MXPA96003385A - Current sensor and electrical board that includes it - Google Patents

Abstract

An inductive current sensor and electrical device that incorporates this sensor. The magnetic circuit of the sensor comprises a detachable part 22 that leads to the detector element 25 and is made of a material having a permeability that is between 5 and 100. (FIG.

Description

CURRENT SENSOR AND ELECTRICAL APPLIANCE THAT INCLUDES This invention relates to an inductive current sirer for electrical apparatus comprising a magnetic circuit of which a part acts as a support for a magnetic field detector element such as a sensing coil and a conductor surrounded by a magnetic circuit and traversed by the current that will be detected. It also relates to the electrical apparatus provided with said sensor or sensors. The current sensors of the type mentioned above are well known and are used in electric power apparatuses such as circuit breakers, overcurrent relays and speed controllers for the purpose of detecting excessive currents, so that the supply of the load connected to the apparatus can be interrupted. When the apparatus is assembled, it is helpful if the current conduit can easily be inserted into the sensor. However, in most cases the current sensors comprise a closed magnetic circuit in which the conductor must be placed, making the assembly in this manner impractical. In addition, the protective device can refer to different sensors depending on the connectable loads and is desirable, either during the manufacture of the apparatus or during its installation, which is adapted or made especially depending on its application. When a current sensor of the type described is constituted by a current transformer, the magnetic material has a strong permeability, typically more than 5000. In this case, a current transformer is sensitive to interference, and when it is desired to make an agnatic circuit with a separable part, the parasitic space formed in the connection of the separable part to the fixed part has a bad influence on the measurement. When the current sensor is formed by a Rogowski core, the permeability is of the order of 1 and the need for a large number of turns for the secondary winding element is such that it is not easy to arrange them in a separable part. In addition, the coil winding must be carried out continuously on the core in order to ensure immunity to electromagnetic interference. The invention seeks to reduce the influence of the parasitic spaces and external interference on a corriet sensor for electrical apparatus. It also seeks to facilitate the assembly of the current sensor in the electrical device and the adaptation of the device to different load characteristics. According to the invention, the magnetic circuit comprises an open magnetic part and a magnetic part separated from the open magnetic part and carrying the sensing element, at least one of the two parts of the magnetic circuit acting on a permeability material. weak. Said permeability may be between 5 and 100, preferably between 8 and 30. As a result, the magnetic circuit space can be considered as scattered along the circuit and the sensor shows little sensitivity to any parasitic space that can be observed in the interface between the separated part and the open part of the magnetic circuit. The electrical apparatus according to the invention is provided with at least one of said current sensors whose open magnetic part is permanently disposed in the housing of the apparatus and whose separate magnetic closing part is fixed to either a printed circuit board comprising a circuit for processing the electrical signal delivered by the detector element, the processing circuit generating a trigger signal when an overcurrent is set, or a part or cover separable housing, part or cover-preferably carrying over the magnetic part side separates, said printed circuit board. It should be understood that the permanent open magnetic part may advantageously belong to a lower general purpose part of the apparatus, while the separate magnetic closure part may belong to a specially designed electronic processing part depending on a classification, particularly a classification of current, of the apparatus. In other words, it can be assembled to an unchanged lower part of the electrical apparatus other than the electronic processing units each adapted to a different electrical size.

