Electrolyser power supply circuit including short-circuiting device and circuit breaker

Abstract

A power supply circuit (20) for supplying a rated direct current of between 20 kA and 100 kA to an electrolytic cell (21), the power supply circuit comprising an upstream busbar (25) and a downstream busbar (26), the upstream and downstream busbars being connected together by a short-circuit (22), when the short-circuit (22) is closed under the action of an actuating mechanism (229), the short-circuit can electrically connect the two busbars together so as to disconnect the power supply to the electrolytic cell (21), the power supply circuit (20) also comprising an anode rod (213) equipped with an anode connection interface (215) intended to be connected to the anode (211) of the electrolytic cell, and a cathode connection interface (214) intended to be connected to the cathode (212) of the electrolytic cell. According to the main features of the present invention, the cathode connection interface is connected to the downstream busbar through a flexible electrical connector (27), and the circuit includes a component for absorbing the movement of the different parts constituting the circuit due to thermal expansion, a circuit breaker (23) connected to the upstream busbar (25) on the one hand and to the anode rod (213) on the other hand, and the circuit breaker opens and electrically disconnects the upstream busbar and the anode rod from each other under the action of an actuating mechanism (239) after a non-zero time interval Tm after the short-circuit has been closed, and the time interval Tm corresponds to the time for establishing the rated current in the short-circuit (22).

Description

Technical Field

[0001] The present invention relates to the technical field of power supply devices for equipment operating at very high current intensities, such as electrolytic cells arranged in series, and in particular to an electrolytic cell power supply circuit comprising a short-circuiting device and a circuit breaker. Background Art

[0002] Copper foil of very small thickness can be manufactured by an electrolytic process in an electrolytic cell comprising a cylindrical negative electrode of titanium called a drum, a positive electrode covered with a metal such as titanium, platinum or iridium or their alloys, and a DC power supply between 20 kA and 100 kA. When direct current flows between the negative and positive electrodes in an electrolyte formed by a suitable acid, copper is electrodeposited on the cylindrical negative electrode, which rotates continuously to form copper foil. The electrolytic cells are generally connected in series in large workshops, where their number can reach several dozen. Such facilities require high currents greater than 1000 amperes, and can reach tens of thousands of amperes, and even hundreds of thousands of amperes for some facilities. The electrolytic cells are powered by a bus of large cross-section. These electrolytic plants are equipped with some devices to isolate and short-circuit the electrolytic cells so that maintenance on them can be carried out without stopping the electrolytic plant.

[0003] The short-circuit is connected to the cathode (i.e., the current output electrode) of the previous electrolyzer and the anode (i.e., the current input electrode) of the next electrolyzer. Closing the short-circuit deflects the entire current and bypasses the electrolyzer. A step of disconnecting the electrolyzer is also necessary. This step is performed by manually disconnecting the bolted contacts connecting the power supply bus and the electrolyzer anode, or by removing the spacers located at the connection. Disconnecting the anode eliminates all current flow in the electrolyzer.

[0004] In the potroom, these short-circuiting devices are mobile so as to be able to connect to the cell to be disconnected and then disconnect in order to connect to another cell as required. These connections and disconnections are partly carried out manually. Besides being dangerous for the operators, these interventions are also detrimental to production since their implementation is generally very time-consuming.

[0005] In addition, these interventions are the source of large variations in the intensity of the current, which lead to large thermal expansions of the supply conductors, such as busbars. In order to absorb these expansions, the supply circuits of the electrolyzers are equipped with flexible conductors adapted to move when the different parts of the supply conductors expand. These flexible conductors are either copper or aluminium strands or copper or aluminium strips. In fact, both the strips and the strands consist of a large number of conductors of very thin thickness, in the form of sheets or strands of about 1 mm thickness, which have a large contact surface with the air and are at the same time very close to each other or even touching each other. The thin thickness of the conductors makes them very flexible. Unfortunately, their large contact surface with the air and their small thickness provide a large area to be subjected to the thermal and chemical attacks in the electrolysis room, so these flexible conductors are fragile and wear out more quickly than other rigid conductor parts. In addition, their wear increases their resistance, which increases the consumption of electrical energy through the Joule effect and reduces the efficiency of the electrolyzer.

[0006] Although flexible conductors have a large area in contact with air, they do not have an air passage area sufficient to effectively remove the heat dissipated by the Joule effect. Therefore, if it is desired to maintain the efficiency of the electrolyzer, these conductors must be replaced frequently, which increases the frequency of electrolyzer shutdowns.

