Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
  • H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
  • H02H9/06—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage using spark-gap arresters
• • 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
  • H01T2/00—Spark gaps comprising auxiliary triggering means
  • H01T2/02—Spark gaps comprising auxiliary triggering means comprising a trigger electrode or an auxiliary spark gap

Definitions

• the present invention relates to the general technical field of protective devices of equipment or electrical installations against voltage disturbances such as overvoltages, and in particular transient overvoltages due for example to a lightning strike.
• the present invention relates more particularly to a device for protecting an electrical installation against overvoltages, in particular transient overvoltages due to a lightning impact, said device being mounted in shunt with respect to the electrical installation and comprising:
• pre-trip circuit sensitive to overvoltages
• said pre-trip circuit being mounted in shunt with respect to the electrical installation and connected to the pre-trip device so as to control the spark gap of the spark gap when an overvoltage occurs.
• spark gap arrester comprising a main spark gap, to protect an installation against overvoltages.
• the main spark gap is then, for example, arranged between the phase to be protected and the earth, so as to allow, in case of overvoltage, the flow of lightning current to the ground.
• a pre-trigger circuit It is also known to control the priming of the main spark gap in advance using a pre-trigger circuit.
• the output of the pre-trip circuit can be directly connected to one of the main electrodes of the main spark gap.
• a pre-trip element generally formed by a priming electrode, to which the pre-trip circuit is connected.
• Protective devices incorporating such a pre-trigger circuit advantageously make it possible to obtain a starting voltage of the main spark gap which is lower than the protective devices without such a circuit.
• the known pre-trigger circuits may comprise several components, the respective values of which are chosen so as to obtain a given level of protection.
• non-linear protection components such as varistors, which have a level of protection substantially lower than the main spark gap and which, for example associated with a current transformer, are used to control priming the main spark gap for a voltage level lower than the intrinsic trip voltage level of the main spark gap.
• other components such as a capacitor, the operation of the pre-trigger circuit is then based on the charge of the capacitor.
• the known protection devices are traversed by a leakage current flowing in the pre-trip circuit when it is supplied at its steady state voltage.
• this leakage current can disrupt the sensitive electronic systems arranged downstream of the protection device, such as for example low-value differential circuit breakers or isolation controllers.
• the pre-trip circuits operating on the principle of the charge of a capacitor suffer from a delay effect at tripping, related to the charging time of the capacitor.
• the known protection devices are not fully effective and have a number of weak points related in particular to the design of the pre-trip circuit.
• the objects assigned to the invention therefore aim to remedy the various disadvantages listed above and to propose a new device for protecting an electrical installation against overvoltages which, in the absence of an overvoltage, consumes substantially no leakage current. .
• Another object of the invention is to propose a new device for protecting electrical installations against overvoltages making it possible to reduce, then eliminate, the current flowing in the pre-trip circuit once the main spark gap has been initiated. .
• Another object of the invention is to provide a new device for protecting an electrical installation against overvoltages for discharging high currents to earth, while maintaining a level of protection compatible with conventional electrical equipment.
• Another object of the invention is to provide a new device for protecting an electrical installation against overvoltages with improved operational safety.
• Another object of the invention is to provide a new device for protecting an electrical surge installation designed so that all of the lightning current flows through the main spark gap.
• a device for protecting an electrical installation against overvoltages, in particular transient overvoltages due to a lightning strike said device being mounted in shunt with respect to the electrical installation and comprising:
• the pre-trip circuit comprises at least one voltage-breaking element, specifically designed to pass, when the voltage at its terminals exceeds a predetermined threshold value, from a non-conducting state, in which it prevents the current from flowing, to an on state, in which it allows the passage of current, said voltage cutoff element being disposed so as to prevent, in its non-conducting state, the flow of current in the pre-trip circuit such that in the absence of overvoltage, the leakage current consumed by the pre-trip circuit is substantially zero.
• FIG. 1 illustrates, in the form of an electrical block diagram, one embodiment of an overvoltage protection device according to the invention.
• FIG. 2 illustrates, in the form of an electrical block diagram, a variant of the protection device according to the invention.
• FIG. 3 illustrates, in the form of an electrical block diagram, another alternative embodiment of the protection device according to the invention.
• FIG. 4 illustrates, in schematic form, a particular arrangement of the components used in the protection device according to the invention.