The assembly operation can be executed either by the manufacturer or by the user. The following description of a modality read with reference to the accompanying drawings will provide an explanation of the particularities and advantages of the invention. Figure 1 is a schematic illustration of an inductive current sensing according to the invention. Figure 2 is a sectional view of a sensor assembled in an apparatus according to the invention. Figure 3 shows a schematic view of a contactor-circuit breaker apparatus. The current sensor 20 is housed in an insulating housing 10 of a voltage electrical apparatus, this housing showing a front face 11 that is accessible to an operator from the outside. The sensor 20 comprises a fixed, open magnetic circuit 21, for example of configuration II or L, fixed by any appropriate means in the housing 10 of the apparatus, and a separate magnetic circuit 22 formed for example by an added pad of way to bridge the fixed circuit in order to establish a magnetic path without a nominal space for the magnetic flux. When the circuit 21 is of L configuration, an identical L-shaped part can be used for the circuit 22. An energy conductor 23 belonging to a low frequency current path, for example 50 or 60 Hz of the apparatus is inserted. in the opening 24 of the magnetic circuit 21 fixed to the apparatus and remains fixed in a well-terminated position by the retaining element. A coil 25 wound around a coil frame 25a associated with the separate magnetic circuit 22 is mounted on a printed circuit board 26, the same fixed to a detachable cover or housing 27 in insulating material and accessible from the outside of the housing. to, on the front wall side 11 of the housing; the cover 27 can form a part of the front face of the housing (see Figure 2). The magnetic circuit 22 is fixed to the board 26 by legs 28. The circuits 21, 22 have a weak magnetic permeability, preferably remaining between 8 and 30, and for the purpose, are made of carbon-based iron material. or other analogous material of low permeability. An elastic element 12 can be placed between the open magnetic circuit 21 and the housing, in combination with a stop not shown for this circuit 21, in order to help reduce the space e or the parasite. Depending on the case, both circuits 21, 22 are of low permeability material or only one of the circuits 21 22 is of said material. It will be observed that the runner measurement is not sensitive to the presence of spaces and the light parasites. An electrical apparatus considered to be a disconnector, a contactor, a protective relay or a velocity controller, and various sensors present, the printed circuit board 26 retains the circuit 30 for processing the signals supplied by the various sensors, so as to generate a trigger signal. The separable cover 27 can be a simple plate (FIG. 2) or can be arranged as a housing that supports other members. In Figure 2, the separated part 22 of the magnetic circuit and its removable carrier cover 27 in the extracted position are represented by dashed lines; it should be understood that this arrangement facilitates both the installation of the conductor 23 and the change of the detector element 25. The cover itself, of course, can retain two or three separate magnetic circuits of corresponding sensors associated with respective phases. A separable single rail 22 can be provided for a plurality of phases, the rail having the respective coils 25. The detector element illustrated in the form of a coil 25 can be constituted by a Hall-effect detector or other analogous element that detects the magnetic field generated by the passage of the current in the conductor 23. Figure 23 shows an apparatus disjoint polyphase contactor of the housing 10 of which comprises a base body 10a and a front portion 10b assembled to the base body; The front part itself may comprise a functional unit or a plurality of functional units. The base body 10a has for each phase two ends 13, 14 to which the respective flush-fitting parts 15, 16 are attached, which are fixedly supported on the contacts 17 facing the movable contacts 18 placed on a bridge 19 of touch. The contact bridges 19 are carried by a movable support 3. The arc extinguishing chambers provided with arc extinguishing plates 32 are located near the contacts. The conductive part 15 is raised in a region 15a close to the plane P of the set of the housing parts 10a, 10b, so as to pass through the fixed U-configuration 21 of the magnetic circuit; this part 21 remains on the supers 33 of the base body 10a and projects slightly beyond the plane P towards, from the front part 10b of the housing. The front part 10b of the apparatus housing has an electromagnet 34 which can act directly, as shown by the arrows 35, the contact support 31. On the front side of the part 10b there is provided a manual control button 36 which cooperates, as shown by the arrow 37, with the contgrol unit formed by the electromagnet 34 and an electronic processing block 39. The block 39 comprises the closing parts 22 of the magnetic circuits, the detection coils 25 and the board 26 which isolate the processing circuit 30 over current. The circuit 30 is electrically connected to the lectro-magnet coil 34, as shown by the arrow 40.

The base body 10a of the apparatus remains the same for a plurality of types of apparatuses or sizes and it should be understood that the differentiation between the apparatus is provided by the front part 10b of the housing, due to the interchangeable magnetic circuit closure parts 22. , its secondary coils 25 and the specific processing circuits 30.

Claims (7)

CLAIMS:

1. - an inductive current sensor for electrical appliances, comprising: a magnetic circuit of which a part acts as a support for a detector element, an energy conductor surrounded by the magnetic circuit and crossed by the current to be detected, the magnetic circuit comprising an open magnetic part and a magnetic closing part separated from the open magnetic part and leading to the detector element, characterized in that at least one of the two parts of the magnetic circuit is in a material of low permeability.

2. The sensor according to claim 1, characterized in that the permeability of the material of the magnetic circuit is between 5 and 100, preferably between 8 and 30.

3. A sensor according to claim 2, characterized in that The material of the magnetic circuit is a carbonyl iron base.

4. An electrical apparatus provided with at least one inductive current sensor comprising: a magnetic circuit of which a part acts as a support for a detector element, a conductor surrounded by the magnetic circuit and traversed by the current that is going to detect, the magnetic circuit comprising an open magnetic part and a magnetic closing part separated from the open magnetic part and leading to the detector element, characterized in that at least one of the two parts of the magnetic circuit is of a low material. permeability, the open magnetic part is permanently disposed in the housing of the apparatus and the magnetic closing part is fixed to an interchangeable electronic processing unit.

5. The apparatus according to claim 4 characterized in that the exchangeable processing unit carries, on the side of the magnetic closing part, a printed circuit board comprising an electrical signal processing circuit delivered by the element detector.

6. The apparatus according to claim 4, characterized in that the open magnetic part of the sensor magnetic circuit is associated with a power conductor located in a base body of the apparatus, the base body comprising fixed contacts. and movable contacts associated with the driver and arc extinguishing chambers close to the contacts, while the closing part of the magnetic sensor circuit is housed with the exchangeable processing unit in a housing in the forntal part attached to the body.

7. An apparatus according to claim 6 characterized in that the open magnetic part is placed in a raised region of a conductive part housed in the base body close to an assembly plane of the housing parts.