Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
  • H01T1/00—Details of spark gaps
  • H01T1/12—Means structurally associated with spark gap for recording operation thereof
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01T—SPARK GAPS; OVERVOLTAGE ARRESTERS USING SPARK GAPS; SPARKING PLUGS; CORONA DEVICES; GENERATING IONS TO BE INTRODUCED INTO NON-ENCLOSED GASES
  • H01T1/00—Details of spark gaps
  • H01T1/14—Means structurally associated with spark gap for protecting it against overload or for disconnecting it in case of failure

Definitions

• the present invention relates to the general technical field of equipment protection devices or electrical installations against overvoltages, including transient overvoltages due to lightning.
• the present invention relates more particularly to a protection device against overvoltages due in particular to a lightning strike intended to be connected to an electrical installation and comprising at least two electrodes defining an inter-electrode space forming a spark gap.
• the invention also relates to a method for electrically isolating a surge protection device intended to be connected to an electrical installation and comprising at least two electrodes delimiting an inter-electrode space forming a spark gap.
• the surge arrester and the circuit breaker are sometimes located at a distance from each other and the impedance of the connecting conductors is often difficult, if not impossible to calculate precisely, which can lead to errors and an underestimation of the actual level of protection of the electrical installation.
• the objects assigned to the invention therefore aim to propose a new device for protecting an electrical installation against overvoltages that do not have the drawbacks listed above and that, in the event of a failure, to be definitively disconnected from the electrical installation. .
• Another object of the invention is to propose a new device for protecting an electrical installation against overvoltages having a good reliability of disconnection.
• Another object of the invention is to propose a new device for protecting an electrical installation against overvoltages which is particularly easy to use, thus limiting the risk of error for the operator.
• Another object of the invention is to propose a new device for protecting an electrical installation against overvoltages whose operating state can be easily monitored.
• the objects assigned to the invention are also intended to propose a new method of electrical insulation of a protection device of an electrical installation against overvoltages allowing, in a simple way and using standard components, to effectively isolate the device in case of failure of the latter.
• Another object of the invention is to propose a new method of electrical insulation of a protection device of an electrical installation against overvoltages allowing a close monitoring of the operating state of the device.
• a surge protection device due in particular to a lightning strike intended to be connected to an electrical installation, which comprises at least two electrodes delimiting an inter-electrode space. forming a spark gap, as well as:
• detection means responsive to the state of the spark gap and capable of detecting a disruption of the current of the dead, means of disconnection, capable of ensuring, under the control of the detection means, the isolation of the protection device with respect to the electrical installation when a failure of the spark gap is detected by the detection means.
• the disconnecting means are formed by insulating means, adapted to come, under the control of the detection means, to be positioned between the electrodes in order to increase the isolation between the latter.
• the objects assigned to the invention are also achieved by means of a method of electrically isolating an overvoltage protection device intended to be connected to an electrical installation and comprising at least two electrodes delimiting an internal space. spark gap electrodes, said process comprising successively:
• FIG. 1 illustrates, in a sectional view, a protective device against overvoltages according to the invention.
• FIG. 2 illustrates, in a schematic view, a first embodiment of the overvoltage protection device according to the invention in its operating position.
• FIG. 3 illustrates, in a schematic view, the protection device shown in Figure 2 in its disconnected position.
• FIG. 4 illustrates, in a schematic view, a second embodiment of the protection device according to the invention in its service position.
• FIG. 5 illustrates, in a schematic view, the protection device shown in Figure 4 in its disconnected position.
• the overvoltage protection device according to the invention is intended to be connected bypass (or parallel) on the equipment or electrical installation to be protected.
• electrical installation refers to any type of device or network that is susceptible to voltage disturbances, including transient overvoltages due to lightning.
• the overvoltage protection device according to the invention is advantageously intended to be disposed between a phase of the installation to be protected and the earth. It is also possible, without departing from the frame ⁇ déTinrvehtio ⁇ rq ⁇ ê " protection device, instead of being connected bypass between a phase and earth, or connected between the neutral and the earth, between phase and neutral , or between two phases (case of a differential protection).
