Electrical protection device, electrical installation and associated control process

Abstract

Electrical protection device, associated electrical installation and control method The present invention relates to an electrical protection device comprising: a mechanical switch; an interruption cell (18) comprising N switching modules (32, 42), N being greater than or equal to 2, each switching module (32, 42) comprising a voltage limiting element (39, 49), each voltage limiting element having a different limiting voltage (Ulim1, Ulim2);a control unit comprising a cell control module (66), configured to control each switching module in the blocked configuration, the limiting voltages, alone and / or summed together, form at least 2N-1 distinct steps, and the cell control module is configured to control in the blocked configuration the switching module(s) whose limiting voltages form a step being the largest step less than or equal to a dielectric withstand of the mechanical switch. Figure for the abbreviation: Figure 2;

Description

Title of the invention: Electrical protection device, electrical installation and associated control method

[0001] The present invention relates to an electrical protection device, an electrical installation and an associated control method.

[0002] It is known to use electrical protection devices comprising a mechanical switch and an interruption cell comprising at least one switching module including a semiconductor element connected in parallel with a voltage-limiting element. These protection devices are also called hybrid circuit breakers. US2022122801A1 describes a hybrid circuit breaker for high-voltage direct current, comprising a main circuit breaker with several switching modules connected in series. When a short-circuit fault is detected and the electrical current must be interrupted, the switching modules are opened successively, thereby reducing the interruption time of the short-circuit fault and limiting the peak current in the installation.

[0003] However, this known hybrid circuit breaker includes an auxiliary switch connected in series with the mechanical switch, with the assembly comprising the auxiliary switch and the mechanical switch being connected in parallel with the main circuit breaker. The auxiliary switch generates significant electrical losses, for example, losses due to heat dissipation, and increases the number of components required to construct the hybrid circuit breaker. Furthermore, the sequential opening of the switching modules does not allow for a reduction in the interruption time of a short-circuit fault or for optimally limiting the peak current.

[0004] The aim of the invention is therefore to propose a protection device that reduces electrical losses and limits the number of components while reducing the interruption time of the short-circuit type fault and limiting the peak current.

[0005] To this end, the invention relates to an electrical protection device, configured to be connected between a source and a load, the device comprising: - a mechanical switch, configured to switch between a closed configuration, in which the mechanical switch conducts a current flowing between the source and the load, and an open configuration, in which the mechanical switch does not conduct the current; - an interrupt cell, connected in parallel with the mechanical switch, the interrupt cell comprising N switching modules connected in series with each other, N being greater than or equal to 2, each switching module

[0006]

[0007]

[0008]

[0009]

[0010] mutation including: • at least one semiconductor element; • a voltage limiting element, connected in parallel with the semiconductor element(s), each voltage limiting element having a limiting voltage, different from the limiting voltage of the other voltage limiting elements, each switching module being configured to switch between a forward configuration, in which current flows in the or one of the semiconductor elements of the switching module, and a blocked configuration, in which if current flows in the switching module, it flows in the voltage limiting element; - a current sensor configured to measure current intensity; - a control unit comprising: • a detection module configured to detect an electrical fault of the short-circuit type based on the intensity measured by the current sensor; • a mechanical switch control module, configured to control the mechanical switch in the open configuration when an electrical fault is detected, • a cell control module, configured to control each switching module in the locked configuration. According to the invention, an input of the mechanical switch and an input of the interrupt cell are connected to each other by an uninterruptible electrical link, and an output of the mechanical switch and an output of the interrupt cell are connected to each other by an uninterruptible electrical link. The limiting voltages, alone and / or summed together, form at least 2N-1 distinct plateaus, and the cell control module is configured to: • control in locked configuration the switching module(s) whose voltage limiting elements form a given plateau, the given plateau being the largest plateau less than or equal to the dielectric strength of the mechanical switch, and • control the other switching modules in a forward configuration. The fact that the electrical connection is uninterruptible means that the device does not include an auxiliary switch. Thus, thanks to the invention, the number of components in the electrical device is reduced and electrical and thermal losses are minimized, thereby improving the device's performance.

[0011] Furthermore, thanks to the invention, the switching modules are no longer controlled sequentially, but rather the limiting voltages of the different switching modules are combined to form a maximum number of steps, in this case 2N-1 steps, and not N steps. Thus, the current is limited more precisely, as soon as the dielectric strength of the mechanical switch is greater than or equal to one of the steps. This makes it possible, without increasing the number of switching modules compared to the case where the switching modules are controlled sequentially, to limit an increase in current caused by a short-circuit type electrical fault as early as possible, and therefore to limit the stresses in the loads or even in the cables connecting the device, the source, and the load, while ensuring a leakage current in the voltage limiting elements compatible with the energy capacity of the device components.

[0012] According to other advantageous aspects of the invention, the device comprises one or more of the following features, taken individually or in all technically possible combinations:

[0013] - Each switching module comprises two semiconductor elements which are unidirectional in current and connected to each other in anti-series, and for each semiconductor element, a diode is connected in anti-parallel to the semiconductor element.

[0014] - The interrupt cell comprises two rectification branches, the input and the output of the interrupt cell forming respectively a midpoint of one of the rectification branches, each rectification branch comprising two diodes arranged on either side of the midpoint, connected in anti-series with respect to each other; - the switching modules are connected in parallel with the rectifier branches; and - Each switching module comprises a single semiconductor element connected in parallel with the voltage limiting element.

[0015] - The device comprises at least three switching modules.

