Patent Application
20150212117
The invention relates to a measuring device for at least one contactless current measurement at an electrical conductor which conducts current, with the features indicated in the preamble of claim 1.
A current measuring device of the kind in question is known from DE 20 2008 012 593 U1. The current measuring device indicated therein comprises a single-part or multi-part housing in which a sensor is arranged in the immediate vicinity of the current-conducting conductor to be measured. The measurement range, which is defined by the magnetic-field sensitivity of the sensor, of the conductor is surrounded by a screening chamber consisting of a screen of a non-magnetisable metallic material when the housing is closed. As sensor, use is made of a Hall sensor with polarity recognition, this being incorporated in a downstream amplifier circuit. The electrical evaluating device is similarly accommodated in the housing. Recesses of half-shell shape for reception of the conductor are formed in the side walls of the housing. The openable lid forms the other half of the recess and includes a part of the screen. In addition, a terminal to enable reading of measurement data out of the memory is provided in the housing at the lower side. The Hall sensor detects the magnetic field resulting from current flow through the conductor and thus delivers a proportional signal for the magnitude of the current flowing.
A measuring device for contactless current measurement at an electrical conductor conducting current is similarly known from 20 2007 005 947 U1, in which at least one Hall sensor is provided as current measuring sensor and is arranged with an appropriate evaluating device in a housing, which is at least partly surrounded by an electrically screening cover and which is fixable by means of a releasable holding device on an electrical conductor through which current flows. Further, an electrical plug connector accessible via a passage in a side wall is fastened to the circuitboard present in the housing. The measuring device is clamped onto a current conductor. In that case, the housing does not enclose the current conductor.
A measuring device for contactless current measurement of an electrical conductor through which current flows is known from U.S. Pat. No. 7,164,263 B2, in which a plurality of magnetic field sensors is arranged on a curved circuitboard. The circuitboard is arranged to extend radially in curved housing halves which in the closed state surround the conductor.
A current measuring device is also known from EP 2 541 261 A1, in which a housing upper part is mounted to be pivotable relative to the housing lower part and has a recess for reception of a current-conducting conductor. A magnetic film which partially surrounds the conductor when the two housing halves are pressed together is insertable into the pivotable housing half. Disposed below the conductor is the current sensor on a circuitboard, which is covered by the magnetic film.
A device for measuring electrical current, direct current and alternating current, which is imposed on the direct current, is known from DE 25 43 828 A1. This device consists of tongs with inductive coils, the jaws of which enclose a recess for the current-conducting conductor in the closed state.
Starting from the prior art defining the genre the invention has the object of designing the measuring device in such a way that the housing parts can be opened without hindrance so as to be able to push the housing in simple manner onto individual conductors of a cabled system and in a further refinement to make possible not only contactless current measurement, but also energy analysis and a flat elongated mode of construction of the housing.
The invention fulfils the object by design of the measuring device in accordance with the technical teaching given in claim 1. In order to make possible energy analysis, a voltage measurement is additionally provided in a further embodiment.
Advantageous developments of the invention are indicated in detail in the subclaims.
According to the invention it is provided in accordance with claim 1 that the first and second housing parts each have at the joint sides in the interior at least one respective substantially semi-cylindrical bearing shell, which shells substantially concentrically enclose the conductor when the housing is closed, that the bearing shells have a diameter which is such a size relative to the conductor that at least one flexible shape-matched conductor track carrier with at least one magnetic field sensor is insertable therein, the carrier having two curved sections which are connected together at the side facing the pivot bearing by way of a loop-shaped connecting section so mounted in the housing as to ensure or not obstruct at least the relative pivot movement of the housing parts during opening and closing of the housing, and that the section, which is placed in the first housing part, of the flexible conductor track carrier provided with conductor tracks is mechanically and electrically connected with a rigid or flexible circuitboard.
According to the invention, use can be made of, for example, a Hall sensor or a magnetoresistive sensor as magnetic field sensor. It has additionally proved that at least two Hall sensors lead to a satisfactory measurement result. The magnetic field sensors are so arranged on the flexible conductor track carrier that the magnetic field components are determinable by tangential measurement. For this purpose, they can be coated on the chip surface, for example of an ASIC, to extend parallelly and not—as usual with Hall sensors—vertically. Such Hall sensors are known from, for example, 20 2007 005 957 U1. Magnetoresistive sensors usable for magnetic field measurement are described in, for example, the periodical Automotive, issue of Aug. 7, 2004, pages 24 ff.
