EP4088294B1 - Protected switch - Google Patents

Description

The present invention relates to a secure switch and, more generally, to the field of electrical switching devices.

Secure electrical switching devices are known, such as relay-based switches, which are used to authorize or, alternately, interrupt the flow of an electric current in an electrical circuit.

Particularly known are switching devices containing one or more electromechanical relays whose contacts are connected together in series to form an electrical interruption circuit, called a safety chain, which is used for example to electrically connect an electrical load to an electrical source .

The safety chain is switchable, depending on the state of the relays, between a blocking state, in which at least one of the contacts is open to prevent the circulation of an electric current, and a passing state, in which all the contacts are closed to allow the flow of current.

Such devices are generally used in control-command systems, for example for controlling railway installations or railway equipment, and must meet high safety and reliability requirements.

Such a device must be able to guarantee that in the absence of a control signal, the safety chain is switched to an open state, and therefore that the electrical load cannot be supplied. In particular, such a device must guarantee that the safety chain cannot remain in a conducting state in the event of a failure, for example following the accidental maintenance of one of the contacts in the closed state.

For example, so-called intrinsic safety relays are known, in which, when the relay is no longer powered, the electrical contacts of the safety chain open under the effect of gravity, such as the NS1 relays defined in the standard NF 70-030. These relays, however, have the disadvantage of being heavy and bulky. They must also be installed with a particular orientation depending on the direction of earth's gravity. Their use is therefore complicated. These relays are also difficult to miniaturize, which can hinder their use in certain applications.

On the other hand, devices are known containing two electromechanical relays with guided contacts controlled by an electronic control unit which permanently measures the state of each of the two contacts. If one of these contacts remains closed while the corresponding relay is not controlled, then the control unit detects it and prevents the excitation of the other relay in order to maintain the safety chain in its blocking state.

However, such a device has the disadvantage of requiring a dedicated electronic control unit to measure the state of the relays which, in addition to being expensive and complicate the installation and operation of the device, requires constantly providing a power supply.

DE 35 41 338 A1 discloses a switch according to the preamble of claim 1.

Finally, DE 44 41 171 C1 describes a switching device containing electromechanical relays interconnected with each other. However, the operation of this device is not satisfactory in certain circumstances, in particular with regard to the switching order of the relays during a change of state.

It is these drawbacks that the invention more particularly intends to remedy by proposing a secure switch for the power supply of electrical appliances of simplified design and which ensures, in a secure manner, the opening of an electrical circuit in the event of a failure.

To this end, one aspect of the invention relates to a switch as defined in claim 1.

Thanks to the invention, the interconnection circuit conditions the power supply of the electromagnet of each relay according to the state occupied by the other relay, which ensures, intrinsically, control of the state of the Interrupt circuit contacts, without the need for an electronic control unit.

Thus, if one of the two electrical contacts of the interruption circuit suffers a failure and the relay to which it belongs is in an abnormal state, the other relay cannot be energized, which allows the other contact to be maintained electrical of the interrupt circuit in the open state.

This intrinsic safety is ensured here without relying on earth's gravity, which makes it possible to reduce the mechanical complexity and the size of the switch compared to known intrinsic relays. In addition, the switch is not dependent on Earth's gravity and can therefore be installed without orientation constraints.

In addition, the configuration of the interconnection circuit makes it possible to guarantee that the opening or closing of the relays is done with a specific sequencing defined in advance, in particular to prevent the safety chain from being in the on state while 'she shouldn't be.

Advantageous but not obligatory aspects of the invention are set forth in the other claims.

• [Fig 1] la figure 1 représente, de façon schématique, un interrupteur conforme à des modes de réalisation de l'invention ;
• [Fig 2] la figure 2 représente, de façon schématique, le schéma électrique équivalent de l'interrupteur de la figure 1, dans un premier état au cours de son fonctionnement ;
• [Fig 3] la figure 3 représente, de façon schématique, le schéma électrique équivalent de l'interrupteur de la figure 1, dans un deuxième état au cours de son fonctionnement ;
• [Fig 4] la figure 4 représente, de façon schématique, le schéma électrique équivalent de l'interrupteur de la figure 1, dans un troisième état au cours de son fonctionnement ;
• [Fig 5] la figure 5 représente, de façon schématique, le schéma électrique équivalent de l'interrupteur de la figure 1, dans un quatrième état au cours de son fonctionnement.