[0007] On the other hand, electrolytic cells for the production of copper foil with a supply current of between 20 kA and 100 kA require more specific anodes than the graphite electrolytic cells generally used for the production of aluminum. These specific anodes are coated with rare materials such as titanium, platinum or iridium. During the short-circuiting of the electrolytic cell, reverse current peaks of two to three times the rated intensity can pass through the anode. This phenomenon is described in reference Figure 4 This reverse current peak destroys the coating of the anodes, which requires frequent shutdowns of the electrolyzer in order to perform interventions on the anodes in order to repair or replace them, which incurs considerable costs.

[0008] An example of a short-circuiting device in which a resistor is associated with a short-circuiter is described in document FR 2805098. This is a complex device that polarizes the cell and performs the short-circuiting after a long time, of the order of several hours, corresponding to the cell discharge step. Moreover, it can only be applied to chlor-alkali cells and not to the electrolysis of copper.

[0009] In practice, in a cell plant, the current intensity through the cells is reduced before the short-circuiting operation in order to minimize the peak intensity of the reverse current. This step of reducing the intensity takes time and affects all cells on the same series supply line. This interferes with the operation of the cells, which therefore produce copper foils of poor quality. The energy consumption of the cells accounts for a large part of the production costs. This energy consumption can be improved by reducing the heat losses through the different conductor parts that make up the circuit according to the invention. Summary of the invention

[0010] That is why the object of the present invention is to overcome these drawbacks by providing an autonomous power supply and short-circuiting circuit of an electrolyser which has a low resistance and allows a rapid short-circuiting of an electrolyser without affecting the operation of the other electrolyser.

[0011] Another object of the present invention is to provide a circuit for powering and shorting an electrolytic cell which can eliminate the reverse current generated when the electrolytic cell is short-circuited and thus avoid damage to the electrodes.

[0012] The object of the present invention is therefore a power supply circuit for supplying electrolytic cells with a rated direct current comprised between 20 kA and 100 kA, said power supply circuit comprising an upstream busbar to which the current of the preceding electrolytic cell arrives, a downstream busbar connected to the upstream busbar of the next electrolytic cell, these two busbars being connected together by a short-circuit which, when closed under the action of an actuating mechanism, enables said two busbars to be electrically connected together so as to disconnect the power supply to the electrolytic cells. The circuit also comprises an anode rod equipped with an anode connection interface intended to be connected to the anode of the electrolytic cell and a cathode connection interface intended to be connected to the cathode of the electrolytic cell. According to the main features of the present invention, the cathode connection interface is connected to the downstream busbar through a flexible electrical connector, the circuit includes a component for absorbing the movement of the different parts constituting the circuit due to thermal expansion, and a circuit breaker connected to the upstream busbar on the one hand and to the anode rod on the other hand, the circuit breaker opens under the action of an actuating mechanism and electrically disconnects the upstream busbar and the anode rod from each other after a non-zero time interval Tm after the short-circuit has been closed, and the time interval Tm corresponds to the time for establishing the rated current in the short-circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The objects, goals and features of the present invention will become more apparent from the following description with reference to the accompanying drawings, in which:

[0014] [ Figure 1 ] is a schematic diagram showing an electrical circuit diagram of an electrolytic cell production line equipped with a circuit according to the present invention;

[0015] [ Figure 2 ] represents a schematic front view of a circuit according to the present invention;

[0016] [ Figure 3 ] represents a schematic partial side view of a circuit according to the present invention;

[0017] [ Figure 4 ] represents the curve of the evolution of the current flowing in the anode when the electrolytic cell is disconnected from the circuit in the absence of the circuit according to the invention;

[0018] [ Figure 5 ] represents the curve of the evolution of the current flowing in the anode when the electrolytic cell equipped with the circuit according to the invention is disconnected from the circuit; DETAILED DESCRIPTION

[0019] The electrolyzers of the production line are powered in series by a closed-loop direct current. The current passes through different electrical parts: busbar or bus, anode rod, anode connection, anode, electrolyte, cathode, cathode connection, cathode rod, then bus, and so on.

