Method and shielding arrangement for shielding the connection section of a cable on a power converter with frame or bracket, and power converter

Abstract

Method and shielding arrangement (100) for shielding a connection section of a cable (10) on a power converter (200), comprising a frame or a holder (19). The method comprises obtaining (310) an electrically conductive grid element (12), arranging (320) the electrically conductive grid element (12) around and along the connection section and a cable entry (13) on the cable, thereby forming a grid tube around the connection section and the cable entry (13), and clamping (330) the electrically conductive grid element (12) at a first position along the connection section between a first terminal (14) and the cable (10) and at a second position along the connection section between a second terminal (20) and a cable entry (13), wherein the electrically conductive grid element (12) is connected to the frame or holder (19) via at least one of the first terminal (14) and the second terminal (20).A power converter (200) is also disclosed.

Description

TECHNICAL FIELD OF THE INVENTIONThe present invention relates generally to methods and arrangements for shielding cables. More particularly, but not exclusively, the present invention relates to shielding a terminal portion of a cable from a power converter, such as a frequency converter, inverter or rectifier.BACKGROUNDSolutions are known which provide shielding of cables. It is known that the cable itself may contain a shield shield shield as a common conductive layer around its electromagnetic shielding / interference (EMC / EMI) conductors. The shield may then be connected to ground potential, e.g., to the power converter to which it is connected. However, the shield shield is stripped from the vicinity of the conductors at a terminal portion of the cable used to connect to the power converter, thereby exposing the terminal portion to potential electromagnetic compatibility (EMC / EMI) related disturbances. Therefore, there is still a need for development of shielding solutions that can be applied to the electric devices.SUMMARYAn object of the present invention is to provide a method and a shield assembly for shielding a terminal portion of a cable to a power converter, which includes a frame or a bracket and a power converter such as a frequency converter, an inverter, or a rectifier. Another object of the present invention is that the method and shield arrangement facilitate providing or retrofitting a shield, e.g., an EMI / EMC shield, to a power converter.The objects of the invention are achieved by a method and a shielding arrangement for shielding a terminal portion of a cable to a power converter comprising a frame or a bracket, and a power converter such as a frequency converter, an inverter or a rectifier, according to the respective independent claims.According to a first aspect, a method for shielding a terminal portion of a cable from a power converter is provided, which comprises a frame or a holder. The method includes obtaining an electrically conductive grid element and disposing the electrically conductive grid element around and along the terminal portion and a cable lead-in on the cable, thereby forming a grid tube around the terminal portion and the cable lead-in. The method also includes clamping the electrically conductive grid member at a first position along the connection portion between a first terminal and the cable and at a second position along the connection portion between a second terminal and the cable lead-in, wherein the electrically conductive grid member is connected to the frame or the bracket via at least one of the first and second terminals.The method may also include disposing the cable through the cable inlet such that the connection portion is on one side of the cable inlet and the remainder of the cable is on the opposite side of the cable inlet.Moreover, both the first clamp and the second clamp may be connected to the frame or the bracket.The cable introduction can be a grommet, for example a rubber or silicone grommet, which is fastened to the frame or the holder. Thus, the method may include attaching the spout to the frame or the bracket.The first position may be closer to a cable end of the connection portion than the second position. The term "cable end" refers to the portion of the connection portion having one or more exposed conductors for connection to one or more connectors, e.g., the power converter.The electrically conductive grid element may be tubular. The method may therefore comprise arranging the connection portion through the tubular electrically conductive grid element before the cable is connected to one or more connectors of the power converter.The method may comprise wrapping the electrically conductive grid element around and along the connection portion, for example, if the electrically conductive grid element is planar at least after straightening, i.e. before clamping the electrically conductive grid element to the first and second terminals. The wrapping should result in portions of the electrically conductive grid member overlapping so that the cable is completely enclosed in its lateral direction.There may be a clamping arrangement comprising the first clamp, a screw for tightening a clamping part against the cable, the clamping arrangement being adapted for a cable jacket of the cable in a wide diameter range which allows and ensures that the cable jacket can still be tightened by the clamping arrangement within the wide diameter range.According to a second aspect, there is provided a shield arrangement for a terminal portion of a cable on a power converter, comprising a frame or a bracket. The shield assembly includes an electrically conductive grid member for positioning around and along the terminal portion and a cable lead-in on the cable to form a grid tube around the terminal portion and the cable lead-in. The shield assembly also includes a first terminal for clamping the electrically conductive grid member at a first position along the connection portion between a first terminal and the cable and a second terminal for clamping the electrically conductive grid member at