• FIG. 1 An exemplary embodiment of a protection device 1 according to the invention is illustrated in FIG.
• the protection device 1 is advantageously in the form of a spark gap arrester.
• the protection device 1 thus comprises at least two electrodes, for example a first electrode 2 and a second electrode 3 delimiting an inter-electrode space 4 forming a spark gap.
• the first and second electrodes 2, 3 can thus advantageously form the main electrodes of the spark gap.
• the protection device 1 according to the invention also advantageously comprises connecting branches 5, 6 to the electrical installation or to the power supply network, making it possible to electrically connect the protection device 1 to the electrical installation (not shown) to protect.
• the electrodes 2, 3 and the connecting branches 5, 6 may advantageously be formed by the same conductive part, for example a metal part. All of these elements is advantageously mounted within an insulating casing 7.
• the housing 7 may constitute a plug-in module (or cartridge) on a base, thus facilitating the installation or removal of the protection device 1 by the operator.
• the inter-electrode space 4 is filled, at least partially, with a gas, preferably with air so as to form a dielectric medium between the electrodes 2, 3.
• the inter-electrode space 4 form in this case an air gap.
• the protective device 1 is based on the technology of air gaps.
• the protective device 1 according to the invention uses encapsulated spark gap technology, the air then being replaced by a gas, for example a rare gas maintained under controlled pressure.
• Such spark gaps undergo, during their lifetime, degradation. This degradation can be gradual or abrupt, especially the spark gap is used intensively or repeatedly, with a high frequency. Several phenomena, specific to the gaps, can lead to this degradation of the protective device.
• an electric arc 15, corresponding to the ionization of the gas located in the inter-electrode space 4 is formed. between the electrodes 2, 3 and flows, for example to earth, the current corresponding to the overvoltage.
• the protective device 1 then deflects the current and allows to preserve the electrical installation.
• the electric arc can cause erosion of the electrodes 2, 3, tearing metal particles on the surface thereof. These metal particles are then likely to be deposited at another place in the inter-electrode space, thus creating a conductive pollution within the spark gap. This pollution can lead, when important, to a failure of the spark gap, several evolutions then being possible until the end of life of the spark gap.
• the metal particles can be deposited on the surface of the dielectric lamella, thus forming a conductive deposit between the electrodes.
• This conductive deposit gradually forms a metal bridge between the electrodes, short-circuiting the spark gap.
• a large short-circuit current can then flow, by conduction, to the surface of the dielectric lamella, thus causing significant heating of the spark gap.
• the protection device should be disconnected as soon as possible and replaced, since it is no longer able to properly protect the electrical installation.
• the end of life of the spark gap is random, so that it is particularly difficult, if not impossible, to predict in advance its replacement.
• the protection device 1 comprises detection means 8, sensitive to the state of the spark gap and capable of detecting a detection are designed to detect a possible failure of the behavior of the spark gap, causing, for example, a heating excessive of the latter.
• the detection means 8 are advantageously sensitive to excessive heating of the spark gap, which may occur when the spark gap is faulty.
• the detection means 8 are sensitive to the temperature, and are advantageously located close to the spark gap in order to detect as quickly as possible an abnormal heating of the latter, independently of the heating of a possible electronic circuit. associated tripping, or other means of breaking, of the circuit-breaker type, located near the protection device 1.
• the protective device 1 of the electrical installation should be disconnected as soon as possible and then replaced.
• the protection device 1 comprises disconnection means 9, able to ensure, under the control of the detection means 8, isolation of the device of the invention. protection 1 vis-à-vis the electrical installation when a failure of the spark gap is detected.
• the detection means 8 being directly sensitive to the state of heating of the spark gap, they are designed to trigger the disconnection means 9 when the temperature of the spark gap exceeds a predetermined threshold value.