The construction has the advantage that the magnetic field sensor or sensors, which is or are preferably mounted on the inner side of the flexible conductor track carrier in the curved sections, which enclose the conductor, can be in direct contact with the conductor tracks. The electrical current in a conductor is detected by approximation of the ring integral of the magnetic flow density around the conductor. For that purpose, advantageously as magnetic field sensors a plurality of identical, highly integrated Hall sensor ASICs is coated on a flexible conductor track carrier. In that case the conductor track carrier does not have to be separated. The flexible conductor track carrier is wound around the conductor to form a closed curve. This can be carried out directly by the shell-shaped receptacles or, however, also by pre-shaping by means of inserts in the bearing shells. As a consequence of the mechanical construction, the arrangement of the magnetic field sensors on the flexible substrate and the capability of the sensors to be able to measure magnetic fields parallel to the chip surface the error with respect to approximation of the ring integral is negligible. It is possible with the magnetic field sensors to measure the magnetic flux density at equidistant points along an arcuate curve about the current-conducting conductor in a direction tangential to the notional integral gradient curve and this serves as a measure for the current. The Hall sensors in one embodiment are incorporated as magnetic field sensors in ASICs and offer the advantage that DC currents and not just alternating currents can also be measured. The measuring and evaluating methods are, as such, known.
The arrangement according to the invention ensures that installation of the flexible conductor track carrier in the plane is made possible and that thereafter through corresponding shaping or through pushing into the bearing shells the conductor is completely enclosed in desired manner by the two curved sections. The loop-shaped connecting member between the two sections ensures that the housing can always be opened, thus the upper housing part can be pivoted open relative to the lower to enable withdrawal of the lower housing part and the upper housing part from a conductor. The stated production advantages in installation and also in the introduction into the housing parts of a housing, are obvious.
The two housing parts are connected together at one side by way of one or more pivot joints or also by way of a hinge consisting of pivot joints, whilst at the other side a detent connection can be provided; however, a different lock securing means can also connect together the parts. It will be similarly obvious that the passages in the side walls, which consist of half shells, have to be of such a size that the conductor, which in diameter can be between, for example, 1 millimetre and 24 millimetres in size, can be inserted. In principle, uninsulated conductors can be inserted. However, it is also possible to insert conductors provided with an insulating layer, thus encased.
In order that the conditions of the German Association for Electrical, Electronic and Information Technologies, part 100, are adhered to and there is a sufficient contact spacing between the flexible conductor track carrier and the conductor tracks disposed thereon as well as of the components from the current-conducting conductor, a further embodiment provides that flat elements of insulating material with recessed portions enclosing the conductor are inserted into the housing parts between the conductor and the flexible conductor track carrier at least in the region of the bearing shells. It will be obvious that the loop-shaped connecting section is then placed above and below the flat elements, which lie one on the other, rearwardly in the recess of the two housing parts so as to enable opening of the two housing parts by pivotation about pivot joints present at the side walls.
In order to make possible even easier insertion of the conductor the pivot joint can also be realised by a simple assembly fixing, thus a solid unit of the two housing parts does not have to be produced by a static pivot joint. The housing parts can thus be connected together in such a way that the second housing part is displaceable relative to the first housing part, after being swung over, in height through a defined travel during closing, for which purpose interengaging guide elements and guides can be provided at the first and second housing parts. Thus, in an advantageous construction upwardly protruding, column-shaped guide elements can be provided, for example in the corner regions, at the lower housing part or at an insert, which receives all the components inserted therein, in the lower housing part, the guide elements slidably engaging in guide channels in the second housing part. Detent lugs, which engage with a detenting action over a detent edge in the guide in the second housing part, can be provided at the guide elements for fixing the unit. The guides are U-shaped channels adapted in shape to the cross-section of the column-like guide elements. The guide channel can have at the joint side of the housing part a chamfered entry which engages a locking front side during tilting of the housing part, in which the channel is present, relative to the guide element and at the same time makes possible an open inclined setting of the housing part. The pivot joint is thereby realised and can be used when the upper housing part is brought from the lower to the upper height position.
In principle, the bearing shells, mounts, support elements and the like can be accommodated in the housing of the lower housing part or formed integrally from plastics material. However, it is also possible to provide these parts and mountings at an insert which is made separately and also provided with the guide elements if these are present, which insert is then inserted in the housing part after installation. Such an insert can obviously also be provided in the upper housing part and connected with the lower housing part.
The conductor can consist of a plurality of wires and be of stranded construction, it can be flexible or, however, also provided as a current-conducting monofilament. The evaluating device is applied to a solid conductor track or a flexible conductor track carrier, which can form a unit with the flexible carrier for the magnetic field sensors and, for example, be mounted on an insulating plate. It can be an electrical amplifier, an ASIC carrying out the evaluation, and/or a programmed microprocessor. The data can be obtained by way of a fixed interface, for example a plug connector interface. The corresponding bushes or plug contacts are connected with the circuitboard and accessible by way of a recess in the housing or the plug connector protrudes into this recess, so as to be able to plug on the member complementary to the plug connector. However, the measurement data can also be filed in a memory which is a component of an RFID transponder, so that the measurement data can be read out by an RFID receiver and evaluated. Moreover, the measurement data can also be read out by remote technology if an appropriate coupling into the conductor is made.
