FR2904893A1 - TWO ELECTRODES PRIMER DEVICE FOR ECLATOR AND CORRESPONDING METHODS - Google Patents

Abstract

The component has two main electrodes (2, 3) arranged so as to form a spark-gap (4), and trigger elements (10, 11) distinct from the main electrodes. The trigger elements are arranged such that a disruptive discharge (12) appears between the trigger elements to cause a sparkover of an electric arc (6) between the electrodes. The trigger elements are formed by auxiliary electrodes (14, 15). The elements extend in an inter-electrode space (5) that separates the main electrode (2) from the main electrode (3). Independent claims are also included for the following: (1) a method for triggering an electric component (2) a method for manufacturing an electric component.

Description

TWO ELECTRODES PRIMER DEVICE FOR ECLATOR AND METHODS

  The present invention relates to the general technical field of devices for protecting installations and electrical equipment against overvoltages, especially against transient overvoltages due to lightning. The present invention more particularly relates to an electrical component comprising at least a first and a second main electrode forming a spark gap.

  The present invention also relates to a device for protecting an electrical installation against overvoltages, said device being provided with a first and a second connection terminal intended to be connected to said electrical installation. The present invention also relates to a method of tripping an electrical component comprising at least a first and a second main electrode forming a spark gap. The present invention finally relates to a method of manufacturing an electrical component comprising a step of producing at least a first and a second main electrode forming a spark gap. It is known to use protection devices for electrical installations in order to protect the latter against overvoltages, in particular transient overvoltages caused by atmospheric phenomena of lightning or by maneuvering incidents at the level of the networks. B60355 / EN 2904893 2 These protection devices, generally designated by the term surge arrester or surge arrester, have for their essential purpose the grounding of the fault currents and the clipping of the overvoltages to values compatible with the behavior of the device. electrical installation and equipment to which they are connected. Known surge arresters may be based on different technologies depending on the nature of the protection component they implement. In particular, spark gap arresters are known, that is to say using, as a protective component, a device comprising two electrodes 10 placed facing each other, one being electrically connected to the phase to be protected while the other is electrically connected to the earth. Said electrodes are separated by an insulating zone, formed for example by a gas strip, such as air, or by a dielectric body. When the voltage between the two electrodes reaches a predetermined level, there is a priming phenomenon leading to the establishment of an electric arc between said electrodes. Said electric arc creates a short circuit that allows the flow of the fault current to earth, which has the effect of protecting the equipment connected downstream of the surge arrester.

  Although they provide some protection against lightning strikes, such lightning arresters nevertheless suffer from significant disadvantages related to their initiation.  Indeed, for an electric arc to form between said electrodes, it is necessary to apply between them a significant potential difference in order to create an electric field of sufficient intensity to cause the breakdown of the insulating zone, by example the ionization of the air space.  B60355 / FR 2904893 3 This ignition voltage, which depends in particular on the distance separating the two electrodes forming the spark gap, is particularly high, generally of the order of several kilovolts.  However, said starting voltage directly conditions the level of protection of the surge arrester.  In fact, a spark gap arrester can only trip and discharge the fault current to ground when the overvoltage applied to its terminals exceeds the starting voltage.  The existence of such a tripping threshold has the consequence that the electrical installation to which the spark gap arrester is connected is liable to be repeatedly exposed to overvoltages whose value lies between the nominal voltage operating and starting voltage.  In order to reduce the starting voltage of the spark gap arresters, which in particular means reducing their response time with regard to transient overvoltages, it is known to provide these arresters with pre-triggering auxiliaries which promote arcing when the spark gap is overvoltage.  In particular, it is known to interpose between the main electrodes of the spark gap an auxiliary electrode or needle in order to be able to cause a spark between said needle and one of the main electrodes by controlled application of a voltage pulse between said needle and said main electrode.  Experience shows that for spark gap arresters of the prior art, the voltage required to create a certain spark between the needle and the main electrode is about 7 kilovolts if the distance between said needle and the main electrode is about said main electrode is 2 millimeters.  The time required for the establishment of an electric arc between the two main electrodes is then of the order of 7 to 8 microseconds.  However, to show a spark between the needle and the main electrode, the arresters of the prior art generally use electronic trip circuits, which frequently prove to be a weak point of said arresters, both technically than economically.  Indeed, the known trigger circuits, which often use a large number of expensive components, are particularly sensitive to the stresses to which they are subjected during the operation of the arrester and age rapidly when they are solicited for flow. fault currents.  