[0016] - One of the switching modules, called the variable voltage switching module, includes a plurality of voltage limiting elements, each having a limiting voltage different from each other and different from the limiting voltages of the voltage limiting elements of the other switching modules; - each voltage limiting element of the variable voltage switching module is associated with a switching element with which it is connected in series, each voltage limiting element and its associated switching element being connected in parallel with the semiconductor element(s); - the bearings are formed at most by a limiting voltage of a lithium element

[0017]

[0018]

[0019]

[0020]

[0021] Voltage modulation of the variable voltage switching module, possibly summed with one or more limiting voltages from the other switching modules; and - the cell control module is further configured to, when a given limiting voltage element of the variable voltage switching module forms part of a given step, the given step being the largest step less than or equal to the dielectric strength of the mechanical switch, switch the switching member associated with the given limiting voltage element from a passing state to a blocked state, and control the other switching members of the variable voltage switching module in the blocked state. - The device also includes a disconnector, connected in series to the mechanical switch without being connected in parallel to the interrupt cell. -A triggering time between the detection of the electrical fault of the short circuit type by the detection module and a transition of all the switching modules into the blocked configuration is less than 1ms, preferably less than 800 ps, ​​preferably even less than 400 ps. The invention also relates to an electrical installation comprising a source, a load connected to the source, and an electrical protection device as described above, connected between the source and the load, a nominal voltage of the current flowing between the source and the load being less than 1500 V. The invention also relates to a method for controlling an electrical protection device, the method comprising at least the following steps: - measurement of the current intensity by the current sensor; - detection of a short-circuit type electrical fault by the module detection, based on the intensity measured by the current sensor; - when a short-circuit type electrical fault is detected, the mechanical switch is controlled in the open configuration by the mechanical switch control module; and - when the dielectric strength of the mechanical switch is greater than or equal to a given level, the given level being the largest level less than or equal to the dielectric strength of the mechanical switch, control of the switching module(s) whose limiting voltages of the limiting elements form the given level, and of the other switching modules in the forward configuration. Advantageously, the method further comprises, when a given limiting voltage element of the variable voltage switching module forms part of a given bearing and the dielectric strength of the mechanical switch is greater than or equal to the given bearing, a control step of the associated switching component to the given limiting voltage element in the on state, and the other switching components of the variable voltage switching module in the off state.

[0022] The invention will become clearer upon reading the following description, given solely by way of non-limiting example, and made with reference to the drawings in which: - [Fig.1] [Fig.1] is a diagram of an electrical installation including an electrical protection device conforming to a first embodiment of the invention; - [Fig.2] [Fig.2] is a diagram of an interrupt cell of the device electrical protection according to the first embodiment of the invention; - [Fig.3] [Fig.3] is a graphical representation of a tension and a intensity of a current flowing in a protective device according to the invention as a function of time; - [Fig.4] [Fig.4] is a logic diagram of a control process according to the invention. - [Fig. 5] [Fig. 5] is a diagram of an interrupt cell of a device electrical protection according to a second embodiment of the invention; and - [Fig. 6] [Fig. 6] is a diagram of an interrupt cell of a device electrical protection according to a third embodiment of the invention.

[0023] Figure 1 is a diagram of an electrical installation 1 comprising a source 3 and a load 5, electrically connected to each other by a phase conductor 7 and a neutral conductor 8. The source 3 supplies electricity and is, for example, an electric generator or an electrical network, for example, a mains electricity network. The load 5 is a device consuming electricity, such as a household electrical appliance, industrial equipment such as an electric motor, or a server. Thus, an electric current, hereafter simply referred to as current, flows between the source 3 and the load 5 through the phase conductor 7, and returns to the source 3 through the neutral conductor 8.

[0024] The current is a low voltage current, that is to say that a nominal voltage Us of the current, also called mains voltage, is less than 1500 V. The current is an alternating current or, alternatively, a direct current.

[0025] The electrical installation 1 also includes an electrical protection device 10, also referred to hereafter as the device, connected between the source 3 and the load 5. The device 10 is configured to switch between an armed configuration, in which the device 10 conducts the current flowing between the source 3 and the load 5, and a tripped configuration, in which the device 10 electrically isolates the source 3 from the load 5.

[0026] The device 10 includes a mechanical switch 12, also known as the The name is bypass switch, or fast mechanical switch, also called FMS (Fast Mechanical Switch). The mechanical switch 12 is connected in series to the phase conductor 7, via an input 12a and an output 12b, and is configured to switch between a closed configuration, in which it conducts the current flowing between the source 3 and the load 5, and an open configuration, in which it does not conduct the current. In [Fig. 1], the mechanical switch 12 is shown in the open configuration. The device 10 advantageously includes an actuator 16 which, when activated, switches the mechanical switch 12 to the open configuration.

[0027] The device 10 includes an interrupt cell 18, connected in parallel with the mechanical switch 12, such that the input 12a and the output 12b of the mechanical switch 12 are connected respectively to an input 18a and to an output 18b of the interrupt cell 18.More specifically, the input 12a of the mechanical switch 12 and the input 18a of the interrupt cell 18 are connected by the electrical link 19a, which is uninterruptible, and the output 12b of the mechanical switch 12 is connected to the output 18b of the interrupt cell 18 by the electrical link 19b, which is also uninterruptible. In other words, the electrical links 19a and 19b are each an electrical cable or wire; neither of the electrical links 19a and 19b includes a switch or, more generally, any means of interrupting the electric current. The interrupt cell 18 is configured to allow or interrupt the current flowing through it, as explained later.

[0028] The device 10 advantageously comprises a first disconnector 23 and, optionally, a second disconnector 24, connected respectively to the phase conductor 7 and the neutral conductor 8. In particular, the disconnector 23 is connected to the phase conductor 7 in series with the mechanical switch 12, without being connected in parallel with the interrupting cell 18. Furthermore, the disconnector 23 is connected in series with the neutral conductor 8. The disconnectors 23 and 24 are configured to switch between a closed configuration in which the disconnectors 23 and 24 conduct current, and an open configuration in which the disconnectors 23 and 24 do not conduct current. Advantageously, and as shown in [Fig.[l] The device 10 includes an actuator 25 of the first disconnector 23 and an actuator 26 of the second disconnector 24 which, when activated, interact respectively with the first disconnector 23 and the second disconnector 24 to switch them to the open configuration. The actuators 25 and 26 are, for example, coils and are activated when a current flows through the turns of the coils.