• the isolation of the spark gap is immediate, which in particular limits the risk of fire.
• the disconnection means 9 are formed by movable insulating means 10 capable of coming, under the control of the detection means 8, that is to say when a failure of the spark gap is detected by these, position themselves between the electrodes 2, 3 to increase the isolation between them.
• the insulating means 10 are adapted to increase the electrical isolation capacitances of the inter-electrode space 4, and therefore the energy required for an electric arc to be formed between the electrodes 2, 3.
• the protection device 1 according to the invention also makes it possible to avoid using a complex additional cut-off device, such as a circuit breaker.
• FIGS. 2 to 5 Several embodiments of the protection device 1 according to the invention will now be described with reference to FIGS. 2 to 5.
• the insulating means 10 are formed by an insulating part 11 mounted movably within the housing 7 so as to be able to move between the electrodes 2, 3 in to increase the isolation distance between the latter when a failure, and in particular a heating of the spark gap, is detected by the detection means 8.
• isolation distance here refers to the distance that the electric arc must travel to electrically connect the electrodes 2, 3. It exists, when the spark gap is operational, that is to say non-degraded , a so-called “functional" isolation distance, which corresponds substantially to the width of the inter-electrode gap 4 necessary for an electric arc to start when an overvoltage reaching or exceeding a predetermined threshold value occurs.
• the insulating part 11 is therefore advantageously designed to increase the isolation distance between the electrodes 2, 3, so that the latter exceeds the above-mentioned functional isolation distance.
• the protective device 1 according to the invention is advantageously dimensioned so that this energy is never reached in the usual operating conditions of the spark gap, which ensures the electrical insulation of the latter.
• the width of the inter-electrode space is not necessarily constant and can vary along the electrodes 2, 3.
• the electrodes 2, 3 can advantageously have a V shape, the V hollow, which has the distance the weakest isolation, then advantageously forming the ignition zone 40 of the electric arc.
• the insulating part 11 is advantageously mounted movably between a first position (illustrated in FIG. 2) in which it allows the free operation of the protection device 1, and in particular the formation of an electric arc 15 in the inter-electrode space 4 , more precisely in the priming zone 40, and a second position (illustrated in FIG. 3) in which it increases the isolation distance between the electrodes 2, 3, thus preventing the maintenance or rebooting of the electric arc , and ensuring simultaneously the final disconnection of the protective device 1 vis-à-vis the electrical installation.
• the insulating part 11 is mounted mobile in translation between its first and second positions, under the constraint of an actuating means, and preferably under the constraint of an elastic return means 12 of the spring type.
• the electrodes 2, 3 comprise parallel branches 2A 1 3A spaced apart from one another and forming a slideway 13 in which the insulating part 11 is capable of sliding under the stress exerted by the elastic return means 12.
• the second position of the insulating part 11 may advantageously be defined by a stop member B against the displacement thereof.
• said abutment B may be located, at least partially, within the inter-electrode space 4, so that the insulating part 11, after having been released, continues its race until it meets said abutment B in said inter-electrode space 4.
• the insulating part 11 is advantageously maintained by the detection means 8, which are for example formed by a fuse element 14, fixed relative to the housing 7 and for example secured to the latter.
• the fuse element 14 is preferably located near and preferably in physical contact with the insulating part 11, so as to detect, by conduction, heating of the latter.
• the fuse element 14 is preferably formed by a calibrated tin-lead alloy to break or melt beyond the usual operating temperatures of the spark gap.
• the fuse element 14 is advantageously electrically isolated from the electrodes 2, 3, for example by interposition of a dielectric material.
• the detection means 8 are preferably mounted within the protective device 1 so as to release the disconnection means 9, and in particular the insulating means 10 (for example the insulating part 11) when a malfunction of the spark gap is detected.
• the insulating means 10, in particular the insulating part 11, are held directly or indirectly by the fuse element 14, such that the melting or breaking of the latter causes the release of the insulating means 10.
