Electrical protection devices and systems with an integrated switch module

Abstract

An electrical protection system (2) has a housing (4), connecting terminals (6, 8), separable electrical contacts (10), a switching mechanism (12) and at least one power switch (22) connected in series with the separable electrical contacts, wherein the system further comprises an electronic control circuit (24) coupled to the at least one power switch, the or each power switch has a metallic heat dissipation plate (86) connected to an electrode of said power switch, said heat dissipation plate being thermally connected to the body of the power switch, and wherein the or each power switch is connected in series with the separable electrical contacts between the connecting terminals via a conductive plate (90, 92) connected to the heat dissipation plate of the respective power switch.

Description

TECHNICAL FIELD

[0001] The present invention relates to the technical field of electrical protection devices and systems, such as circuit breakers. STATE OF PRIOR ART

[0002] Many electromechanical electrical switching devices, such as air-break circuit breakers, and in particular miniature circuit breakers (MCBs), typically incorporate a breaking chamber. The breaking chamber is designed to extinguish an electrical arc that occurs in the air between the device's electrical contacts when those contacts are separated following a trip.

[0003] The cutoff chamber typically consists of a stack of metal plates placed one on top of the other to lengthen and extinguish the electric arc. One or more openings in the casing allow the cutoff gases to be released outside the device.

[0004] However, in order to improve the performance of these protective devices, it has been proposed to replace the breaking chamber with an electronic breaking device comprising power switches based on semiconductor components.

[0005] Such improved performance is, for example, advantageous in direct current (DC) electrical systems with electrochemical accumulator batteries, for which electrical protection devices must be able, in the event of an electrical fault, to interrupt high currents with a very fast reaction time.

[0006] WO 2019 / 096692 A1 describes hybrid switching devices, which include both mechanical and solid-state switches. For the sake of compatibility with existing installations, it is desirable that these protective devices can be contained in a housing of the same size as the housings of electromechanical type switching devices.

[0007] It is also necessary that these devices be able to properly dissipate the heat generated by the power switches.

[0008] There is therefore a need for electrical protection devices, such as circuit breakers, based on semiconductor components, which at least partially remedy these drawbacks. DESCRIPTION OF THE INVENTION

[0009] To this end, one aspect of the invention relates to an electrical protection system, comprising a housing, connection terminals, separable electrical contacts connected between the connection terminals, a switching mechanism and at least one power switch connected in series with the separable electrical contacts, the separable electrical contacts being movable between an open state and a closed state, the switching mechanism being coupled with the separable electrical contacts to switch the separable electrical contacts to the open state, the electrical protection system further comprising an electronic control circuit coupled with said at least one power switch, the power switch or each power switch comprising a metal heat dissipation plate connected to an electrode of said power switch,said heat dissipation plate being thermally connected to the body of said power switch, and wherein the power switch(es) is connected in series with separable electrical contacts between the connection terminals via a conductive plate connected to the heat dissipation plate of said respective power switch.

[0010] Thanks to this invention, the space freed up by the omission of components from a conventional miniature circuit breaker (these components typically include a bimetallic strip, a magnetic trip unit, magnetic shielding, a gas-generating side plate, and the stack of metal plates in the breaking chamber) is utilized to house the breaking unit containing the power switches between at least one (preferably several) conductive plates and the walls of the device's enclosure. Another advantage is that the more thermal energy the plates dissipate, the fewer solid-state breaking components are required.

[0011] Depending on advantageous but not mandatory aspects, such an electrical protection device may incorporate one or more of the following characteristics, taken individually or in any technically permissible combination: The power switch(s) associated with a pole of the device are mounted on a plate-shaped substrate integrated into a block, the respective conductive plate of each power switch being mounted on the same side of the block's substrate; the system comprises two groups of at least one power switch associated with the same pole of the system, mounted on the substrate, each group having at least one power switch and its respective conductive plate mounted on opposite sides of the substrate; the block(s) are received in a dedicated housing; the conductive plate(s) cover at least 40% of the area of ​​the corresponding face of the housing's side wall; the conductive plate(s) extend parallel to the widest walls of the housing; the heat dissipation plate is a metal plate natively attached to a ceramic body of the power switch;said at least one power switch is a field-effect transistor, preferably a MOSFET transistor; each conductive plate is made of metal; each metal plate is made primarily of copper or aluminum; one of the conductive plates has a portion adapted to form an electrical contact, the portion being used as a fixed electrical contact which cooperates with a movable contact of the system to together form said separable electrical contacts; each conductive plate is connected to a respective connection terminal of the system.

