EP4088294A1

EP4088294A1 - Protected switch

Info

Publication number: EP4088294A1
Application number: EP20719471.3A
Authority: EP
Inventors: Guillaume Pressouyre; Patrick Sauvage; Denis Sabatier
Original assignee: Clearsy
Current assignee: Clearsy
Priority date: 2019-04-24
Filing date: 2020-04-23
Publication date: 2022-11-16
Anticipated expiration: 2040-04-23
Also published as: FR3095548A1; FR3095548B1; WO2020216825A1; CA3133328A1; EP4088294B1; US11657994B2; US20220208493A1

Abstract

A protected switch (1) comprises first (10) and second (11) electromechanical relays with guided contacts, each including an electromagnet (101, 111) and electrical contacts (102, 103, 104, 105, 112, 113, 114). A first contact (105) of the first relay (10) and a first contact (114) of the second relay (11) are connected in series in order to form a switching circuit (2). The switch (1) further comprises an interconnection circuit (13) which connects at least a portion of the other electrical contacts of the first and second relays (10, 11). The excitation of the first electromagnet (101) is conditional on the state of the second relay (11) and the excitation of the second electromagnet (111) is conditional on the state of the first relay (10).

Description

TITLE: Secure switch

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

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

Switching devices are in particular known which contain one or more electromechanical relays, the contacts of which 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 flow of an electric current, and an on state, in which all the contacts are closed to allow the flow of current.

Such devices are generally used in instrumentation and control 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 ensure that the safety chain cannot remain in a conducting state in the event of failure, for example following the accidental maintenance of one of the contacts in the closed state.

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

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

However, such a device has the drawback of requiring a dedicated electronic control unit to measure the state of the relays which, in addition to being expensive and complicating the installation and operation of the device, requires a constant supply of power. in energy.

Finally, DE 44 41 171 C1 describes a switching device containing electromechanical relays interconnected with one another. However, the operation of this device is not satisfactory under 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 powering electrical devices of a simplified design and which ensures, in a secure manner, the opening of an electrical circuit in the event of failure.

To this end, one aspect of the invention relates to a secure switch comprising: a first electromechanical relay with guided contacts comprising a first electromagnet and a plurality of electrical contacts;

a second electromechanical relay with guided contacts comprising a second electromagnet and a plurality of electrical contacts, a first electrical contact of the first relay and a first electrical contact of the second relay being electrically connected in series between terminals of the switch;

a rechargeable energy reserve;

an interconnection circuit which connects at least some of the other electrical contacts of the first and second relays and in which:

the first electromagnet is connected to control electrodes of the switch via second electrical contacts of the second relay and second electrical contacts of the first relay to condition the connection of the first electromagnet to the control electrodes to the state of the second relay ;

the second electromagnet is connected to the control electrodes via third and fourth electrical contacts of the first relay and said second electrical contacts to connect or alternately disconnect the second electromagnet from the control electrodes depending on the state of the first relay, the third contact being a normally closed contact connected between the energy reserve and the first electromagnet, the fourth contact being a normally open contact connected between the energy reserve and the second electromagnet. Thanks to the invention, the interconnection circuit conditions the supply to the electromagnet of each relay according to the state occupied by the other relay, which intrinsically ensures control of the state of the contacts of the interrupting circuit, without the need for an electronic control unit.

Thus, if one of the two electrical contacts of the interrupting circuit fails and the relay to which it belongs is in an abnormal state, the other relay cannot be energized, which makes it possible to maintain the other contact. electrical circuit breaker in the open state.

This intrinsic safety is ensured here without resorting to 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 ensures 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 'it shouldn't be.

According to advantageous but non-mandatory aspects of the invention, such a switch can incorporate one or more of the following characteristics, taken individually or in any technically admissible combination:

- The control voltage of the first electromagnet is different from the control voltage of the second electromagnet.

- The control voltage of the first electromagnet is greater than the control voltage of the second electromagnet, preferably greater than twice the control voltage of the second electromagnet.

- The second contact of the first relay and the second contact of the second relay are connected in parallel with each other, the second contact of the first relay being a normally open contact, the second contact of the second relay being a normally closed contact.

- The second electromagnet is further connected to one of the control electrodes via a fourth contact of the second relay, this fourth contact being a normally open contact.

- The switch has an electrical resistance connected to the second electromagnet and configured to lower the electrical voltage across the power reserve when the latter is in a charging configuration.