This relative fragility of the trip circuit tends in practice to prematurely cause the failure of the arrester as a whole, even though the main protective spark gap is still functional.  In addition, despite the presence of an auxiliary electrode, the tripping time of known spark gap arresters remains relatively high compared with the characteristic durations of the transient disturbances, so that the level of protection conferred by them remains relatively poor.  This handicap has the consequence of limiting the use of spark gaps to Type 1 surge arresters, that is to say primary surge arresters whose role is to limit, at the origin of the electrical installation, currents which result from direct lightning shocks (modeled by a 10/350 shock wave).  In particular, known spark gap arresters can not be used as Type 2 surge arresters, i.e. as secondary arresters which provide indirect lightning current withstand (modeled by a shock wave 8/20) whose role is to clip overvoltages so that they are not dangerous for sensitive electrical equipment.  To achieve such secondary surge arresters, it is customary to favor varistor-type protection components, which are particularly expensive and less enduring than the spark-gaps with respect to lightning strikes.  The objects assigned to the invention therefore aim to remedy the various disadvantages listed above and to propose a new electric spark gap type component which has an improved priming capability.  Another object of the invention is to provide a new electric spark gap type component which is particularly simple, compact design and which has an optimized cost.  Another object of the invention is to propose a new electrical spark gap type component which simplifies the installation and maintenance operations.  Another object of the invention is to propose a new device for protecting an electrical installation against overvoltages which confers an optimized level of protection to the installation to which it is connected.  Another object of the invention is to propose a new device for protecting an electrical installation against overvoltages which is of simple design and which has an optimized cost price.  Another object of the invention is to provide a new device for protecting an electrical installation against overvoltages which has a longer life.  Another object of the invention is to propose a new method for triggering an electrical spark gap type component which makes it possible to optimize the initiation of said spark gap.  Another object of the invention is to provide a method of manufacturing a spark gap type electrical component which has an improved priming capability.  Finally, another object of the invention is to provide a method of manufacturing a spark gap type electric component that is simple and inexpensive to implement.  The objects assigned to the invention are achieved by means of an electrical component comprising at least a first and a second main electrode forming a spark gap, characterized in that it comprises at least a first trigger element and a second trigger element both separate from said first and second main electrodes, said first and second trigger elements being arranged such that a disruptive discharge can occur between them and that the occurrence of said disruptive discharge can cause the initiation of an electric arc between the first and second main electrodes.  The objects assigned to the invention are also achieved by means of a device for protecting an electrical installation against overvoltages, said device being provided with a first and a second connection terminal intended to be connected. to said electrical installation, characterized in that it comprises at least one electrical component 860355 / FR 2904893 7 according to the present invention, the first and the second main electrode of said electrical component being electrically connected to said electrical installation to be protected via said first and second terminals.  The objects assigned to the invention are also achieved by means of a method of triggering an electrical component comprising at least a first and a second main electrode forming a spark gap, characterized in that it comprises a step ( a) during which a disruptive discharge is generated between at least a first trigger element and a second trigger element both separate from said first and second main electrodes, so that the occurrence of said disruptive discharge can cause initiating an electric arc between the first and second main electrodes of said spark gap.  The objects assigned to the invention are finally achieved by means of a method of manufacturing an electrical component comprising a step of producing at least a first and a second main electrode forming a spark gap, characterized in that it comprises a step (E1) during which said spark gap is associated with at least a first trigger element and a second trigger element, both of which are separate from said first and second main electrodes and a step (E2) during wherein said first and second triggering elements are arranged so that a disruptive discharge can occur between them and that the occurrence of said disruptive discharge can cause the initiation of an electric arc between the first and second main electrodes.  Other features and advantages of the invention will appear in more detail on reading the description which follows, and with the aid of the accompanying drawings provided for purely illustrative and non-limiting purposes, among which: B60355 / FR 2904893 8 - Figure 1 illustrates a schematic representation of a spark gap type electric component according to the invention.  FIG. 2 illustrates an electrical diagram of a first variant embodiment of an overvoltage protection device according to the invention.  FIG. 3 illustrates a circuit diagram of a second variant embodiment of an overvoltage protection device according to the invention.  FIG. 4 illustrates a circuit diagram of a third variant embodiment of an overvoltage protection device according to the invention.  