[0012] According to another aspect, the electrical protection device is a miniature circuit breaker, the width of the case is a multiple of 9mm and the electrical protection device is an air-break circuit breaker. BRIEF DESCRIPTION OF THE FIGURES

[0013] The invention will be better understood and other advantages thereof will become more apparent in the light of the following description of an embodiment of an electrical protection system given solely by way of example and with reference to the accompanying drawings, in which: there figure 1 is a schematic representation, in cross-section, of an electrical protection device conforming to embodiments of the invention; the figure 2 is a functional diagram of the electrical protection device of the figure 1 , in the case of a bipolar device; the figure 3 is a schematic representation of the first step in a sequence of movements of a switching mechanism of the electrical protection device of the figure 1 when the device is switched to an open state; the figure 4 is a schematic representation of a second step in a sequence of movements of a switching mechanism of the electrical protection device of the figure 1 when the device is switched to an open state; the figure 5 is a schematic representation of a third step in a sequence of movements of a switching mechanism of the electrical protection device of the figure 1 when the device is switched to an open state; the figure 6 is a graph representing the evolution over time of the angular position of a control lever associated with the switching mechanism of the figures 3 à 5 when switching the device to an open state; the figure 7 is a schematic representation, in perspective view (insert A) and exploded view (insert B), of a particular embodiment of a part of the protective device of the figure 1 . there figure 8 is a functional diagram of the electrical protection device of the figure 1 according to a first variant in which the device is a single-phase device; the figure 9 is a functional diagram of the electrical protection device of the figure 1 according to a second variant in which the device is a three-phase device; the figure 10 is a functional diagram of the electrical protection device of the figure 1 according to a third variant in which the device is a three-phase device with a neutral line; the figure 11 is a functional diagram of the electrical protection device of the figure 1 according to a fourth variant in which the device is a tetrapolar device. DETAILED DESCRIPTION OF CERTAIN METHODS OF IMPLEMENTATION

[0014] THE figures 1 And 2schematically represent an electrical protection device 2 conforming to embodiments of the invention.

[0015] In many embodiments, the electrical protection device 2 is a circuit breaker.

[0016] Preferably, device 2 is a miniature circuit breaker.

[0017] Device 2 includes a housing 4 inside which are housed at least some of the components of device 2.

[0018] The housing 4 is preferably made of a rigid and electrically insulating material, such as a thermoformed polymer, for example polyamide PA 6.6, or any other suitable material.

[0019] For example, case 4 is a molded plastic case.

[0020] Preferably, the dimensions of the enclosure 4, and in particular the width of the enclosure or the form factor of the enclosure 4, are compatible with the dimensions of the enclosures of existing protective devices 4.

[0021] In a non-limiting example of implementation given for illustrative purposes, the width of the case is preferably a multiple of 9mm, for example equal to 9mm, or 18mm, or 27mm.

[0022] It is understood that, in this example, the components of the electrical protection system are housed in a single enclosure 4. However, in some variations, certain components could be housed in different enclosures. What is described here with reference to device 2 can therefore be generalized to an electrical protection system 2 that can be separated from the enclosure 4.

[0023] The device 2 also includes connection terminals 6 and 8, separable electrical contacts 10 connected between the connection terminals 6 and 8, and a switching mechanism 12 comprising a control element 14 (also referred to as a control handle or control lever in the following). The control lever 14 is, for example, a pivoting lever accessible from outside the housing 4 and intended to be operated by a user.

[0024] For example, the contacts 10 can be formed by the association of a fixed electrical contact and a movable electrical contact that can be moved relative to the fixed contact, the switching mechanism 12 being coupled to the movable mechanical contact.

[0025] In practice, each electrical contact 10 can have a plurality of electrical contact fingers, although other implementations are possible as an alternative.

[0026] The separable electrical contacts can be moved between an open state and a closed state. In the open state, the contacts 10 are separated from each other by a volume of ambient air acting as an electrical insulator, which prevents the flow of an electric current.

[0027] In the example of the figure 2 , device 2 has two pairs of connection terminals 6,8: a first input terminal 6 connected to a first output terminal 8 via a first connection line, and a second input terminal 6 connected to a second output terminal 8 via a second connection line.

[0028] This example, given for illustrative purposes, corresponds to the case of a bipolar device (with two electrical poles, or two electrical phases). Other examples are possible, however.

[0029] In many embodiments, the switching mechanism 12 is configured to move the electrical contacts 10 to an open state in response to a switching command. The switching command may be sent by a trigger or result from a user action on the control lever 14.

[0030] For example, the switching mechanism 12 is a toggle mechanism, such as a switching mechanism analogous or similar to the switching mechanism described in patents EP 2975628 B1 or EP 1542253 B1.

[0031] Device 2 also includes an electronic breaking module 16 configured to interrupt an electric current between the connection terminals 6 and 8. The electronic breaking module 16 is based on solid-state breaking components, specifically semiconductor components such as power transistors. In this respect, Device 2 differs from electromechanical protection devices with air-break technology that incorporate a breaking chamber (arc-extinguishing chamber).

[0032] Preferably, the electronic breaking module 16 is received in a dedicated housing of the box 4. Even more preferably, when the box 4 is of the same type (or even identical) as the boxes of the electromechanical protection devices, said housing corresponds to the space normally occupied by the breaking chamber as well as by means of detecting an electrical fault (of the so-called thermal and magnetic type), such as a bimetallic strip and a coil.

[0033] This allows the existing circuit breaker architecture to be preserved and ensures compatibility with existing installations.

[0034] Device 2 thus includes at least one power switch 22 connected in series with the separable electrical contacts 10.

[0035] In the illustrated example, which corresponds to the illustrative case of a bipolar device, the device 2 has four power switches 22, identified here by the references T1, T2, T3 and T4.