[0029] The disconnectors 23 and 24 are configured to switch to the open position in particular when no current flows between the source 3 and the load 5, in other words, when the current has been interrupted by the mechanical switch 12 and / or by the cell Interruption 18.

[0030] The interrupt cell 18 comprises N switching modules, for example N=2 switching modules 32 and 42, as shown in [Fig.2]. Alternatively, there are three or more switching modules, as symbolized by the dashed line in [Fig.2].

[0031] The switching modules 32 and 42 are connected in series with each other. Each switching module 32 and 42 comprises at least one switchable semiconductor element, for example at least one thyristor or at least one transistor, such as a field-effect transistor, also called a FET (from the English Field Effect Transistor), an insulated-gate field-effect transistor, also called a MOSFET (from the English Metal Oxide Semiconductor Field Effect Transistor), an insulated-gate bipolar transistor, or IGBT (from the English Insulated Gate Bipolar Transistor), or a combination of these different semiconductor elements.

[0032] In the example of [Fig. 2], each switching module 32 comprises two current-unidirectional transistors 34 and 35, for example, two IGBTs. The direction of conduction of transistors 34 and 35 is indicated by an arrow on each transistor 34, 35. Transistors 34 and 35 are connected to each other in anti-series, that is, transistors 34 and 35 are connected in series but back-to-back, so that they do not conduct current at the same time. Two diodes 36 and 37 are connected to transistors 34 and 35, respectively. Diode 36 is connected in anti-parallel to transistor 34, that is, diode 36 and transistor 34 do not conduct electric current at the same time: if transistor 34 is conducting, diode 36 is blocking, and vice versa. In other words, transistor 34 and diode 36 are connected in parallel, back-to-back. The same is true for transistor 35 and diode 37.This arrangement allows each switching module 32 and 42 to conduct alternating current without interruption at each change of sign of the current.

[0033] The switching module 32 includes a voltage limiting element 39. The voltage limiting element 39 is connected in parallel with a set formed by transistors 34 and 35, and is, for example, a metal oxide varistor (MOV), a transil diode, or a gas discharge tube. The voltage limiting element 39 has a limiting voltage Uiimi, which corresponds to the voltage across its terminals when it is traversed by the current flowing between the source 3 and the load 5.

[0034] Similarly, the switching module 42 comprises two transistors 44 and 45 and two diodes 46 and 47, similar at least functionally and connected in the same way as described for transistors 34, 35 and diodes 36 and 37. The switching module 42 comprises a voltage limiting element 49, similar at least functionally to the voltage limiting element 39 and connected in parallel of transistors 44 and 45. The voltage limiting element 39 has a voltage limiting voltage Uiim2.

[0035] The limiting voltages Uiimi and Uiim2 are different, for example the limiting voltage Uiimi is equal to 440V and the limiting voltage Uiim2 is equal to 900V.

[0036] The switching modules 32 and 42 are configured to switch between a forward-biased and a reverse-biased configuration. In the forward-biased configuration, current flows through the switching module 32 either through transistor 34 and diode 37, or through transistor 35 and diode 36, and through the switching module 42 either through transistor 44 and diode 47, or through transistor 45 and diode 46. In particular, when the current through the device 10 is alternating, transistor 34, diode 37, transistor 44, and diode 47 conduct current initially, and then, when the current reverses direction, transistor 35, diode 36, transistor 45, and diode 46 conduct current. More generally, in the forward configuration, at least one of the transistors 34, 35 and at least one of the transistors 44, 45 conduct current.

[0037] In the blocked configuration, transistors 34 and 35 do not conduct current and, if current flows in the switching module 32, it flows through the voltage limiting element 39. Similarly, when the switching module 42 is in the blocked configuration, transistors 44 and 45 do not conduct current and if current flows in the switching module 42, it flows through the voltage limiting element 49.

[0038] Thus, in the blocked configuration, the voltages across the switching modules 32 and 42 are respectively the limiting voltage Uiimi and the limiting voltage Uiim2.

[0039] By combination, the limiting voltages Uiimi and Uiim2 form 2N-1 distinct steps. Here, the number Np of switching steps is equal to Np = 2N-1, where N is the number of switching modules. The steps are formed by the limiting voltages Uiimi and Uiim2 taken individually, or summed together. The list of resulting steps is shown in the table below. For N=2 switching modules, three distinct steps P1, P2, P3 are obtained, with 3 = 22-1. Here, P1 is the step with the lowest value, equal to Uiimi, which is, for example, 440V; P2 is greater than P1 and has a value equal to Uiim2, which is, for example, 900V; and P3 is greater than P2, with a value equal to the sum of Uiimi and Uiim2, for example, 1340V. Advantageously, the P3 step, or generally the largest step, is on the order of 1.5 times the mains voltage Us.

[0040] [Tables 1] Level Value PI Uiimi P2 Ulim2 P3 Uliml + Ulim2

[0041] The control device 10 also includes a current sensor 52. The current sensor 52 is configured to measure an intensity I of the current flowing between the source and the load, and in particular the current flowing in the phase conductor 7. The current sensor 52 is, for example, a Rogowski torus.

[0042] The control device 10 includes a control unit 60, comprising a detection module 62, connected to the current sensor 52 and configured to detect an electrical fault of the short-circuit type as a function of the current I, measured by the current sensor 52. In the following, the term short-circuit will be used to designate an electrical fault of the short-circuit type.

[0043] The control unit 60 also includes a mechanical switch control module 64, a cell control module 66 and, advantageously, a disconnector control module 68, connected to the detection module 62 and respectively configured to control the mechanical switch 12, the interrupting cell 18 and the disconnectors 23 and 24.

