Current measurement device, manufacturing method, protection module and differential circuit breaker including such a device

A current measurement device including current sensors positioned around current conductors in order to form a passage for the current conductors along an axis oriented in a first direction and a differential current sensor positioned around the set of current conductors in order to form a common passage for the current conductors along an axis oriented in a second direction. The current sensors and the differential current sensor are located in spaces that are separated by an interface plane. A method for manufacturing such a current measurement device, to a protection module and a differential circuit breaker including such a device.

TECHNICAL FIELD

The present invention relates to a device intended for measuring the current flowing through electrical lines and for measuring a differential current. The invention also relates to a method for manufacturing the current measurement device. The invention also relates to a module for protection from electrical faults and a differential circuit breaker including such a current measurement device.

PRIOR ART

Devices for protection from fault currents find very wide use in electrical installations supplied with power by lines of an AC network. The function thereof is to detect any fault current, regardless of whether it is linked to an overcurrent in one of the lines or to an insulation fault resulting in a current leakage to ground. These protection devices include a current measurement function so as to detect any threshold crossing and a function for opening the electrical circuit so as to remove the fault. Generally, when only the function of measuring the current flowing through the lines is required, it is grouped together with the function for opening the electric circuit in one and the same unit. However, when the detection of ground leakage current is also required, multiple difficulties arise: measuring the current flowing through the lines requires one sensor per line, while measuring the ground leakage current, also referred to as the differential current, requires a sensor for calculating the vector sum of all of the currents flowing through all of the current lines. The routing of the current conductors becomes complicated, and the need to provide insulation between the conductors and the need for production on an industrial scale at an acceptable cost exacerbate the construction difficulties.

A first means for solving these problems lies in carrying out the function of measuring the differential current by means of a first, separate product and in carrying out the function of measuring the current flowing through the lines and the function of opening the circuit by means of a second product. For example, the document US 2011/0116197 A1 describes a differential current measurement device incorporated within a separate product. The document FR 2 772 979 B1 discloses a differential block that can be connected to the side of a circuit breaker. However, incorporating a function for opening the circuit, sensors for measuring the currents flowing through the lines and a sensor for detecting the differential current within a single device is economically advantageous by virtue of the smaller number of housings and of connection terminals. Additionally, it is very advantageous for the footprint of the product to be similar to that of a protection device without differential protection: this simplifies installation on an electrical switchboard, with all of the equipment being aligned, and the connections are simpler, in particular in the case of connection by means of rigid copper busbars. Lastly, decreasing the footprint allows the user to install a larger number of units on an electrical switchboard.

The document JP 2011-34714 A discloses a differential circuit breaker incorporating current sensors6for measuring the currents flowing through the lines and a sensor7for detecting the differential current. The sensor7is placed in the extension of the current sensors6, which increases the length of the housing and changes its size with respect to a circuit breaker not having a differential function. Additionally, the oblong shape of the differential current sensor7makes the sensor7sensitive to the current flowing through the lines50and the accuracy of the differential current measurement may be negatively affected when the current flowing through the lines becomes substantial.

The document JPH0878259 A describes a three-phase differential circuit breaker employing only two sensors11U and11W for measuring the currents flowing through the lines32U and32W and a differential current sensor33. An evaluation of the current flowing through the line32V is obtained by calculating the vector sum of the currents flowing through the lines32U and32W. This solution obviously decreases the amount of space occupied and simplifies production but calculating the current in the phase32V accumulates errors in the measurement of the currents flowing through the lines32U and32W and must take into account the differential current that is present. This solution is advantageous in the context of ground fault protection but it is not suitable for differential protection intended for protecting persons, for which the differential current protection threshold is low, for example 30 mA, nor for accurately measuring the current flowing through the phases for the purpose of measuring power or energy.