• FIG. 5 illustrates, in the form of an electrical block diagram, another embodiment of a protection device according to the invention.
• the overvoltage protection device according to the invention is intended to be connected bypass on the equipment or electrical installation to be protected.
• the term "electrical installation” refers to any type of device or network that is susceptible to voltage disturbances, including transient overvoltages due to a lightning strike. In the latter case, the surge protection device is commonly called “surge arrester”.
• 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 conceivable, without departing from the scope of the invention, that the device, instead of being connected bypass between a phase and the earth, is connected between the neutral and the earth, between the phase and the neutral, or between two phases (case of differential protection).
• Voltage cut-off elements are, within the meaning of the invention, components capable of passing from a non-conducting state, in which they prevent the current from flowing, to an on state in which they allow the passage of current.
• the current flowing through these components grows very rapidly after being primed, whereas the voltage at their terminals decreases very quickly on the contrary.
• spark gaps or thyristors are voltage cut-off elements.
• the voltage limiting elements have a voltage-current upward curve, the voltage at the terminals of these components remaining substantially constant or even increasing very slightly as the current increases. Indeed, when a given voltage threshold is reached, the current increases rapidly in the voltage limiting element, because of the decrease in its resistance, while the voltage at its terminals remains substantially constant. Zener diodes and varistors are, in the sense of the invention, voltage limiting elements. In the remainder of the description, the terms "voltage cut-off element" and “voltage-limiting element” will be interpreted in accordance with the definitions given above.
• FIG. 1 and FIG. 5 illustrate a protection device 1 according to the invention. As shown in Figures 1 and 5, the protective device 1 is mounted in parallel with respect to an electrical installation 2 to be protected.
• the illustrative examples of FIGS. 1 and 5 show, in particular, a protection device 1 connected in shunt between a phase to be protected P and earth T.
• the protective device 1 comprises a main spark gap E1, for example an air gap, advantageously provided with two main electrodes 3, 4 separated by an insulating medium 5, such as an air gap, in which the electric discharge and the formation of the electric arc occur between the main electrodes 3, 4.
• the main spark gap E1 is advantageously mounted in parallel with the electrical installation 2 to be protected.
• the protection device 1 also comprises a pre-triggering circuit 10 (illustrated in dotted lines), sensitive to overvoltages and in particular to the voltage at its terminals 10A, 10B .
• the pre-trip circuit 10 is shunted relative to the electrical installation 2, and is connected to the main spark gap E1 so as to control the priming of the main spark gap E1 when an overvoltage occurs.
• the main spark gap E1 is provided with a pre-triggering member 6 allowing its initiation, preferably formed by a priming electrode. Initiating the spark gap E1 occurs, in a conventional manner, when the voltage between the pre-trigger member 6 and one of the main electrodes 3, 4 exceeds a certain value.
• the pre-trip circuit 10 is connected to the pre-trip device 6 and advantageously designed such that when a current flows through it, the voltage at its output S is found in a substantially identical manner between one of the main electrodes 3, 4 and the pre-triggering element 6.
• the main spark gap E1 does not comprise a third pre-trigger electrode, and its initiation takes place when the voltage between the main electrodes 3, 4 exceeds a certain value.
• the pre-trip circuit 10 is connected to one of the main electrodes 3, 4 so as to generate, in the event of an overvoltage, a voltage greater than the intrinsic tripping voltage of the main spark gap E1.
• the pre-trip circuit 10 comprises at least one voltage cutoff element G, such as a spark gap or a thyristor, specifically designed to pass, when the voltage at its terminals exceeds a predetermined threshold value, d a non-conducting state, in which it prevents the current from flowing, to an on state, in which it allows the passage of current.
• G such as a spark gap or a thyristor
• the voltage cut-off element G is represented for illustrative purposes by a spark gap symbol.
• another voltage cutoff element such as for example a thyristor.
• the voltage cut-off element G is disposed within the pre-trip circuit 10 so as to prevent, when it is in its off state, the flow of current in the pre-trip circuit 10, so that in the absence of overvoltage, the leakage current consumed by the pre-trip circuit 10 is substantially zero.
• the "leakage current” is the current capable of supplying the protection device 1 during normal operation, that is to say in the absence of overvoltage.
• the leakage current consumed by the protection device 1 is substantially no.
• Such a device therefore significantly reduces the risk of damage to sensitive electronic devices disposed downstream of the protective device 1.