a second position along the connection portion between a second terminal and the cable lead-in. The electrically conductive grid element is connected to the frame or the bracket via at least one of the first and second terminals.Both the first clamp and the second clamp can be connected or at least connectable to the frame or the holder.The cable entry may be a grommet, e.g. a rubber or silicone grommet, attached to the frame or the bracket.The first position may be closer to a cable end of the connection portion than the second position.The electrically conductive grid element may be tubular. The method may therefore comprise arranging the connection portion through the tubular electrically conductive grid element before the cable is connected to one or more connectors of the power converter.The electrically conductive grid element may be wound around and along the connection portion, for example, when the electrically conductive grid element is planar at least after being straightened.According to a third aspect, a power converter is provided. The power converter comprises a frame or a holder, a plurality of switching devices for converting one or more currents and / or voltages, one or more connectors for a cable and the shielding arrangement according to the second aspect.Optionally, the power converter comprises a cable inlet which is a grommet, such as a rubber or silicone grommet.The present invention provides a method and a shield arrangement for shielding a terminal portion of a cable to a power converter comprising a frame or bracket and a power converter. The present invention offers advantages over known solutions, since it enables 360 degree shielding of the terminal section of the cable on the converter. The costs are very low, since a piece of electrically conductive grid element is sufficient to ensure shielding. Moreover, the electrically conductive grid element can be used easily in new installations or in retrofitting existing installations.Various other advantages will become apparent to those skilled in the art from the following detailed description.The term "a number of" may refer herein to any positive integer from one (1).The term "a plurality of" may refer to any positive integer from two (2).The terms "first" and "second", etc., are used herein to distinguish one element from another, and not to give them a particular priority or order unless expressly stated otherwise.The exemplary embodiments of the present invention presented herein are not to be construed as limiting the applicability of the appended claims. The verb "comprise" is used herein as an open limitation that does not exclude the presence of features not mentioned either.The features listed in the appended claims can be freely combined with one another, unless expressly stated otherwise.The novel features which are considered characteristic of the present invention are set forth with particularity in the appended claims. The present invention itself, however, both as to its construction and operation, together with additional objects and advantages, will be best understood from the following description of specific embodiments when read in conjunction with the accompanying drawings.BRIEF DESCRIPTION OF THE FIGURESSome embodiments of the invention are illustrated by way of example and not limitation in the figures of the accompanying drawings. Figures 1 to 6 schematically show a shielding arrangement.In FIG. 7, electrically conductive grid elements are shown. FIG. 8 shows a flow chart of a method. FIGS. 9A-9C schematically show power converters.DETAILED DESCRIPTION OF SOME EMBODIMENTSFIGS. 1-6 schematically show a shield arrangement 100. The shield arrangement 100 is provided for a terminal portion of a cable 10 on a power converter comprising a frame or bracket 19. The terminal portion refers to a portion of the cable 10 which is stripped of several layers, if necessary, to expose the conductors. The frame or bracket 19 is preferably located in or connected to the ground potential and / or the housing of the converter and / or to the electrical ground on the side of the power grid.The shield assembly 100 comprises an electrically conductive grid member 12 for positioning around and along the connection portion and a cable lead-in 13 on the cable 10 to form a grid tube around the connection portion and the cable lead-in 13. The shield assembly 100 also includes a first terminal 14 for clamping the electrically conductive grid member 12 at a first position along the connection portion between a first terminal and the cable 10, such as its cable jacket 10A, and a second terminal 20 for clamping the electrically conductive grid member 12 at a second position along the connection portion between the second terminal 20 and the cable lead-in 13.Optionally, the length of the electrically conductive grid element 12, i.e. the longitudinal dimension of the cable 10 around which it is or is to be arranged, is at least three centimeters, preferably in the range of 5-35 centimeters, more preferably in the range of 10-25 centimeters, i.e. for example about 20 centimeters.The distance between the first clamp 14 and the second clamp 20 may be in the range of 2 to 30 centimeters, for example.In some cases, both the first terminal 14 and the second terminal 20 are connected or connectable to the frame or bracket 19.Moreover, the cable inlet may be a grommet, for example a rubber or silicone grommet or a grommet of another electrically insulating material, which is fastened to the frame or the holder 19.The first position may be closer to a cable end of the connection portion than the second position, as seen in FIGS. 1-5, showing the first clip 14 over the second clip 20.In some examples, the electrically conductive grid member 12 is tubular. Thus, it constitutes a grid tube that can be arranged around the connection portion and the cable inlet 13. The cable 10, or at least its terminal portion, may therefore have to be passed through the tubular electrically conductive grid element 12 before the cable is connected to one or more connectors of the converter.In alternative examples, the electrically conductive grid element 12 may be planar at least after straightening. The