DISCLOSURE OF THE INVENTION

The present invention aims to overcome the drawbacks presented by the prior art documents. More particularly, the present invention describes a compact device making it possible to measure the current flowing through each electrical line and to measure the differential current. This device may be incorporated within a module for protection from overvoltages for the purpose of providing differential protection and thus allowing a conventional circuit breaker to be turned into a differential circuit breaker simply by changing the protection module, without negatively affecting the footprint of the circuit breaker. This aspect is very advantageous for the user.

To this end, the current measurement device is arranged so as to be incorporated within a substantially parallelepipedal housing including an upstream face opposite a downstream face, a front face opposite a back face, and a first lateral face opposite a second lateral face, said current measurement device including:at least two upstream connection lugs, which lugs are intended to be electrically connected to connection lugs of an electric current breaking device for protecting at least two electrical lines;at least two downstream connection lugs, which lugs are intended to be electrically connected to operating terminals;at least two current conductors, each current conductor being arranged so as to electrically link an upstream connection lug to a downstream connection lug, respectively;at least two current sensors, each current sensor being positioned around a respective current conductor so as to form a respective passage for the current conductor along an axis oriented in a first direction in the upstream face-downstream face direction; anda differential current sensor,
said current measurement device being such that the differential current sensor is positioned around the set of the at least two current conductors so as to form a common passage for the current conductors along an axis oriented in a second direction in the front face-back face direction.

Preferably, the current sensors and the differential current sensor are respectively embedded in spaces that are superposed between the front face and the back face, such that:the current sensors are positioned in a first space of the housing, said first space being delimited by the front face, the first lateral face, the second lateral face, the upstream face, the downstream face, and an interface plane that is located between the front face and the back face; andthe differential current sensor is positioned in a second space of the housing, said second space being delimited by the interface plane, the first lateral face, the second lateral face, the upstream face, the downstream face and the back face.

Preferably, the upstream connection lugs are located level with the second space of the housing.

Preferably, the downstream connection lugs are located level with the first space of the housing.

Advantageously, each upstream connection lug is aligned along an axis that is oriented in the first direction with each respective downstream connection lug to which said upstream connection lug is linked by a respective current conductor.

Preferably, each current conductor is composed of three portions:a first conductor portion that is electrically connected, by a first of its ends, to the upstream connection lug, said first conductor portion being arranged so as to pass through the common passage through the differential current sensor and arranged so as to be electrically connected, by a second of its ends, to a first end of a second conductor portion;the second conductor portion of rectangular section that is electrically connected, by a first of its ends, to the second end of the first conductor portion, said first end being positioned substantially in the interface plane, and bent at a second of its ends to form a flat lug that is oriented in a plane perpendicular to the first direction; anda third conductor portion that is electrically connected, by a first of its ends, to the flat lug formed by the second end of the second conductor portion, said third conductor portion being arranged so as to pass through the passage through a current sensor and arranged so as to be electrically connected, by a second of its ends, to the downstream connection lug.

In one particular embodiment, each third conductor portion passes through the passage through the current sensor that surrounds it at least twice, forming a loop.

Preferably, the section of the first, second and third portions of each conductor is substantially identical in terms of area.

Preferably, the current measurement device such as described above is intended to measure the currents flowing through three phase lines and one neutral line of a three-phase electrical network, and includes a first, a second and a third current sensor, each current sensor being intended to measure a current flowing through each of the phases, and includes a fourth current sensor, intended to measure a current in the neutral line, which fourth current sensor is positioned around a neutral conductor so as to form a passage for the current conductor along an axis oriented in a third direction in a first lateral face-second lateral face direction.

The invention also relates to a method for manufacturing a current measurement device such as described above, said method including the following steps:welding each first end of each second conductor portion to each second end of each first conductor portion so as to form a segment of each current conductor;depositing an insulating coating on each conductor segment so as to electrically insulate each conductor segment, first and second ends of each of said conductor segments being left free of coating for the purpose of later welding;welding each downstream connection lug to each second end of each third portion, respectively;passing each third portion of each of the conductors through the passage formed by the respective current sensor;selecting a single or double pass-through production variant and, in the case of a double pass-through:a step of bending the third portions of the current conductors so as to form a loop around each respective sensor; andpassing each third portion of each of the conductors through the passage a second time;welding each first end of each third portion to each segment at the second end of the second portions, respectively;passing the first ends of the conductor segments through the common passage formed by the differential current sensor;welding each upstream connection lug to each first end of each conductor segment, respectively; andpositioning a brace for holding the first ends of the first portions in a predefined position.

