contact members (29, 30) are movable with respect to the second contact members (35, 36) between an open position not earthing said DC intermediate link (12, 13) and a contacting closed position earthing the DC intermediate link, and a handle (34) is connected to the first or second contact members while being electrically insulated with respect thereto to be manually operated for moving the contact members connected thereto between a position of not earthing and a position of earthing the DC intermediate link.

2. An arrangement according to claim 1, comprising a carrier (31) onto which both contact members (29, 30) connected to the handle (34) are arranged and which is guidedly displaceable along a member (32) fixed with respect to said chassis part.

3. An arrangement according to claim 2, wherein said carrier (31) has at least portions (33) made of insulating material connecting the carrier and the contact members (29, 30) arranged thereon to said handle.

4. An arrangement according to claim 1, wherein said first contact members (29, 30) are plate-like metal members.

5. An arrangement according to claim 4, wherein said second contact members (35, 36) are configured to bear under pretention against large surfaces of the first contact members (29, 30) in said closed position.

6. An arrangement according to claim 5, wherein each said second contact member (35, 36) forms a jaw configured to receive a said first contact member (29, 30) while bearing under pretention from opposite directions thereagainst in said closed position.

7. An arrangement according to claim 1, configured to be arranged inside a converter casing (22) with said handle (34) accessible to be operated under the condition that a front cover of the casing is removed for exposing an opening (38) into the casing.

8. An arrangement according to claim 7, wherein the handle (34) is configured to be arranged to be pulled out of the casing (22) for obtaining said contacting closed position and pushed into the casing for obtaining said open position.

9. An arrangement according to claim 7, wherein the front cover is in a position of closing the opening (38) of the casing configured to hold the handle (34) in a position corresponding to a position of said contact members not earthing the DC intermediate link.

10. An arrangement according to claim 1, comprising means (39, 40) for locking the handle with the first (29, 30) and second (35, 36) contact members in the closed position.

11. An arrangement according to claim 10, configured to be arranged inside a converter casing (22) with said handle (34 accessible to be operated under the condition that a front cover of the casing is roved for exposing an opening (38) into the casing, wherein said means (39, 40) is configured to lock the handle (34) with the first (29, 30) and second (35, 36) contact members in the closed position in a position of the handle preventing said front cover to close the converter casing opening (38).

12. An arrangement according to claim 1, wherein said conducting members (23, 24) are flexible.

13. An arrangement according to claim 12, wherein the conducting members (23, 24) are electrical cables.

14. A method for earthing a DC intermediate link (12, 13) connected to a converter (6, 7, 14, 15) on board a track-bound vehicle (1), and utilizing an arrangement (18, 19) according to claim 1, comprising the steps of: opening a front cover of a converter casing (22) containing said converter and DC intermediate link, and pulling the handle (34) out through a casing opening (38) previously covered by the front cover to a position in which the first contact members (29, 30) and the second contact members (35, 36) are in mutual contact connecting the DC intermediate link (12, 13) to earth.

15. A method according to claim 14, comprising the further step of locking the handle (34) in the pulled-out position for preventing the handle to be unintentionally pushed into the casing (22) to a position corresponding to not earthing the DC intermediate link (12, 13).

16. A track-bound vehicle having for at least one converter on board thereof, an arrangement (18, 19) according to claim 1 for earthing a DC intermediate link (12, 13) connected to the converter (6, 7, 14, 15).

17. An arrangement according to claim 3, wherein said first contact members (29, 30) are plate-like metal members.

18. An arrangement according to claim 2, wherein said first contact members (29, 30) are plate-like metal members.

19. An arrangement according to claim 18, wherein said second contact members (35, 36) are configured to bear under pretention against large surfaces of the first contact members (29, 30) in said closed position.

20. An arrangement according to claim 17, wherein said second contact members (35, 36) are configured to bear under pretention against large surfaces of the first contact members (29, 30) in said closed position.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0024] With reference to the appended drawings, below follows a specific description of an embodiment of the invention cited as an example.

[0025] In the drawings:

[0026] FIG. 1 is a very schematic view illustrating how different types of converters may be arranged in a track-bound vehicle,

[0027] FIG. 2 is a perspective view of an arrangement according to an embodiment of the invention in a position of not earthing a DC intermediate link connected to a converter,

[0028] FIG. 3 is a perspective view of the arrangement shown in FIG. 2 in a position of earthing a said DC intermediate link connected to a converter,

[0029] FIG. 4 is a view illustrating a converter casing containing an arrangement according to FIGS. 2 and 3 with the front cover removed from the casing and the arrangement in the position of not earthing a said DC intermediate link, and

[0030] FIG. 5 is a view corresponding to FIG. 4 with a handle of the arrangement pulled out through the casing opening and the arrangement in a position of earthing said DC intermediate link.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

