AN APPARATUS FOR INDICATING A STATUS OF AN ELECTRICAL CABLE

Abstract

An apparatus and a method for indicating a status of an electrical cable, in particular in a power system of a vehicle the apparatus being configured to be attached to the electrical cable, the apparatus comprising: voltage measuring means for continuously measuring a voltage level of the electrical cable, at least one light-emitting indicator configured to be visibly attached to the electrical cable, control means for controlling emission of light from the at least one light-emitting indicator based on the measured voltage of the electrical cable. The apparatus is adapted to be powered by a power source other than the electrical cable.

Claims

1. An apparatus for indicating a status of an electrical cable, the apparatus being configured to be attached to the electrical cable, the apparatus comprising: voltage measuring means for continuously measuring a voltage of the electrical cable, at least one light-emitting indicator configured to be visibly attached to the electrical cable, control means for controlling emission of light from the at least one light-emitting indicator based on the measured voltage of the electrical cable, characterized in that the apparatus is adapted to be powered by a power source other than the electrical cable.

2. The apparatus according to claim 1, wherein the at least one light-emitting indicator is configured so that light may be emitted along a length of the electrical cable.

3. The apparatus according to claim 2, wherein the at least one light-emitting indicator comprises a plurality of light-emitting indicators configured to be mounted along the electrical cable.

4. The apparatus according to claim 1, wherein the voltage measuring means comprises at least two voltage probes for measuring a voltage between at least two conductors of the electrical cable, the control means being configured to control the emission of light from the at least one light-emitting indicator based on the measured voltage between the conductors.

5. The apparatus according to claim 1, wherein the voltage measuring means is configured to contact a conductor of the electrical cable at a non-shielded portion of the conductor, and wherein the apparatus further comprises a shield configured to electromagnetically shield the non-shielded portion of the conductor when the apparatus is attached to the electrical cable.

6. The apparatus according to claim 1, wherein the apparatus comprises at least one electronic control unit configured to control the voltage measuring means and the emission of light from the at least one light-emitting indicator, preferably wherein the apparatus comprises at least two such electronic control units configured to work in redundancy.

7. The apparatus according to claim 1, wherein the control means is configured to control at least one of a colour, an intensity and a flashing pattern of light emitted from the at least one light-emitting indicator based on the measured voltage of the electrical cable.

8. The apparatus according to claim 1, wherein the control means is configured to determine the status of the electrical cable based on the measured voltage thereof to one of at least a first status and a second status, wherein the first status is associated with a measured voltage below a predefinable threshold level or within a first predefinable range, and the second status is associated with a measured voltage above the predefinable threshold level or within a second predefinable range, and wherein the control means is further configured to control the emission of light based on the determined status.

9. The apparatus according to claim 8, wherein each one of the at least first and second statuses is associated with the emission of light of at least one of a predefinable distinguishing colour, a predefinable distinguishing intensity and a predefinable distinguishing flashing pattern.

10. The apparatus according to claim 1, further comprising current measuring means for measuring an electric current of the electrical cable.

11. The apparatus according to claim 1, further comprising a signal interface for communicating data to and/or from the apparatus.

12. A cable assembly comprising an electrical cable and an apparatus according to claim 1, wherein the at least one light-emitting indicator is attached to the electrical cable and wherein the voltage measuring means is configured for measuring a voltage of the electrical cable.

13. An energy storage system comprising at least one power source and at least one cable assembly according to claim 12 connected to the at least one power source.

14. A vehicle or a working machine or a vessel comprising an apparatus according to claim 1, a cable assembly comprising an electrical cable and an apparatus, wherein the at least one light-emitting indicator is attached to the electrical cable and wherein the voltage measuring means is configured for measuring a voltage of the electrical cable and an energy storage system comprising at least one power source and at least one cable assembly connected to the at least one power source.

15. A method for indicating a status of an electrical cable, the method comprising: continuously measuring (101) a voltage of the electrical cable, controlling emission of light from at least one light-emitting indicator based on the measured voltage of the electrical cable, the at least one light-emitting indicator being visibly attached to the electrical cable, wherein a power for measuring the voltage and for controlling the emission of light is obtained from a power source other than the electrical cable.

16. The method according to claim 15, wherein controlling the emission of light from the at least one light-emitting indicator comprises controlling at least one of a colour, an intensity and a flashing pattern of light emitted from the at least one light-emitting indicator based on the measured voltage of the electrical cable.

17. The method according to claim 15, wherein controlling the emission of light from the at least one light-emitting indicator comprises: determining the status of the electrical cable based on the measured voltage thereof to one of at least a first status and a second status, wherein the first status is associated with a measured voltage below a predefinable threshold level or within a first predefinable range, and the second status is associated with a measured voltage above the predefinable threshold level or within a second predefinable range, controlling the emission of light from the at least one light-emitting indicator based on the determined status.

18. A computer program comprising program code performing the steps of claim 15, when said computer program is run on a computer.