Another subject of the invention is a module for protection from electrical faults that is intended to cooperate with an electric current breaking device, said protection module including:a processing unit;an actuator for actuating the electric current breaking device; andan adjustment device that is linked to the processing unit, said adjustment device being arranged so as to adjust at least a first trip threshold and/or a second trip threshold;a current measurement device such as described above and including:at least two current sensors;a differential current sensor; andat least two current conductors that are electrically linked to upstream lugs and downstream lugs,
the processing unit being connected to the current sensors and to the differential current sensor so as to form:at least one measurement of the current flowing through each of the current conductors; anda measurement of the differential current across all of the current conductors, the processing unit being arranged so as to activate the actuator to actuate the electric current breaking device when at least one current measurement or when the current measurement is higher than the first trip threshold or when the measurement of the differential current is higher than the second trip threshold.

The invention also relates to a differential circuit breaker intended to protect an electrical circuit including at least two electrical lines from electrical faults, said circuit breaker including:at least two upstream connection terminals for connecting at least the two electrical lines;at least two internal connection terminals; andan electric current breaking device;a module for protection from electrical faults such as described above, and such that:the electric current breaking device is connected between the at least two upstream connection terminals and the at least two internal connection terminals, said electric current breaking device including contacts allowing the current flowing between the at least two upstream connection terminals and the at least two internal connection terminals to be established or interrupted;the at least two internal connection terminals being connected to the at least two upstream lugs of the protection module;the electric current breaking device of the differential circuit breaker being connected and arranged so as to receive and to execute a command transmitted by an actuator of the protection module.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The current measurement device1is preferably intended for the measurement of current in an electrical installation supplied with power by a three-phase network including a neutral line, but may also be used on any electrical network including at least two phases or at least one phase and a neutral. The device makes it possible to measure the current flowing through the electrical lines and to measure a differential current.

FIG. 1shows a perspective view of the current measurement device1according to one preferred embodiment. The current measurement device1is arranged so as to be incorporated within a substantially parallelepipedal housing2including an upstream face3opposite a downstream face4, a front face5opposite a back face6, and a first lateral face7opposite a second lateral face8. The front face5is preferably oriented towards the user. The current measurement device1includes:upstream connection lugs11,21,31,41for connection to an electric current breaking device that is located upstream in an electrical circuit, these lugs being positioned on the upstream face side3;downstream connection lugs15,25,35,45, for connection to operating terminals that are intended to provide an electrical connection to electrical loads, these lugs being positioned on the downstream face side4;current conductors10,20,30,40for providing an electrical connection between the upstream connection lugs11,21,31,41and the downstream connection lugs15,25,35,45, respectively;current sensors51,52,53and54, each sensor surrounding a current conductor so as to measure the current flowing through said current conductor; anda differential current sensor55surrounding all of the current conductors so as to measure the differential current, i.e. the result of the vector sum of the currents flowing through all of the current conductors. A nonzero differential current corresponds to a current leakage generally looping back via a protective conductor.

According to the preferred embodiment illustrated inFIG. 1, the current measurement device1is intended to be connected to a three-phase network with a distributed neutral line, the neutral line having to be connected to the upstream connection lug41, the connection of the neutral on the downstream side for the user having to be made to the downstream connection lug45.