The invention will be better understood and other advantages thereof will appear more clearly in the light of the description which follows, of an embodiment of a switch given solely by way of example and made with reference to the appended drawings, in which:

• [ Figure 1 ] there figure 1 represents, schematically, a switch according to embodiments of the invention;
• [ Figure 2 ] there figure 2 represents, schematically, the equivalent electrical diagram of the switch of the figure 1 , in a first state during its operation;
• [ Figure 3 ] there Figure 3 represents, schematically, the equivalent electrical diagram of the switch of the figure 1 , in a second state during its operation;
• [ Figure 4 ] there Figure 4 represents, schematically, the equivalent electrical diagram of the switch of the figure 1 , in a third state during its operation;
• [ Figure 5 ] there figure 5 represents, schematically, the equivalent electrical diagram of the switch of the figure 1 , in a fourth state during its operation.

There figure 1 represents a secure switch 1, which includes an interruption circuit 2, also called a safety chain.

For example, circuit 2 is intended to be connected to an electrical circuit, for example an electrical appliance to an electrical power source. For this purpose, circuit 2 is provided with connection terminals 22.

Circuit 2 is switchable, selectively and reversibly, between a blocking state, which prevents the circulation of an electric current through circuit 2, and a passing state, which authorizes the circulation of an electric current through the circuit 2.

This switching is controlled here by supplying a control signal to the control electrodes of switch 1, which here bear the references 131 and 132.

In the absence of a control signal, switch 1 remains in the blocking state and in the presence of a control signal, switch 1 switches to the on state.

In this example, the control signal is an electrical voltage, denoted Vcc, applied between electrodes 131 and 132.

As an illustrative example, the electrical voltage Vcc is a direct voltage, of amplitude greater than or equal to 24 V and less than or equal to 110 V.

The switch 1 is configured to guarantee secure switching of circuit 2 between its blocking and conducting states, in particular to prevent circuit 2 from remaining in the conducting state while no control signal is applied to the switch 1.

Preferably, the switch 1 has a high level of safety, for example level “SIL 4” on the safety scale called “Safety Integrity Level” as defined by the IEC 61508 standard of the International Electrotechnical Commission or by the standard EN 50129.

The switch 1 is preferably intended to be used in a control-command system, for example in the railway sector. According to variants, switch 1 can also be used in a power circuit to control the power supply to an electrical device.

By way of illustrative and not necessarily limiting example, circuit 2 is adapted to receive, between its terminals 22, a continuous electrical signal having an electrical voltage less than or equal to 110 Volts and an electric current less than or equal to 3.5 A .

As illustrated in the example of figure 1 , the switch 1 comprises a first electromechanical relay 10, a second electromechanical relay 11 and an interconnection circuit 13 which connects the relays 10 and 11 together as explained in the following.

Advantageously, the switch 1 also comprises an external housing, not illustrated, for example made of plastic material, and inside which the components of the switch 1 are housed. As an illustrative example, the housing can have a paving stone shape with dimensions for example equal to 12cm x 9 cm x 2cm.

The relay 10 comprises an electromagnet 101 and movable electrical contacts 102, 103, 104 and 105 coupled with the electromagnet 101. Each of the contacts 102, 103, 104 and 105 is switchable between an open state and a closed state.

In this example, contact 102 is of the “normally closed” type, while contacts 103, 104 and 105 are of the “normally open” type.

Switching is carried out by means of the electromagnet 101, also called coil 101 in the following, which exerts an electromagnetic force on the contacts 102, 103, 104 and 105 when it is electrically powered.