The electrical component 1 according to the present invention comprises at least a first main electrode 2 and a second main electrode 3, said main electrodes being arranged to form a spark gap 4.  Said first and second main electrodes, formed for example by metal strips, are separated by an inter-electrode space 5 formed of an insulating material, such as gas, in particular air, or a dielectric solid body.  Thus, when a sufficient voltage is applied between said first and second main electrodes 2, 3, an electric arc 6 is likely to be formed between them by breakdown of the insulator forming the inter-electrode gap 5.  According to an important characteristic of the invention, the electrical component 1 comprises at least a first trigger element 10 and a second trigger element 11, both distinct from said first and second main electrodes 2, 3, and arranged such that a disruptive discharge 12 may occur between them and that the occurrence of said disruptive discharge 12 may cause the initiation of an electric arc 6 between the first and second main electrodes 2, 3.  In a particularly advantageous manner, as will be explained in more detail in the rest of the description, the use of a pair of trigger elements 10, 11 distinct from the main electrodes 2, 3 makes it possible to facilitate the appearance of the electric arc 6 by accelerating the ionization of the inter-electrode space 5 and reducing the necessary starting voltage between the first and the second main electrode, compared to what would be observed in a spark gap comprising two main electrodes and a only trip element.  On the other hand, such an arrangement according to the invention is also likely to limit the intensity of the electric current flowing through the triggering elements 10, 11.  Preferably, the first trigger element 10 is formed by a first auxiliary electrode 14.  Likewise, the second trigger element 11 is preferably formed by a second auxiliary electrode 15.  Preferably, the first and second trigger elements 10, 11 extend, at least in part, into the inter-electrode space 5 which separates the first main electrode 2 from the second main electrode 3.  Thus, if a potential difference is applied between the first and the second auxiliary electrode 14, 15, the electrical environment between the auxiliary electrodes 2, 3 can be modified, in particular by ionizing the corresponding part of the the inter-electrode space 5, and thus create, in the vicinity of the main electrodes 2, 3, conditions conducive to the initiation of an electric arc 6.  According to a preferred embodiment illustrated in FIG. 1, the first and second main electrodes 2, 3 delimit a flared, preferably substantially V-shaped, inter-electrode gap 5, said inter-electrode gap 5 extending between a narrow section 5A and a wide section 5B.  Thus, it will be possible to cause the electric arc 6 formed at the narrow section 5A to blow towards the wide section 5B, and consequently to promote the extinction of said arc 6.  This variant embodiment of the electrical component 1 according to the invention is therefore particularly suitable for the production of a device 15 of the lightning arrestor type intended firstly to rapidly discharge the defect current to ground via the arc 6. caused by an overvoltage affecting an electrical installation to be protected and on the other hand to extinguish the electric arc just after the flow of said fault current to cut the current away and ensure continuity of service.  However, it is conceivable, without departing from the scope of the present invention, to use the electrical component 1 according to the invention for purposes other than that of the overvoltage protection component.  As illustrated in FIG. 1, the first and second trigger elements 10, 11 are preferably located at the narrow section 5A of the inter-electrode space 5.  In fact, the shorter the distance between the main electrodes 2 and 3, the lower the corresponding priming voltage.  In other words, to show the disruptive discharge 12 in the vicinity of said narrow section 5A, in particular at the base of the V formed by the main electrodes 2, 3 advantageously makes it possible to exploit the area of the spark gap 4 the most conducive to the appearance of the electric arc 6.  Of course, the electrical component 1 according to the invention is in no way limited to a particular geometry of the main electrodes 2, 3, nor to any particular arrangement of the auxiliary electrodes 14, 15.  In particular, the first and the second triggering element 10, 11 can be set back, flush or project in the inter-electrode space 5.  According to a preferred embodiment illustrated in FIG. 1, the assembly formed by the first and the second trigger elements 10, 11 is substantially centered between the first and second main electrodes 2, 3.  In other words, considering an average plane P substantially equidistant from the two main electrodes 2, 3, the first and the second auxiliary electrode 14, 15 are preferably arranged substantially symmetrically with respect to said plane P.  In a particularly preferred manner, the main electrodes 2, 3 are constituted by substantially flat conductive strips arranged opposite one another so as to form a V whose sagittal plane also corresponds to the sagittal plane of the auxiliary electrode pair 14, 15.  According to the invention, the smallest functional distance d1 which separates the first trigger element 10 from the second trigger element 11 is substantially smaller than the smallest functional distance d2 which separates the first main electrode 2 from the first second main electrode 3.  By functional distance, the distance separating two conductive portions belonging to two distinct conducting elements 5 (first and second trigger element for example) and between which a disruptive discharge (or an arc) is intended to be formed during normal operation is considered. of component 1.  