The current sensors51,52and53are positioned around a respective current conductor10,20and30so as to form a respective passage for the current conductor along an axis oriented in a first direction X in the upstream face3-downstream face4direction. To produce a compact current measurement device, the differential current sensor55is positioned around all of the current conductors10,20,30,40so as to form a common passage55A along an axis oriented in a second direction Y in the front face5-back face6direction. To clearly show the first direction X and the second direction Y,FIG. 2shows an arrangement of the upstream connection lug11, of the current conductor10, of the differential current sensor55, of the current sensor51and of the downstream lug15. The current conductor10is composed of three portions:a first portion12that is mechanically and electrically connected, preferably by welding, by a first of its ends12A to the upstream connection lug11;a second portion13that is mechanically and electrically connected, preferably by welding, by a first of its ends13A to the second end12B of the first portion12; anda third portion14that is mechanically and electrically connected, preferably by welding, by a first of its ends14A to the second end13B of the second portion13and mechanically and electrically connected, by a second of its ends14B, to the downstream connection lug15.

The first portion12forms a bend between its two ends12A and12B. The differential current sensor55forms a passage55A through which the second end12B of the first portion12of the current conductor10passes. The passage55A is oriented along an axis that is oriented in the second direction Y, in the front face5-back face6direction. The third portion14of the current conductor10passes through the passage51A formed by the current sensor51along an axis that is oriented in the first direction X in the upstream face3-downstream face4direction. The axis that is oriented in the first direction X and the axis that is oriented in the second direction Y are substantially orthogonal.

Two spaces90and91are defined inside the housing2. A first space90is delimited by the front face5, the first lateral face7, the second lateral face8, the upstream face3, the downstream face4, and an interface plane9that is located between the front face5and the back face6. A second space91is formed by the space in the housing2not forming part of the first space90. The second space91is delimited by the interface plane9, the first lateral face7, the second lateral face8, the upstream face3, the downstream face4and the back face6. The current sensor51is located within the first space90. The differential current sensor55is positioned within the second space91. The interface plane passes through the first end13A of the second portion13of the current conductor10.

Incorporating the current sensors as described allows incorporation within the housing2while minimizing the distance between the front face5and the back face6and especially the distance between the upstream face3and the downstream face4. Specifically, orienting the differential current sensor55in the second direction Y, which is substantially orthogonal to the first direction X, allows the volume occupied by the sensor55in the second space91to be optimized: said sensor preferably being a toroidal sensor, incorporating said sensor “flat” allows the distance between the interface plane9and the back face6to be minimized without significantly affecting the distance between the upstream face3and the downstream face4. Furthermore, orienting the current sensor51along the axis that is oriented in the first direction X, substantially orthogonal to the second direction Y of the differential current sensor55, minimizes the effect of the electromagnetic field radiated by the current sensor51on the differential current sensor55.

The upstream connection lug11is located level with the second space91in the housing2. This arrangement, in association with the “flat” incorporation of the differential current sensor55, contributes to the compactness of the measurement device1by limiting the length and the complexity of the first end12A of the first portion12. The downstream connection lug15is located level with the first space90in the housing. The upstream connection lug11is aligned, in the first direction X, with the downstream connection lug15.

The first conductor portion12preferably consists of a solid electrical conductor of substantially circular section having a diameter of 5 mm. This portion may also be produced by means of an electrical conductor of rectangular or square section, or else by means of a braided conductor or any other electrically conductive linkage that is able to follow a tight radius of curvature between the ends12A and12B. The end12B is mechanically and electrically connected to the first end13A of the second conductor portion13.

The second conductor portion13is preferably of rectangular section and forms a right-angled bend between the ends13A and13B. The first end13A is positioned substantially in the interface plane9. The second end13B forms a flat lug that is oriented in a plane perpendicular to the first direction X so as be connected to the first end14A of the third conductor portion14. The section of the second portion is preferably equal to 12 mm in width and 2 mm in thickness. The second portion may also be produced by means of a solid electrical conductor of circular, oval or square section or else by means of a braided conductor.

The third portion preferably consists of a solid electrical conductor, preferably of circular section having a diameter of 5 mm. The third portion passes through the passage51A formed by the current sensor51along an axis that is oriented in the first direction X. This third portion may also be produced by means of a solid electrical conductor of rectangular or square section, or else by means of a braided conductor.