When the electromagnet 101 is not powered, the relay 10 remains in an inactive state, also called a rest state, and the contacts 102, 103, 104 and 105 remain in a corresponding rest state. Here, in the rest state, the “normally closed” type contact 102 remains closed, while the contacts 103, 104 and 105 remain open. To the figure 1 , relay 10 is illustrated in its inactive state.

When the electromagnet 101 is electrically powered, here by the control signal, then the contacts 102, 103, 104 and 105 switch to their opposite state. Here, contact 102 opens, while contacts 103, 104 and 105 close. Relay 10 is said to be activated or energized. As long as the electromagnet 101 is powered, the contacts 102, 103, 104 and 105 are maintained in this state and the relay 10 remains energized.

The relay 10 here is an electromechanical relay with guided contacts, that is to say that the contacts 102, 103, 104 and 105 are mechanically coupled to each other. Such a relay with guided contacts is for example described by standard NF EN 50205.

Thus, if one of the contacts 102, 103, 104 and 105 accidentally remains blocked in a given state, whatever the state of the electromagnet 101, then the other contacts 102, 103, 104 and 105 are kept blocked in a corresponding state. For example, if contact 102 remains stuck in the open state even in the absence of excitation of the electromagnet 101, then contacts 103, 104 and 105 remain in the closed state. Relay 10 then remains blocked in the energized state. In other words, the contacts of such a relay cannot switch between their open and closed states independently of each other.

Analogously, the relay 11 comprises an electromagnet 111 and movable electrical contacts 112, 113 and 114 coupled to the electromagnet 111. Each of the contacts 112, 113 and 114 is switchable between an open state and a closed state by means of the electromagnet 111. In this example, contact 112 is of the “normally closed” type, while contacts 113 and 114 are of the “normally open” type. On the figure 1 , relay 11 is illustrated in its inactive state. Relay 11 is also an electromechanical relay with guided contacts.

The contacts 105 and 114 are electrically connected in series with each other to form the interruption circuit 2. Thus, the circuit 2 is in the blocking state when at least one of the contacts 105 and 114 is open, and is in the The on state only when the two contacts 105 and 114 are closed.

Advantageously, the relays 10 and 11 belong to different manufacturing series and/or come from different manufacturers. This considerably reduces the risk that relays 10 and 11 are both affected simultaneously by the same manufacturing defect likely to compromise their operation.

Preferably, the relay 10 comprises a housing inside which the electromagnet 101 and the contacts 102, 103, 104 and 105 are housed. Likewise, the relay 11 comprises a housing inside which the electromagnet is housed 111 and contacts 112, 113 and 114.

Alternatively, the switch 1 may also include one or more additional interrupt circuits, similar to the interrupt circuit 2. For example, the relays 10 and 11 may include additional mobile contacts, of the "normally open" type. which are mechanically coupled with contacts 102, 103, 104, 105 or 112, 113 and 114, respectively. Each additional interruption circuit may include an additional contact of the first relay 10 and an additional contact of the second relay 11, electrically connected in series. What is described with reference to interruption circuit 2 therefore also applies to these additional interruption circuits.

According to another variant, the relays 10 and 11 may include additional contacts, which are not connected to the interconnection circuit 13 nor to the interruption circuit 2.

Advantageously, the switch 1 further comprises a resistor 14 connected in series between the electromagnet 111 and the contact 113 of the second relay 11. According to Examples, resistor 14 is a wirewound resistor, although alternatively other implementations are possible.

For example, the resistor 14 forms a voltage divider bridge which makes it possible to lower the electrical voltage present between the terminals of the energy reserve 12 when the latter is in a loading configuration, for example when the contacts 104 and 113 are closed and the control voltage Vcc is applied between terminals 131 and 132.

The switch 1 advantageously includes a rechargeable energy reserve 12, the role of which is described in more detail in the following. For example, energy reserve 12 is a capacitor.

Preferably, the electromagnet 101 of the first relay 10 has a control voltage different from the control voltage of the electromagnet 111 of the second relay 11.