electrically conductive grid element 12 can therefore be wound around and along the connection section.Figures 1 to 6 also show that the frame or support 19 may comprise two plate-like parts connected by a support member 19A. The base plate 22, which has openings for passage of the cable 10, may be comprised by the frame or the bracket 19.Moreover, the first clamp 14 may comprise a first clamp portion, e.g. in U-shape, that may be attached to the frame or bracket 19 at the ends of the U-shape (may also have another shape, e.g. V or C or more complex shapes). FIG. 4, which shows the shield assembly 100 from the opposite side of FIG. 1, shows terminal attachment portions 14A or terminal fittings, for example, having openings to which the first terminal portion may be attached. Moreover, the first clamp 14 may also comprise a second clamp portion 16 which may be tightened on the cable 10 by a screw 15 having a shank 17, for example against a thread 18 of the clamp 14, or a similar adjustment mechanism, such that the electrically conductive grid element 12 is clamped therebetween in the first position. Thus, the first clamp 14 may be comprised of multiple parts and the adjustment mechanism. The clamping arrangement of the clamp 14, screw 15 and clamp member 16 ensures that the cable jacket 10A can range in a wide range of diameters that can be tightened by the clamping arrangement.Thus, in some embodiments, a clamping arrangement, which may include the first clamp 14, a screw 15 for tightening a clamp portion 16 against the cable 10, i.e., such that the electrically conductive grid element 12 is disposed therebetween, is preferably configured for a cable jacket 10A of the cable 10 in a wide diameter range such that the cable jackets 10A may be tightened within the wide diameter range by the clamping arrangement.The second terminal 20 may be a plate-shaped terminal, according to some embodiments, that may be placed on the lower part of the cable lead-in 13, thereby pressing the electrically conductive grid element 12 against the cable lead-in 13, as can be clearly seen in FIGS. 1-5. Denoted by 21 is a fastening device, such as a screw, bolt, bracket or the like, by which the second terminal 20 is fixed in place to clamp the electrically conductive grid element 12 against the cable lead-in 13.FIG. 6 shows a cable jacket 10A of the cable 10.In FIG. 7, electrically conductive grid elements 12, preferably made of wire grids, are shown. The electrically conductive grid elements 12 are shown in FIG. 7 as grid rollers, from which the element 12 can optionally be cut to suitable dimensions. The grid rollers in Fig. 7 comprise either tubular grids or planar grids. The material of the electrically conductive grid 12 can be (stainless) steel, but can also consist of another electrically conductive material, such as copper, silver, aluminum or a metal alloy. The length of the electrically conductive (wire) grid element 12 may be as described above.FIG. 8 shows a flow chart of a method.Item or step 300 relates to the starting phase of the method. Suitable devices and components may be obtained and systems assembled.Item 310 refers to obtaining an electrically conductive grid element 12.Item 320 refers to disposing the electrically conductive grid member 12 around and along the connecting portion and a cable lead-in 13 on the cable 10, thereby forming a grid tube around the connecting portion and the cable lead-in 13.Item 330 refers to clamping the electrically conductive grid member 12 at a first position along the connection portion between a first terminal 14 and the cable 10, such as its cable jacket 10A, and at a second position along the connection portion between a second terminal 20 and the cable lead-in 13, wherein the electrically conductive grid member 12 is connected to the frame or bracket 19 via at least one of the first terminal 14 and the second terminal 20.Execution of the method may be aborted at point or step 399.The method may also include disposing the cable 10 through the cable inlet 13 such that the connection portion is on one side of the cable inlet 13 and the remainder of the cable 10 is on the opposite side of the cable inlet 13.Also, both the first clamp 14 and the second clamp 20 may be connected to the frame or bracket 19.The cable entry 13 may be a grommet, for example a rubber or silicone grommet, which is fastened to the frame or the holder 19. The method may thus comprise attaching the spout to the frame or support 19.The first position may be closer to a cable end of the connection portion than the second position.The electrically conductive grid element 12 may be tubular. The method may therefore comprise passing the connection portion through the tubular electrically conductive grid member 12 before connecting the cable to one or more connectors of the converter.The method may also comprise wrapping the electrically conductive grid element 12 around and along the connection portion, for example when the electrically conductive grid element is planar at least after straightening.FIGS. 9A-9C schematically show power converters 200. The power converter 200 may be, for example, a frequency converter as schematically illustrated in FIG. 9A, an inverter as illustrated in FIG. 9B, or a rectifier as illustrated in FIG. 9C. The power converter 200 preferably includes one or more connectors 210 for connecting a cable 10.As those skilled in the art will appreciate, the power converter 200 may also include various components not shown and described in detail herein. For example, the power converter 200 may include a controller and various sensors for measuring current / current(s) and voltage(s) and thereby control operation of the apparatus 200.The power converter 200 includes a frame or bracket 19, a plurality of switching devices (not shown in FIGS. 9A-9C but included in the symbol with AC / DC or DC / AC as known to those of skill in the art) for converting one or more currents and / or voltages, and one or more connectors 210 for a cable 10.In various embodiments, the power converter 200 comprises a cable inlet 13 in the form of a bushing, for example made of rubber or silicone, which is fastened, for example, to the frame or the holder 19.