- The resistor is connected in series between the second electromagnet and the fourth contact of the second relay. - The energy reserve is a capacitor.

- The amount of energy that can be stored by the energy reserve is greater than or equal to the amount of energy needed to power the second electromagnet in order to switch the second relay to an energized state.

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 accompanying drawings, in which:

[Fig 1] Figure 1 shows, schematically, a switch according to embodiments of the invention;

[Fig 2] Figure 2 shows, schematically, the equivalent electrical diagram of the switch of Figure 1, in a first state during its operation;

[Fig 3] Figure 3 shows, schematically, the equivalent circuit diagram of the switch of Figure 1, in a second state during operation;

[Fig 4] Figure 4 shows, schematically, the equivalent electrical diagram of the switch of Figure 1, in a third state during operation;

[Fig 5] Figure 5 shows, schematically, the equivalent electrical diagram of the switch of Figure 1, in a fourth state during operation.

Figure 1 shows a secure switch 1, which has an interrupt circuit 2, also called a safety chain.

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

Circuit 2 is selectively and reversibly switchable between a blocking state, which prevents the flow of an electric current through circuit 2, and an on state, which allows an electric current to flow 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 electric voltage, denoted Vcc, applied between the electrodes 131 and 132.

By way of illustrative example, the electric voltage Vcc is a direct voltage, with an amplitude greater than or equal to 24 V and less than or equal to 1 10 V. Switch 1 is configured to guarantee safe switching of circuit 2 between its blocking and on states, in particular to prevent circuit 2 from remaining in the on state when no control signal is applied to the switch. switch 1.

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

Switch 1 is preferably intended for use in an instrumentation and control system, for example in the railway sector. According to variants, the switch 1 can also be used in a power circuit to control the power supply of an electrical device.

By way of illustrative and not necessarily limiting example, circuit 2 is suitable for receiving, between its terminals 22, a direct electrical signal having an electrical voltage less than or equal to 1 10 volts and an electrical current less than or equal to 3.5 AT.

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 what follows.

Advantageously, the switch 1 also comprises an outer casing, not shown, for example made of plastic material, and inside which the components of the switch 1 are housed. By way of illustrative example, the housing may have the shape of a block with dimensions for example equal to 12cm x 9cm x 2cm.

The relay 10 has 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, the contact 102 is of the “normally closed” type, while the contacts 103, 104 and 105 are of the “normally open” type.

The switching is performed by means of the electromagnet 101, also referred to as coil 101 in the following, which exerts an electromagnetic force on the contacts 102, 103, 104 and 105 when it is electrically supplied.

When the electromagnet 101 is not supplied, the relay 10 remains in an inactive state, also called the rest state, and the contacts 102, 103, 104 and 105 remain in a corresponding rest state. Here, in the idle state, the contact 102 of the “normally closed” type remains closed, while the contacts 103, 104 and 105 remain open. In Figure 1, relay 10 is shown in its inactive state. When the electromagnet 101 is supplied electrically, 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 energized, the contacts 102, 103, 104 and 105 are maintained in this state and the relay 10 remains energized.

The relay 10 is here an electromechanical relay with guided contacts, that is to say that the contacts 102, 103, 104 and 105 are mechanically coupled together. Such a guided contact relay 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 state corresponding. For example, if contact 102 remains stuck in the open state even without energization of the solenoid 101, then contacts 103, 104 and 105 remain in the closed state. Relay 10 then remains blocked in the excited state. In other words, the contacts of such a relay cannot switch between their open and closed states independently of each other.

Similarly, the relay 1 1 comprises an electromagnet 1 1 1 and mobile electrical contacts 1 12, 1 13 and 1 14 coupled to the electromagnet 1 1 1. Each of the contacts 1 12, 1 13 and 1 14 is switchable between an open state and a closed state by means of the electromagnet 1 1 1. In this example, the contact 1 12 is of the "normally closed" type, while the contacts 1 13 and 1 14 are of the "normally open" type. In Figure 1, the relay 1 1 is shown in its inactive state. The relay 1 1 is also an electromechanical relay with guided contacts.

The contacts 105 and 1 14 are electrically connected in series with each other to form the interrupt circuit 2. Thus, the circuit 2 is in the blocking state when at least one of the contacts 105 and 1 14 is open, and is found. in the on state only when the two contacts 105 and 1 14 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 the relays 10 and 11 are both simultaneously affected by the same manufacturing defect liable to compromise their operation.