The expression "control voltage" here designates the electrical voltage which it is necessary to apply to the terminals of the electromagnet to energize the relay. In other words, the relay is not energized if a voltage lower than the control voltage is applied across the electromagnet terminals.

Preferably, the control voltage of the electromagnet 101 of the first relay 10 is greater than the control voltage of the electromagnet 111 of the second relay 11, more preferably greater than twice the control voltage of the electromagnet 111.

For example, the control voltage of the electromagnet 101 of the first relay 10 is equal to 24 Volts. The control voltage of the electromagnet 111 of the second relay 11 is equal to 6 Volts.

Advantageously, the energy reserve 12 is dimensioned so that, once the relays 10 and 11 are energized, the electrical voltage that it delivers when discharging is strictly lower than the control voltage of the electromagnet 101 of the first relay 10 while being greater than the control voltage of the electromagnet 111 of the second relay 11.

Preferably, the quantity of energy storable by the energy reserve, denoted E, is greater than or equal to the quantity of energy, denoted Emin, which is necessary to power the second electromagnet 111 so as to switch the second relay 11 from the inactive state to the excited state. For example, the amount of energy E is greater than or equal to the amount of energy Emin and is less than or equal to 1.5 x Emin, or less than or equal to 1.2 x Emin.

As an illustrative example, the energy reserve 12 is a capacitor with a capacity equal to 47 µF. The electromagnet 111 here has a resistance equal to 500 Ω.

The interconnection circuit 13 connects the relays 10 and 11 to each other and, more precisely, connects the electromagnets 101, 111 and the contacts 102, 103, 104, 112, 113 to each other as described below. The interconnection circuit 13 further connects the energy reserve 12 to the relays 10 and 11.

Preferably, circuit 13 is electrically isolated from interruption circuit 2.

For example, circuit 13 comprises a substrate on which electrically conductive tracks are provided. The relays 10 and 11 are mounted on this substrate and electrodes corresponding to the electromagnets 101, 111 and the corresponding contacts are connected to these electrically conductive tracks.

Alternatively, circuit 13 can be made using cables to connect relays 10 and 11.

In this example, the circuit 13 comprises the control electrodes 131 and 132. Alternatively, the circuit 13 may comprise other control electrodes, for example a pair of control electrodes dedicated to each of the electromagnets 101 and 111 and intended to receive the same control signal to control switch 1.

There figure 2 represents the electrical diagram of switch 1 when circuit 13 connects relays 10 and 11 and relays 10 and 11 are inactive.

In this example, the first electromagnet 101 is connected to the control electrodes 131, 132 via the contact 112 and the contact 103. More precisely, the contact 103 and the contact 112 are connected in parallel to each other with respect to the 'other. Contact 103 and contact 112 are both connected between electrode 132 and a first terminal of electromagnet 101. A second terminal of electromagnet 101 is connected to the other electrode 131.

In this way, the connection of the electromagnet 101 to the control electrodes 131, 132 is conditioned by the state of the second relay 11.

The second electromagnet 111 is here connected to the control electrodes 131, 132 via contacts 102, 104 and 103 to connect or, alternately, disconnect the second electromagnet 111 from the control electrodes 131, 132 depending on the state of the first relay 10.

In addition, the energy reserve 12 is connected to the electrodes 131, 132 and to the second electromagnet 111 via contacts 102 and 104.

• autorisent le chargement de la réserve d'énergie 12 depuis les électrodes de commande 131, 132 lorsque le contact 105 est ouvert, et
• autorisent le déchargement de la réserve d'énergie 12 dans le deuxième électroaimant 111 lorsque le premier contact 105 est fermé.

Circuit 13 is thus arranged so that contacts 102 and 104:

• authorize the charging of the energy reserve 12 from the control electrodes 131, 132 when the contact 105 is open, and
• authorize the discharge of the energy reserve 12 into the second electromagnet 111 when the first contact 105 is closed.