[0020] according to Figure 1 , which shows a circuit of a portion of an electrolytic cell production line consisting of three electrolytic cells 11, 21 and 31, each of which includes an anode 111, 211 and 311 and a cathode 112, 212 and 312. In general, the current passes through the anode of the first electrolytic cell, through the electrolyte and from the cathode to the next electrolytic cell (or downstream electrolytic cell), and so on. Thus, in the example, the current reaches the anode 111, passes through the electrolyte of the electrolytic cell 11, enters the cathode 112, and then goes to the anode 211 of the adjacent downstream electrolytic cell 20 through the electrical connection in the conductor.

[0021] The circuit according to the invention is a power supply circuit 10, 20, 30 connected to the electrodes of an electrolytic cell 11, 21, 31, which can supply the electrolytic cell with power and disconnect the electrolytic cell from the circuit in the case of maintenance.

[0022] Each circuit 10, 20, 30 comprises a short-circuit 12, 22, 32 capable of disconnecting the electrolytic cell 11, 21, 31 from the circuit, a circuit breaker 13, 23, 33 capable of isolating the anode 111, 211, 311 of the electrolytic cell, respectively, and a set of connections, conductors and components for actuating the short-circuit and the circuit breaker.

[0023] Circuit breakers and short-circuits are interrupting devices for high-current intensity power supply lines of the type described in document WO 2014 / 068201.

[0024] When it is necessary to disconnect the electrolytic cell 21 from the circuit, the short-circuit 22 is closed, which allows the entire current from the cathode 112 of the preceding electrolytic cell 11 located upstream to be diverted to the anode 311 of the following electrolytic cell 31 located downstream. Similarly, the circuit breaker 23 is opened, isolating the anode 211 of the electrolytic cell 21 and eliminating the entire flow of current so that intervention can be performed on the electrolytic cell.

[0025] Figure 2The circuit 20 according to the invention is shown in a schematic front view, wherein the circuit 20 is located in front of an electrolytic cell 21 indicated by a dashed line in the figure. The circuit 20 further comprises an upstream busbar 25, through which the current reaches the previous electrolytic cell 11, and more precisely, the upstream power supply circuit 10 of the previous electrolytic cell 11 (similar to the circuit 20), a downstream busbar 26, and a short-circuit 22, through which the current enters the next electrolytic cell 31, and more precisely, the downstream power supply circuit 30 of the next electrolytic cell 31 (similar to the circuit 20). The connecting plate of the short-circuit can electrically connect the busbar to the short-circuit by means of bolt connections 225, 226, so that the two busbars 25 and 26 are connected together by the short-circuit 22. Between the busbars 25, 26 and the connecting plate of the short-circuit there is an ECOCONTACT (registered trademark) foam layer consisting of a metal foam skeleton selected from the group including iron, cobalt, nickel and their alloys and covered with at least one covering layer of tin, indium or their alloys. The surface of the foam layer comprises a plurality of contact points. By means of these points, the foam layer has a plurality of contacts with the busbars on the one hand and with the connection plate on the other hand, which makes it possible to obtain a high electrical conductivity and therefore a low electrical resistance. All bolted connections of the circuit according to the invention are equipped with an ECOCONTACT metal foam layer located between the contact surfaces before they are tightened.

[0026] The anode rod 213 is connected to the upstream busbar via a circuit breaker 23. The circuit breaker is electrically connected to the anode rod and the upstream busbar via two bolt connections 235 and 236. The anode rod 213 includes an anode connection interface 215 intended to be connected to the anode 211 of the electrolytic cell 21 via a connection conductor not shown in the figure. The cathode connection interface 214 intended to be connected to the cathode 212 of the electrolytic cell 21 is electrically connected to a flexible electrical connector 27. The connector 27 is electrically connected to the busbar 26 via a bolt connection 275. The connector 27 includes components for absorbing the movement of the different parts constituting the circuit and the electrolytic cell due to thermal expansion.

[0027] The devices according to the invention are interconnected by means of flexible electrical connectors of the same type as the connector 27. The circuit 20 is thus electrically connected to the circuit 10 situated upstream via the flexible electrical connector 24 connected by two bolt connections 245 and 246. The circuit 20 is also connected to the circuit 30 situated upstream via a connector of the same type. The electrical connector 24 comprises means for absorbing the movements of the busbars due to thermal expansion.