• the pre-trip circuit 10 comprises a triggering transformer TR provided with a primary coil L1 and a secondary coil 12 magnetically coupled.
• the secondary coil L2 is connected, preferably directly, to the pre-trip element 6 so that when the primary coil L1 is traversed by a current, in particular a lightning current , the voltage induced across the secondary coil L2 causes the priming of the main spark gap E1.
• the secondary coil L2 is connected, preferably directly, to one of the main electrodes 3, 4 in order to ensure the priming of the main spark gap E1.
• the secondary coil L2 advantageously comprises a number of turns greater than the number of turns of the primary coil L1, so that the voltage across the secondary of the transformer is substantially greater than the voltage at the terminals of the primary.
• the pre-trip circuit 10 comprises a branch B connected in parallel on the one hand with the electrical installation 2 and on the other hand with the main spark gap E1.
• the branch B comprises on the one hand the primary coil L1 and, on the other hand, connected in series with said primary coil L1, the breaking element in tension G.
• the voltage cutoff element G is thus specifically arranged such that in the absence of overvoltage, the leakage current is substantially zero not only in the branch B, but also in the whole of the pre-trip circuit 10.
• the voltage cut-off element G is thus advantageously arranged within the pre-trip circuit 10, so that all the current I, and in particular the lightning current, entering the pre-trip circuit 10 necessarily passes through the gate. G. Voltage cutoff element
• the pre-trip circuit 10 comprises at least one voltage limiting element V1 connected in series with the voltage cutoff element G.
• This element voltage limitation V1 is preferably formed by a varistor.
• the mounting of the voltage limiting element V1 in series with the voltage cut-off element G on the one hand, and with the primary coil L1, on the other hand, makes it possible to limit the current flowing in the primary coil L1 of the TR transformer.
• the main spark gap E1 when the main spark gap E1 is primed, the latter flows the majority of the lightning current.
• the pre-trip circuit 10 the phase to be protected P to the earth T, in particular in the primary coil L1 of the transformer TR. This phenomenon may have the effect of irreparably damaging the pre-warning circuit. trigger 10, which is not a priori designed to discharge the lightning current.
• a voltage limiting element V1 placed in series with the voltage cutoff element G thus makes it possible to limit the intensity of the current flowing in the pre-trip circuit 10 and especially to cut off the current flowing through the voltage cut-off element G, which amounts, in the case where the voltage cut-off element G is formed by a spark gap, to cut off the current flowing through the spark gap.
• the following current is the short-circuit current that the spark gap continues to flow, after its initiation, until the extinction of the electric arc.
• the voltage limiting element V1 does not intervene in the triggering of the main spark gap E1 but is simply arranged within the pre-trip circuit 10 so as to operate in association with the element cut-off voltage G to turn off the current flowing through it. Therefore, the voltage limiting element V1 has different characteristics, and consumes in particular a much lower energy than the voltage limiting elements conventionally used to ensure the triggering of a spark gap in the devices of the prior art. .
• the majority of the energy from the overvoltage will be able to be used for the triggering of the main spark gap E1 whereas, in the devices of the prior art, a not insignificant part of the energy coming from the overvoltage was consumed by the pre-trip circuit, in particular by non-linear tripping components such as varistors.
• the current-voltage characteristic of the voltage limiting element V1 is therefore specifically chosen as a function of the characteristic of the voltage cut-off element G.
• the value of the operating voltage of the voltage-limiting element V voltage limitation V1 used in the context of the present invention is significantly lower than the value of the operating voltage of voltage limiting elements conventionally used to ensure the triggering of a spark gap.
• a main spark gap E1 having an intrinsic starting voltage, that is to say without pre-tripping, of the order of 3.5 to 4 KV a voltage cut-off element G of threshold value spark gap type of the order of 800 V, a voltage limiting element V1 of the varistor type, of operating voltage of the order of 150 V and a transformer with a primary coil L1 of 12 ⁇ H and a secondary coil L2 of 4 mH.
• the operating voltage of this varistor should necessarily be at least equal to 255 V (nominal voltage 230V network + 10%) and therefore consume much more energy than the voltage limiting element V1 used in the context of the present invention.
• the pre-trip circuit 10 advantageously comprises at least one additional voltage limiting element V2 of the varistor type, connected in parallel with the primary coil L1.