[0036] For example, the first connection line has two power switches T1 and T2 connected in series with the separable contact between the first terminals 6 and 8. Similarly, the second connection line has two power switches T3 and T4 connected in series with the second separable contact 10 between the second terminals 6 and 8. For example, each of the said first and second connection lines corresponds to an electrical phase.

[0037] In practice, the number of power switches may vary, depending on the topology of the device and in particular the number of poles (single-phase, poly-phase, with or without neutral line) but also depending on the current rating of the device.

[0038] Each power switch can, in practice, be implemented by several components (such as transistors) connected in parallel depending on the rating of the circuit breaker that one wants to make.

[0039] For example, in device 2, which, for illustrative purposes only and not as a limitation, has a current rating of sixteen amps, two pairs of transistors are connected in series, with the transistors in each pair connected in parallel. In a variant with a higher current rating, for example, thirty-two amps, it is possible to use a greater number of transistors connected in parallel.

[0040] Each power switch 22 is switchable between an electrically blocking state and an electronically conducting state.

[0041] For example, the 22 power switches are power transistors.

[0042] According to a preferred embodiment, the power switches 22 are MOSFETs (“Metal Oxide Semiconductor Field Effect Transistor”).

[0043] This type of transistor is preferred because it has low resistance in the on state, but also because it remains in the blocked state when at rest (for example when no control signal is sent to the control electrode).

[0044] Other semiconductor technologies can however be considered depending on the size of the circuit breaker, such as insulated gate bipolar transistors (IGBTs), or thyristors, or integrated gate switching thyristors (IGCTs), or other technologies.

[0045] Alternatively, the power switches 22 can be JFETs (Junction Field Effect Transistors). In this case, the operation of the control circuit 24 may need to be modified to take into account that such JFETs are in the conducting state when at rest.

[0046] In practice, a diode is present in parallel with each of the power switches 22, as illustrated in the figure 2 Although other embodiments are possible as alternatives, it is generally a parasitic diode inherent in the construction of the power switch.

[0047] The electrical protection device further comprises an electronic control circuit 24 coupled with at least one power switch 22 (i.e., with each power switch 22). In other words, the electronic control circuit 24 allows each of the power switches 22 to be controlled.

[0048] In many embodiments, the electronic control circuit 24 includes a processor, such as a programmable microcontroller or a microprocessor.

[0049] The processor is advantageously coupled to a computer memory, or to any computer-readable data recording medium, which includes executable instructions and / or software code designed to implement a method for detecting an electrical fault when these instructions are executed by the processor.

[0050] In particular, this process makes it possible to detect an electrical fault such as an overload current fault, a short circuit fault, a differential current fault, a fault of presence of series (or differential) arc on the line to be protected, but also overvoltages or undervoltages.

[0051] According to variants not described in detail, the electronic control circuit 24 may include a digital signal processor (DSP), or a field program gate array (FPGA), or a specialized integrated circuit (ASIC), or any equivalent element, or any combination of these elements.

[0052] Advantageously, the device 2 may include one or more overvoltage protection elements 26, connected in parallel with the power switch(es) 22, in order to protect the power switches 22 against overvoltages, in particular in the event of the occurrence of an electric arc during the separation of the contacts 10.

[0053] This helps to protect live switches during a power outage in cases where the installation includes inductive circuits.

[0054] For example, the protection elements 26 are clippers or varistors (MOV, for "Metal Oxide Varistor" in English) or Transil diodes (TVS, for "Transient Voltage Suppression" in English).

[0055] In many embodiments, the device 2 includes an internal power supply unit 28 configured to electrically supply the electrical control circuit, preferably from the electrical current flowing between the connection terminals 6, 8 when the device 2 is in operation.

[0056] Alternatively, the internal power supply 28 may include a battery, or any other means enabling autonomous power supply.

[0057] For example, the electronic control circuit 24 is configured to switch the power switches 22 to an open state when an electrical fault is detected by a measuring circuit 30. For example, the device 2 has current sensors 30, here coupled to each connecting line.

[0058] For example, electrical faults can be overcurrents or short circuits, but also other electrical faults such as a differential current fault, or a fault in the presence of a series (or differential) arc on the line to be protected, or even overvoltages or undervoltages.

[0059] The switching of device 2 during a trip (i.e., following the detection of an electrical fault requiring the immediate interruption of the electrical current) can be achieved by the combined action of the switching mechanism 12 with the power switches 22.

[0060] In addition, according to embodiments, the device 2 also includes a synchronization system 32 aimed at synchronizing the switching of the power switches 22 with the opening of the contacts 10, in order to avoid the occurrence of electric arcs when the electrical contacts 10 are opened.

[0061] For this purpose, the device 2 includes a sensor 34 configured to measure a position of the switching mechanism 12. Preferably, the sensor is configured to measure the position of the control lever 14 of the switching mechanism 12, or of a part integral with the control lever 14.

[0062] For example, the sensor 34 is connected to an input of the electronic control circuit 24 so as to send a measurement signal. The sensor 34 can be positioned opposite a part of the switching mechanism 12 (for example, opposite the mechanical part carrying the control lever 14). In other words, the sensor 34 can be coupled to the control lever 14.

[0063] According to a non-limiting implementation example given by way of illustration, the sensor 34 can be configured to emit a binary signal, taking a first value when the switching mechanism 12 is in a position in which the electrical contacts 10 are closed, and taking a second value (different from the first value) when the switching mechanism is in a position preceding the position from which the electrical contacts 10 begin to separate (when the opening movement of the lever continues).