[0028] The short-circuit 22 and the circuit breaker 23 have substantially the same features. They are composed of a plurality of circuit breaker modules described in the document WO2014 / 068201. Each circuit breaker module is capable of passing a current of about 3000A and comprises at least one first fixed contact conductor part for establishing an electrical connection with a current inlet and a second fixed contact conductor part for establishing an electrical connection with a current outlet, the fixed contact parts being electrically connected through two connecting plates, and each circuit breaker module further comprises at least one movable contact conductor part adapted to contact the first and second fixed contact parts simultaneously under the action of an actuating mechanism. In the rated position, the short-circuit is open and the circuit breaker is closed. In the case of the circuit breaker 23, the actuating mechanism is actuated to eliminate the contact between the fixed contact part and the movable contact part, and thus the circuit breaker is opened, while in the case of the short-circuit 22, the actuating mechanism is actuated in the other direction, so that the movable contact part contacts the fixed contact part, and thus the short-circuit is closed. The closing of the short-circuit 22 can electrically connect the two busbars 25 and 26 together so as to disconnect the power supply of the electrolyzer 21.

[0029] The circuit breaker and short-circuiter of the circuit according to the present invention comprises a certain number of parallel disconnecting modules, the number of which is adapted to the current to be disconnected. For the circuit breaker and short-circuiter, the disconnecting modules are placed in a sealed housing preferably filled with an inert gas, and two connection plates are located outside the housing and are electrically connected to the first fixed contact conductor parts and the second fixed contact conductor parts of all modules respectively.

[0030] Preferably, for each breaking module, a silver ingot sheet is fixed on a surface of each of the movable contact parts to be in contact with each of the first fixed contact part and the second fixed contact part.

[0031] According to a preferred embodiment, at least one fixed contact part comprises an aluminum lower layer, a copper upper layer including a silver covering layer, and a foam intermediate layer, which is composed of a metal foam skeleton selected from the group including iron, cobalt, nickel and their alloys and covered with at least one covering layer of tin, indium or their alloys.

[0032] The opening capacity of the short circuit 22 is greater than that of the circuit breaker 23 in terms of load, because the short circuit is actuated by a load opposite to that of the circuit breaker, while the circuit breaker is actuated by a weak load or zero load.

[0033] The circuit according to the invention comprises a support part 29 situated in the centre of the circuit and to which the upstream busbars 25 and the downstream busbars 26 as well as the cathode rods 213 are fixed by means of electrically insulating means. Due to its central position, the support part reinforces the circuit as a whole and in particular the part of the circuit situated in its vicinity. In fact, the further away from this part, the greater the movement of the conductors due to thermal expansion.

[0034] The circuit breaker 23 and the short circuit 22 are placed as close to the support part 29 as possible so as to be as little affected as possible by the movement due to the expansion of the conductor. Each of the circuit breaker and the short circuit has its actuating mechanism. Preferably, the actuating mechanism or the first actuating mechanism of the short circuit 22 is a pneumatic jack 229, and the actuating mechanism or the second actuating mechanism of the circuit breaker 23 is a pneumatic jack 239.

[0035] The circuit breaker 23 is placed perpendicular to the short-circuit, so that the circuit breaker module of the short-circuit is perpendicular to the circuit breaker module of the circuit breaker 23. This can reduce the volume. Therefore, the two jacks are also placed perpendicular to each other.

[0036] Reference Figure 3 Describe the features of the flexible electrical connectors 27, 24 in detail, Figure 3 A side view of a circuit according to the invention is shown, in particular a side view of a flexible electrical connector 27 .

[0037] according to Figure 3 It can be seen that the shape of the flexible electrical connector 27 is suitable for carrying current between the downstream busbar 26 and the cathode connection interface 214, so that it allows changing direction and bypassing the anode rod 213, while allowing different busbars, rods and electrical conductors and electrolytic cells to move.

[0038] In fact, the passage of electric current in the current supply conductor and the electrolytic cell may cause the metal parts of the circuit to move, thermally expand and deform in the electrolytic cell. Figure 3 As can be seen in the figure, in order to be able to absorb these deformations, the flexible electrical connector 27 is composed of a plurality of thin sheets 28, preferably aluminum sheets. In the example, the connector comprises eight thin sheets, four of which are connected to one side of the busbar 26 and four to the opposite side. The connector is in close contact with the busbar by means of bolt connections 275. A metal foam layer 60 as previously described is located between the contact surfaces to reduce the contact resistance and improve the conductivity of the connection.