[0044] The control modules for the mechanical switch 64 and the disconnectors 68 are advantageously configured to actuate the actuators 16, 25 and 26 respectively, in order to switch the switch 12 and the disconnectors 23 and 24 into the open configuration.

[0045] The cell control module 66 is configured to control, in a blocked configuration, the switching module(s) 32, 42 whose limiting voltages Uiim, Uiim2 of the limiting elements 29 and 39 form a given plateau. The given plateau being the largest plateau less than or equal to the dielectric strength of the mechanical switch 12, and to control, in a forward configuration, the other switching modules, as will be explained later.

[0046] The control unit 60 is an electronic circuit designed to manipulate and / or transform data represented by electronic or physical quantities in registers of the control unit 60 and / or memories, into other similar data corresponding to physical data in register memories or other types of display devices, transmission devices or storage devices.

[0047] As specific examples, the control unit 60 is implemented in the form of a programmable logic component, such as an FPGA (Field Programmable Gate Array), or an integrated circuit, such as an ASIC (Application Specifies Integrated Circuit).

[0048] In an alternative variant not shown, the control unit 60 comprises an information processing unit consisting, for example, of a memory and a processor associated with the memory. The detection module 62, the mechanical switch control module 64, the cell control module 66, and the disconnector control module 68 are each implemented as software, or a software component, executable by the processor. The memory of the control unit 60 is then capable of storing detection software, mechanical switch control software, cell control software, and disconnector control software. The processor is then capable of executing each of the following software programs: detection software, mechanical switch control software, cell control software, and disconnector control software.

[0049] In an alternative not shown, the detection module 62, the mechanical switch control module 64, the cell control module 66 and the disconnector control module 68 are each made in the form of a programmable logic component, such as an FPGA (Field Programmable Gate Array), an integrated circuit, such as an ASIC (Application Specified Integrated Circuit) or in the form of an analog component.

[0050] Advantageously, the device 10 also includes a power supply module 70, connected to conductors 7 and 8 and to the control unit 60, in order to supply electricity to the control unit 60. In an alternative embodiment not shown, the power supply module 70 is connected to an external circuit, not connected to conductors 7 and 8. In another alternative embodiment not shown, the power supply module 70 is powered by transformer effect from the current flowing in conductors 7 and 8.

[0051] A method of operation of the device 10 will now be explained, with reference to figures 3 and 4.

[0052] Initially, and advantageously, the device 10 is in the armed configuration, that is, the disconnectors 23 and 24 are in the closed configuration, the mechanical switch 12 is in the closed configuration, and the transistors 34, 35, 44, and 45 are conducting. Due to an internal resistance lower than that of the transistors 34, 35, 44, and 45, the mechanical switch 12 conducts all the electric current flowing through the device 10. A voltage U across the device 10 is substantially zero.

[0053] The current sensor 52 measures the intensity I of the current flowing in the phase conductor 7, at step S102.

[0054] The control unit 60 receives the measurement of the current I and detects, via the detection module 62, whether a short circuit is present between the source 3 and the load 5, at the stage S104. If a short circuit is not detected, then the current sensor 52 performs step S102 again and continues to measure the current intensity I. An iterative operation is then implemented. If a short circuit is detected, which corresponds to time A in [Fig. 3], then the control unit 60 commands the mechanical switch 12 to switch to the open position, via the mechanical switch control module 64, during step S106. The opening of the mechanical switch 12 corresponds to time B in [Fig. 3].

[0055] When a short circuit is present between the source 3 and the load 5, or in the load 5, the current I increases significantly and rapidly, for example by several tens of amperes per microsecond. Thus, the short circuit is detected, for example, when the current I exceeds a predetermined threshold, or when a derivative of the current I exceeds a predetermined threshold, or when a combination of conditions on the current I and its derivative are met.

[0056] When the mechanical switch 12 is in the open position, the electric current is transferred from the mechanical switch 12 to the interrupt cell 18. However, the opening of the mechanical switch 12 generates an electric arc and ionization of the medium between the contacts of the mechanical switch 12. This reduces the dielectric strength of the mechanical switch 12. Thus, before reducing or interrupting the current flowing between the source 3 and the load 5, it is necessary to wait for the dielectric strength of the mechanical switch 12 to be restored to a sufficient level; otherwise, a breakdown may occur at the terminals of the mechanical switch 12, i.e., a re-ignition of the current through the contacts of the mechanical switch 12, while the latter is in the open position, resulting in damage to the mechanical switch 12. The device 10 will then be unable to reduce or interrupt the current.

[0057] The dielectric strength of the mechanical switch 12 increases over time, until it exceeds one or more steps P1, P2, P3. In the example described here, P1 is the smallest step; thus, the dielectric strength of the mechanical switch 12 becomes greater than or equal to step P1, while being less than steps P2 and P3. P1 is then the largest step less than or equal to the dielectric strength of the mechanical switch 12.

[0058] Preferably, the time required between the moment the mechanical switch 12 flips to the open position and the moment the dielectric strength of the mechanical switch 12 reaches the PI plateau is equal to a first waiting threshold Tb. Thus, a waiting time T is measured from the moment the mechanical switch 12 flips to the open position. The control unit 60 determines whether the waiting time T is greater than or equal to the first waiting threshold Tb in step S108. If not, then the control unit 60 waits a predetermined time and then performs step S108 again. An iterative process is then implemented.

[0059] If the waiting time T is greater than or equal to the first waiting threshold, the dielectric strength of the mechanical switch 12 is equal to or greater than the plateau PI, formed solely by the limiting voltage Uiimi. The cell control module 66 controls the switching module 32 in a blocked configuration at step SI 10, which corresponds to time C in [Fig. 3]. Transistors 36 and 37 are blocked and do not conduct current, which then flows through the voltage limiting element 39 and the switching module 42. The voltage U across the device 10, and therefore across the mechanical switch 12, is then equal to the limiting voltage Uiimi. The current flowing through the voltage limiting element 39 limits the increase in current I caused by the short circuit, according to the following formula:

[0060] TA -l-£-

[0061] with: - TA the growth rate of intensity I; - U is the voltage across the terminals of device 10; and - Us is the nominal voltage of the current.

