MXPA06007488A - Device for protection against voltage surges with parallel simultaneously triggered spark-gaps - Google Patents

Abstract

The invention concerns a device for protection against voltage surges, comprising:a first spark gap (E1);a first pre-triggering system (2), electrically connected to the first spark gap (E1), so as to enable its being primed;a control device (4) electrically connected to the first pre-triggering system (2) so as to activate same. The invention is characterized in that it comprises at least a second spark gap (E2) mounted parallel to the first spark gap (E1), and electrically connected to a second pre-triggering system (3), such that the control device simultaneously activates the first and the second pre-triggering systems (2, 3), so as to trigger simultaneously the first and second spark gaps (E1, E2). Theinvention also concerns devices against voltage surges.

Description

PROTECTION DEVICE AGAINST THE VOLTAGE PEAKS WITH PARALLEL DISCHARGERS WITH SIMULTANEOUS TRIGGER FIELD OF THE INVENTION The present invention relates to the technical field of devices for protecting electrical installations against voltage peaks, in particular transient peaks due to lightning. More particularly, the invention relates to a protective device against voltage spikes of the arrester type, the device comprises: a first arrester; a first pre-trigger system electrically connected to the first discharger in a manner that allows an arc to be trapped there; and a control device electrically connected to the first pre-trigger system in such a manner as to activate it. BACKGROUND OF THE INVENTION The devices for protecting electrical installations against power peaks are currently widely used, and are commonly known as "lightning rods". Its essential purpose is to carry lightning currents to the ground, and possibly limit the individual peak voltages for these currents to a level that can be supported by the equipment and devices to which they are connected. It is already known to use arrester arresters to protect an installation against voltage spikes. The arrester then connects between the protected phase and the earth in such a way that in the case of a peak, the lightning current can be ported to the ground. A discharger is a well-known device consisting of two electrodes placed one opposite the other and separated in a dielectric medium. One of the electrodes is electrically connected to the phase to be protected, while the other electrode is electrically connected to ground. In the case of a peak such as that generated by the arrival of the lightning current that reaches a threshold value called "tripping", an electric arc is trapped between the electrodes of the discharger, creating a short circuit between the phase and the earth. The lightning current then flows from the phase to ground and the electrical installation is conserved. The electric arc does not extinguish spontaneously and therefore continues to carry a short-circuit current referred to as "residual current". This residual current must preferably be interrupted without opening the general circuit breakers of the installation, such as the circuit breakers in order to avoid disconnecting the installation. Dumper arresters often only have one arrester, associated with the pre-trip system (a trip electrode) and a control device that is voltage sensitive and electrically connected to the pre-trip system to activate it. Although these individual discharge devices are advantageous because their design is particularly simple, they nevertheless have certain disadvantages associated in particular with their limited capacity to carry lightning current and also their limited capacity to interrupt the residual current. To mitigate these disadvantages, it is known to connect two or more arresters in parallel to better distribute the lightning current and the residual current between the arresters connected in parallel, allowing the overall capacity of the lightning rod to carry the lightning current and to improve the lightning current. interrupt the residual current. These arresters with parallel-connected arresters are generally based on the following concept. Two arresters are connected in parallel and a respective inductor coil is connected in series with each of them. Thus when an arc is trapped in one of the two arresters, the current flowing through the inductor coil connected in series, generates a voltage through its own terminals, voltage that is applied through the terminals of the second unloader, causing him to eliminate the arch. These protective devices, although they provide better protection than devices with a single arrester, however suffer from several disadvantages. First of all when the current flowing through the first discharger is below a predetermined level, the voltage generated across the terminals of the inductor coil is not sufficient to eliminate an arc in the second discharger. Under those circumstances, the current can not be distributed between the two arresters and as a result the ability of the device to carry the lightning current substantially corresponds to the ability to carry the lightning current provided by the first unloader alone. Conversely, when the magnitude of the current flowing through the first arrester is high, the voltage across the terminals of the inductor increases and is added to the voltage across the terminals of the arrester, thus degrading the quality of the limitation. of peaks made by the discharger and thus degrading the level of protection it provides. It can be seen that it will be advantageous to provide a protective device against voltage spikes, which although has a simple and economical design, nevertheless has a better capacity to carry the lightning current and to interrupt the residual current. SUMMARY OF THE INVENTION The objects presented to the invention consequently seek to remedy the different disadvantages listed above and to provide a protective device against voltage spikes that presents the improved characteristics from the point of view of its own capacity to carry the lightning current and also its ability to interrupt the residual current. Another object that the invention seeks to provide a new protective device against voltage spikes is a very good level of protection. Another object that the invention seeks to provide a new protective device against voltage spikes is a design that is particularly simple. Another object that the invention seeks to provide a new protective device against voltage spikes is the implementation of standard