• the additional voltage limiting element V2 can thus advantageously: - either be connected in parallel with the single primary coil L1,
• the additional voltage limiting element V2 is advantageously disposed within the pre-trip circuit 10 in such a way that a current can pass through it only when the voltage cut-off element G is in its phase. passing state.
• the additional voltage limiting element V2 is connected in series with the voltage cutoff element G.
• the additional voltage limiting element V2 may be formed by a service voltage varistor of the order of 275 V.
• the pre-trip circuit advantageously comprises at least one overload protection component F, connected in series with the breaking element.
• the overload protection component F is a thermal fuse positioned physically against the varistor forming the voltage limiting element V1.
• the thermal fuse then forms the means of thermal disconnection of this varistor, and ensures the disconnection of the latter in case of overheating.
• the pre-trip circuit 10 consists exclusively of a transformer TR, a voltage cutoff element G, a voltage limiting element V1 and a component overload protection device F, to the exclusion of any other component, and in particular to the exclusion of a capacitor.
• the pre-trip circuit 10 comprises, connected in series with the primary coil L1 of the transformer TR, two voltage cutoff elements G, G ', two elements voltage limiting device V1, VV and an overload protection component F, specifically a thermal fuse.
• the branch B connected in parallel with the main spark gap E1 consists exclusively of the primary coil L1, the two voltage limiting elements V1, VV, the two voltage cutoff elements G, G 'and the component overload protection F.
• each overload protection component is associated to a given voltage limiting element.
• the two voltage cutoff elements G, G ' are connected in series on either side of the primary coil L1, the latter therefore being electrically connected between a first voltage cutoff element G of a part and a second voltage cutoff element G 'on the other hand.
• the two voltage limiting elements V1, VV are then respectively connected to each of the voltage cutoff elements G, G ', in series with the latter.
• Such an assembly makes it possible, particularly in the case of the variant embodiment illustrated in FIG. 1, to prevent a part of the lightning current from flowing in the secondary coil L2 of the transformer TR, from the phase to the earth. after priming the main spark gap E1.
• the present invention thus makes it possible, by disposing a second voltage cutoff element G 'between said secondary coil L2 and earth T, to eliminate this derived current.
• the secondary coil L2 is connected, by one of its terminals, to the pre-triggering member 6 and the other terminal to the voltage cutoff element G '.
• the voltage cutoff elements G, G ' are thus electrically arranged on either side of the primary coil L1 so as to isolate the transformer TR from the rest of the pre-trip circuit 10, thereby avoiding any current leakage in this circuit. circuit after priming the main spark gap E1.
• Another advantage of this arrangement is that it is symmetrical, so that the protection device 1 is not sensitive to the polarity of the voltage at its terminals and behaves in the same way, whatever its connection direction between phase and earth.
• the overload protection component F specifically the thermal fuse, is arranged between and in contact with the two voltage limiting elements V1, V1 '. so that it suffices that one of these voltage limiting elements V1, V1 'is defective and abnormally heats up so that the two voltage limiting elements V1, VT are disconnected from the rest of the circuit. pre-triggering 10.
• all the voltage cutoff elements G, G ' are formed by spark gaps and all the voltage limiting elements V1, VV are formed by varistors.
• the operation of the protection device according to the invention will now be described with reference to the assembly illustrated in FIG.
• the overvoltage protection device therefore has the advantage of not consuming any leakage current when it is supplied in steady state, in the absence of overvoltage.
• Another advantage of the protection device according to the invention is that it can channel all of the lightning current to the main spark gap E1, so that the lightning current can not flow, even partially, through all or part of the pre-trip circuit 10.
• the invention finds its industrial application in the design, manufacture and use of surge protection devices.

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• 2001
  • 2001-07-25 US US11/572,777 patent/US20090021881A1/en not_active Abandoned
• 2004
  • 2004-07-26 FR FR0408251A patent/FR2873509B1/fr not_active Expired - Fee Related
• 2005
  • 2005-07-25 EP EP05793501A patent/EP1792378A1/de not_active Withdrawn
  • 2005-07-25 BR BRPI0514402-7A patent/BRPI0514402A/pt not_active Application Discontinuation
  • 2005-07-25 MX MX2007001043A patent/MX2007001043A/es not_active Application Discontinuation
  • 2005-07-25 CN CNA2005800288319A patent/CN101036275A/zh active Pending
  • 2005-07-25 WO PCT/FR2005/001916 patent/WO2006018530A1/fr active Application Filing

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