The various portions are preferably connected by means of welding or brazing, providing the current conductor10with a high degree of mechanical rigidity and excellent electrical conductivity. Using a rectangular section of low thickness for the second portion and more particularly for the first end13A makes it possible to minimize the distance between the front face5and the back face6. Specifically, this feature allows the sensor51to be brought closer to the sensor55in the second direction Y as shown clearly inFIG. 2. As a variant, according to the same principle, it is possible to further minimize the distance between the front face5and the back face6by using one and the same rectangular section of low thickness for the first end of the first portion12A. The described technical features relating to the current conductor10, such as shown inFIG. 2, are identical for the current conductors20and30, the lengths of the portions of the conductors differing according to the current conductor.

FIG. 3shows the measurement device, in a right lateral face-left lateral face direction, showing one arrangement of the connection lugs according to the preferred embodiment of the invention, i.e. for a current measurement device1intended for use on a three-phase electrical network with distributed neutral. The upstream connection lugs21and31of the current conductors20and30are located level with the second space91in the housing2. The downstream connection lugs25and35are located level with the first space90in the housing2. The current conductors20and30include a first portion22and32, respectively, which preferably consists of a solid electrical conductor. The first ends of the first portions22and32are electrically linked to the upstream connection lugs21and31, respectively. The second ends of the first portions22and32are mechanically and electrically connected to the first ends23A and33A, respectively, of the second conductor portions23and33. The second conductor portions23and33are of rectangular section and form a right-angled bend between the ends23A and23B and33A and33B, respectively. The first ends23A and33A are positioned substantially in the interface plane. The second ends23B and33B form a flat lug that is oriented in a plane perpendicular to the first direction X so as to be connected to the first ends24A and34A, respectively, of the third conductor portions24and34.

The third conductor portions24and34are preferably of circular section and pass through the passages52A and53A, respectively, formed by the current sensors52and53along an axis that is oriented in the first direction X.

In the same way as for the conductor10, the various portions of the current conductors20and30are preferably connected by means of welding or brazing. The first portions12,22,32of the conductors10,20,30, respectively, form a bend between their respective ends. The differential current sensor55forms a passage55A through which the second ends12B,22B,32B pass along an axis that is oriented in the second direction Y, in the front face5-back face6direction. The third conductor portions14,24and34are parallel to one another. The second ends13B,23B,33B of the second portions13,23,33are positioned in one and the same plane.

The current conductor40is preferably intended for the measurement of the current in the neutral line. In supplement toFIG. 3,FIG. 4schematically shows, in an upstream face-downstream face direction, the arrangement of the upstream41and downstream45connection lugs, of the current conductor40and of the current sensors54and55so as to show the particularities of said current conductor with respect to the other current conductors10,20and30. The current conductor40provides the electrical connection between the upstream connection lug41and the downstream connection lug45. The current conductor40consists of three portions: a first portion42, a second portion43and a third portion44. The first conductor portion42consists of a preferably solid conductor, in the same way as the first portions of the conductors10,20and30. The first portion42forms a bend between its two ends42A and42B. The differential current sensor55forms a passage55A through which the second end42B of the first portion42of the current conductor40passes. The second conductor portion43is of rectangular section and forms a right-angled bend between the ends43A and43B. The first end43A is positioned substantially in the interface plane9and connected to the second end42B of the first portion42. The second end43B of the second portion43forms a flat lug that is oriented in a plane parallel to the first direction X so as be connected to a first end44A of the third conductor portion44. The fourth current sensor54is positioned around the third, neutral conductor portion44as to form a passage for the current conductor54A along an axis that is oriented in a third direction Z, in a first lateral face7-second lateral face8direction. The downstream connection lug45is connected to a second end44B of the third, neutral conductor portion44. Said connection lug45is bent in the first direction X so as to be connected to the second end44B, then in the third direction Z so as to be oriented in the same plane as the other downstream connection lugs15,25and35. The current sensor54, intended for measuring the current in the neutral line, is preferably smaller in size than the current sensors51,52and53. Orienting the passage for the current conductor54A in the third direction Z allows a space to be made between the sensor54and the first lateral face7that can be used, for example, for incorporating electronic boards.