electrical components. The objects of the invention are achieved with a voltage-protective device of the surge arrester type with arresters, the device has: - a first arrester; a first pre-trigger system electrically connected to the first discharger in a manner that allows an arc to be trapped there; and a control device electrically connected to the first pre-triggering system in such a manner to activate it, the protective device is characterized in that it includes at least one second discharger connected in parallel with the first unloader, and electrically connected to a second pre-trigger system. trigger connected in parallel with the first pre-trigger system, such that the control device simultaneously activates the first and second pre-trigger systems to trigger the first and second arresters simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS Other features and advantages of the invention appear and are found in greater detail when reading the following description with reference to the attached drawings, given only by way of illustration, in which: Figure 1 is a diagram of a electrical circuit showing the principle of the protective device against voltage spikes according to the invention, for an electrical connection for an electrical installation; Fig. 2 is a diagram of a detailed electrical circuit showing a mode of the protective device against voltage spikes according to the invention, for connecting to an electrical installation; Figure 3 is a diagram of a detailed electrical circuit showing another embodiment of the protective device against voltage spikes according to the invention; and Figure 4 is a diagram of a detailed electrical circuit showing yet another embodiment of the voltage surge protective device according to the invention. DETAILED DESCRIPTION OF THE INVENTION The protective device against voltages peaks 1 according to the invention is for the connection in parallel with the electrical equipment or installation to be protected. The term "electrical installation" refers to any type of apparatus or network that may be subject to voltage disturbances, in particular to transient peaks due to lightning. The device is described with reference to figures 1 and 2. The protective device against voltage peaks 1 is advantageous for the connection between the phase L of the installation to be protected and the earth T.

However, without leaving the scope of the invention, it is also possible to think that instead of being connected in parallel between a phase L and the earth T, the device could be connected between neutral and earth, between the phase L and the neutral, or well between two phases (for differential protection). Under all circumstances, the protective device 1 according to the invention advantageously constitutes a protective device of a single pole. For reasons that are purely illustrative and descriptive, the following description refers to the protective device 1 which is connected between the L phase to be protected and the ground T. The device, which is a variety of a lightning arrester with arrester, thus consists of according to the invention of a first discharger El and a first pre-trigger system 2 electrically connected to the first discharger DI in such a way as to eliminate the arc in the. The protective device 1 of the invention also has a control device 4 electrically connected to the first pre-trigger system 2, and preferably placed upstream thereof, to activate it. According to the invention, the protective device 1 also includes at least a second discharger E2 connected in parallel with the first unloader El. The second unloader E2 is electrically connected to a second pre-trigger system 3 connected in parallel with the first system of pre-trigger 2, and thus likewise electrically connected to the control device 4 in such a way as to allow it to be activated simultaneously. In this way the control device 4 activates both the first and second pre-trigger systems 2 and 3 simultaneously to trigger the first and second unloaders El and E2 simultaneously. Thus by means of the simultaneous firing of the first and second unloaders El and E2 connected in parallel, referred to as the "main" unloaders, the protective device 1 allows the lightning currents to be distributed between the two main unloaders El and E2, thus improving the ability of the device to carry the current of lightning. In the meaning of the invention, the term "in parallel" means that the arresters El and E2 are subjected to the same voltage. Thus when they become conductors, the unloaders El and E2 both behave like passive circuits of two terminals connected in parallel, the terminals with the same sign being subjected to the same potential. In the same way, pre-trigger systems 2 and 3 are subjected to the same voltage as when a current passes. This design also makes it possible to improve the capacity of the protective device 1 to interrupt the residual current, since each of the main unloaders El and E2 only "see" half of the total magnitude of the residual current, making it easier to interrupt that current by means of arc extinguishing means provided in each of the dischargers s, E2. Naturally, in order to further improve the capacity of the protective device 1, it is possible to think of connecting more than two arresters in parallel, for example three, four or even more, without having to leave the scope of the invention. The following description refers only to two main dischargers connected in parallel, since the characteristics related to the protective device of two unloaders 1 can be transposed in an obvious way to a device having a greater number of unloaders in parallel. The arresters implemented in the context of the invention may be of any type known to those skilled in the art and may for example be constituted by air or gas filled dischargers. The El and E2 arresters are preferably gas filled dischargers, and more preferably, air filled dischargers. The present characteristics and in particular the trigger threshold voltages that are substantially identical, first to ensure that they fire simultaneously, and second to present equivalent lightning current carrying capacities. Thus when they become conductive, the arresters El and E2 carry substantially the same current corresponding to substantially half the total current carried by the protective device 1. In a conventional manner, each arrester El, E2 consists of a first main electrode 11, electrically connected to the phase L to be protected, and a second main electrode 12, electrically connected to ground T.