[0039] The sheet is folded in one direction according to at least a first angle and then in a direction opposite to the first direction according to a second angle, so that the sheet comprises two folds (in a zigzag shape) and so that the sheet is as flexible as possible and can deform in the two angles of the zigzag shape under the effect of the movement and expansion of the conductor and the temperature. In addition, the sheet has a very large surface with the air, the surface consisting of the two faces of the sheet multiplied by the total number of sheets together with the thickness of the air layer between each sheet being sufficient to allow natural convection. The thickness of the sheet is comprised between 1 cm and 3 cm, and the thickness between the sheets is comprised between 5 mm and 2 cm.

[0040] Despite the different shapes, the connector 24 also includes a plurality of thin sheets 28, each thin sheet 28 including folds according to angles adapted to the geometry of the connection to be achieved. For each connector 24 or 27, the length of the thin sheet, the number of folds, and the folding angles are adapted to the geometry of the electrolyzer to be equipped. Compared to flexible conductors of the copper strand or aluminum tape type, the thin sheets of the connectors 24, 27 of the circuit according to the invention have the advantage of providing a certain rigidity that facilitates placement on the electrolyzer. In fact, a force of 100 kg is required to bend them. In addition, the thickness of the thin sheet is greater than that of the strands of the strand or the sheet of the tape, which allows better durability over time. The flexible connectors 24 and 27 of the circuit according to the invention are designed to provide sufficient flexibility to allow the movement of the busbars and other conductor parts mainly due to the thermal expansion or contraction caused by the chemical reactions of the electrolyzer and the high-intensity currents.

[0041] According to an advantageous feature of the flexible connector according to the invention, the thickness of the sheet 28 is constant except for at least one different location where the thickness is reduced. The sheet has a thickness reduction 271 at the fold of the protruding corner side. At the location of the thickness reduction, the through section of the sheet is reduced by more than half over a sheet length not exceeding twice the thickness of the sheet.

[0042] This reduction in thickness at the angles of the folds of the sheet has several advantages. The reduction in thickness is achieved before the folding, which reduces the forces to be provided during the folding operation and facilitates folding. In addition, no flange of material will appear at the protruding corners, compared to folding on a sheet of constant thickness. Material accumulation tends to create stresses at the sheet and reduce the overall flexibility of the sheet. A connector according to the invention having a sheet with at least one or two folds in opposite directions and at least one reduction in thickness at each protruding corner of the fold is more resilient in the Y- and Z-directions than a connector having one or two folds without a reduction in thickness.

[0043] The connector sheet 28 according to the present invention preferably also has a thickness reduction 272 on the straight portion of the sheet to increase the thickness of the sheet in directions perpendicular to the surface plane of the sheet, i.e., in Figure 3 The elasticity along the Z-axis and along the Y-axis.

[0044] Figure 4The figure shows the evolution of the current in the short-circuit indicated by the thin line 41 and the evolution of the current in the anode indicated by the thick line 42 over time, with the power supply circuit according to the prior art, in the case where the electrolyzer is powered and short-circuited. When the short-circuit is open, a rated current of 60 kA flows in the anode of the electrolyzer. In the example, after the closure of the short-circuit is achieved at the moment tcc, the current in the anode decreases, while the current in the short-circuit gradually increases. The gradual rise and fall of the current is normal and is due to the large value of the current intensity. The current in the anode does not just drop to zero, but reverses to reach a peak value of 180 kA. This reverse current then decreases gradually, reaching very low values ​​in a few hours. During the reverse current peak, which lasts only a few seconds, the covering layer of the anode is severely damaged.

[0045] The circuit according to the present invention can avoid reverse current peaks and therefore avoid damage to the anode of the electrolytic cell. In fact, due to the synchronization of the closing and opening times of the short-circuit and the circuit breaker, the operation of the circuit breaker according to the present invention is related to the operation of the short-circuit. In fact, the circuit breaker is adjusted to open when the current in the anode is close to zero, which avoids high-intensity reverse currents passing through the anode. After the short circuit is implemented at the tcc moment, after a non-zero time interval Tm (included between 50ms and 300ms (milliseconds)), the rated direct current is established in the short-circuit. The establishment time of the rated current corresponds to the time when the current intensity in the short-circuit rises from zero to the rated intensity after the electrical contact is established in the short-circuit.