FIG. 5shows a perspective view of the current measurement device, seen from the same angle as inFIG. 1, the device not showing any current sensors so as to clearly show the arrangement of the current conductors and the first direction X and the third direction Z.

FIG. 6shows a perspective view of the current measurement device for the purpose of illustrating an alignment between the upstream connection lugs11,21,31,41and the downstream connection lugs15,25,35,45, respectively. Each upstream connection lug11,21,31,41is aligned along an axis that is oriented in the first direction X with each respective downstream connection lug15,25,35,45to which it is linked by a respective current conductor10,20,30,40. Thus, inFIG. 6, the lugs11and15are aligned along an axis that is oriented in the first direction X, the lugs21and15are aligned along an axis X1that is oriented in the first direction X, the lugs31and15are aligned along an axis X2that is oriented in the first direction X and the lugs41and45are aligned along an axis X3that is oriented in the first direction X. The axes X, X1, X2and X3are parallel to one another. Preferably, the first direction X is parallel to the first lateral face7or to the second lateral face8. This feature makes it possible to have the same interaxial distance, also referred to as the connection “pitch”, between consecutive upstream connection lugs11,21,31,41and between consecutive downstream connection lugs15,25,35,45. Interchangeability of current measurement devices1having adjustable functions or performance levels, or else association with breaking devices71having different technical performance levels, is thus facilitated.

FIG. 7shows a detailed view, in perspective and according to one preferred embodiment, of the current conductor20for the purpose of showing the various constituent portions.FIG. 8shows a detailed view, in perspective and according to one preferred embodiment, of the conductor40, intended to be connected to a neutral line of the electrical installation, for the purpose of clearly showing the various constituent portions.

Preferably, the section of the first, second and third portions of each conductor (12,13,14,22,23,24,32,33and34) is substantially identical in area so as to distribute heating along the entire length of each current conductor, thus avoiding the development of hotspots.

The current measurement device1is preferably intended for the measurement of currents flowing through the phases or the neutral that are comprised between 25 amperes and 160 amperes, but it may be adapted for measuring currents of different amplitudes. For example, to measure a current having an amplitude of 25 amperes using current sensors51,52,53and54that are sized for measuring higher currents, it is advantageous to pass each third conductor portion14,24,34,44twice through each respective passage51A,52A,53A and54A formed by each current sensor51,52,53and54, respectively. Thus, the signal delivered by the current sensors51,52,53and54is twice as high, thereby increasing the accuracy of the measurement.FIG. 9shows a perspective view of the current measurement device, similar toFIG. 4, for the purpose of illustrating a double pass-through of the third portions of the current conductors through the sensors. In the case of a nominal measurement rating that is equal to 25 amperes, the section of the third conductor portions14,24,34,44may be smaller than for higher ratings. The conductive material, preferably copper or copper-clad steel, used for said third portions is curved to form a loop so as to pass through the passage in the respective current sensor twice. To facilitate production on an industrial scale, the first end44A and the second end44B of the third conductor portion44are formed separately, arranged with the current sensor44so as to pass through the current sensor44twice, then the first end44A and the second end44B are welded to one another to form the third portion44.

The current measurement device may be easily adapted for a tripolar variant: since the neutral line is not distributed, the upstream connection lug41, the downstream connection lug45, the current conductor40and the current sensor54are absent. The differential current sensor55forms a passage55A through which the second ends12B,22B,32B of the current conductors10,20and30pass.FIG. 10shows a perspective view of a tripolar current measurement device including the third portions14,24,34of the current conductors10,20,30passing through the sensors51,52and53twice.