(Figure 1) . In the meaning of the invention the term "in parallel" refers to the fact that substantially the same voltage is applied between the main electrodes 11 and 12 of the arresters connected in parallel. The modalities of the invention are described below with reference to Figures 2 and 3. In a first embodiment of the invention, shown in Figure 2, each pre-trigger system 2, 3 is advantageously formed by means of a system electronic having a firing electrode 5, 6 and a transformer TX1, TX2. The firing electrodes 5, 6 are of the conventional type and serve in particular to ionize the gas or air contained in the discharger chamber, leading to an electric arc forming between the electrodes 11, 12 of the arrester, which they become conductors. In a particularly advantageous manner, each trigger electrode 5, 6 is electrically connected to the secondary circuit SI, S2 of the associated transformer TXl, TX2. In a variant of the invention, not shown in the figures, the secondary circuit SI, S2 of the transformer TXl, TX2, is directly connected to the main electrode 11 of the discharger El, E2 to activate it. In this variant, the pre-trigger system 2,3 is then not provided with an additional trigger electrode 5,6 and is formed by means of an electronic system consisting of a transformer TX1, TX2 and a main electrode 11 of the arrester The, E2, main electrode 1 then forms the firing electrode. As shown in Figure 2, the primary circuits Pl, P2 of the transformers correspond respectively to the first and second pre-trigger systems 2,3 are advantageously connected in parallel. In addition, the circuits Pl, P2 of the transformers TXl TX2 are each electrically connected to the output s_ of the control device 4. By means of this particular configuration, the control device 4 can activate both trigger electrodes 5, 6 of simultaneously, which in turn will cause the El and E2 unloaders to work at the same time. The control device 4 is advantageously voltage sensitive, and can be constituted for example by fuses 7, varistors 8 and arresters 9. That voltage sensitive device is well known to those skilled in the art and can also be realized using other non-voltage components. linear, for example, peak-cutting diodes. In a preferred manner, a plurality of components are connected together in series, for example a discharger 9 and a varistor 9 in order to benefit from the advantages of the two technologies. The input e of the control device 4 is advantageously electrically connected to. the L phase for protection. During normal operation the impedance of the control device 4 is such that it prevents the current from passing from the L phase to the device 1, isolating the protective device. In contrast, when a voltage spike occurs, the control device 4 is suitable for going from a very high impedance state to a state of near short circuit, thus allowing the current to flow in the protection device 1. Advantageously the circuit Pl, P2 of each transformer TXl, TX2 is electrically connected to a capacitor Cl, C2 which is charged under the control of the control device 4. In a particularly advantageous manner, the protective device 1 includes a third E3 arrester connected in parallel with the capacitors Cl, C2. In this way, when 1 voltage across the terminals of the capacitors Cl and C2 reach the triggering threshold of the third discharger E3, in short circuits the capacitors Cl, C2 are then discharged into the primary circuits Pl, P2 of the transformers TXl, TX2. In a first variant, the protective device 1 can have a single capacitor Cl advantageously connected between the output s_ of the control device 4 and the earth. The third E3 arrester is then connected in parallel with capacitor Cl and electrically connected to the primary circuit Pl, P2 of each of the transformers connected in parallel TXl, TX2. In a preferred embodiment of the invention, the protective device 1 has a first capacitor Cl and a second capacitor C2, the second capacitor C2 is connected in parallel with the first capacitor Cl, and both capacitors Cl, C2 are also connected in parallel with the third capacitor. E3 discharger. In this variant, each of the first and second capacitors Cl, C2 is electrically connected to the primary circuit Pl, P2 of the associated transform TX1, TX2. Thus, the first capacitor Cl can be connected to the primary circuit Pl of the transformer TXl, and the second capacitor C2 is then connected to the primary circuit P2 of the transformer TX2 (FIG. 2). In a second embodiment of the invention as shown in Figure 3, each pre-trigger system 2, 3 is formed by means of a respective trigger electrode 5,6 of the unloaders El, D2. In this case, the control device 4 advantageously includes a transformer TXl whose secondary circuit SI is connected