[0064] For example, this position may correspond to a specific angular position threshold of the control lever 14.

[0065] For example, the position threshold can correspond to an angle of 20° relative to the original position of the control lever 14. The angle can be chosen differently as an alternative. In practice, the angle is preferably less than or equal to 20°, or 10°, or 5°.

[0066] Preferably, sensor 34 is an optical sensor.

[0067] According to some embodiments, the sensor 34 is an obstruction optical sensor, for example arranged such that the light signal received by a sensitive element of the sensor 34 is obstructed when the control lever 14 reaches a certain position, for example when the control lever 14 has started to move from the closed position.

[0068] Alternatively, the sensor 34 can be made differently and can thus be a mechanical sensor, or an inductive sensor with external field compensation.

[0069] In many embodiments, the sensor 34 is housed in the same housing as the switching mechanism 12 and the control member 14. However, alternatively, the sensor 34 may be housed in one housing and the control member 14, as well as at least part of the switching mechanism 12, are housed in another housing.

[0070] In particular, for devices with multiple poles (for example, a three-phase circuit breaker or a two-pole DC circuit breaker), the control elements (operating levers) of each pole are mechanically linked. In this system, it can be advantageous to use a single sensor for the entire protective device, rather than a separate sensor for each pole. This single sensor can then be housed in a separate enclosure.

[0071] As will be explained in more detail with reference to figures 2 à 6 The electronic control circuit 24 is configured to switch the power switch(es) 22 to the blocking state when the sensor 34 detects that the switching mechanism is moving towards the open position, and more specifically before the electrical contacts 10 separate.

[0072] In optional but nevertheless advantageous embodiments, the device 2 may include an auxiliary sensor (not shown), configured to measure a position of the switching mechanism, the auxiliary sensor being configured to operate jointly with the optical sensor 34. This arrangement is particularly applicable to large circuit breakers, in order to improve the reliability of the detection of the position of the switching mechanism 12. This auxiliary sensor may, however, be omitted.

[0073] Optionally, the synchronizing device 32 may include an actuator 36 configured to actuate the switching mechanism 12. The actuator 36 may, for example, include an electric motor or an electromagnetic actuator with a movable mechanical part that can be moved by the action of an electromagnetic actuator. For example, the actuator 36 may be controlled by the electronic control circuit 24 and may thus control the opening of the electrical contacts 10 via the mechanism 12.

[0074] In optional embodiments, an external trigger outside the electronic control circuit 24 can be connected to an input of the electronic control circuit 24 in order to transmit a trigger command and thus cause the device 2 to be triggered via the electronic control circuit 24.

[0075] The trigger command issued by the external trigger can be transmitted electronically, via a wired connection or by a radio frequency signal.

[0076] In other embodiments, the external trigger can be mechanically coupled to the switching mechanism 12 or to the electronic control circuit 12 (for example, via an electromechanical sensor).

[0077] In some implementations, an auxiliary power supply 38 may be used to provide power to the electronic control circuit 24.

[0078] For example, an external auxiliary power supply 38 to device 2 is connected to terminals A1, A2 of device 2, said terminals being connected to an electrical distribution circuit (such as a power rail).

[0079] An example of the operation of the switching mechanism 12 and the synchronization system 32 is now described with reference to figures 3 à 5 .

[0080] THE figures 3 , 4 And 5 schematically represent a simplified version 50 of the switching mechanism 12 in different successive configurations over time. More precisely, the figure 3 corresponds to the closed state of the switching mechanism 12, in which the electrical contacts 10 are in contact (in the closed state) and allow the flow of current. figure 5 corresponds to an open state of the switching mechanism 12, in which the electrical contacts 10 are separated from each other. figure 4 corresponds to an intermediate state during a transition from the closed state to the open state.

[0081] As illustrated on the figure 3 The switching mechanism 12 comprises: the control lever 14, which has the form of a rotating part 52 mounted to rotate around an axis of rotation fixed to the housing 4 (the hatched areas visible on the figure 3 , one of which bears the reference 51, represent anchor points fixed relative to the housing 4); a transmission rod 54, or connecting rod; a release hook 56, mounted for rotation and coupled to the part 52 via the transmission rod 54; a plate 53, mounted for rotation about an axis of rotation fixed to the housing 4 and coupled to the hook 56; a release bar 58, coupled to the plate 53 and the hook 56; a contact holder 60, which carries the movable electrical contact 10 and which cooperates with the fixed electrical contact 61, the contact holder being mounted for rotation about an axis of rotation fixed to the housing 4; stops 62 which limit the rotational movement of the control lever 52, for example respectively in the open and closed positions.

[0082] The axes of rotation are arranged here in parallel, for example by all being arranged perpendicular to a side wall of the housing 4.

[0083] During the triggering phase, the trigger bar 58 is rotated, which releases the hook 56 and rotates the plate 53 and the contact holder 60 towards the open position. Simultaneously, the movement of the plate triggers a rotational movement of the part 52 via the connecting rod 54.