[0046] According to the present invention, the circuit breaker is adjusted to actuate and open the power supply circuit of the anode before the end of the period Tm of the rated current established in the short-circuit or at the end of the period Tm. During this period Tm, the electrolysis current reduced to zero passes through the electrolyzer. Therefore, there is no reverse current passing through the electrolyzer and the anode. The adjustable time Tm is related to the physical characteristics of the electrolyzer (such as its size). According to the present invention, the circuit breaker is opened under the action of the actuating mechanism 239 and the upstream busbar and the anode rod are disconnected from each other electrically after the non-zero time interval Tm after the short-circuit has been closed.

[0047] Figure 5 The graph shows the result of this time synchronization of the closing and opening of the short-circuit and the circuit breaker, Figure 5 The current intensity in the short-circuit and the anode is shown over time when the electrolytic cell is equipped with a circuit according to the invention.

[0048] At a time t equal to the instant tcc corresponding to the closing of the short-circuit, the current in the short-circuit gradually increases along the curve 51, while the current of 60 kA in the anode decreases. When a period Tm corresponding to the time required for the current in the short-circuit to reach its rated value of 60 kA has elapsed, the circuit breaker opens. Figure 5As can be seen from the curve 52, the circuit breaker is opened at this moment so that the current in the positive and negative electrodes does not reverse and remains zero.

[0049] By means of the circuit according to the invention, the anode supply circuit is opened before the current in the anode is reversed, thus protecting the anode from any reverse current that could damage its cover. The time Tm can be determined either after a series of tests and measurements, or depends on real-time calculations. The circuit according to the invention has the advantage of being able to be remotely actuated, which avoids human intervention in the vicinity of the electrolyzer.

[0050] Each power supply circuit according to the invention comprises a control and maneuvering box comprising interfaces, components for controlling the actuation of the pneumatic jacks 229 and 239, alarms, inhibitors and pressure drop indicators. The alarms can be triggered in the event of exceeding the permissible temperature, lack of air, etc.

[0051] The interface of the control and operation box provides the position of the short circuit and the position of the circuit breaker. If the short circuit is open, the control and operation box prohibits the circuit breaker from opening, and if the circuit breaker is open, the control and operation box prohibits the short circuit from opening.

[0052] The control and operation box is connected to the actuating mechanisms of the short-circuiter and the circuit-breaker and controls their opening and closing. In particular, the control and operation box automatically operates the time interval between the closing of the short-circuiter and the opening of the circuit-breaker. The actuation of the jacks is controlled almost simultaneously by means of the coupling of the two jacks, which is carried out by means of bevel gears and is easily achieved due to the perpendicular positioning of the two jacks to each other.

[0053] Preferably, the bus bars 25 and 26, the anode rod 213, and the flexible connectors 24 and 27 are surface-treated in advance and covered with a black covering layer that reduces their temperature.

[0054] The circuit according to the invention is presented in the form of a module, which has the advantage that it can be prefabricated in the factory and connected directly to the electrodes of the electrolytic cell in the electrolysis room. Thus, compared with a conventional power supply system which requires weeks to assemble part by part in the electrolysis room, the installation time of the circuit according to the invention is reduced to a few hours. The use of the ECOCONTACT metal foam layer also reduces the assembly time. In fact, the use of the foam layer avoids assembly by welding and the circuit breaker or short-circuiter can be replaced by a simple mechanical operation of unscrewing and tightening the bolts.

[0055] Contrary to conventional short-circuiting systems that are active in the pot room and connected to the cells at downtime, the circuit according to the invention is permanent and dedicated to a single cell. The circuit according to the invention reduces the overall resistance of the total power supply circuit and thus has a better energy efficiency, while the circuit according to the invention is located in a reduced volume in front of the cell.

[0056] The circuit according to the invention allows combining the functions of the short-circuit circuit of the electrolyzer and the anode breaker in the same circuit which is easily interchangeable and has a low resistance.

Claims

1. A power supply circuit (20) for supplying an electrolytic cell (21) with a rated direct current comprised between 20 kA and 100 kA, the power supply circuit comprising an upstream busbar (25) to which the current of the previous electrolytic cell (11) reaches, a downstream busbar (26) connected to the upstream busbar of the next electrolytic cell (31), the upstream busbar (25) and the downstream busbar (26) being connected together by a short-circuit (22), when the short-circuit (22) is closed under the action of a first actuating mechanism (229), the short-circuit is capable of electrically connecting the two busbars together so as to disconnect the power supply to the electrolytic cell (21), the power supply circuit (20) also comprising an anode rod (213) equipped with an anode connection interface (215) intended to be connected to the anode (211) of the electrolytic cell, a cathode connection interface (214) intended to be connected to the cathode (212) of the electrolytic cell, It is characterized in that The cathode connection interface is connected to the downstream busbar through a first flexible electrical connector (27), and the first flexible electrical connector (27) includes a component for absorbing the movement of different parts constituting the circuit due to thermal expansion. The circuit also includes a circuit breaker (23) connected to the upstream busbar (25) on the one hand and to the anode rod (213) on the other hand. The circuit breaker opens and electrically disconnects the upstream busbar and the anode rod from each other under the action of a second actuating mechanism (239) after a non-zero time interval Tm after the short-circuit has been closed. The non-zero time interval Tm corresponds to the time for establishing the rated current in the short-circuit (22), and the non-zero time interval Tm is included between 50ms and 300ms.