More specifically, as illustrated in FIG. 1, the minimum functional distance d1 will preferably correspond to the gap between the active tip 14A of the first auxiliary electrode 14 and the active tip 15A of the second auxiliary electrode 15. that is to say between the ends of said auxiliary electrodes between which it is sought to show the disruptive discharge 12 (shown in dashed lines).  According to an alternative embodiment, the auxiliary electrodes 14, 15 may be coated or surrounded by an insulating sheath outside their active tips 14A, 15A which remain exposed, so that the disruptive discharge 12 can appear only in a predetermined functional zone situated substantially at the level of said active points 14A, 15A.  According to another alternative embodiment (not shown), the auxiliary electrodes 14, 15 may be generally parallel and present locally a zone of approach, such as a constriction constituted by two conductive protuberances projecting towards each other from said auxiliary electrodes, such that the disruptive discharge 12 will appear preferentially at said approach zone.  B60355 / FR 2904893 13 Similarly, the functional distance separating the main electrodes 2, 3 in the variant embodiment shown in FIG. 1 will correspond to the (variable) spacing of the branches of the V, the minimum functional distance d2 being measured at level of the narrow section 5A of said V.  Thus, the voltage required to cause the occurrence of a disruptive discharge 12 between the first and the second trigger element 10, 11 distant from d1 is advantageously lower than that required for the initiation of an electric arc 6 between the electrodes main 2, 3 distant from d2 ,.  According to a preferred characteristic of the invention, the triggering elements 10, 11, and more particularly the active tips 14A, 15A of the auxiliary electrodes, are sufficiently distant from the main electrodes 2, 3 to prevent any parasitic electric arc formation, that is, a short-circuit between a trip element 10, 11 and a main electrode 2, 3, in the normal operation of the component 1.  In other words, the preferential spatial arrangement of the triggering elements 10, 11 and the main electrodes 2, 3 makes it possible to prevent the main electric arc 6 from catching on one of the auxiliary electrodes 14, 15 and not is established between a main electrode and an auxiliary electrode.  Thus, in a particularly advantageous manner, the component 1 according to the invention makes it possible to dissociate substantially the control circuit, serving to stimulate the initiation by means of an ephemeral disruptive discharge, of the power circuit by which flow strong currents.  More generally, the component 1 according to the invention can advantageously make it possible to separate the tripping and flow functions by dedicating a separate circuit to each of them.  B60355 / FR 2904893 14 It is remarkable that within the meaning of the invention, the triggering elements 10, 11, and more particularly the auxiliary electrodes 14, 15, can then advantageously be designed to cause and support only a disruptive discharge 12 of 5 moderate power and short duration (spark), while the main electrodes 2, 3 are designed to be able to discharge a high intensity electric current in the form of a relatively more durable electric arc 6, in particular caused by a transient surge due to lightning.  Preferably, the distance di is less than 30% of the distance d2, and still more preferably between 10% and 20% of the distance d2.  According to a particularly preferred embodiment, the minimum functional distance d1 separating the first trigger element 10 from the second trigger element 11, and more particularly the first auxiliary electrode 14 from the second auxiliary electrode 15, is between 0.4 mm. and 1 mm, while the smallest functional distance d2 separating the main electrodes 2, 3 is about 3.5 mm.  Tests have shown that such an arrangement makes it possible to obtain, during the application of a transient overvoltage between the main electrodes 2, 3, an electric arc establishment time 6 (response time) of the order of 2 microseconds, which corresponds to a starting voltage of the order of 1.5 kV.  This represents a particularly appreciable gain over the devices of the prior art in which priming is triggered by a disruptive discharge occurring between a single auxiliary electrode B60355 / FR 2904893 and one of the main electrodes of the spark gap. .  Indeed, under similar bias conditions, the establishment of an electric arc within said prior art devices requires 5 to 8 microseconds, depending on the distance between said auxiliary electrode and said main electrode, which corresponds to at a starting voltage of between 2 kV and 4 kV.  An electrical component 1 in accordance with the invention can therefore advantageously be used for the production of Type 2 surge arresters (surge arresters).  Indeed, since such a component 10 allows the early initiation of an electric arc 6 between its main electrodes 2, 3 when it is subjected to an overvoltage caused by lightning, that is to say that it has a relatively low ignition voltage, it offers a level of protection perfectly compatible with the holding of relatively sensitive electrical equipment.  According to a preferred embodiment, the main electrodes 2, 3 and the triggering elements 10, 11 are integrated in the same insulating casing having at least four electrical connection poles, for example pins projecting from one face of said casing, two of which are respectively connected to the first and second main electrodes 2, 3 and two are respectively connected to the first and second triggering elements 10, 11.  The component 1 can therefore advantageously be in the form of a removable cartridge intended for example to be plugged onto a fixed base.  Such an arrangement confers an interchangeability component 1 and therefore facilitates its implementation or replacement during installation or maintenance of the electrical equipment in which it is used.  In particular, the electrical component 1 may constitute an encapsulated spark gap closed at atmospheric pressure or a sealed spark gap GDT (Gas Discharge Tube).  