[0031] FIG. 1 illustrates schematically how electric power may be fed to a track-bound vehicle 1 from an AC-supply line 2 and used in the vehicle. The vehicle is configured to move along the AC-supply line 2 which accordingly acts as an AC-source and which may for example carry a single phase alternating voltage of 15 kV and 16 Hz (Sweden, Germany etc.) or 25 kV and 50 Hz (Denmark, China, India etc.). The vehicle has a transformer 3 for transforming the voltage from the supply line 2 to a suitable level. The transformer has here two secondary windings 4, 5 connected to a line converter 6, 7 each for delivering a direct voltage of for example 0.8-3 kV on the output thereof. Thus, this direct voltage is then present between poles 8, 9 and 10, 11 of DC intermediate links 12 and 13, respectively. These DC intermediate links are connected to an input of a motor converter 14, 15 each controlled for delivering a three-phase alternating voltage on the output thereof to motors 16, 17 for the propulsion of the vehicle. Electric power may in a corresponding way be delivered from a corresponding DC intermediate link to an auxiliary converter for providing electric power to sockets arranged in the track-bound vehicle, such as for connection of computers, and to lighting, heating and other appliances.

[0032] It is schematically illustrated how an arrangement 18, 19 for earthing the respective DC intermediate link 12, 13 is arranged in connection therewith.

[0033] FIG. 2 shows such an arrangement according to an embodiment of the invention. The arrangement has a frame with a bracket 20 for securing the arrangement to the frame 21 (see FIG. 4) of a converter casing 22 containing the converter and electronic equipment associated with the control thereof and also the DC intermediate link connected thereto.

[0034] The arrangement has two conducting members 23, 24 in the form of electrical cables configured to have one end 25, 26 connected to a pole each of a DC intermediate link and the other end 27, 28 connected to a first contact member 29, 30 each in the form of a metal plate. The first contact members 29, 30 are arranged on a carrier 31 being guidedly displaceable along a member 32 fixed with respect to a chassis part of the vehicle through the bracket 20. The carrier 31 has at least portions 33 made of insulating material connecting the carrier and by that the first contact members 29, 30 to a handle 34.

[0035] The arrangement further comprises second contact members 35, 36 permanently connected to a chassis part of the vehicle connected to earth through an earth connecting member 37.

[0036] The first contact members 28, 29 are movable with respect to the second contact members 35, 36 between an open position not earthing said DC intermediate link shown in FIG. 2 and a contacting closed position earthing the DC intermediate link shown in FIG. 3. The second contact members 35, 36 are designed as jaws configured to receive the first contact member while bearing under pretension from opposite directions thereagainst in the closed position shown in FIG. 3.

[0037] When maintenance work is to be carried out in a converter casing a separation contactor is controlled to obtain a zero voltage between the poles of the DC intermediate link, which however in some cases will in fact be a voltage differing from zero, such as 24 V, still remaining. The front cover is then removed from the converter casing 22 to expose the handle 34 of the arrangement as shown in FIG. 4. It is shown how the front cover has pushed the handle into the casing to ensure that the arrangement is in a not earthing state when the front cover is put in place.

[0038] The handle 34 is then gripped by the maintenance operator and pulled out of the casing opening 38 to the position shown in FIG. 5 in which the first contact members 29, 30 has been brought into contact with the second contact members 35, 36 and by that the poles of the DC intermediate link in contact with a chassis part of the vehicle for earthing the DC intermediate link.

[0039] It is shown in FIG. 5 how the handle 34 has through-holes 39, 40 to enable applying a lock to the handle ensuring earthing of the DC intermediate link to be maintained once obtained by preventing unintentional pushing of the handle into the converter casing 22.

[0040] The invention is of course in no way restricted to the embodiment described above, since many possibilities for modifications thereof are likely to be obvious to one skilled in the art without having to deviate from the scope of the invention defined in the appended claims.

[0041] The handle may be connected to the second contact members then movable for obtaining the movement of the contact members with respect to each other between said open position not earthing the DC intermediate link and said contacting closed position earthing the DC intermediate link. The second contact members may then be permanently connected to a said chassis part connected to earth by conducting members, such as flexible electrical cables.

[0042] FIG. 1 shows the invention applied to earthing a DC intermediate link connected to a converter on board a track-bound vehicle fed by an AC-supply line, but the earthing arrangement according to the invention may also be used for DC applications, such as having DC supplies of 750 VDC or 1500 VDC.

[0043] Auxiliary contacts inside the earthing device not shown in the figures are configured to detect the position of the earthing device, and information provided thereby may be used to supervise the position of the earthing device and to interlock power contactors upstreams to be energized and connect voltage to the DC intermediate link.