Preferably, the relay 10 comprises a housing within which are housed the electromagnet 101 and the contacts 102, 103, 104 and 105. Similarly, the relay 1 1 comprises a housing inside which are housed the electromagnet 1 1 1 and contacts 1 12, 1 13 and 1 14.

As a variant, the switch 1 may further comprise one or more additional interrupt circuits, similar to the interrupt circuit 2. For example, the relays 10 and 11 may include additional movable contacts, of the “normally” type. open ”, which are mechanically coupled with the contacts 102, 103, 104, 105 or 1 12, 1 13 and 1 14, respectively. Each additional interrupt 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 the interrupt circuit 2 therefore also applies to these additional interrupt circuits.

According to another variant, the relays 10 and 11 may include additional contacts, which are not connected to the interconnection circuit 13 or to the interrupt circuit 2.

Advantageously, the switch 1 further comprises a resistor 14 connected in series between the electromagnet 1 1 1 and the contact 1 13 of the second relay 1 1. According to examples, resistor 14 is a wirewound resistor, although alternatively other implementations are possible.

For example, 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 charging configuration, for example when the contacts 104 and 1 13 are closed and that the control voltage Vcc is applied between terminals 131 and 132.

The switch 1 advantageously comprises a rechargeable energy reserve 12, the role of which is described in more detail in the following. For example, the power 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 1 1 1 of the second relay 1 1.

The expression "control voltage" here refers to the electrical voltage that 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 terminals of the electromagnet.

Preferably, the control voltage of the electromagnet 101 of the first relay 10 is greater than the control voltage of the electromagnet 1 1 1 of the second relay 1 1, more preferably more than twice the control voltage of the electromagnet 1 1 1.

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 1 1 1 of the second relay 1 1 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 while 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 1 1 1 of the second relay 1 1.

Preferably, the quantity of energy stored by the energy reserve, denoted E, is greater than or equal to the quantity of energy, denoted Emin, which is necessary to supply the second electromagnet 11 1 so as to switch the second relay 1 1 from inactive to energized 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 power reserve 12 is a capacitor with a capacity equal to 47 pF. The electromagnet 1 1 1 here has a resistance equal to 500 W.

The interconnection circuit 13 connects the relays 10 and 1 1 to each other and, more precisely, connects the electromagnets 101, 1 1 1 and the contacts 102, 103, 104, 1 12, 1 13 between them as described below. The interconnection circuit 13 also connects the energy reserve 12 to relays 10 and 11.

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

For example, circuit 13 comprises a substrate on which electrically conductive tracks are formed. The relays 10 and 1 1 are mounted on this substrate and electrodes corresponding to the electromagnets 101, 1 1 1 and to the corresponding contacts are connected to these electrically conductive tracks.

As a variant, the circuit 13 can be produced by means of cables to connect the relays 10 and 11.

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

Figure 2 shows the circuit 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 1 12 and the contact 103. More precisely, the contact 103 and the contact 1 12 are connected in parallel with each other. to the other. The contact 103 and the contact 1 12 are both connected between the electrode 132 and a first terminal of the electromagnet 101. A second terminal of the 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 1 1 1 is here connected to the control electrodes 131, 132 via the contacts 102, 104 and 103 to connect or, alternately, disconnect the second electromagnet 1 1 1 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 1 1 1 through the contacts 102 and 104.

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

- allow the charging of the energy reserve 12 from the control electrodes 131, 132 when the contact 105 is open, and

- Allow the unloading of the energy reserve 12 in the second electromagnet 1 1 1 when the first contact 105 is closed.

To this end, the contact 104 connects one terminal of the second electromagnet 1 1 1 to a first terminal of the energy reserve 12. A second terminal of the energy reserve 12 and the other terminal of the electromagnet 1 1 1 are here connected to 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 1 12 are connected.

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

The second electromagnet 1 1 1 is also connected to the control electrode 132 via the contact 1 13 of the second relay 1 1.

Thanks to the configuration of the circuit 13, when a control signal is received on the control electrodes 131, 132, the relays 10 and 11 are sequentially switched 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 11 14 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 1 1 1 to the electrode 132 by the contacts, respectively, 103 and 1 13 makes it possible to maintain the excited state of the relay 10, 1 1 corresponding once this relay has switched to the energized state and as long as a control signal is present.