It can also be associated with a breaking chamber 16 for splitting the electric arc 6 in order to facilitate its extinction after the overvoltage has disappeared.  In the foregoing, a preferential geometry of spark gap 4 and trip elements 10, 11 has been described.  However, the shape, the dimensions and the arrangement of the electrical component 1, and in particular those of the main electrodes 2, 3 and the triggering elements 10, 11, can be modified or adapted without depart from the scope of the present invention.  The present invention also relates to the particular use of an electrical component 1 as described above in a device 15 for protecting an electrical installation against overvoltages, in particular against transient overvoltages due for example to lightning.  The term electrical installation refers to any type of device or network powered electrically and likely to experience voltage disturbances, including transient overvoltages due to lightning.  The protection device 20 according to the invention can therefore in particular constitute a surge arrester.  More particularly, the device 20 may advantageously constitute a Type 2 surge arrester in the sense of the IEC 61643-1 standard.  B60355 / FR 2904893 17 The use, by means of the present invention, of a spark gap 4 as a protective component in this type of surge arrester advantageously makes it possible to reconcile increased endurance and lower cost of the device 20 with respect to the Type surge arresters. 2 of the prior art which resort to varistors to form the power circuit.  The protection device 20 according to the invention is in particular intended to be connected bypass (in parallel) on the electrical installation to be protected, and more particularly to be arranged between a phase of the installation to be protected and the earth.  It is also conceivable, without departing from the scope of the invention, that the device 1 is connected between the neutral and earth, between the phase and the neutral, or between two phases to achieve a differential protection.  In order to allow the electrical connection of said device 20 to said electrical installation, it is provided with a first connection terminal 21 and a second connection terminal 22.  According to an important characteristic of the invention, the protection device 20 comprises at least one electrical component 1 according to the invention, the first and the second main electrode 2, 3 of the said electrical component 1 being electrically connected to the said electrical installation 20. protect via said connection terminals 21, 22.  According to an alternative embodiment not shown, one and / or the other of said connection terminals 22, 23 may be doubled to allow for example the simultaneous electrical connection to each of said terminals 22, 23 of two separate conductive elements, such as cables, especially from the installation to be protected.  Of course, the electrical connection between a connection terminal 21, 22 and the corresponding main electrode 2, 3 can be direct or indirect.  In particular, it is conceivable to associate other components in series with the electrical component 1 according to the invention.  Preferably, as illustrated in FIGS. 2 and 3, the protection device 20 comprises an activation means 23 connected to the first and second triggering elements 10, 11 for generating a disruptive discharge 12 between said first and second triggering elements 10, 11 second triggering elements 10, 11 so as to cause the initiation of an electric arc 6 between the first and second main electrodes 2, 3.  In a particularly preferred manner, said activation means 23 is sensitive to the voltage applied to the connection terminals 21, 22 of the device 20 and designed to generate a disruptive discharge 12 between the first and second triggering elements 10, 11 when said voltage crosses a predetermined threshold.  Preferably, the activation means 23 is designed to create a potential difference between the first and the second trigger element 10, 11 and more particularly between the first and the second auxiliary electrode 14, 15.  For this purpose, the first or the second trigger element 10, 11 may be electrically connected to the secondary circuit of a transformer TX1 so that it is possible to vary the potential of said trigger element by circulating a current. in the primary circuit of said first transformer TX1.  According to a particularly preferred variant embodiment illustrated in FIG. 2, the activation means 23 comprises an electronic circuit associating in parallel a gas spark gap 24 and a capacitor IC so that, when said spark gap gas 24 is triggered, it bypasses said capacitor CI which discharges into the primary circuit of the transformer TX1.  Of course, the protection device 20 according to the present invention is not limited to a particular embodiment of the activation means 23, other schemes that can be envisaged to generate an electric field, and in particular a voltage pulse, between the auxiliary electrodes 14, 15.  In a particularly advantageous manner, the protection device 20 according to the invention makes it possible to separate the control circuit comprising the activation means 23 and the trip elements 10, 11 of the power circuit formed by the main electrodes 2, 3 .  This separation takes place first of all thanks to a constructive arrangement linked to a preferential spatial arrangement of the constituent elements of the device 20.  Indeed, the mutual proximity of the auxiliary electrodes 14, 15 and their arrangement relative to the main electrodes 2, 3 makes it possible to substantially confine in a controlled space the disruptive discharge 12 which closes the control circuit 10, 11, 23, while maintaining an isolation distance between said control circuit 10, 11, 23 and the power circuit 2, 3 which is sufficient to substantially limit any risk of short-circuit interference between them.  