[0084] In the illustrated example, the sensor 34 is positioned such that, in the open state, at least part of the component 52 is positioned in front of the sensor 34, thus, for example, obscuring at least one sensitive portion of the sensor 34. Conversely, in the closed state, the component 52 remains away from the sensor 34 and does not obscure the sensitive portion of the sensor 34. The position at which the sensitive portion of the sensor 34 is obscured by the component 52 can correspond to an angular position threshold. When the component 52 passes in front of the sensor, the sensor 34 changes state and then sends a different measurement signal.

[0085] With the configuration used in the illustrated example, the angular position threshold is reached at the latest just before the electrical contacts 10 begin to separate, as illustrated in the figure 4 and on the figure 6 .

[0086] On the figure 6 Chronogram 70 represents the evolution as a function of time (denoted "t" on the x-axis): of the position of the switching mechanism 12, represented here by the angular position of the control lever 14 (curve 72), of the state of the optical sensor 34 (curve 74, which here can take either a low value or a high value, depending on whether the measurement signal takes the first value or the second value, respectively); of the closed or open state of the separable electrical contacts 10 (curve 76, which here can take either a low value or a high value, corresponding respectively to the open state and the closed state).

[0087] Thus, following a trigger, the angle of the control lever 14 reaches a threshold (represented here by the first vertical dotted line on curve 74) at which point the sensor changes state. In response, the electrical control circuit 24 triggers the switching of the power switches 22 to their blocking state, in order to interrupt the flow of current. After a certain delay, here immediately after the position visible on the figure 4 , the electrical contacts 10 are finally separated by the switching mechanism 12, which then reaches the end of the opening movement.

[0088] Such operation can be advantageously achieved with specific switching mechanisms, such as toggle switching mechanisms, such as those described above, in which the relative movement of the parts of the mechanism is configured to cause the appearance of an angular offset between the rotation of the control lever 14 and the effective opening of the contacts 10, for example to briefly delay the separation of the contacts 10 when triggering to open.

[0089] This offset allows to compensate for a decrease in the clearance in the insertion of the electrical contacts caused by the gradual wear of the electrical contacts throughout the life of the device 2.

[0090] In practice, in these embodiments, the control circuit 24 takes advantage of this delay so that the switching of the power switches (caused by the start of rotation of the control lever 14, as detected by the sensor 34) anticipates the separation of the electrical contacts 10.

[0091] Thanks to the invention, during the opening phase, the electronic control circuit 32 and the sensor 34 synchronize the action of the power switches 22 and the switching mechanism 12, specifically to command the switching of the power switches 22 to their blocking state before the electrical contacts 10 are separated. This prevents the formation of an electric arc between the electrical contacts 10 and thus allows the current to be interrupted safely.

[0092] In other words, we are using here the delay between the switching of the power switches and the separation of the electrical contacts which results from the design of the switching mechanism 12.

[0093] This is particularly useful when the device is used in a DC installation, as the separable electrical contacts 10 are generally not sufficient on their own to interrupt the current.

[0094] On the other hand, once in the open position, the separable electrical contacts 10 make it possible to create electrical insulation in the air and prevent an electric current from flowing again between the terminals 6 and 8 after the device 2 has been triggered.

[0095] To close the contacts 10 (i.e., to switch the device 2 back to the closed state), the control lever 14 is moved to the corresponding position by a user. This movement, via the connecting rod 54, causes the hook 56 to rotate and engage with the release bar 58. The connecting rod 54 then rotates the plate 53 until the contacts 10 are closed.

[0096] Furthermore, using a housing 4 that is analogous, similar, or even identical to the housings of electromechanical protective devices ensures compatibility with previous product lines. For example, device 2 can be installed in an electrical panel to replace an earlier generation protective device without requiring modifications to the rest of the installation. This also allows the use of existing auxiliary devices.

[0097] The use of an optical sensor 34 is advantageous because such a sensor is small and can be easily integrated into the device 2, thus enabling a compact device 2. An optical sensor also has the advantage of being precise and not sensitive to surrounding electromagnetic interference (nor does it generate electromagnetic interference that could harm the operation of the installation or the device 2 itself).

[0098] Finally, using a toggle mechanism as the switching mechanism 12 allows for play compensation in the contact depressment before reaching the contact opening position, as explained above.

[0099] There figure 7 represents an advantageous but not mandatory example of the construction of the electronic cutoff module 16.

[0100] In this example, at least part of the electronic switching module 16 is constructed in the form of an integrated block 80, or even several such integrated blocks 80.

[0101] Preferably, the integrated block or each integrated block 80 includes the power switches 22 associated with a pole of the device (i.e., with one of said electrical conduction lines, itself associated with an electrical phase of the device 2).

[0102] The integrated module 80 includes a plate-shaped substrate 82, for example made of an electrically insulating material.

[0103] In practice, this could be a composite material, such as glass fiber reinforced epoxy resin, commonly noted under the reference "FR4".

[0104] At least some of the power switches 22 are mounted on the substrate 82, in particular on main faces of the substrate 82.

[0105] For example, transistors T1 and T2, associated with the first connection line, are mounted on opposite faces of substrate 82 as seen in insert B) of the figure 7 , these switches here bearing the numerical reference 84.

[0106] Indeed, as explained previously, each transistor T1, T2 illustrated on the figure 2 can be implemented in practice by a group of two transistors connected in parallel, depending in particular on the size of device 2 and the properties of the transistors used.