[0062] In practice, the voltages induced by the resistance of conductors 7 and 8, and by the fault are considered negligible, and the rate of increase TA is thus considered equal to 1-^.

[0063] In [Fig. 3], the limiting voltage Uiimi is lower than the nominal voltage of the current Us, for example, on the order of 440V, for a nominal voltage of the current Us on the order of 450V. Thus, when the switching module 32 is controlled in the blocked configuration, the voltage U across the device 10 is on the order of 440V and the current I increases more slowly than when the switching module 32 was in the forward configuration.

[0064] The dielectric strength of the mechanical switch 12 continues to increase, becoming equal to and then greater than the plateau P2. Thus, it is the plateau P2 that is the largest plateau less than or equal to the dielectric strength of the mechanical switch 12. Preferably, the time between the moment when the mechanical switch 12 switches to the open configuration and the moment when the dielectric strength of the mechanical switch 12 becomes equal to the plateau P2 is equal to a second waiting threshold T2.

[0065] The control unit 60 determines whether the waiting time T is greater than or equal to the second waiting threshold T2 in step SI 12. If the waiting time T is less than the second waiting threshold T2 then the control unit 60 waits a predetermined time and then performs step SI 12 again. An iterative operation is then implemented.

[0066] If the waiting time T is greater than or equal to the second waiting threshold T2, then the cell control module 66 commands the switching module 42 to the blocked configuration and the switching module 32 to the conducting configuration at step SI 14, which corresponds to time D in [Fig. 3]. Transistors 46 and 47 are blocked and do not conduct current, which then flows through the voltage limiting element 49 and the switching module 32. The voltage U across the device 10, and therefore across the mechanical switch 12, is then equal to the limiting voltage Uiim2.

[0067] In [Fig.3], the limiting voltage Uiim2 is greater than the nominal voltage of the current Us, for example on the order of 900V, for a nominal voltage of the current Us on the order of 450V. Thus, when the switching module 32 is controlled in the blocked configuration, the voltage U across the device 10 is on the order of 900V and the current I decreases.

[0068] The dielectric strength of the mechanical switch 12 continues to grow and becomes equal to and then greater than the plateau P3, which then becomes the largest plateau less than or equal to the dielectric strength of the mechanical switch 12.

[0069] Preferably, the time between the moment when the mechanical switch 12 switches to the open configuration and the moment when the dielectric strength of the mechanical switch 12 becomes equal to the P3 plateau is determined in advance, and is equal to a third waiting threshold T3.

[0070] The control unit 60 determines whether the waiting time T is greater than or equal to the second waiting threshold T3 in the SI step 16. If the waiting time T is less than the third waiting threshold T3 then the control unit 60 waits a predetermined time and then performs the SI step 16 again. An iterative operation is then implemented.

[0071] If the waiting time T is greater than or equal to the third waiting threshold T3, then the cell control module 66 commands the switching modules 32 and 42 in a blocked configuration at step SI 18, which corresponds to the instant E on the [Fig.3], the plateau P3 being formed by the limiting voltages Uiimi and Uiim2 summed together.

[0072] During step SI 18, transistors 34, 35, 44, and 45 are blocked. Current then flows through the voltage limiting element 39 and the limiting element 49. The voltage U across device 10 is therefore equal to the sum of the limiting voltages Uiim1 and Uiim2.

[0073] Since the voltage across the terminals of the device 10 is greater than the network voltage and greater than the limiting voltage Uiim2, which was previously applied across the terminals of the device 10, the intensity I of the current flowing through the device 10 decreases more rapidly than when the limiting voltage Uiim2 was applied across the terminals of the device 10, until it becomes zero, as can be seen in area G in [Fig.3]. When the current I becomes zero, the current is interrupted between the source 3 and the load 5, and the voltage across the device 10 becomes equal to the nominal voltage of the current Us, and is visible from time F. Advantageously, a tripping time Td between the moment the short circuit is detected and the moment all the switching modules have switched to the blocked configuration, i.e. a time between times A and F, is less than 1ms, preferably less than 800ps, preferably even less than 400ps.

[0074] Advantageously, when the current I becomes zero, the disconnector control module 68 activates actuators 25 and 26, in order to switch disconnectors 23 and 24 to the open configuration in step S120. For example, if actuators 25 and 26 are coils, the disconnector control module 68 sends an electrical pulse to actuators 25 and 26. This generates a magnetic field that interacts with disconnectors 23 and 24 and allows them to switch to the open configuration. Device 10 is then in the tripped configuration.

[0075] The disconnectors 23 and 24 switch to open configuration only once the current has been interrupted and serve to galvanically isolate the source 3 and the load 5, but do not participate in the interruption of the current as such.

[0076] Advantageously, the standby thresholds Tb, T2, and T3 are determined in advance, for example by the manufacturer of the device 10, based on the characteristics of the mechanical switch 12 and the values ​​of the thresholds P1, P2, and P3, formed by the limiting voltages Uiim1 and Uiim2. Alternatively, the standby thresholds T1, T2, and T3 are determined by the control unit 60, for example based on the current intensity I at the moment the mechanical switch 12 switches to the open configuration, and the values ​​of the thresholds P1, P2, and P3. More generally, if the device 10 comprises more than two modules, the standby thresholds are determined based on the characteristics of the mechanical switch 12 and the values ​​of the thresholds formed by the limiting voltages of the voltage-limiting elements of the switching modules.