In addition, when the control signal ceases to be received on the electrodes 131, 132, if one of the contacts 105 or 1 14 remains blocked in the closed state, then the switching of the other contact 105, 1 14 is prevented.

Thus, an operational failure of one or the other of the contacts 105, 1 14, for example following a sticking in the closed state caused by a partial melting of the contact, causes a switching of the circuit 2 in the blocking state. This keeps switch 1 in a secure state. On the contrary, if the control signal received on the electrodes 131, 132 was directly applied simultaneously to the electromagnets 101 and 1 1 1 without the latter being conditioned by the contacts of the various relays 10 and 1 1, then the switching of the relay 10 and 1 1 would be simultaneous regardless of the state of one or the other relay 10, 1 1.

Thanks to the invention, during the switching of the switch 1, the control of the state of the contacts 105, 1 14 is carried out intrinsically, without using an external electronic control unit, and either without using an external electronic control unit. use of a mechanical device dependent on terrestrial gravitation for its operation.

In addition, the relays 10 and 11 undergo different wear due to the selected switching sequence. For example, the second relay 1 1 tends to wear out more quickly than the first relay 10 because it experiences current inrushes more frequently than the first relay 10, especially during the closing sequence of the safety chain. This differentiated wear makes it possible to prevent the two relays 10 and 1 1 from suffering a simultaneous failure from the same cause of wear.

According to a variant not shown, the second electromagnet 1 1 1 can be connected to second control electrodes. For example, the contact 1 13 can connect the electromagnet 11 1 to a second electrode separate 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 to both these second control electrodes and to the electrodes 131 and 132.

An example of the operation of switch 1 is now described, with reference to 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 Figure 2, the relays 10 and 11 are initially inactive. Contacts 102 and 1112 are in the closed state, while contacts 103, 104, 105, 1113, 1114 are in the open state. No control signal is applied between the electrodes 131, 132. The contacts 105, 1 14 are in the open state and the circuit 2 is therefore in a blocking state.

At this stage, the energy reserve 12 is not able to supply 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 coil 101. In addition, in practice, the energy reserve 12 is generally empty or partially discharged at this stage.

The energy reserve 12 can then be discharged in the coil 101 without however managing 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 electric voltage Vcc, is applied between the electrodes 131 and 132.

On the one hand, the power reserve 12 is connected to the electrode 132 through the contacts 102 and 1 12 which are both in the closed state. It is therefore recharged from a fraction of the electric voltage Vcc. In parallel, the electromagnet 101 is connected to the electrode 132 via the contact 1 12. At this stage, the contact 1 12 is in the 'closed state and contact 103 is in the open state.

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

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

Thus, as shown in Figure 4, relay 10 switches to the energized state. The contact

102 opens and contacts 103, 104 and 105 close. The arrow F1 illustrates the closure of contact 105.

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

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

The solenoid 101 continues to be energized, this time through the 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 at the end of 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 1 13 is still in the open state.

On the other hand, as the contact 104 is closed, the electromagnet 1 1 1 is connected with the energy reserve 12, which allows the energy reserve 12 to be discharged in the electromagnet 1 1 1 to supply electric power. this last.

In this way, as the voltage supplied by the energy reserve 12 is greater than the control voltage of the electromagnet 1 1 1, the electromagnet 1 1 1 triggers the switching of the relay 1 1 to the excited state, as illustrated in figure 5. Contact 1 12 opens and contacts 1 13 and 1 14 close. The arrow F2 illustrates the closure of contact 1 14.

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

Thus, circuit 2 switches to the on state, thus allowing the flow of an electric current.

At the end of this switching, the electromagnet 1 1 1 continues to be supplied, this time through contact 1 13 which is closed. This ensures that relay 1 1 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 electric voltage applied to the terminals of the energy reserve 12 is reduced to reach a hold voltage with a predefined value, chosen to ensure that only a small amount of energy is actually stored in the energy reserve 12. This makes it possible, among other things, to guarantee rapid switching of relay 1 1 when the control signal is interrupted, since the energy reserve 12 will not be able to maintain relay 1 1 for too long in the excited state.