[0107] In the illustrated example, given for illustrative purposes, the group of two transistors connected in parallel are used to implement the "transistor T1", these two transistors being mounted on one face of the substrate 82. A group of two other transistors connected in parallel are used to implement the "transistor T2", these two other transistors being mounted on a second face of the substrate 82, the second face of the substrate 82 being opposite the first face of the substrate 82.

[0108] Still in this example, the transistors T3, T4 associated with the second connection line are mounted on opposite faces of the substrate 82 of a second integrated block 80, this second integrated block 80 being connected in parallel with the present integrated block 80 and being identical or at least similar to the present integrated block 80.

[0109] This second block 80, for example, is mounted alongside the first block 80.

[0110] Preferably, the integrated block or each block 80 is received in the aforementioned dedicated housing of the case 4 mentioned above.

[0111] In practice, each power switch 22 may include a heat dissipation plate 86, also called a base plate, which sits atop the body of the power switch 22. In other words, the heat dissipation plate 86 is thermally connected to the body of said power switch.

[0112] For example, the heat dissipation plate 86 is a metal plate natively attached to the ceramic body of the power switch 22 by the manufacturer of the power switch 22.

[0113] Optionally, components of the electronic control circuit 24 can also be mounted on one or both of the main faces of the substrate 82.

[0114] For example, one or more of the current sensors 30 associated with a connection line can be integrated into the corresponding module 80 and mounted on the substrate 82.

[0115] The block 80 also includes two electrically conductive plates 90 and 92, each plate 90, 92 being mounted on each face of the substrate 82 so as to cover this substrate 82. It is understood that in the assembled position, the plates 90 and 92 also cover the components mounted on the faces of the substrate 82.

[0116] In this description, plates 90 and 92 are made of metallic material and are referred to as "metal plates" hereafter. However, alternatively, other materials or material compositions may be used as long as plates 90 and 92 are electrically conductive.

[0117] Advantageously, each metal plate 90, 92 is in contact (preferably in direct contact) with the metal base 86 of the corresponding power switches (i.e., power switches 84 located under this metal plate 90, 92). In other words, each metal plate 90, 92 is electrically and thermally connected to the corresponding power switches 84.

[0118] This arrangement allows the plates 90 and 92 to be used both as a heat sink and as an electrically conductive element allowing the connection of the power switches 22.

[0119] Indeed, when the power switch 22 is a MOSFET transistor, the metal plate 86 is connected to the drain. Thus, the power current flowing in the device 2's connection line can pass through the plate 86. The metal plates 90 and 92 are then connected respectively to terminals 8 and 6 of the corresponding connection line.

[0120] Using the sole 86 to conduct power current does not pose a risk to user safety, since the sole 86 is electrically insulated from the outside by the housing 4 of the device, which is made of electrically insulating material and prevents a user from touching the sole 86.

[0121] The thermal energy released by the switches 22 is dissipated here to the outside of the device 2 by conduction along the electrical conductors.

[0122] For example, thermal energy is mainly dissipated by conduction and radiation from the conductive parts to the outside of the device 2.

[0123] Advantageously, heat dissipation phenomena by air convection can also be used, provided that ventilation openings compatible with electrical insulation criteria are provided, such as ventilation slots or louvers.

[0124] For the dissipation of thermal energy by conduction, the entire current passage chain inside the circuit breaker is concerned, that is to say all the electrical conductors, power supply cables and electrical conduction lines which allow the current to flow from upstream to downstream of the device 2.

[0125] For example, by design, the circuit breaker connection ranges are compatible with the maximum temperature of the cable insulation, this temperature being able to reach a maximum of 90°C at the connection ranges connected with copper cables fitted with PVC sheaths.

[0126] In practice, the hottest point is generally at the center of device 2, so a decreasing temperature profile is observed from the center of device 2 towards the cable connection areas.

[0127] Advantageously, the 90 and 92 metal plates are made mainly of copper, which has good electrical and thermal conductivity properties.

[0128] Alternatively, however, other materials with good electrical and thermal conductivity properties can be used, such as aluminum.

[0129] For constructing metal plates 90 and 92, surface-treated materials such as tin-plated plates or plates partially or completely coated with a thin layer of silver can also be used to improve certain properties, such as contact resistance between the power switches and the metal plates. Surface treatment can also improve radiation dissipation, for example, through painting or anodizing.

[0130] Preferably, the metal plates 90 and 92 are oversized to increase the dissipation of thermal energy primarily by conduction, but also by radiation and convection. This oversizing also helps to reduce Joule effect losses.

[0131] Preferably, in the assembled configuration, the metal plates 90 and 92 extend parallel to the widest walls of the housing 4. In the illustrated example, these are the side walls of the housing 4 of the device 2, these walls being oriented vertically when the device 2 is mounted in an electrical cabinet or switchboard. Preferably, each metal plate 90, 92 covers at least 40% of the surface area of ​​the corresponding face of the side wall of the housing 4.

[0132] The thickness of each of the plates 90 and 92 is preferably less than or equal to 5 mm and, even more preferably, between 1 mm and 3 mm.