It has proved particularly advantageous to let the bearing shells open at the rear side into chamber-shaped recesses or into a cavity in the housing parts, in which the loop-shaped connecting section can engage the flexible conductor track carrier, wherein the outer curved section of the connecting section lies near, at or on the pivot axis of the two housing parts. It will be evident that pivotation open and pivotation closed of the two housing parts about the hinge is thereby made possible without mechanical overloading of the loop-shaped connecting section occurring. This significantly increases the service life of such measuring devices even when these are subject to multiple use for line measurement of different conductors.
In a further embodiment it is provided that mounted on a rigid or flexible circuitboard is a further, flexible section or a prolongation, to which a measuring pin is fastened and contacted by a conductor track. The measuring pin is pressed by its point onto the conductor for the voltage measurement and, if insulation surrounds the conductor, this is penetrated, during closing of the housing, up to the conductor. This enables energy analysis, since in parallel with the current measurement the voltage is measured at the same time and thus the power is detectable and an energy analysis can be created therefrom. The included microprocessor has to be appropriately programmed in order to be able to carry out time-dependent evaluation of the measurement values for the energy analysis.
It will be apparent that the contacting of the measuring pin is equally possible with the conductor track on a flexible conductor track carrier, which, for example, is laid in the housing over a terminal tongue parallel to the flexible conductor track carrier for the magnetic field sensors. In principle, the bearing shells for reception of the flexible conductor track carrier for the magnetic field sensors can be mounted on one side. The measuring pin can be arranged between these and the housing wall. However, a spaced arrangement is also possible, in which the circuitboard on which the evaluating device is present is arranged between the two measuring points. This is within the discretion of the expert.
The bearing shells for the curved sections of the flexible conductor track carrier for the magnetic field sensors can be fixedly formed in the housing. However, they can also be realised by shaped parts—at least at one side—insertable into the housing. If these shaped parts are insertable, adaptation of the diameter of the passage to the diameter of the conductor or the cable can be carried out in simple manner by appropriate fitting, so that a smaller spacing between the conductor and the magnetic field sensor is given. Beyond that, the bearing shells can be of closed trough-shaped construction or, however, also defined only by lateral contours, so that the middle region of the curved section at which the magnetic field sensors are mounted is exposed, whilst the side parts rest on the half-shell surfaces or are held at these, as already indicated, by retaining means. The curved sections can also be glued to the half shells. In every case, the housing consisting of plastics material or ceramic can ensure by its shell-shaped receptacles that all parts are effectively insulated relative to one another. It is possible with one and the same housing to carry out, for example, current measurements of 240 V alternating voltage lines or direct current lines and also at lines conducting multiple KV voltages.
In order to be able to undertake adaptation of the measuring pin in simple manner in the case of different diameters it is provided in a further embodiment that the measuring pin is arranged in the first housing part in front of the passage in the side wall and is so supported against the force of a spring and/or engaged under by a setting element that the conductor after insertion into the housing can be pressed down by pressing-down means at least in the region of the measuring pin against this pin. It is ensured by the spring pressure that the measuring tip of the measuring pin, which consists of metal, penetrates the insulation layer and an adaptation to different diameters is possible within a defined range in simple manner.
In order to be able to basically undertake adaptation to different diameters of the current-conducting conductor the receptacles can be provided at the housing parts to be able to be clipped or plugged on, which receptacles can, for example, be plugged into recesses in the housing parts and have bearing shells for engaging over the conductor. It is possible through such a modular arrangement to not only design the bearing shells to be exchangeable, but also to change the conductor guidance in the measuring region of a measuring pin, also with respect to the passage in the side walls of the housing. The individual subassemblies are insertable into the housing or can be plugged onto the housing and form with the surface of the housing a closed unit.
In addition, the receptacles for the conductor can, for example, be constructed so that the measuring pin can pass through a wall. This receptacle can, as a receptacle shaped part, also at the same time, for example, form the pivot joint or a part of the pivot joint and is externally detented on the housing in corresponding recesses. The mating joint is then located on the second housing part and is connectible with the first in a simple manner, after meshing assembly, by connecting pins forming the pivot axis. These parts can also be constructed to be rotatable so that a lefthand/righthand opening is made possible, subject to the condition that the bearing shells for the flexible circuitboard are also arranged to be displaceable or are arranged to be rotatable through 180°. This also applies analogously to the circuitboard in the housing, so that a laterally offset arrangement is made possible. In addition, the housing can be vertically arranged to come into closing abutment not only on the left, but also on the right.