When the control signal is interrupted, the electromagnets 101 and 1 1 1 cease to be supplied. Relays 10 and 1 1 return to their inactive state. The contacts 102, 1 12 close, while the contacts 103, 104, 105, 1 13 and 1 14 reopen. Circuit 2 then switches to the blocking state.

Even though the energy reserve 12 may be transiently connected to the electromagnet 1 1 1 when the relays 10 and 1 1 return to their inactive state, it does not contain enough energy to energize the relay 1 1 again.

In addition, the energy reserve 12 is just as 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 the 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 1 14 remains stuck in the closed state when the control signal is absent.

In particular, in this example, if the contact 105 is initially abnormally stuck in its closed state, then the contact 1 14 cannot be closed when a control signal is then applied. Indeed, as the contacts of relay 10 are coupled together, then the contacts 104 and 103 are closed and the contact 102 is open when the contact 105 is closed, even in the absence of power supply to the electromagnet 101. In this case, the electromagnet 1 1 1 is disconnected from the electrode 132, because the contacts 102 and 1 13 are open. The electromagnet 1 1 1 is only connected to the energy reserve 12 which at this stage does not contain sufficient energy to switch the relay 1 1. The electromagnet 1 1 1 can therefore not be energized and therefore the relay 1 1 cannot be switched to energized state. Circuit 2 remains in the blocking state.

In the event that it is contact 1 14 which is initially abnormally stuck in its closed state, then contact 105 cannot be closed when a control signal is then applied. Indeed, as the contacts of relay 1 1 are coupled together, then contact 1 13 is closed and contact 1 12 is open when contact 1 14 is closed, even in the absence of power supply to the electromagnet 1 1 1. In this case, the electromagnet 101 is disconnected from the electrode 132, because the contacts 1 12 and 103 are open. The electromagnet 101 therefore cannot 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 maintaining circuit 2 in a safe configuration.

The probability of simultaneous failure of contacts 105 and 1114 is here extremely low, for example less than 10 ⁹ occurrences per hour, which guarantees a good level of safety for switch 1.

The embodiments and the variants considered above can be combined with one another to generate new embodiments.

Claims

1. Switch (1), characterized in that it comprises:

- 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 (1 1) with guided contacts comprising a second electromagnet (1 1 1) and a plurality of electrical contacts (1 12, 1 13, 1 14), a first electrical contact (105) of the first relay and a first electrical contact (1 14) 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 part of the other electrical contacts (102, 103, 104, 1 12, 1 13) of the first and second relays (10, 1 1) and in which:

- the first electromagnet (101) is connected to the control electrodes (131, 132) of the switch (1) by means of second electrical contacts (1 12) of the second relay (1 1) and of 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 (1 1);

- the second electromagnet (1 1 1) 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, 1 12) to connect or, alternately, to disconnect the second electromagnet (1 1 1) of the control electrodes (131, 132) according to 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 (1 1 1).

2. Switch according to claim 1, wherein the control voltage of the first electromagnet (101) is different from the control voltage of the second electromagnet (1 1 1).

3. Switch according to claim 2, wherein the control voltage of the first electromagnet (101) is greater than the control voltage of the second electromagnet (1 1 1), preferably greater than twice the control voltage of the second electromagnet ( 1 1 1).

4. Switch according to any one of the preceding claims, wherein the second contact (103) of the first relay (10) and the second contact

(1 12) of the second relay (1 1) are connected in parallel with each other, the second contact (103) of the first relay (10) being a normally open contact, the second contact (1 12) of the second relay (1 1) being a normally closed contact.

5. Switch according to any one of the preceding claims, wherein the second electromagnet (1 1 1) is further connected to one of the control electrodes (131, 132) via a fourth contact (1 13) of the second relay (1 1), this fourth contact being a normally open contact.

6. Switch according to any one of the preceding claims, which comprises an electrical resistor (14) connected to the second electromagnet (1 1 1) and configured to lower the electrical voltage at the terminals of the energy reserve (12) when that - this is in a load configuration.

7. Switch according to claims 5 and 6, in the resistor (14) is connected in series between the second electromagnet (1 1 1) and the fourth contact.

(1 13) of the second relay (1 1).

8. A switch according to any preceding claim, wherein the power reserve (12) is a capacitor.

9. Switch according to any one of the preceding claims, wherein the amount of energy stored by the energy reserve (12) is greater than or equal to the amount of energy required to power the second electromagnet (1 1 1). in order to switch the second relay (1 1) to an energized state.