To guarantee dielectric strength between the current conductors, the first and second portions of the current conductors10,20,30,40are coated with an insulating protective layer, preferably an epoxy coating, after the first and second portions have been assembled. The ends12A,22A,32A,42A and the ends13B,23B,33B and43B are left free of insulating coating for the purpose of welding in a manufacturing method. Lastly, a brace80made of an insulating material covers the first ends12A,22A,32A,42A of the first portions so as to hold the current conductors10,20,30,40in a predefined position facilitating the handling and assembly of the current measurement device1in the housing2.FIG. 11shows the measurement device1including the brace80.

The invention also relates to a method for manufacturing a current measurement device1. Said method, shown in the form of a flowchart inFIG. 12, may be used to manufacture a current measurement device suitable for an electrical network including at least two phases and hence including at least two current conductors10,20. For a current measurement device suitable for a three-phase electrical network with neutral, i.e. including four current conductors10,20,30and40, the method includes the following steps:welding100the first end13A of the second conductor portion13to the second end12B of the first conductor portion12so as to form a first current conductor segment123, then, respectively and in the same way, welding the first end23A,33A,43A of each second conductor portion23,33,43to each second end22B,32B,42B of each first conductor portion22,32,42so as to form a second, third and fourth segment223,323,423of each current conductor, respectively;depositing110an insulating coating on each conductor segment123,223,323,423so as to provide electrical insulation, the first ends12A,22A,32A,42A and the second ends12B,22B,32B and42B of each of said conductor segments being left free of coating for the purpose of later welding;welding120each downstream connection lug15,25,35,45to each second end14B,24B,34B,44B of each third portion14,24,34,44, respectively;passing130each third portion14,24,34,44of each of the conductors respectively through the passage51A,52A,53A and54A formed by the respective current sensor51,52,53,54.

The method is suitable for manufacturing a current measurement device1including the third portions of the current conductors passing once or twice through the current sensors51,52,53,54. A selection step131selects a single or double pass-through production variant and, in the case of a double pass-through, a step of bending132the third portions14,24,34,44of the current conductors is carried out so as to form a loop around each respective sensor51,52,53,54, then each third portion14,24,34,44of each of the conductors is passed through the respective passage51A,52A,53A and54A a second time133and the method moves on to step140. If the current measurement device1includes the third portions of the current conductors passing through only once, the method goes directly from step131to step140.

The method continues with the following steps:welding140each first end14A,24A,34A,44A of each third portion14,24,34,44to each conductor segment123,223,323,423at the second end13B,23B,33B and43B of the second portions13,23,33and43, respectively;passing150the first ends12A,22A,32A,42A of the conductor segments through the common passage55A formed by the differential current sensor55;welding160each upstream connection lug11,21,31,41to each first end12A,22A,32A,42A of each conductor segment123,223,323,423, respectively; andpositioning170a brace80so as to hold the first ends12A,22A,32A,42A of the first portions a predefined position facilitating the handling and incorporation of the current measurement device1within the housing2.

The set of steps100,110may be carried out in parallel, such as shown inFIG. 12, or in series with the set of steps120,130,131,132and133. Preferably, steps150and160are carried out sequentially on each of the current conductors and performed in the following specific order: first the current conductor20, then the current conductor30, then the current conductor10and finally the current conductor40(neutral line). By way of illustration, steps150and160carried out for the current conductor20include the following operations:in step150, the first end22A of the conductor segment223is passed through the common passage55A formed by the differential current sensor55;in step160, the upstream connection lug21is welded to the first end22A of the conductor segment223.

The manufacture of the current measurement device1is most straightforward when the order and the sequencing of the steps described above are followed.

The current measurement device1of the invention is particularly suitable for incorporation within a module60for protection from electrical faults, also referred to as a “tripping device”.FIG. 13is an overview of such a protection module60. Said module includes:a processing unit61, preferably including circuits for digitizing electrical signals and for calculations, for example one or more microprocessors or equivalent circuits;an actuator63for actuating the electric current breaking device71; andan adjustment device62that is linked to the processing unit61, said adjustment device62being arranged so as to adjust at least one or more trip thresholds. A trip threshold may be adjusted during the production cycle for manufacturing the protection module in the factory and in this case it cannot be adjusted later on; in particular, the user of the protection module does not have access thereto.