For this purpose, contact 104 connects one terminal of the second electromagnet 111 to a first terminal of the energy reserve 12. A second terminal of the energy reserve 12 and the other terminal of the electromagnet 111 are here connected to the electrode 131. The contact 102 connects the first terminal of the energy reserve 12 to a first terminal of the electromagnet 101 to which the contacts 103 and 112 are connected.

Thus, the energy reserve 12 can only be connected to the electrode 132 via contacts 102 or 104.

The second electromagnet 111 is further connected to the control electrode 132 via contact 113 of the second relay 11.

Thanks to the configuration of circuit 13, when a control signal is received on the control electrodes 131, 132, the relays 10 and 11 are switched sequentially one after the other to their active state.

Switching is however prevented if one of the relays 10, 11 is initially in an abnormal state, for example because one of the contacts 105 or 114 is stuck in the closed state. Circuit 2 then remains in the blocked configuration, which ensures that the interrupt circuit of switch 1 remains in the open state.

The connection of the electromagnets 101 and 111 to the electrode 132 by the contacts, respectively, 103 and 113 ensures that the corresponding relay 10, 11 is maintained in the excited state once this relay has switched to the excited state and as long as a control signal is present.

Furthermore, when the control signal ceases to be received on the electrodes 131, 132, if one of the contacts 105 or 114 remains stuck in the closed state, then switching of the other contact 105, 114 is prevented .

Thus, an operating failure of one or the other of the contacts 105, 114, for example following sticking in the closed state caused by partial melting of the contact, results in switching of circuit 2 into the state blocking. This keeps switch 1 in a safe state.

On the contrary, if the control signal received on the electrodes 131, 132 was directly applied simultaneously to the electromagnets 101 and 111 without these being conditioned by the contacts of the different relays 10 and 11, then the switching of the relays 10 and 11 would be simultaneous whatever the state of one or the other relay 10, 11.

Thanks to the invention, when switching the switch 1, the control of the state of the contacts 105, 114 is carried out intrinsically, without using an external electronic control unit, and without using either to a mechanical device dependent on earth's gravitation for its operation.

In addition, relays 10 and 11 undergo different wear due to the switching sequence chosen. For example, the second relay 11 tends to wear out more quickly than the first relay 10 due to the fact that it experiences current inrush more frequently than the first relay 10, particularly during the closing sequence of the safety chain. This differentiated wear makes it possible to prevent the two relays 10 and 11 from suffering simultaneous failure from the same cause of wear.

According to a variant not illustrated, the second electromagnet 111 can be connected to second control electrodes. For example, the contact 113 can connect the electromagnet 111 to a second electrode distinct from the electrode 132. The contact 102 can also connect the first terminal of the energy reserve 12 to this second electrode. The control signal is then applied both to these second control electrodes and to the electrodes 131 and 132.

An example of operation of switch 1 is now described, with reference to the figures 2 to 5 . In this example, circuit 2 is switched from the blocking state to the on state in response to a control signal.

As illustrated by the figure 2 , relays 10 and 11 are initially inactive. Contacts 102 and 112 are in the closed state, while contacts 103, 104, 105, 113, 114 are in the open state. No control signal is applied between the electrodes 131, 132. The contacts 105, 114 are in the open state and circuit 2 is therefore in a blocking state.

At this stage, the energy reserve 12 is not able to power the coil 101 to activate the first relay, in particular because the maximum voltage that the energy reserve 12 can deliver is lower than the control voltage of the coil 101. Furthermore, in practice, the energy reserve 12 is generally empty or partially discharged at this stage.

The energy reserve 12 can then discharge into the coil 101 without being able to change the state of the relay 10, since it cannot provide enough energy.

As illustrated in Figure 3 , a control signal, such as an electrical voltage Vcc, is applied between the electrodes 131 and 132.

On the one hand, the energy reserve 12 is connected to the electrode 132 via contacts 102 and 112 which are both in the closed state. It is therefore recharged from a fraction of the electrical voltage Vcc. In parallel, the electromagnet 101 is connected to the electrode 132 via the contact 112. At this stage, the contact 112 is in the state closed and contact 103 is in the open state.