Claims

A method for shielding a terminal portion of a cable (10) on a power converter (200) comprising a frame or bracket (19), the method comprising: obtaining (310) an electrically conductive grid element (12); arranging (320) the electrically conductive grid element (12) around and along the connection portion and a cable lead-in (13) on the cable, thereby forming a grid tube around the connection portion and the cable lead-in (13); and clamping (330) the electrically conductive grid element (12) at a first position along the connection portion between a first terminal (14) and the cable (10) and at a second position along the connection portion between a second terminal (20) and a cable lead-in (13), wherein the electrically conductive grid element (12) is connected to the frame or the holder (19) via at least one of the first terminal (14) and the second terminal (20).The method of claim 1, comprising disposing the cable (10) through the cable inlet (13) such that the connection portion is on one side of the cable inlet (13) and the remainder of the cable (10) is on the opposite side of the cable inlet (13).The method of claim 1 or 2, wherein both the first clamp (14) and the second clamp (20) are connected to the frame or bracket (19).Method according to any one of claims 1 to 3, wherein the cable inlet (13) is a grommet fixed to the frame or the bracket (19).The method of any of claims 1-4, wherein the first position is closer to a cable end of the connection portion than the second position.Method according to any one of claims 1 to 5, wherein the electrically conductive grid element (12) is tubular.The method of any one of claims 1 to 5, comprising wrapping the electrically conductive grid element (12) around and along the connection portion.The method of any one of claims 1 to 7, wherein a clamping arrangement comprising the first clamp (14), a screw (15) for tightening a clamp portion (16) against the cable (10), is configured for a cable jacket (10A) of the cable (10) in a wide diameter range such that the cable jacket (10A) can be tightened by the clamping arrangement.A shielding arrangement (100) for a connection portion of a cable (10) to a power converter (200) comprising a frame or a bracket (19), the shielding arrangement (100) comprising an electrically conductive grid element (12) for arranging around and along the connection portion and a cable lead-in (13) on the cable (12) to form a grid tube around the connection portion and the cable lead-in (13), a first clamp (14) for clamping the electrically conductive grid element (12) at a first position along the connection portion between the first clamp (14) and the cable (10), and a second clamp (20) for clamping the electrically conductive grid element (12) at a second position along the connection portion between the second clamp (20) and the cable lead-in (13), wherein the electrically conductive grid element (12) is connected to the frame or the holder (19) via at least one of the first terminal (14) and the second terminal (20).The shield assembly (100) of claim 9, wherein both the first terminal and the second terminal are connected or connectable to the frame or the bracket.The shielding assembly (100) of claim 9 or 10, wherein the cable entry is a grommet attached to the frame or the bracket.The shield assembly (100) of any one of claims 9 to 11, wherein the first position is closer to a cable end of the connection portion than the second position.The shielding arrangement (100) according to any one of claims 9 to 12, wherein the electrically conductive grid element (12) is tubular.The shielding arrangement (100) according to any one of claims 9 to 13, wherein the electrically conductive grid element (12) is planar.A power converter (200) comprising a frame or bracket (19), a plurality of switching devices for converting one or more currents and / or voltages, one or more connectors (210) for a cable (10), and the shielding arrangement (100) according to any of claims 8 to 13.The power converter (200) according to claim 15, comprising a cable inlet (13) that is a grommet.

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