Preferably, a switch or a keypad associated with a screen that is positioned on the front face of the protection module allows the trip threshold to be adjusted by the user. A first trip threshold SD is intended for protection from overcurrents in the electrical installation. For example, the value of the first threshold is 25, 50, 100 or 160 amperes. A second threshold SDD is intended for protection from differential currents. For example, the value of the second threshold SDD is 30 mA, 100 mA, 300 mA, 1 ampere or 5 amperes. The protection module60includes a current measurement device1such as is described above. Depending on the needs of the user, said module includes at least two current sensors51,52and preferably a third sensor53for use with a three-phase network or four current sensors51,52,53,54for use with a three-phase network with a distributed neutral line. The module60includes a differential current sensor55and at least two current conductors10,20that are electrically linked to the upstream connection terminals11,21and to the downstream connection terminals15,25and preferably a third current conductor30for use with a three-phase network and a fourth current conductor40for use with a three-phase network with a distributed neutral line, said conductors being electrically linked to the upstream connection lugs11,21,31,41and to the downstream connection lugs15,25,35,45, respectively.

The processing unit61is connected to the current sensors51,52,53and54and to the differential current sensor55so as to form:at least one measurement M of the current flowing through each of the current conductors51,52,53,54; anda measurement of the differential current MD across all of the current conductors51,52,53and54, the processing unit61being arranged so as to activate the actuator63to actuate the electric current breaking device71when at least one current measurement M or when the measurement of the differential current MD is higher than at least one trip threshold SD or SDD, respectively.

The module60for protection from electrical faults is intended to cooperate with the electric current breaking device71so as to protect the electrical installation in the case of a fault of electrical origin. The association of the protection module60and the electric current breaking device71forms a circuit breaker70. Since the protection module is capable of measuring the differential current MD and of activating the electric current breaking device71when the measurement of the differential current MD is higher than a trip threshold SDD, the circuit breaker70is a differential circuit breaker.

FIG. 14is an overview of such a differential circuit breaker70. The circuit breaker is connected to at least two electrical lines19,29,39,49, and includes:at least two upstream connection terminals18,28,38,48for connecting the at least two electrical lines19,29,39,49;at least two internal connection terminals17,27,37,47; andan electric current breaking device71including contacts allowing the current flowing between the at least two upstream connection terminals18,28,38,48and the at least two internal connection terminals17,27,37,47to be established or interrupted.

The upstream connection lugs11,21,31,41of the protection module60are connected to the internal connection terminals17,27,37,47, respectively, of the electric current breaking device71. The downstream connection lugs15,25,35,45of the protection module60are connected to or form part of operating terminals16,26,36,46that are intended for the connection of electrical loads. The actuator63of the protection module60is linked to the electric current breaking device71, preferably by a mechanical linkage, and, in the event that a trip threshold SD or SDD is exceeded, the protection module60transmits a command by means of the actuator63to actuate the electric current breaking device71so as to interrupt the flow of the current through the electrical lines19,29,39,49.

The particular manner of incorporation of the sensor55within the first space90and of the current sensors51,52,53,54within the second space91, the positioning of the upstream connection lugs11,21,31and41level with the second space91and the use of a rectangular section of low thickness for the first end13A,23A,33A,43A of the second conductor portions allow the distance between the front face5and the back face6and between the upstream face3and the downstream face4to be minimized, thereby contributing to the compactness of the measurement device1. Thus, it is possible to have a differential protection function in a housing2of the same size and having the same locations for connections as a housing having until now only an overcurrent protection function. Having these functionalities in one and the same product is particularly advantageous for the user: it allows interchangeability of said protection module depending on the needs of the user, who may then size an electrical switchboard so as to subsequently fit it out with protection units having or not having differential protection without having to modify the connections or the mechanical mounting on the switchboard.