The separation can also be carried out or supplemented by separation means, for example electronic, capable of providing a limitation of the intensity of the current flowing in the control circuit, and thus avoiding in particular that said control circuit does not tend spontaneously short-circuiting B60355 / FR 2904893 20 all or part of the power circuit.  For this purpose, as shown in FIGS. 2, 3 and 4, separating varistors VI, V2, V3, V4, V5, V6 may be interposed in series with the triggering elements 10, 11 and activation means 23, so that the latter are not directly electrically connected to the connection terminals 21, 22.  It will be noted in this respect that the variant embodiment of a protection device 20 illustrated in FIG. 3 differs from that illustrated in FIG. 2 only by the arrangement of the varistors VI, V2, V4 which makes it possible to define the limits and the distribution of the electric current capable of flowing in the first auxiliary electrode 14 and in the gas spark gap 24.  Moreover, it is particularly remarkable that the fact of accelerating the initiation of the electric arc 6 between the main electrodes 2, 3 by effectively and rapidly ionizing the inter-electrode space 5 by virtue of the control circuit according to the invention. the invention further contributes to relieve in a very short time said control circuit, by switching the flow of electrical energy from said control circuit to the power circuit during the flow of fault currents.  Therefore, the control circuit 10, 11, 23 according to the invention 20 is not stressed during each priming cycle of the spark gap 4, both in power and duration.  It is therefore advantageously possible to minimize its size by reducing the size of its various components, while preserving or even increasing its longevity compared to known devices.  According to an alternative embodiment illustrated in FIG. 4 and which may constitute an entirely separate invention, the activation means 23 is formed by a first varistor V5 which preferably directly connects the first terminal of FIG. connection 21 to the first trigger element 10 and a second varistor V6 which, preferably directly connects the second connection terminal 22 to the second trigger element 11.  Such an activation means, unlike those capable of being implemented on the basis of the variants shown in FIGS. 2 and 3, does not have a voltage amplifier TX1, and simply exploits the priming phenomenon. natural that allows the occurrence of a disruptive discharge 12 between the auxiliary electrodes 14, 15 when an overvoltage is applied to the connection terminals 21, 22.  However, the rapidity of occurrence of the said disruptive discharge 12 due to the proximity of the said auxiliary electrodes, and the efficiency of the ionization of the inter-electrode space that results from this, confers on this variant of the device 20 in terms of response time well above that of a spark gap 4 alone.  Advantageously, the first and the second varistor V5, V6 simultaneously fulfill the roles of activation means 23 and separation means with respect to the power circuit.  The main advantage of such an alternative embodiment lies in the extreme simplification of the control circuit which considerably reduces both the size and the cost price of the device 20.  Finally, the protection device 20 according to the invention may comprise operating indicators 26, as well as safety fusible bridges 25 for opening the power circuit and / or the control circuit in case it flows. abnormally high current or abnormally high intensity, for example when the spark gap 4 reaches the end of its life under the effect of a conductive pollution.  The operation of an alternative embodiment of an overvoltage protection device will now be briefly described with reference to FIG.  When the device 1 is electrically connected to an electrical installation to be protected by means of its connection terminals 21, 22, the protection component 1 can be traversed by a discharge current.  As long as the voltage applied between the connection terminals 21, 22, which corresponds, in the variant illustrated in FIG. 2, to the voltage between the first and the second main electrode 2, 3, does not substantially exceed the nominal voltage of operation of the installation, the protective component 1, and more particularly the spark gap 4, is in its blocking state.  When an overvoltage occurs at the connection terminals 21, 22, for example following a lightning strike, the voltage rise across the capacitor C1 causes the starting voltage of the spark gap 24 to be exceeded.  By becoming on, the latter bypasses the capacitor CI which discharges by creating a current pulse through the primary circuit of the transformer TX1.  The transformer TX1 converts, and preferably amplifies, this current pulse into a voltage pulse applied to the second auxiliary electrode 15, such that a potential difference occurs between the first and the second auxiliary electrode 14, 15.  B60355 / EN 2904893 23 The application of this potential difference, even if it may be moderate compared to that required for the direct priming of an electric arc between the main electrodes 2, 3, creates an intense electric field due to the proximity between the auxiliary electrodes 14, 15.  This electric field generates a local ionization of the inter-electrode space 5, which is likely to lead to the occurrence of a spark discharge 12, in the form of a spark, between said auxiliary electrodes 14, 15.  Particularly advantageously, the electrical power and more particularly the intensity of the current flowing through the triggering elements 10, 11 during their activation remains moderate thanks to the separation varistors VI, V2, V3.  This avoids, in particular, the formation of a high-power arc between the auxiliary electrodes 14, 15, which would have the double negative consequence of disturbing the operation of the installation to be protected because of the difficulty that it would have to extinguish it because of the mutual proximity of said auxiliary electrodes 14, 15, and secondly to cause accelerated aging, or even destruction, of the control circuit.  