to each of the pre-trigger systems 2,3, that is, to each of the trigger electrodes 5,6. Of course, without departing from the scope of the invention, it is possible to think of a secondary SI circuit of the transformer TX1 which is directly connected to one of the main electrodes 11 of the parallel-connected arresters El, E2. In this variant, which is not shown in the figures, the electrode 11 then forms the pre-trigger system of the associated arresters El, E2. By means of this particular configuration, the control device 4 can activate the two trigger electrodes 5,6 simultaneously which in turn eliminate the 1 arcs at the same time in the main unloaders El, E2. In this mode the output _s of the control device 4 advantageously corresponds to the output of the secondary circuit SI of the transformer TXl. The protective device 1, and more particularly the control device 4, advantageously includes a capacitor Cl electrically connected to the primary Pl of the transformer TXl. The protective device 1, and in particular the control device 4, preferably also includes a third discharger E3 connected in parallel with the capacitor Cl. In the same manner as described in the first embodiment, when the voltage across the capacitor Cl terminals reaches the trigger threshold value for the third arrester E2, it short-circuits the capacitor Cl which is then discharged into the circuit transformer transformer TXl. Each of the firing electrodes 2,3 connected to the output s_ of the control device 4, and more precisely to the output of the secondary circuit SI and thus is simultaneously subjected to the same potential, thus serves to eliminate the arc at the same time in both main unloaders El, E2. In a third embodiment of the invention shown in Figure 4, each pre-trigger system 2,3 is formed by a system comprising a trigger electrode 5,6 for each of the arresters El, E2, and a respective circuit secondary SI, SI 'of a TXl transformer. In this variant, the transformer TXl has only one primary circuit Pl and two secondary circuits SI, SI 'respectively connected to the trigger electrodes 5,6. The primary circuit Pl of the transformer TXl advantageously forms part of the control device 4 which also includes the capacitor Cl and the third discharger E3. In this way when the voltage across the capacitor terminals Cl reaches the trigger threshold value of the third discharger E2, it causes a short circuit in the capacitor Cl which is then discharged through the primary circuit Pl of the transformer TXl. Secondary circuits SI, SI 'of the transformer TXl are advantageously connected in parallel and are preferably formed by electric cables, in such a way that the voltages generated through their terminals are identical and have the effect of activating firing electrodes 5 and 6 simultaneously, thus eliminating the arcs at the same time in the main unloaders El, E2. In a variant mode, not shown in the figures, the outputs of the secondary circuits SI, SI 'of the transformer TXl are directly directly connected to the respective main electrodes 11 of the unloaders El and E2 to ensure that the arcs are simultaneously eliminated. In this variant, the El, E2 arresters do not have firing electrodes 5,6 and each of the pre-firing systems 2,3 is formed by means of a system comprising one of the secondary circuits SI, SI 'of the transformer TXl together with the corresponding main electrode 11 of the El, E2 arresters. By firing the two main dischargers connected in parallel El and E2 simultaneously, the protective device 1 of the invention thus considerably improves the capacity of the lightning rod to carry the current of the lightning and to interrupt the residual current. The protective device 1 according to the invention operates in the manner described below with reference to Figures 1, 2, 3, and 4. The single pore protective device 1 of the invention is connected in parallel between phase 1 of a electrical installation for protection and earth, to allow carrying the lightning current if any, to ground. In normal operation, this is when it is not present in the phase line L, the protection device 1 is isolated from the electrical installation by the control device 4 which then has a very high impedance. In contrast, in the event that a power peak occurs in phase L, in particular a voltage peak of transient origin, and assuming that the amplitude of the voltage peak is sufficient to trigger the voltage sensitive control device 4, in particular a discharger 9 located inside the device, then the control device 4 is It becomes a conductor and allows the current to flow from the L phase to the protective device 1, thus charging the capacitor Cl or substantially simultaneously charging the capacitors connected in parallel Cl and C2. Since the