[0077] Controlling the switching modules 32 and 42 thus makes it possible to limit the current earlier, specifically as soon as the first standby threshold Ti is reached, and to limit it or even reduce it as quickly as possible, by applying to the terminals of the device 10 a voltage as close as possible to the dielectric strength of the mechanical switch. This makes it possible, in particular, to limit the increase in current I, to prevent overheating of the conductors 7 and 8, and also to choose transistors 34, 35, 44 and 45 whose current rating is lower than for an equivalent device without successively controlled switching modules in the blocked configuration, while ensuring a leakage current of the voltage limiting elements 39 and 49 compatible with the energy rating of the components of the device 10.

[0078] Figure 5 is a diagram of an interrupting cell 118 of an electrical protection device 10 according to a second embodiment of the invention, as a variant of the interrupting cell 18. The interrupting cell 118 is, similarly to the interrupting cell 18, connected in parallel with the mechanical switch 12, such that the input 12a and the output 12b of the mechanical switch 12 are connected respectively to an input 118a and an output 118b of the interrupting cell 118. More specifically, the input 12a of the mechanical switch 12 and the input 118a of the interrupting cell 118 are connected by the non-interruptible electrical link 19a, and the output 12b of the mechanical switch 12 is connected to the output 118b of the mechanical switch 19a. The interrupt cell 118 is connected via the electrical link 19b, which is also non-interruptible. The interrupt cell 118 comprises two rectifier branches 120 and 122.Each rectifier branch 120 and 122 comprises two diodes, respectively 136 and 137 for rectifier branch 120 and 146 and 147 for rectifier branch 122. Diodes 136 and 137 are connected anti-series with respect to each other, that is, diodes 136 and 137 are connected in series and never conduct current at the same time. The same is true for diodes 146 and 147.

[0079] The input 118a and the output 118b of the interrupt cell 118 correspond respectively to the midpoint of the rectifier branch 120, between diodes 136 and 137 and to the midpoint of the rectifier branch 122, between diodes 146 and 147. Thus, the interrupt cell 118 is connected in parallel with the mechanical switch 12 by the midpoint of each rectifier branch 120 and 122.

[0080] The interrupt cell 118 comprises two interrupt modules 132 and 142, but, in an alternative configuration not shown, comprises more than two interrupt modules. The interrupt modules 132 and 142 are connected in parallel with the rectifier branches 120 and 122 and in series with each other. Alternatively, the interrupt cell 118 comprises more than two interrupt modules, connected in series with the interrupt module 142 and in parallel with the branches 120 and 122, as symbolized by the dashed line in [Fig. 5].

[0081] The interrupt modules 132 and 142 comprise, respectively, a switchable semiconductor element, which are in this case transistors 134 and 144, and a voltage limiting element 139 and 149. The voltage limiting element 139 is connected in parallel with transistor 134, and the voltage limiting element 149 is connected in parallel with transistor 144. In the example of [Fig. 5], transistors 134 and 144 are current-unidirectional transistors, the direction of which is indicated by an arrow on each transistor. The voltage limiting elements 139 and 149 are similar, at least functionally, to the voltage limiting elements 39 and 49. and have limiting voltages Uiimn and Uiimi2 respectively. The limiting voltage Uiimii is advantageously different from the limiting voltage Uiimi2, but alternatively these voltages are identical.

[0082] The interrupt cell 118 is configured to be independent of the current direction by means of diodes 136, 137, 146, and 147, so that the unidirectional switching modules 132 and 142 can be used bidirectionally. The arrangement of diodes 136, 137, 146, and 147 limits the number of diodes in the interrupt cell 118 to four. Thus, even when the interrupt cell 118 includes more than two switching modules, only the four diodes 136, 137, 146, and 147 are required for their operation, thereby reducing the number of diodes needed compared to the interrupt cell 18.

[0083] The method of controlling the protection device 10 comprising an interrupt cell 118 is similar to that described previously for the protection device comprising the interrupt cell 18, and is not described again in detail.

[0084] The [Fig.6] is an electrical diagram of an interrupt cell 218 of an electrical protection device 10 according to a third embodiment of the invention, as an alternative embodiment of interrupt cells 18 and 118.

[0085] The elements of interrupt cell 218 that are similar to those of interrupt cell 118 are designated by the same reference number and are not described again in detail.

[0086] The interrupt cell 218 includes a switching module 232, which replaces the switching module 132 and differs from it in that it comprises several limiting elements, here two limiting elements 239a and 239b. The switching module 232 is said to be a variable voltage switching module. The limiting elements 239a and 239b have distinct limiting voltages Uiim2i and Uiim22, respectively, which are different from the limiting voltage Uiim2. Each limiting element 239a and 239b is associated with a switching element 240a and 240b, respectively, with which it is connected in series. In the example of [Fig. 6], the switching elements 240a and 240b are thyristors. Alternatively, the switching elements 240a and 240b are switchable semiconductors. The limiting element 239a and its associated switching element 240a are connected in parallel with transistor 134.The same applies to the limiting element 239b and its associated switching element 239b.

[0087] In an alternative not shown, other limiting elements, each associated with a switching element to which they are connected in series, are connected in parallel with transistor 134.

[0088] In this embodiment, the number N of switching modules is equal to 2.

[0089] The limiting voltages Uiim2, Uiim2i and Uiim22 form distinct plateaus. The number of plateaus formed is equal to:

[0090] Np= (x+1) (y+1)-1

[0091] With Np the number of switching stages;

[0092] x the number of parallel limiting elements of transistor 134; and

[0093] y the number of parallel limiting elements of transistor 144.

[0094] In the example of [Fig.6], x=2 and y=l, i.e. a total of 5 levels P' 1 to P'5 listed in the table below.

[0095] [Tables2] Level Value P'1 Ulim2l P'2 Uliml2 P'3 Ulim22 P'4 Ulim2l + Uümi2 P'5 Uiim22 + Ulim12

[0096] In table 2, the levels P' 1 to P'5 are listed in ascending order, with P' 1 the smallest level and P'5 the largest level.