• the element fuse 14 and the insulating means 10 are thus advantageously mounted relative to each other so that the fuse element 14 forms a stop against the displacement of the insulating means 10 under the action of the restoring force F exerted by the resilient return means 12.
• the restoring force F exerted by the elastic return means 12 is directed towards the inter-electrode space 4, so as to push back the part insulating 11 deeper inside the inter-electrode space 4 when a failure of the spark gap is detected.
• the insulating part 11 can form, in its first position, an insulating initiation aid to control the initiation of the electric arc 15 between the electrodes 2, 3.
• the insulating part 11 then allows better to control the level of protection of protection device 1 compared to devices without a booster auxiliary.
• an overvoltage greater than the trigger threshold of the spark gap occurs, an electric arc 15 is initiated between the electrodes 2, 3, along the surface S of the insulating piece 11 located at the interface with the gas.
• the insulating element 11 and the priming aid may be arranged superimposed between the parallel branches 2A 1 3A, electrodes 2, 3.
• the priming aid is preferably fixed and the insulating part 11 is mobile. so as to be able to assume its function of isolation of the protective device 1.
• the insulating part 11 and the priming aid are preferably formed by an insulating material such as ceramic.
• the protection device 1 advantageously comprises an isolating insulating auxiliary 16 which, in the operative position, is arranged between the electrodes 2, 3 in a better way control and control the initiation of an electric arc 15 between the electrodes.
• the electric arc 15 is then formed in the air, along the surface S 'of the priming aid 16.
• the priming aid 16 is advantageously mounted movably between its functional position (illustrated in FIG. 4) and a withdrawal position (illustrated in FIG. 5) in which it is located outside the inter-electrode space 4.
• a large short-circuit current flows between the electrodes 2, 3, along of the ignition auxiliary 16, which has the effect of significantly increasing the temperature of the spark gap, and therefore, by conduction, that of the ignition auxiliary 16.
• the elastic return means 12 'is thus adapted to move from an extension configuration, illustrated in Figure 4, to a rest configuration shown in Figure 5.
• the insulating means 10 are advantageously formed by a gas, and for example by the air G located inside the housing 7 and able to be substituted, in the inter-electrode space 4, for the ignition aid 16 when the latter comes into its withdrawal position shown in FIG. 5.
• the used ignition auxiliary 16 and the conductive deposit 18 are simultaneously removed from the inter-electrode space 4, and replaced by the gas.
• the gas, whose insulating capacity is greater (lower dielectric constant) than the priming aid 16, thus effectively ensures the isolation of the electrodes 2, 3 relative to each other.
• the protective device 1 may advantageously comprise indicating means (not shown) of the state of the spark gap.
• These indication means are advantageously functionally connected to the detection means, and preferably mechanically connected, directly or indirectly, to the insulating piece 11 or to the triggering aid 16.
• the indication means can be formed by a separate piece of the insulating part 11 or the trip auxiliary 16, capable of moving opposite a window in the housing 7, when a failure of the spark gap e_sJLetecté_e. _JJ_e_st_lichement_enyisageable. to provide a protection device 1 in which the indicating means and the insulating part 11 (or the priming aid 16) are formed by one and the same piece.
• the protective device 1 advantageously comprises a breaking chamber 20, formed by an arrangement of metal splitting plates 21 located at the end of the inter-electrode space. 4 opposite to the priming zone 40.
• the interrupting chamber 20 thus ensures the cutting of the electric arc into a plurality of elementary arcs, so as to allow its extinction.
• the electric arc 15, initially formed in the priming zone 40 propagates, thanks to the V-shape of the electrodes 2, 3, to the breaking chamber 20 where it extinguishes.
• the displacement of the latter inside the inter-electrode space 4 in the direction of of the breaking chamber 20, has the effect of causing an elongation of the electric arc 15 and to drive the latter to the breaking chamber 20, thus accelerating its extinction.
• the breaking chamber 20 will be arranged, at least partially, on the path of the insulating part 11, so that the latter will come to a standstill when its end comes into contact. of said breaking chamber 20, for example at one or more fractionating plates 21.