[0133] In particular, the greater the thickness of the 90 and 92 plates, the greater the thermal conductivity, which makes heat dissipation more efficient.

[0134] As an illustrative example, in the case of a module 80 comprising four transistors (two transistors connected in parallel on each face of the substrate 82), each transistor dissipating a thermal power of 1 watt, for the case of a monopolar device with a current rating of 16 amps, it was observed that a thickness of 1.0 mm of copper for the plates 90 and 92 allows an internal temperature of 114.6 °C to be obtained, while a thickness of 3 mm of copper for the plates 90 and 92 allows the internal temperature to be reduced to 105 °C.

[0135] In practice, the substrate 82 may have fixing holes 88 which, in assembled configuration, are aligned with corresponding holes drilled in the metal plates 90 and 92.

[0136] In the illustrated example, one of the metal plates (in this case, metal plate 92) has a folded portion 94 that is folded relative to the rest of the metal plate 92, for example, by extending perpendicularly from one edge of said metal plate to the plane of said metal plate. Specifically, portion 94 is folded at 90 degrees to the metal plate to align with the pivoting direction of the moving electrical contact and thus form a fixed contact portion.

[0137] The folded portion 94 is used here as a fixed electrical contact which cooperates with the movable contact 10 to together form the said separable electrical contacts, as illustrated in the figure 1 , and thus achieve the galvanic isolation function when the contacts are open.

[0138] Alternatively, portion 94 could be replaced by a contact portion with a different shape. For example, the contact portion could be formed directly on an edge or slice of the metal plate, without having a folded protrusion.

[0139] Alternatively, the folded portion 94 can be omitted. The contact portion can also be omitted, particularly when the plates 90 and 92, and more generally the block 80, are housed in a separate enclosure from the one containing the moving electrical contact, as for example in the case mentioned above where the power switches are housed in a separate enclosure from the one containing the switching mechanism. This allows, for example, the use of a larger circuit board and metal plates.

[0140] The metal plates 90 and 92 are brought into contact here via a surge-limiting element 96, which corresponds to a surge protection element 26 described with reference to the figure 2 .

[0141] The overvoltage limiter element 96 is electrically connected to the metal plates 90 and 92, for example, by means of tin solder. Alternatively, other soldering or assembly methods are possible. For example, element 96 can be directly screwed to the metal plates 90 and 92.

[0142] In some variants, when the protective element 26 is omitted, element 96 can be replaced by an electrical conductor.

[0143] However, as an alternative, block 80 can be constructed differently.

[0144] For example, in the case of a direct current (DC) device with unidirectional current flow, only one power switch may be used. In this case, only one face of the substrate 82 may be used, and only one metal plate 90 or 92 may be used covering this face of the substrate, this plate being connected between terminals 6 and 8. Preferably, this single plate is mounted on the side of the substrate 82 opposite the moving electrical contact 10.

[0145] The embodiments relating to block 80 and in particular to plates 90 and 92 can be implemented independently of the previous embodiments, and in particular of the embodiments relating to the control methods of switches 22 and the operation of sensor 34.

[0146] Block 80 can be built with other types of power switches, for example IGBT transistors, SiC MOSFETs, GaN MOSFETs and SiC JFET transistors, these examples are not limiting.

[0147] In general, embodiments relating to block 80 may relate to an electrical protection device 2 comprising a housing 4, connection terminals 6, 8, separable electrical contacts 10 connected between the connection terminals 6, 8, a switching mechanism 12 and at least one power switch 22 connected in series with the separable electrical contacts.

[0148] The separable electrical contacts 10 being movable between an open state and a closed state, the switching mechanism 12 comprising a control lever 14 and being coupled with the separable electrical contacts 10 to switch the separable electrical contacts to the open state, the electrical protection device further comprising an electronic control circuit 24 coupled with said at least one power switch 22.

[0149] The electrical protection device 2 further comprises at least one power switch, or even a pair of power switches, such as field-effect transistors T1, T2, and preferably MOSFET transistors, each power switch comprising a metal base 86 connected to the drain (or more generally to an electrode) of said power switch.

[0150] The said metal base 86 being thermally connected to the body of said power switch, and the power switches are connected in series with separable electrical contacts (capable of forming an air gap) between the connection terminals 6, 8 by means of metal plates 90, 92 connected (electrically and thermally) to the metal bases 86 of the respective power switches.

[0151] Other embodiments of device 2 are nevertheless possible.

[0152] In particular, device 2 can be modified for use in a single-phase installation, or in a polyphase installation, as explained previously.

[0153] There figure 8 represents an embodiment of a 200 single-phase device.

[0154] Device 200 is similar to device 2 described with reference to the figure 2 , except that one of the connection lines is replaced by a neutral conductor line without T3 and T4 power switches (and the protection component 26).

[0155] Apart from these differences, the elements of device 200 which are analogous to the corresponding elements of device 2 bear the same references and are not described in detail, insofar as the above description can be transposed to them.

[0156] For the sake of readability, certain optional components of device 2, such as the auxiliary power supply 38, are not shown on the figure 8 , although they could optionally be included in this embodiment.

[0157] There figure 9 represents an embodiment of a 300 three-phase device.

[0158] Device 300 is similar to device 2 described in reference to the figure 2 , except that device 300 has a third connection line connected in parallel with the first connection line and the second connection line between terminals 6 and 8.