[0097] In the embodiment of [Fig.6], the number Np of switching stages is 5, which is strictly greater than the value 2N-1, with N equal to 2, i.e. 3.

[0098] The steps are formed by at most one limiting voltage of a limiting element belonging to the variable voltage switching module 232. In other words, the same step cannot be formed with the two limiting voltages Uiim2i and Ulim22. In the case where the device 10 includes the interrupt cell 218, the cell control module 66 is further configured to control the switching elements 240a and 240b in a conducting state and in a blocking state, in addition to being configured to control in blocking configuration the switching module(s) whose limiting voltages of the limiting elements form a given step, the given step being the largest step less than or equal to the dielectric strength of the mechanical switch 12, and to control in conducting configuration the other switching modules.

[0099] When the switching members 240a or 240b are in the conducting state, they allow current to pass, and when they are in the blocked state, current cannot flow through the switching members 240a and 240b.

[0100] The method for controlling the protection device 10 comprising an interrupt cell 218 is similar to that described previously for the protection device comprising the interrupt cell 18, except for the differences listed below. below. In the example of [Fig. 6], the control method will be carried out for five stages P'1 to P'5, and no longer three. Moreover, when the control module 66 controls in blocked configuration the switching module(s) whose limiting voltages of the limiting elements form a given stage, the given stage being the largest stage less than or equal to the dielectric strength of the mechanical switch 12, and this given stage is formed by one of the limiting voltages of a switching element belonging to the variable voltage switching module 232, the cell control module 66 also controls the associated switching element in the conducting state, and the other switching elements of the variable voltage switching module 232 in the blocked state.

[0101] For example, if the P'4 step is the largest step less than or equal to the dielectric strength of the mechanical switch 12, the cell control module 66 controls modules 232 and 142 in the off state by blocking transistors 134 and 144, controls switching element 240a in the on state and switching element 240b in the off state. Current thus flows through the voltage limiting elements 239a and 149. In practice, the P'4 step can only be reached after a transient passage through the P'2 step, in order to allow sufficient time for the current flowing through the thyristors to drop to zero, which enables transistor 240a to turn on and thyristor 240b to turn off.

[0102] In an alternative not shown, the interrupt cell 218 comprises more than two variable voltage switching modules.

[0103] For example, in the case where the interrupt cell 118 or 218 comprises three variable voltage switching modules, the number Np of switching steps is greater than or equal to 23-l, i.e. 7. According to another example where the interrupt cell 118 or 218 comprises four variable voltage switching modules, the number Np of switching steps is greater than or equal to 24-l, i.e. 15. The other possible minimum values ​​of the number Np of switching steps are deduced from the above by calculation.

[0104] In an alternative not shown, the source 3 and the load 5 are connected to each other by several phase conductors, for example three. In this case, the device 10 advantageously comprises, for each phase conductor, a mechanical switch and an interrupt cell connected in parallel with the mechanical switch.

[0105] Optionally, a mechanical switch is connected to the neutral conductor, with an interruption cell connected in parallel with the mechanical switch.

[0106] In an alternative not shown, the electrical installation 1 does not include a neutral conductor 8.

[0107] Any feature described for an embodiment or variant in the foregoing may be implemented for the other embodiments and variants described above, provided that it is technically feasible.

Claims

1. Demands Electrical protection device (10), configured to be connected between a source (3) and a load (5), the device (10) comprising: - a mechanical switch (12), configured to switch between a closed configuration, in which the mechanical switch (12) conducts a current flowing between the source (3) and the load (5), and an open configuration, in which the mechanical switch (12) does not conduct the current; - an interrupt cell (18; 118; 218), connected in parallel with the mechanical switch (12), the interrupt cell (18; 118; 218) comprising N switching modules (32, 42; 132, 142; 232) connected in series with each other, N being greater than or equal to 2, each switching module (32, 42; 132, 142; 232) comprising: • at least one semiconductor element (34, 35, 44, 45; 134, 144); • a voltage limiting element (39, 49; 139, 149; 239a, 239b), connected in parallel with the semiconductor element(s) (34, 35, 44, 45; 134, 144), each voltage limiting element (39, 49; 139, 149; 239a, 239b) having a limiting voltage (Uiimi, Uiim2; Uiimn, Uiimi2; Uiim2i, Uiim22), different from the limiting voltage (Uiimi, Uiim2; Uiimn, Uiimi2; Uiim2i, Uiim22) of the other voltage limiting elements (39, 49; 139, 149; 239a, 239b), each switching module (32, 42; 132, 142; 232) being configured to switch between a forwarding configuration, in which current flows in the or in one of the semiconductor elements (34, 35, 44, 45; 134, 144) of the switching module (32, 42; 132, 142; 232), and a blocked configuration, in which if current flows in the switching module (32, 42; 132, 142; 232), it circulates in the voltage limiting element (39, 49; 139, 149; 239a, 239b); - a current sensor (52) configured to measure an intensity (I) of the current; - a control unit (60) comprising: • a detection module (62) configured to detect an electrical fault of the short-circuit type based on the intensity (I) measured by the current sensor (52); • a mechanical switch control module (64), configured to control the mechanical switch (12) in the open configuration when an electrical fault is detected, • a cell control module (66), configured to control each switching module (32, 42; 132, 142; 232) in the locked configuration, characterized in that an input (12a) of the mechanical switch (12) and an input (18a; 118a; 218a) of the interrupt cell (18; 118; 218) are connected to each other by an uninterruptible electrical link (19a) and an output (12b) of the mechanical switch (12) and an output (18b; 118b; 218b) of the interrupt cell (18;118;218) are connected to each other by an uninterruptible electrical link (19b), in that the limiting voltages (Uiimi, Uiim2; Uiimn, Uiimi2; Un™?!, Uiim22), alone and / or summed together, form at least 2N-1 distinct levels (PI, P2, P3; P'1, P'2, P'3, P'4, P'5), and in that the cell control module (66) is configured to: • to control in locked configuration the switching module(s) (32, 42; 132, 142; 232) whose limiting voltages (Uiimi, Uiim2; Uiimii, Uiimi2; Uiim2i, Uiim22) of the voltage limiting elements (39, 49; 139, 149; 239a, 239b) form a given step (PI, P2, P3; P'1, P'2, P'3, P'4, P'5), the given step (PI, P2, P3; P'1, P'2, P'3, P'4, P'5) being the largest step less than or equal to a dielectric strength of the mechanical switch (12), and • control the other switching modules (32, 42; 132, 142; 232) in a passing configuration.