19. A computer readable medium carrying a computer program comprising program code performing the steps of claim 15 when said computer program is run on a computer.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

[0057] In the drawings:

[0058] FIG. 1 is a perspective view of a vehicle according to an embodiment of the invention,

[0059] FIG. 2 is a perspective view of a power system including an apparatus according to an embodiment of the invention,

[0060] FIG. 3 is a perspective view of an apparatus according to an embodiment of the invention,

[0061] FIG. 4 is a schematic view of the apparatus according to an embodiment of the invention, and

[0062] FIG. 5 is a flow chart illustrating a method according to an embodiment of the invention.

[0063] The drawings show diagrammatic exemplifying embodiments of the present invention and are thus not necessarily drawn to scale. It shall be understood that the embodiments shown and described are exemplifying and that the invention is not limited to these embodiments. It shall also be noted that some details in the drawings may be exaggerated in order to better describe and illustrate the invention. Like reference characters refer to like elements throughout the description, unless expressed otherwise.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

[0064] FIG. 1 schematically depicts a motor vehicle 11 in the form of an electrically operated bus. The bus is an example of a vehicle in which an apparatus 1 according to embodiments of the invention may be applied. The vehicle 11 comprises a schematically illustrated energy storage system 10 connected to an electric motor (not shown) for propelling drive wheels 22 of the vehicle 11. The energy storage system 10 includes a battery 14 comprising a plurality of battery units, an electrical cable 2 connecting the battery 14 to a power converter/inverter assembly 15, and an apparatus 1 for indicating a status of the electrical cable 2. The energy storage system 10 forms part of an electric propulsion system of the vehicle 11.

[0065] A 600 V battery 14 and a pre-charge device 17 for use in a vehicle or working machine is shown in FIG. 2. The pre-charge device 17 is connected to the battery 14 by means of two electrical cables 2a, 2b, which are herein bound together in a cable harness 16. An apparatus 1 for indicating a status of the electrical cables 2a, 2b is furthermore provided, i.e. for indicating whether any one of the cables 2a, 2b is energised by a potentially hazardous voltage level or not. The apparatus 1 has a housing 18 mounted around the cables 2a, 2b and attached to a casing of the battery 14. The apparatus 1 includes a plurality of light-emitting indicators 4 that are visibly attached to the cable harness 16. The light-emitting indicators 4 are configured to emit light indicating the status of the electrical cables 2a, 2b based on a measured voltage level thereof as will be further explained below.

[0066] FIG. 3 shows a cable assembly 23 including an apparatus 1 according to an embodiment of the invention and two electrical cables 2a, 2b, bound together in a cable harness 16. The cables 2a, 2b may in this case be connected to e.g. a 600 V DC power source of a vehicle, in which case one of the cables 2a may be at a voltage level of +600 V, and the other cable 2b is ground, i.e. at a 0 V voltage level. In the shown embodiment, the cable harness 16 comprises a transparent hose inside which the cables 2a, 2b extend. The apparatus 1 includes a housing 18, mounted around the cables 2a, 2b, which housing 18 is configured to be attached to e.g. a battery casing by means of fastening elements (not shown), similarly to what is shown in FIG. 1. The apparatus 1 further comprises voltage measuring means 3 for continuously measuring a voltage level between the respective electrical cables 2a, 2b. The voltage measuring means 3 is controlled by an electronic control unit 7. In this case, the voltage measuring means 3 comprises two voltage probes, such that a voltage level between the cables 2a, 2b can be determined, thereby determining if it would be hazardous to touch the cables.

[0067] Two sets of light-emitting indicators 4a, 4b are provided, each set of light-emitting indicators 4a, 4b being mounted on and along the respective electrical cable 2a, 2b. In the shown embodiment, the sets of light-emitting indicators 4a, 4b are provided as LED strips attached to the electrical cables 2a, 2b. The electronic control unit 7 is adapted for controlling emission of light from the two sets of light-emitting indicators 4a, 4b based on the measured voltage level between the electrical cables 2a, 2b. Thus, the emission of light from the two sets of light-emitting indicators 4a, 4b is controlled based on the same measured voltage level between the cables 2a, 2b.

[0068] The apparatus 1, including the voltage measuring means 3, the electronic control unit 7 and the light-emitting indicators 4a, 4b, is configured to be powered by a power source other than the electrical cables 2a, 2b. In other words, the apparatus 1 is not parasitically coupled to the cables 2a, 2b. Instead, another power source (not shown in FIG. 3) is provided. For this purpose, the apparatus 1 comprises connection means (not shown) for connecting a power source such as an external or internal battery (not shown).