This ionization of the inter-electrode space 5 facilitates the tilting of the spark gap 4 in its conducting state.  It indeed leads to the initiation of an electric arc 6 between the main electrodes 2, 3 for a priming voltage applied between said main electrodes 2, 3 much lower than that which would be necessary for the breakdown of the insulation filling the inter-electrode gap 5 in the absence of triggering elements 10, 11 (or in the absence of activation thereof).  Thus, the response time of the device 20 is considerably shortened.  It is remarkable that by centering the auxiliary electrodes 14, 15 between the main electrodes 2, 3, a substantially homogeneous ionization of the inter-electrode space 5 is obtained which makes it possible to optimize the priming speed. of the electric arc 6, and to lower as much as possible the threshold that must be crossed voltage applied to the main electrodes 2, 3 to cause said priming.  When the arc 6 is primed, the spark gap 4 is able to discharge the high intensity fault current caused by the overvoltage.  It is remarkable that in such an alternative embodiment, the maintenance of the arc 6 after its initiation is independent of the activation of the first and second triggering elements 10, 11.  Thus, after a small portion of the power carried by the overvoltage has been allocated to the triggering of the device 20, most of said power can be discharged freely through the power circuit formed by the main electrodes 2, 3 while that the control circuit is deactivated.  As such, it is also remarkable that the control circuit 15 according to the invention is solicited for a very short time thanks to the speed of the priming of the arc 6 and therefore the transfer of the energy flow from said control circuit to said power circuit.  As is well known to those skilled in the art, the electric arc 6 formed between the main electrodes 2, 3 tends to be blown towards the breaking chamber 16 which facilitates its extinction after the flow of the fault current.  The present invention also relates to a method of triggering an electrical component 1 comprising at least a first and a second main electrode 2, 3 forming a spark gap 4.  According to an important characteristic of the invention, said triggering method comprises a step (a) during which there is shown a disruptive discharge 12 between at least a first trigger element 10 and a second trigger element. tripping 11, both distinct from said first and second main electrodes 2, 3, the occurrence of said disruptive discharge 12 can cause the initiation of an electric arc between the first and second main electrodes 2, 3 of said spark gap 4.  Particularly preferably, step (a) comprises a substep (a1) during which a potential difference is applied between a first auxiliary electrode 14 and a second auxiliary electrode 15 which extend, at least in part, in the inter-electrode space 5 which separates the first main electrode 2 from the second main electrode 3.  Advantageously, said triggering method, when applied to an electrical component 1 according to the invention within

  An overvoltage protection device 20 as described above may constitute a method of protecting an electrical installation against overvoltages. In this case, said method may comprise a step (b) during which the voltage applied to the connection terminals 21, 22 is evaluated and it is decided to implement step (a) if said voltage exceeds a value of predetermined threshold value. Advantageously, the steps (a) and (b) can be intimately linked by the use of an activation means 23 sensitive to the voltage applied to the connection terminals 21, 22, as described above, in order to stimulate the initiation of an electric arc 6 concomitantly with the appearance of an overvoltage at said connection terminals 21, 22. Finally, the present invention also relates to a method of manufacturing an electrical component 1 comprising a step of producing a B60355 / FR 2904893 26 a first and second main electrode 2, 3 forming a spark gap 4, said manufacturing method comprising a step (El) in which said spark gap 4 is associated with at least a first trigger element 10 and a second trigger element 11, both 5 distinct from said first and second main electrodes 2, 3, and a step (E2) in which said first and second elements of triggering 10, 11 so that a disruptive discharge can occur between them and that the occurrence of said disruptive discharge can cause the initiation of an electric arc 6 between the first and second main electrodes 2, 3. Of course. , the steps (E1) and (E2) can advantageously be simultaneous and merged. According to an alternative embodiment of said manufacturing method, the step (E1) may comprise a sub-step during which is reported within the spark gap 4 formed by said first and second main electrodes 2, 3 a prefabricated subassembly comprising the first and the second triggering element 10, 11. Advantageously, it will therefore be possible to apply the manufacturing method according to the invention to the catching up of existing or installed spark gaps by equipping them with a new one. tripping subassembly comprising for example two auxiliary electrodes 14, 15 held in an insulating base of appropriate dimensions, said base being connectable between the main electrodes 2, 3 of the existing spark gap. In addition, the manufacturing method mentioned above can be implemented for the production of an overvoltage protection device 20 according to the invention, and constitute for example a lightning arrester manufacturing method. Preferably, such a method of manufacturing an overvoltage protection device 20 further comprises a step (E3) in which the auxiliary electrodes 14, 15 are electrically connected to an activating means. 23 as previously described.

Thus, the electrical component 1 according to the invention advantageously makes it possible to provide particularly effective overvoltage protection devices which make it possible to reconcile the good resistance of spark gaps with respect to lightning currents with a low starting voltage. .