third discharger E3 is connected in parallel with the first capacitor Cl, the voltage across the terminals of that third discharger E3, which is designated as UE3? is it substantially equal to the voltage UC? through the capacitor Cl terminals. Similarly in the first embodiment as shown in Figure 1, the voltage across the terminals of the second capacitor C2, designated as U2, is substantially equal to the voltage UE3 across the terminals of the third discharger E3. So when the voltages UC? and Uc2. as the case may be, it reaches the trigger threshold voltage of the third discharger E3, an avalanche phenomenon occurs and becomes conductive. The capacitor (s) first and / or second Cl, C2 can then be discharged through the primary circuits Pl, P2 of the corresponding transformer TX1, TX2. Transformer TXl, TX2 then performs its conventional function of amplifying the voltage, allowing a voltage to be obtained across the terminals of the secondary circuit SI, SI ', S2 having an amplitude that is greater in absolute value than the voltage across of the terminals of the primary circuit Pl, P2. The secondary circuit SI, Si ', S2 of the transformer TXl, TX2 then generates a voltage pulse and the firing electrodes 5,6 are simultaneously subjected to it causing the discharge to be trapped between the main electrodes 11 and 12, thus ensuring that The El and E2 unloaders act simultaneously. In this way, the lightning current can be shared between the two main unloaders El, E2, which, being associated in this way, thus presents characteristics that are superior to a simple unloader. In the same way, since the residual current that is distributed between the two main unloaders El, E2, is easier to extinguish. SUCEPTIBILITY OF THE INDUSTRIAL APPLICATION The industrial application of the invention consists of the manufacture of devices to provide protection against transient voltage spikes.

Claims (12)

1. CLAIMS 1. A protective device against voltage peaks of the lightning rod type with arresters, the device has: - a first arrester; a first pre-trigger system electrically connected to the first discharger in a manner that allows an arc to be trapped there; and a control device electrically connected to the first pre-triggering system in such a manner to activate it, the protective device is characterized in that it includes at least one second discharger connected in parallel with the first unloader, and electrically connected to a second pre-trigger system. trigger connected in parallel with the first pre-trigger system, such that the control device simultaneously activates the first and second pre-trigger systems to trigger the first and second arresters simultaneously.
2. 2. A device according to the claim 1, characterized in that each pre-trigger system is formed by a trigger electrode.
3. 3. A device according to the claim 1, characterized in that each pre-trigger system is formed by a system consisting of a trigger electrode together with a secondary circuit of a transformer.
4. A device according to claim 1, characterized in that each pre-trigger system is an electronic system consisting of a trigger electrode in conjunction with a transformer.
5. 5. A device according to claim 2, 3 or 4, characterized in that each pre-triggering system is connected to a secondary circuit of an associated transformer. '
6. 6. A device according to the claim 4 or 4, characterized in that the primary circuits of the transformers corresponding respectively to the first and second pre-trigger systems are connected in parallel.
7. 7. A device according to one of claims 4 to 6, characterized in that the primary circuits of the transformers are electrically connected to the output of the control device.
8. A device according to one of claims 3 to 7, characterized in that the primary circuit of each of the transformers is electrically connected to a capacitor under the control of the output of the control device.
9. A device according to claim 8, characterized in that it includes a third discharger connected in parallel with the capacitor in such a way that when the voltage across the capacitor terminals reaches the trigger threshold value for that third arrester, it causes a short-circuit in the capacitor that is then discharged through the primary circuit of the transformer.
10. A device according to claim 9, characterized in that it has first and second capacitors connected in parallel with the third discharger, and each one is electrically connected to the primary circuit of an associated transformer.
11. 11. A device according to one of claims 1 to 10, characterized in that the control device is voltage sensitive.
12. 12. A device according to the claim 11, characterized in that the control device is formed by fuses, varistors and arresters.