2. The circuit according to claim 1, wherein the actuating mechanism of the short-circuiter (22) and the circuit breaker (23) is a pneumatic jack.

3. The circuit of claim 2, wherein the circuit breaker (23) is perpendicular to the shorting circuit (22), and wherein the first jack (229) is perpendicular to the second jack (239).

4. The circuit according to claim 1, electrically connected to an upstream circuit (10) by means of a second flexible electrical connector (24) connected by two first bolt connections (245, 246).

5. The circuit according to claim 4, wherein the first and second flexible electrical connectors (24, 27) are composed of a plurality of thin sheets for absorbing circuit deformation, each of the thin sheets having a thickness between 1 cm and 3 cm, and the thin sheets including at least one fold (271), the at least one fold forming a first angle and having a reduced thickness at the fold on the protruding angle side.

6. The circuit according to claim 5, wherein the sheets (28) of the first and second flexible electrical connectors (24, 27) have a thickness reduction (272) at their straight parts to increase the elasticity of the sheets in a direction perpendicular to the plane of the sheet surface.

7. The circuit of claim 1, wherein the short-circuit is connected to the busbars (25, 26) by a second bolt connection (225, 226), wherein the circuit breaker is electrically connected to the upstream busbar (25) and the anode rod (213) by two third bolt connections (235, 236), and wherein the first flexible electrical connector (27) is connected to the downstream busbar (26) by a fourth bolt connection (275).

8. The circuit of claim 4, wherein the first bolt connection (245, 246) is provided with a metal foam layer (60) located between the contact surfaces before the contact surfaces are locked.

9. The circuit of claim 7, wherein the second, third and fourth bolt connections (225, 226, 235, 236, 275) are provided with a metal foam layer (60) located between the contact surfaces before the contact surfaces are locked.

10. The circuit of claim 8, wherein the foam layer is composed of a metal foam skeleton selected from the group consisting of iron, cobalt, nickel and alloys thereof and covered with at least one capping layer of tin, indium or alloys thereof.

11. The circuit of claim 9, wherein the foam layer is composed of a metal foam skeleton selected from the group consisting of iron, cobalt, nickel and alloys thereof and covered with at least one capping layer of tin, indium or alloys thereof.

12. The circuit according to claim 1, comprising a support part (29) located in the center of the circuit, and the upstream busbar (25) and the downstream busbar (26) and the anode rod (213) are fixed to the support part (29) by means of electrical insulating parts.

13. Circuit according to claim 12, wherein the circuit breaker (23) and the short-circuit (22) are placed as close as possible to the supporting part (29).

14. The circuit of claim 1, comprising a control and manipulation box including an interface, components for controlling actuation of the actuating mechanism, an alarm, an inhibitor and a voltage drop indicator.

15. The circuit of claim 4, wherein the busbars (25, 26), the anode rods (213) and the first and second flexible electrical connectors (24, 27) are covered with a black covering layer.

16. The circuit of claim 1, wherein the load-breaking capability of the short-circuit (22) is greater than the load-breaking capability of the circuit breaker (23).

17. A circuit according to any one of claims 1 to 16, wherein the circuit breaker (23) and the short-circuit (22) include a plurality of circuit breaker modules, each circuit breaker module includes at least one first fixed contact conductor part for establishing an electrical connection with a current inlet and a second fixed contact conductor part for establishing an electrical connection with a current outlet, the fixed contact parts are electrically connected via two connecting plates, each circuit breaker module also includes at least one movable contact conductor part suitable for simultaneously contacting the first fixed contact part and the second fixed contact part under the action of an actuating mechanism, and the circuit breaker module is placed in a sealed housing filled with an inert gas.

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