• the breaking chamber 20 will preferably form the stop B which defines the second position of the insulating part 11.
• the present invention also relates to a method of electrically isolating a protective device 1 of an electrical installation against overvoltages comprising at least two electrodes 2, 3 delimiting an inter-electrode space 4 forming a spark gap.
• the method comprises a step (a) for detecting a malfunction of the spark gap, followed, if a failure is detected, with a step (b) of disconnection of the spark gap vis-à-vis the electrical installation.
• the step (a) of detection comprises a phase of detection of heating of the spark gap.
• the step (b) of disconnection advantageously comprises a phase of interposition of insulating means 10 between the electrodes 2, 3 of the protection device 1 so as to increase the isolation between the latter, thus ensuring the electrical isolation the protection device 1 vis-à-vis the electrical installation.
• the interposition phase advantageously comprises a phase of increasing the isolation distance between the electrodes 2, 3 with the aid of an insulating part 11.
• the interposition phase comprises a phase of displacement of the insulating part 11 in the inter-electrode space 4.
• a variant of this method which can be implemented when the protective device 1 comprises an insulating initiator 16 disposed between the electrodes 2, 3, consists in carrying out, during the interposition phase, a substitution of the ignition auxiliary 16 by a gas, in particular air, the gas then forming the insulating means 10.
• the isolation method according to the invention further comprises a step (c) of indicating to a third party, for example to an operator, that the protective device 1 is faulty and that it is necessary to make his change.
• the insulating part 11, or the priming aid 16 are arranged so as to allow the initiation of an electric arc 15 along the surface s, S ' between the electrodes 2, 3.
• the electric arc 15 then allows to flow, for example to earth, the current generated by the overvoltage.
• This electric arc 15 can lead, gradually or rapidly, depending on the intensity and duration of the voltage disturbances, to an erosion of the surface of the electrodes 2, 3, thus causing the formation of a conductive pollution in the internal space.
• This conductive pollution is reflected in particular by the formation of a conductive deposit 18 on the surface S or S '. In this case, there is conduction of a large current along the conductive deposit 18, resulting in excessive heating of the spark gap and the insulating part 11 (respectively of the priming aid 16).
• This excessive heating is then transmitted, for example by conduction, to the fuse element 14 which, when the temperature exceeds a predetermined critical value, begins to melt (or to break).
• the fusion (or rupture) of the fuse element 14 then releases the insulating means 10, for example the insulating part 11 or the gas, which then penetrate inside the inter-electrode space 4, interposing between the electrodes 2, 3 so as to increase the isolation, and for example the isolation distance, between them.
• the electric arc 15 elongates, then is driven to the coface [20], the energy required for the formation of a new arc.
• the high isolation distance between the electrodes 2, 3, the protection device 1 is isolated, so effective and definitive, of the electrical installation.
• the invention therefore ensures, in the event of failure of the spark gap, a quick and reliable disconnection of the protection device 1 vis-à-vis the electrical installation, without disturbing the latter.
• protection device 1 can be in the form of an interchangeable cartridge, thus facilitating its handling by a non-expert user.
• Another advantage of the protective device 1 according to the invention is that it is not resettable and therefore constitutes a safer device than the devices of the prior art.
• the protection device 1 according to the invention also makes it possible to immediately report to the user any malfunction, thus enabling its rapid replacement.
• the invention finds its industrial application in the manufacture of devices for protecting electrical installations against overvoltages.

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• 2004
  • 2004-10-25 FR FR0411376A patent/FR2877155B1/fr not_active Expired - Fee Related
• 2005
  • 2005-10-25 EP EP05814818A patent/EP1829176B1/de not_active Not-in-force
  • 2005-10-25 DE DE602005021693T patent/DE602005021693D1/de active Active
  • 2005-10-25 WO PCT/FR2005/002657 patent/WO2006045947A1/fr active Application Filing
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