Particularly advantageously, the excellent level of protection afforded by the electrical component according to the invention allows in particular its use in Type 2 surge arresters according to the IEC 61643-1 standard. Such surge arresters in accordance with the invention combine robustness and simplicity, and therefore have increased durability and reduced manufacturing cost, particularly with respect to prior art devices which employ varistors as protection components. B60355 / EN

Claims (14)

  1 - Electrical component (1) comprising a first main electrode (2) and a second main electrode (3) forming a spark gap (4), characterized in that it comprises at least a first trigger element (10) and a second trigger element (11), both distinct from said first and second main electrodes (2, 3), said first and second trigger elements (10, 11) being arranged such that a disruptive discharge (12) can occur between they and the occurrence of said disruptive discharge (12) can cause the initiation of an electric arc (6) between the first and second main electrodes (2, 3).   2 - electrical component according to claim 1 characterized in that the first and the second trigger element (10, 11) are respectively formed by a first auxiliary electrode (14) and a second auxiliary electrode (15).   3 - Electrical component according to one of claims 1 or 2 characterized in that the first and the second trigger element (10, 11) extend, at least in part, in the inter-electrode space (5) which separates the first main electrode (2) from the second main electrode (3).   4 - electrical component according to claim 3 characterized in that the assembly formed by the first and the second trigger element (10, 11) is substantially centered between the first and the second main electrode (2, 3). B60355 / FR 2904893 29   5 - Electrical component according to one of the preceding claims characterized in that the smallest functional distance d1 separating the first trigger element (10) from the second trigger element (11) is substantially less than the smallest functional distance d2 which separates the first main electrode (2) from the second main electrode (3).   6 - electrical component according to claim 5 characterized in that the distance di is less than 30% of the distance and preferably between 10% and 20% of said distance d2. 10   7 - Electrical component according to one of the preceding claims characterized in that the minimum functional distance d1 between the first trigger element (10) of the second trigger element (11) is between 0.4 mm and 1 mm.   8 - electrical component according to one of the preceding claims 15 characterized in that the first and the second main electrode (2, 3) delimit an inter-electrode space (5) flared, preferably substantially V-shaped, said inter space -electrodes (5) extending between a narrow section (5A) and a wide section (5B).   9 - Electrical component according to claim 8 characterized in that the first and the second trigger element (10, 11) are located at the narrow section (5A) of the inter-electrode space (5).   10 -The electrical component according to one of the preceding claims characterized in that the main electrodes (2, 3) and the triggering elements (10,   11) are integrated in the same insulating housing having at least four electrical connection poles, two of which are respectively connected to the first and second main electrodes B60355 / FR 2904893 (2, 3) and two are respectively connected to the first and second trigger elements (10, 11). 11 - Protection device (20) of an electrical installation against overvoltages, said device (20) being provided with a first and a second connection terminal (21, 22) intended to be connected to said electrical installation , characterized in that it comprises at least one electrical component (1) according to one of claims 1 to 10, the first and the second main electrode (2, 3) of said electrical component (1) being electrically connected to said electrical installation 10 to be protected via said connection terminals (21, 22). 12 protection device according to claim 11 characterized in that it comprises an activation means (23) connected to the first and second trigger elements (10, 11) for generating a disruptive discharge (12) between said first and second elements triggering means (10, 11) so as to cause the initiation of an electric arc (6) between the first and second main electrodes (2, 3). 13 -Dispositif according to claim 12 characterized in that the activation means (23) is responsive to the voltage applied across the terminals (21, 22) 20 said device (20) and designed to generate a disruptive discharge (12) between the first and second triggering elements (10, 11) when said voltage exceeds a predetermined threshold. 14 -Dispositif according to one of claims 12 or 13 characterized in that the activation means (23) is designed to create a potential difference between the first and the second trigger element (10, 11). B60355 / EN 2904893 31 15 -Dispositif according to claim 14 characterized in that the first or the second trigger element (10, 11) is electrically connected to the secondary circuit of a transformer (TX1) so that it is possible varying the potential of said trigger element (10, 11) by circulating an electric current in the primary circuit of said transformer (TX1). 16 -Dispositif according to claims 13 and 15 characterized in that the activation means (23) comprises an electronic circuit combining in parallel a gas spark gap (24) and a capacitor (CI) so that, when said spark gap to gas (24) is triggered, it bypasses said capacitor (CI) which discharges into the primary circuit of the transformer (TX1). 17 - Device according to one of claims 12 to 14 characterized in that the activation means (23) is formed by a first varistor (V5) which connects, preferably directly, the first connection terminal (21) to first trigger element (10) and a second varistor (V6) which preferably directly connects the second connection terminal (22) to the second trigger element (11). 18 -Dispositif according to one of claims 11 to 17 characterized in that it 20 constitutes a surge arrester. 19 -Dispositif according to one of claims 11 to 18 characterized in that it constitutes a Type 2 surge arrester in the sense of IEC 61643-1. Method for tripping an electrical component (1) comprising at least a first and a second main electrode (2, 3) forming a spark gap (4), characterized in that it comprises a step (a) during wherein a disruptive discharge is generated between at least one first trigger element (10) and a second trigger element (11), both of which are distinct from said first and second main electrodes (2, 3), occurrence of said disruptive discharge (12) capable of causing the initiation of an electric arc (6) between the first and second main electrodes (2, 3) of said spark gap (4). 21 -Process of manufacturing an electrical component (1) comprising a step of producing at least a first and a second main electrode (2, 3) forming a spark gap (4), characterized in that it comprises a step (E1) in which said spark gap (4) is associated with at least one first trigger element (10) and a second trigger element (11), both of which are distinct from said first and second main electrodes (2, 3) as well as a step (E2) during which said first and second trigger elements (10, 11) are arranged so that a disruptive discharge (12) can appear between them and that the appearance of said discharge disruptive (12) can cause the initiation of an electric arc (6) between the first and second main electrodes (2, 3). 22 - Manufacturing method according to claim 21 characterized in that step (E1) comprises a substep during which is reported within the spark gap (4) formed by said first and second main electrodes (2). , 3) a prefabricated subassembly comprising the first and the second triggering elements (10, 11). B60355 / EN