In the example of the Figure 3 , the electrical voltage applied between the terminals of the energy reserve 12 is equal to the electrical voltage applied between the terminals of the first electromagnet 101. This electrical voltage is, for example, greater than the control voltage of the first electromagnet 101.

As coil 101 is supplied with a voltage greater than its control voltage, relay 10 is energized. For example, coil 101 generates an electromagnetic force which causes contacts 102, 103, 104 and 105 to switch.

Thus, as illustrated in Figure 4 , relay 10 switches to the excited state. Contact 102 opens and contacts 103, 104 and 105 close. Arrow F1 illustrates the closing of contact 105.

In practice, this switching is not instantaneous but occurs after a first switching time, for example less than or equal to 100ms.

At this stage, the control signal is maintained on the electrodes 131, 132. Circuit 2 is still in a blocking state, which prevents the flow of current through circuit 2.

The electromagnet 101 continues to be powered, this time via contact 103 which is closed. This ensures that relay 10 is maintained in the energized state as long as the control signal is supplied to switch 1.

However, due to the new configuration of the contacts 103, 104 and 102 following the switching of the relay 10, the energy reserve 12 is no longer connected to the electrode 132 and therefore is no longer electrically recharged from the voltage Vcc. In fact, contact 102 is now in the open state and contact 113 is still in the open state.

On the other hand, as contact 104 is closed, electromagnet 111 is connected with energy reserve 12, which allows energy reserve 12 to discharge into electromagnet 111 to electrically power the latter.

In this way, as the voltage supplied by the energy reserve 12 is greater than the control voltage of the electromagnet 111, the electromagnet 111 triggers the switching of the relay 11 to the excited state, as illustrated in Fig. figure 5 . Contact 112 opens and contacts 113 and 114 close. Arrow F2 illustrates the closing of contact 114.

In practice, this switching is not instantaneous but occurs after a second switching time, for example less than or equal to 100ms.

Thus, circuit 2 switches to the on state, thus authorizing the circulation of an electric current.

At the end of this switching, the electromagnet 111 continues to be powered, this time via contact 113 which is closed. This ensures that relay 11 is maintained in the energized state as long as the control signal is supplied to switch 1.

In addition, thanks to the resistor 14, the electrical voltage applied to the terminals of the energy reserve 12 is reduced to reach a holding voltage with a predefined value, chosen to guarantee that only a small quantity of energy is actually stored in the energy reserve 12. This makes it possible, among other things, to guarantee rapid switching of the relay 11 when the control signal is interrupted, since the energy reserve 12 will not be able to maintain the relay 11 in the position for too long. excited state.

When the control signal is interrupted, the electromagnets 101 and 111 cease to be powered. Relays 10 and 11 return to their inactive state. Contacts 102, 112 close, while contacts 103, 104, 105, 113 and 114 reopen. Circuit 2 then switches to the blocking state.

Even if the energy reserve 12 can be transiently connected to the electromagnet 111 when the relays 10 and 11 return to their inactive state, it does not contain sufficient energy to energize the relay 11 again.

Furthermore, the energy reserve 12 is equally incapable of energizing the relay 10 at the end of the switching, because although it is connected to the electromagnet 101 via the relay 102, which returns to its closed state once relay 10 becomes inactive again, the voltage supplied by the energy reserve 12 remains lower than the control voltage necessary to excite the electromagnet 101.

The operation of switch 1 is said to be “secure” in that it guarantees that circuit 2 cannot switch to the on state if one of the contacts 105 or 114 remains stuck in the closed state when the control signal is missing.

In particular, in this example, if contact 105 is initially abnormally stuck in its closed state, then contact 114 cannot be closed when a control signal is subsequently applied. Indeed, as the contacts of relay 10 are coupled together, then contacts 104 and 103 are closed and contact 102 is open when contact 105 is closed, even in the absence of power to the electromagnet 101. In In this case, the electromagnet 111 is disconnected from the electrode 132, because the contacts 102 and 113 are open. The electromagnet 111 is only connected to the energy reserve 12 which at this stage does not contain sufficient energy to switch the relay 11. The electromagnet 111 cannot therefore be energized and therefore the relay 11 cannot be switched to the excited state. Circuit 2 remains in the blocking state.