[0069] Reference is now also made to FIG. 4, schematically showing an apparatus 1 for indicating the status of an electrical cable 2 in further detail. For simplicity, only one elongated conductor 12 of the electrical cable 2 is shown in FIG. 4, although it is to be understood that this cable 2 typically includes a set of at least two insulated conductors, which may be in the form of separate cables such as shown in FIG. 3. The cable 2 may e.g. include a ground conductor and a “live” conductor for a DC power source, or a phase conductor and a neutral conductor for an AC power source, or alternatively three phase conductors for an AC power source. Around the elongated conductor 12, a shielding layer 19, protecting against electromagnetic interference (EMI), and an electrically insulating layer 20, are provided. The voltage measuring means 3, comprising a voltage probe, is in contact with a non-shielded portion 13 of the conductor 12. A separate shield 14, enclosing the non-shielded portion 13, is provided. The shield 14 is configured to electromagnetically shield the non-shielded portion 13 of the conductor 12 when the apparatus is attached to the electrical cable 2. A current measuring means 8 in the form of a Rogowski coil is positioned around the non-shielded portion 13 of the conductor 12. The voltage measuring means 3 and the current measuring means 8 are both connected to and controlled by an electronic control unit 7. The set of light-emitting indicators 4 are also connected to the electronic control unit 7 such that a control means 5 for controlling the emission of light from the light-emitting indicators 4 based on the voltage of the electrical cable 2, i.e. a measured voltage between the conductors 12 forming part of the electrical cable 2, is provided. The electronic control unit 7, and thereby also the voltage measuring means 3, the control means 5, the current measuring means 8 and the light-emitting indicators 4, are powered by a power source 6 in the form of a battery. The power source 6 may be placed inside a housing of the apparatus 1 or provided separately. A signal interface 9 for communicating data to and/or from the electronic control unit 7 is also provided.

[0070] Two electronic control units 7 configured to work in redundancy may be provided, such that the fail-safe arrangement is achieved.

[0071] The control means 5, i.e. the electronic control unit 7, is configured to control a colour and/or an intensity and/or a flashing pattern of light emitted from the light-emitting indicators 4 based on the voltage of the electrical cable 2, i.e. the measured voltage between the conductors 12.

[0072] The electronic control unit 7 is in the shown embodiment configured to determine the status of the electrical cable 2 based on the measured voltage between the conductors 12 thereof (of which only one is shown in FIG. 4) to one of a first status and a second status. The first status, which may be labelled “safe”, is associated with a measured voltage below a predefinable threshold level. For example, a threshold level of 30 V for DC voltage and a threshold level of 12 V for AC voltage may be set, which levels are usually considered as safe voltage levels in wet conditions. The second status, which may be labelled “hazardous”, is associated with a measured voltage above the predefinable threshold level. The electronic control unit 7 is configured to control the emission of light from the light-emitting indicators 4 based on the determined status. The first status is associated with the emission of light of a first distinguishing colour, such as green, and a first distinguishing flashing pattern, such as steady, i.e. non-flashing. The second status is associated with the emission of light of a second distinguishing colour, such as red, and a second distinguishing flashing pattern, such as blinking. The intensity of the light, and/or the blinking frequency, may also be set to vary with the measured voltage. For example, the intensity and/or blinking frequency may be set to increase with increasing voltage.

[0073] A method according to an embodiment of the invention is illustrated in FIG. 5. An apparatus 1 attached to at least one electrical cable 2 as described above is used in the method.

[0074] In a first step 101, a voltage of the electrical cable 2 is continuously measured by means of the voltage measuring means 3.

[0075] In a second step 102, the emission of light from the at least one light-emitting indicator 4, 4a, 4b is controlled based on the measured voltage of the electrical cable 2 determined in the first step 101.

[0076] Power for measuring the voltage in the first step 101 and for controlling the emission of light in the second step 102 is obtained from a power source 6 other than the electrical cable 2.

[0077] According to an example, the electrical cable 2 as illustrated in FIG. 4 forms part of an energy storage system 10 such as illustrated in FIG. 2, including both a pre-charge device 17 and a hazardous voltage battery 14. The energy storage system 10 is connected to a power converter/inverter assembly 15 as shown in FIG. 1 configured for providing electrical power to drive an electric machine. The apparatus 1 is used for continuously monitoring the status of the electrical cable 2. At a first point in time, a pre-charge device switch is turned on, and a hazardous voltage of 600 V, which is well above a preset threshold level of 30 V, is applied. The cable 2 is thus energised. The voltage measuring means 3 measures a voltage above the threshold level and determines that the status of the cable 2 is the second status, i.e. “hazardous”. The control means 5 controls the light-emitting indicators 4 to emit red, blinking light. At a second later point in time, the pre-charge device switch is switched off to disconnect the battery 14, and the measured voltage starts to decrease. However, due to discharging of capacitors forming part of the power converter/inverter assembly 15, the measured voltage of the cable 2 may still be above the threshold level of 30 V for a certain time period, and the light-emitting indicators 4 continue to emit red, blinking light. As soon as the measured voltage decreases below the threshold level, the control means 5 controls the light-emitting indicators 4 to emit green, steady light.

[0078] The control functionality of the example embodiments may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwire system. Embodiments within the scope of the present disclosure include program products comprising machine-readable medium for carrying or having machine-executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine-readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a machine, the machine properly views the connection as a machine-readable medium. Thus, any such connection is properly termed a machine-readable medium. Combinations of the above are also included within the scope of machine-readable media. Machine-executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions.

[0079] It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.