In order to make possible easier assembly of the flexible conductor track carrier, in a further embodiment shaped parts are laterally provided at the bearing shells, which parts are insertable into bearing recesses in the housing parts and have at least one recess adapted to the shape of the bearing shell, a groove or an edge for reception or support of at least the side strip, which protrudes beyond the bearing shell, of the flexible conductor track carrier. It will be apparent that, after insertion of the flexible conductor track carrier and through pressing in these shaped parts, shaping to the bearing shell takes place automatically by the edge engaging thereon and, in addition, a positional securing is given by corresponding interengaging projections and recesses. In a case of incised grooves a lateral attachment of the flexible conductor track carrier is possible.
Cutting free of the side walls of the bearing shell has proved to be an advantageous development of the receptacle for the conductor, since the side walls can thereby resiliently yield when, for example, a conductor which is somewhat thicker than the predetermined diameter is inserted. Such deviations can occur particularly when the conductor is surrounded by an insulating layer. The arrangement in the shaped part insertable into a recess of the housing part has the advantage that pivot joint elements can be mounted thereon so that a double function is achievable. The pivot joint elements consist, in known manner, of pivot bearing blocks which are arranged at a spacing from one another and between which an individual bearing block, which engages by lateral protrusions in mounting recesses of the lateral bearing block, is insertable. However, passage bores can also be provided and a bearing bolt or bearing pin inserted so as to enable pivot movement between two such parts. If, in addition, the parts are of symmetrical construction a hinge with the same components can be realised by simple 180° rotation and mounting on the two housing parts. Such shaped parts consist of plastics material and advantageously are clipped on. Elevations can be provided at the inner side of the bearing shell for centring of the inserted conductor.
The shape of the housing shall be constructed to be substantially polygonal at least in longitudinal direction in order, for example, to also be able to be mounted behind a current-conducting conductor extending parallel to a mounting wall. In the case of measurements in the milliampere range the influence of extraneous magnetic fields, inclusive of the earth's magnetic field, can be eliminated by covering the curved sections by a metallic layer of non-magnetic materials, such as is known from the specification DE 20 2008 012 593 U1 cited in the introduction. The housing can obviously also be constructed to be elongate and have curved end sections. However, any other form can also be realised. For insertable shaped parts, however, it is recommended to select an elongate, polygonal construction so that the same shaped parts are, through turning, usable not only in the upper housing part, but also in the lower housing part.
The invention is explained in more detail in the following by way of the embodiments illustrated in the drawings, in which:
The embodiment illustrated in the figures shows a lower housing part 3 of a closed housing 2 and an upper housing part 5. The two housing parts 3 and 5 are connected together by way of two pivot joints 4 arranged in a row. These pivot joints 4 are of modular construction and externally detented in recesses 22 of the housing 2. As apparent from
The flexible conductor track carrier 13, which is connected by way of a tongue-shaped transition part with the circuitboard 15 and can be pivoted open in transversely extending direction, is important to the invention. This conductor track carrier 13 receives the magnetic field sensors, for example Hall sensors, which are not illustrated and can be, for example, components of ASICs. The conductor track carrier 13 is so shaped that it has a lower curved section, which is insertable into a bearing shell 11 or into lateral bearing-shell-shaped receptacles and semicircularly engages under the conductor 1 at a spacing, whilst the upper end is embedded in the bearing shell 12 in the upper housing part 5 and forms the second arcuate part. Through the mounting of the conductor track carrier in the bearing shells 11 and 12 a complete enclosure of the conductor 1 together with the insulation in the closed state of the housing 2 is ensured.
In order that simple pivoting open of the housing part 3, 5 is possible the two curved sections of the conductor track carrier 13 are connected together by way of a connecting section 14, which is of loop-shaped form, or are constructed integrally therewith. This connecting section 14 lies in a chamber region or cavity region of the housing 2. The rear curved member is located close to the pivot axis, which is formed by the pivot joints 4, of the housing 2. It will be apparent that when the housing 2 is opened by pivotation of the upper housing part 5 relative to the lower housing part 3 about the rotary joint 4 the shaped parts 23, which are provided in the upper housing part 5 and have bearing shells 12 and which are insertable, are pivoted open therewith, whereby the upper curved section of the conductor track carrier 13 is pivoted open so that the conductor 1 can be inserted or removed or the housing 2 can be pulled off the conductor 1.
The shaped parts 23 are conceived as exchange parts so that different radii of the bearing shells 11 and 12 can also be realised. This is required if, for example, a conductor 1 with a larger diameter is to be inserted. The parts can be inserted in corresponding receptacles not only in that of the lower housing part 3, but also of the upper housing part 5.
It will be evident from
The shaped part 23 is illustrated in enlarged form in
A further embodiment of a housing construction is illustrated in
| Number | Date | Country | Kind |
|---|---|---|---|
| 20 2012 103 071.3 | Aug 2012 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2013/066868 | 8/13/2013 | WO | 00 |