2. Device (10) according to claim 1 in which each module of switching (32, 42; 132, 142; 232) comprises two semiconductor elements (34, 35, 44, 45) which are unidirectional in current and connected to each other in anti-series, and for each semiconductor element (34, 35, 44, 45) a diode (36, 37, 46, 47) is connected in anti-parallel to the semiconductor element (34, 35, 44, 45).

3. Device (10) according to claim 1 in which: - the interrupt cell (118; 218) comprises two rectifier branches (120, 122), the input (118a) and the output (118b) of the interrupt cell (118; 218) forming respectively a midpoint of one of the rectifier branches (120, 122), each rectifier branch (120, 122) comprising two diodes (136, 137, 146, 147) arranged on either side of the midpoint, connected in anti-series with respect to each other; - the switching modules (132, 142; 232) are connected in parallel with the rectifier branches (120, 122); and - each switching module (132, 142; 232) comprises a single semiconductor element (134, 144) connected in parallel with the voltage limiting element (139, 149; 239a, 239b).

4.

5. Device (10) according to claim 3, comprising at least three switching modules. Device (10) according to any one of the preceding claims, wherein: one of the switching modules (232), called the variable voltage switching module, comprises a plurality of voltage limiting elements (239a, 239b) each having a limiting voltage (Uiim2i, Uiim22) different from each other and different from the limiting voltages (Uiimi2) of the voltage limiting elements (149) of the other switching modules (142); Each voltage limiting element (239a, 239b) of the variable voltage switching module (232) is associated with a switching element (240a, 240b) with which it is connected in series, each voltage limiting element (239a, 239b) and its associated switching element (240a, 240b) being connected in parallel with the semi-element(s) conductors (134); - the bearings (P' 1, P'2, P'3, P'4, P'5) are formed at most of a limiting voltage (Uiim2i, Uüm22) of a voltage limiting element (239a, 239b) of the variable voltage switching module (232), possibly summed with one or more limiting voltages (Uiimi2) of the other switching modules (142);and - the cell control module (66) is further configured to, when a given limiting voltage element (239a, 239b) of the variable voltage switching module (232) forms part of a given bearing (P' 1, P'2, P'3, P'4, P'5), the given bearing (P' 1, P'2, P'3, P'4, P'5) being the largest bearing less than or equal to the dielectric strength of the mechanical switch (12), switch the switching member (240a, 240b) associated with the given limiting voltage element (239a, 239b) from a conducting state to a blocking state, and control the other switching members (240a, 240b) of the variable voltage switching module (232) into the blocking state.;

6. Device (10) according to any one of the preceding claims, further comprising a disconnector (23), connected in series with the mechanical switch (12) without being connected in parallel with the interrupt cell (18; 118; 218).

7. Device (10) according to any one of the preceding claims, wherein a tripping time (Td) between the detection of the short-circuit type electrical fault by the detection module (62) and a transition of all the switching modules (32, 42; 132, 142; 232) into the blocked configuration is less than 1ms, preferably less than 800 ps, ​​preferably even less than 400 ps.

8. Electrical installation (1) comprising a source (3), a load (5) connected to the source (3), and an electrical protection device (10) according to any one of the preceding claims, connected between the source (3) and the load (5), a nominal voltage (Us) of the current flowing between the source (3) and the load (5) being less than 1500 V.

9. A method for controlling an electrical protection device (10), the device (10) being according to any one of claims 1 to 7, the method comprising at least the following steps: - measurement (S 102) of the intensity (I) of the current by the current sensor(52); - detection (S 104) of an electrical fault of the short-circuit type by the detection module (62), depending on the intensity (I) measured by the current sensor (52); - when a short-circuit type electrical fault is detected, the mechanical switch (12) is activated in the open configuration by the mechanical switch control module (64); and - when the dielectric strength of the mechanical switch (12) is greater than or equal to a given step (PI, P2, P3; P'1, P'2, P'3, P'4, P'5), the given step (PI, P2, P3; P'1, P'2, P'3, P'4, P'5) being the largest step less than or equal to the dielectric strength of the mechanical switch (12), control (S 110, SI 14, SI 18) of the switching module(s) (32, 42; 132, 142; 232) whose limiting voltages (Uiimi, Un™?; Uiimn, U iimi2; Uiim2i, Uiim22) of the limiting elements (39, 49; 139, 149; 239a, 239b) form the step (PI, P2, P3; P'1, P'2, P'3, P'4, P'5) given, and other switching modules (32, 42; 132, 142; 232) in through configuration.

10. A control method according to claim 9, the electrical protection device (10) being according to claim 5, the method further comprising, when a given limiting voltage element (239a, 239b) of the variable voltage switching module (232) forms part of a given bearing (P' 1, P'2, P'3, P'4, P'5) and the dielectric strength of the mechanical switch (12) is greater than or equal to the given bearing (P' 1, P'2, P'3, P'4, P'5), a control step of the switching component (240a, 240b) associated with the given limiting voltage element (239a, 239b) in the conducting state, and the other switching components (240a, 240b) of the variable voltage switching module (232) in the blocked state.

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