[0159] The third electrical connection line is similar or identical to the first connection line and the second connection line and includes at least one of said power switches 22 (here two in number and marked T5 and T6) and an electrical contact 10 as described previously, connected in series with the power switch(es) 22 by one or more electrical conductors.

[0160] Advantageously, the third connection line includes an overvoltage protection element 26, connected in parallel with the power switches 22, as previously described.

[0161] Here again, for the sake of readability, certain optional elements of device 2, such as the auxiliary power supply 38, are not shown on the figure 9 , although they could optionally be included in this embodiment.

[0162] There figure 10 represents an embodiment of a 400 three-phase (three-pole) device with neutral comprising three electrical connection lines and a neutral line similar to the neutral line of the 200 device.

[0163] Device 400 is similar to device 300 described in reference to the figure 9 , except that device 400 also includes a neutral line connected in parallel with the first connection line and the second connection line between terminals 6 and 8.

[0164] Apart from these differences, the elements of device 400 which are analogous to the corresponding elements of device 300 bear the same references and are not described in detail, insofar as the above description can be transposed to them.

[0165] There figure 11 represents an embodiment of a 500 four-phase (tetrapole) device comprising four electrical connection lines similar to the connection lines previously described.

[0166] Device 500 is similar to device 4 described in reference to the figure 10 , except that device 500 has, instead of the neutral line, a fourth connection line connected in parallel with the first connection line and the second connection line between terminals 6 and 8.

[0167] The fourth electrical connection line is similar or identical to the first connection line and the second connection line and includes at least one of said power switches 22 (here two in number and marked T7 and T8) and an electrical contact 10 as described previously, connected in series with the power switch(es) 22 by one or more electrical conductors.

[0168] Advantageously, the fourth connection line includes an overvoltage protection element 26, connected in parallel with the power switches 22, as previously described.

[0169] Apart from these differences, the elements of device 500 which are analogous to the corresponding elements of device 400 bear the same references and are not described in detail, insofar as the above description can be transposed to them.

[0170] Here again, in both cases, for the sake of readability, certain optional elements, such as the auxiliary power supply 38, are not shown on the figures 10 And 11 , although they could optionally be included in these embodiments.

Claims

1. An electrical protection system (2) comprising a housing (4), connection terminals (6, 8), separable electrical contacts (10) connected between the connection terminals (6, 8), a switching mechanism (12) and at least one power switch (22) connected in series with the separable electrical contacts, the separable electrical contacts being movable between an open state and a closed state, the switching mechanism being coupled with the separable electrical contacts to switch the separable electrical contacts to the open state, the electrical protection system further comprising an electronic control circuit (24) coupled with said at least one power switch (22), characterised in that the or each power switch comprises a metal heat dissipation plate (86) connected to an electrode of said power switch, said heat dissipation plate is thermally connected to the body of said power switch, and wherein the or each power switch is connected in series with the separable electrical contacts between the connection terminals (6, 8) via a conductive plate (90, 92) connected to the plate of the respective power switch.

2. A system according to claim 1, wherein the or each power switch associated with a pole of the apparatus is mounted on a plate-like substrate (82) integral with a block (80), the respective conductive plate (90, 92) of each power switch being mounted on the same side of the substrate (82) of the block (80).

3. A system as claimed in claim 2, wherein the system comprises two groups of at least one power switch (22) associated with a same pole of the system which are mounted on the substrate (82), each at least one power switch (22) and the respective conductive plate (90, 92) of said group being mounted on opposite sides of the substrate (82).

4. A system according to any one of claims 2 or 3, wherein the or each block (80) is received in a dedicated housing of the housing (4).

5. A system according to any one of the preceding claims, in which the or each conductive plate (90, 92) covers at least 40% of the surface area of the corresponding face of the side wall of the housing (4).

6. A system according to any one of the preceding claims, wherein the or each conductive plate (90, 92) extends parallel to the widest walls of the housing.

7. A system according to any one of the preceding claims, wherein the heat sink plate is a metal plate natively attached to a ceramic body of the power switch.

8. A system according to any of the preceding claims, wherein said at least one power switch (22) is a field effect transistor, preferably a MOSFET transistor.

9. A system according to any one of the preceding claims, wherein the or each conductive plate (90, 92) is made of metal.

10. A system as claimed in claim 9, wherein the or each metal plate (90, 92) is made primarily of copper or aluminium.

11. A system according to any one of the preceding claims, wherein one of the conductive plates (92) includes a portion (94) adapted to form an electrical contact, the portion (94) being used as a fixed electrical contact which cooperates with a movable contact (10) of the system (2) to form together said separable electrical contacts.

12. A system according to any one of the preceding claims, wherein the or each conductive plate (90, 92) is connected to a respective connection terminal (6, 8) of the system.

13. An electrical protection device comprising the electrical protection system (2) according to any of the preceding claims, wherein the electrical protection device (2) is a miniature circuit breaker.

14. An electrical protection device according to claim 13, wherein the width of the housing (4) is a multiple of 9mm.

15. An electrical protection device comprising a housing and the electrical protection system (2) according to any one of claims 1 to 12, wherein the electrical protection device (2) is an air circuit breaker.

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