In the case where it is contact 114 which is initially abnormally stuck in its closed state, then contact 105 cannot be closed when a control signal is subsequently applied. Indeed, as the contacts of relay 11 are coupled together, then contact 113 is closed and contact 112 is open when contact 114 is closed, even in the absence of power supply to the electromagnet 111. In this case, the electromagnet 101 is disconnected from the electrode 132, because the contacts 112 and 103 are open. The electromagnet 101 cannot therefore be energized and therefore the relay 10 cannot be switched to the energized state. Circuit 2 remains in the blocking state.

Such a failure of switch 1 therefore leads to circuit 2 being maintained in a safe configuration.

The probability of simultaneous failure of contacts 105 and 114 is extremely low here, for example less than 10 ^-9 occurrences per hour, which guarantees a good level of security for switch 1.

The embodiments and variants considered above can be combined with each other to generate new embodiments.

Claims (8)

1. A switch (1), comprising:

   - a first electromechanical relay (10) with guided contacts comprising a first electromagnet (101) and a plurality of electrical contacts (102, 103, 104, 105);

   - a second electromechanical relay (11) with guided contacts comprising a second electromagnet (111) and a plurality of electrical contacts (112, 113, 114), a first electrical contact (105) of the first relay and a first electrical contact (114) of the second relay being electrically connected in series between terminals (22) of the switch (1);

   - a rechargeable energy reserve (12);

   - an interconnection circuit (13), which connects at least some of the other electrical contacts (102, 103, 104, 112, 113) of the first and second relays (10, 11),

   characterized in that:

   - the first electromagnet (101) is connected to control electrodes (131, 132) of the switch (1) via second electrical contacts (112) of the second relay (11) and second electrical contacts (103) of the first relay (10) to condition the connection of the first electromagnet to the control electrodes (131, 132) to the state of the second relay (11);

   - the second electromagnet (111) is connected to the control electrodes (131, 132) via third and fourth electrical contacts (102, 104) of the first relay (10) and said second electrical contacts (103, 112) for alternately connecting or disconnecting the second electromagnet (111) to the control electrodes (131, 132) depending on the state of the first relay, the third contact (102) being a normally closed contact connected between the energy reserve (12) and the first electromagnet (101), the fourth contact (104) being a normally open contact connected between the energy reserve (12) and the second electromagnet (111); and

   - the second electromagnet (111) is further connected to one of the control electrodes (131, 132) via a third contact (113) of the second relay (11), this third contact being a normally open contact.
2. The switch according to claim 1, wherein the control voltage of the first electromagnet (101) is different from the control voltage of the second electromagnet (111).
3. The switch according to claim 2, wherein the control voltage of the first electromagnet (101) is greater than the control voltage of the second electromagnet (111), preferably greater than twice the control voltage of the second electromagnet (111).
4. The switch according to any of the preceding claims, wherein the second contact (103) of the first relay (10) and the second contact (112) of the second relay (11) are connected in parallel with each other, the second contact (103) of the first relay (10) being a normally open contact, the second contact (112) of the second relay (11) being a normally closed contact.
5. The switch according to any one of the preceding claims, which contains an electrical resistor (14) connected to the second electromagnet (111), configured to lower the electrical voltage across the energy reserve (12) when the latter is in a charging configuration.
6. The switch according to claim 5, wherein the resistor (14) is connected in series between the second electromagnet (111) and the third contact (113) of the second relay (11).
7. The switch according to any one of the preceding claims, wherein the energy reserve (12) is a capacitor.
8. The switch according to any one of the preceding claims, wherein the amount of energy storable by the energy reserve (12) is greater than or equal to the amount of energy required to energize the second electromagnet (111) to switch the second relay (11) to an energized state.

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