Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01C—RESISTORS
  • H01C7/00—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material
  • H01C7/10—Non-adjustable resistors formed as one or more layers or coatings; Non-adjustable resistors made from powdered conducting material or powdered semi-conducting material with or without insulating material voltage responsive, i.e. varistors
  • H01C7/12—Overvoltage protection resistors
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01C—RESISTORS
  • H01C13/00—Resistors not provided for elsewhere
  • H01C13/02—Structural combinations of resistors

Definitions

• the present invention relates to the general technical field of devices for protecting electrical installations against overvoltages, in particular transient overvoltages due to lightning.
• the invention relates more particularly to a device for protection against overvoltages adapted to provide protection according to the common and differential modes, and comprising at least one electrically insulating box, specifically adapted to receive at least one electrical binomial, formed by a varistor called phase. earth, with a phase terminal and an earth terminal, disposed between a first phase to be protected and the earth, and a varistor called phase-neutral, with a phase terminal and a neutral terminal, disposed between said first phase protect and neutral, said phase-earth and phase-neutral varistors being mounted one next to the other within said housing so as to form a mounting binomial.
• a varistor called phase. earth with a phase terminal and an earth terminal, disposed between a first phase to be protected and the earth
• a varistor called phase-neutral with a phase terminal and a neutral terminal, disposed between said first phase protect and neutral
• said phase-earth and phase-neutral varistors being mounted one next to the other within said housing so as to form a mounting binomia
• Surge arresters Devices for protecting electrical installations against overvoltages are widely used, and can be commonly referred to as "surge arresters". Their essential purpose is in fact to drain lightning currents to the earth, and possibly to cleave additional voltages induced by these currents at levels compatible with the behavior of the equipment and devices to which they are connected.
• protection devices comprising varistors.
• a varistor is generally mounted per branch, that is to say that to protect a single-phase network, the protection device must include an electrical binomial formed by at least two varistors in order to ensure protection according to the two modes mentioned above.
• the electrical binomial will generally include a varistor called phase-earth connected between the phase to be protected and the earth, and a varistor called phase-neutral, connected between said phase to be protected and the neutral.
• phase-earth connected between the phase to be protected and the earth
• phase-neutral connected between said phase to be protected and the neutral.
• at least three electrical pairs will be required to perform the same function.
• Known common mode / differential mode protection devices thus generally comprise at least two boxes (or motors) for provide protection according to the two modes mentioned above in the case of a single-phase network, and at least six boxes (or motors) to ensure the same function in the case of a three-phase network, each box (or motor) comprising a single varistor.
• plug-in versions of known devices are generally produced with two cartridges per phase, that is to say with at least two interchangeable cartridges in the case of a single-phase network and with at least six interchangeable cartridges in the case of '' a three-phase network.
• the surge arrester is then composed of a varistor called phase-neutral connected between the phase to be protected and the neutral point, and a spark gap, connected between the neutral point and earth.
• each protection component is integrated in an individual cartridge so that the arrester has two interchangeable cartridges, only one of which is connected to the phase to be protected, which corresponds well to the logical configuration expected by the user.
• the surge arrester in the case of a three-phase network, will include three varistors each connected between a phase to be protected and, the neutral, and a spark gap, connected between neutral and earth, each protection component being integrated in a individual cartridge.
• the surge arrester thus comprises, in three-phase, four withdrawable cartridges, among which three cartridges are connected to the three phases to be protected, ie one cartridge per phase, which corresponds to what the user intuitively expects to find.
• Such devices thus make it possible to ensure network protection on the one hand in common mode, by placing the two phase-neutral and neutral-earth branches in series, and on the other hand in differential mode, thanks to the phase branch. -neutral.
• connection diagram for neutral to earth is of the IT type (neutral isolated from earth or impedant).
• this arrangement is not suitable for cascading surge arresters.
• a first arrester, located upstream includes a varistor in its neutral-earth branch
• a second arrester, placed downstream includes a spark gap in its neutral-earth branch
• the spark arrester placed downstream will flow , in case of overvoltage, most of the lightning current, and the varistor placed upstream will be little requested, which goes against the objectives sought when coordinating two surge arresters.
• the objects assigned to the invention therefore aim to remedy the various drawbacks listed above and to propose a new overvoltage protection device adapted to provide protection according to the common and differential modes which does not have the drawbacks listed above, and which, while being compatible with all the neutral earth connection schemes, has a limited space requirement.
• Another object of the invention is to propose a new protection device whose maintenance is particularly easy.
• Another object of the invention is to propose a new protection device which, in its withdrawable version, is particularly easy to use, in a logical and intuitive manner.
• Another object of the invention is to propose a new protection device whose adaptation to each type of network is particularly easy.
• the objects assigned to the invention are achieved using a surge protection device adapted to provide protection according to the common and differential modes, and comprising at least one electrically insulating housing, specifically adapted to receive at least one electrical binomial, formed by a varistor called phase-earth, with a phase terminal and a ground terminal, disposed between a first phase to be protected and the ground, and a varistor called phase-neutral, with a phase terminal and a terminal neutral, disposed between said first phase to be protected and neutral, said phase-earth and phase-neutral varistors being mounted one next to the other within said housing so as to form a mounting binomial, characterized in that that the protection device comprises electrical isolation means, adapted to electrically isolate the earth terminal of the phase-earth varistor from the neutral terminal of the vari phase-neutral stance.
• FIG. 1 illustrates, in a partial sectional view, a housing in which is mounted the mounting binomial.
• FIG. 2 illustrates, in a general perspective view, the housing according to the invention in a withdrawable version.
• FIG. 3 illustrates, in a perspective view, a base on which the housing illustrated in Figure 2 is intended to be mounted.
• - Figure 4 illustrates a schematic electrical diagram of the overvoltage protection device according to the invention in the case of a single-phase network.
• FIG. 5 illustrates a schematic electrical diagram of the overvoltage protection device according to the invention in the case of a three-phase network.
• the overvoltage protection device according to the invention is intended to be connected bypass to the electrical equipment or installation to be protected.
• electrical installation refers to all types of devices or networks liable to undergo voltage disturbances of various origins, and in particular transient overvoltages due to lightning.
• the protection device according to the invention is preferably a low voltage surge arrester, that is to say it is preferably intended to protect low voltage installations (for example from 50 volts to 750 volts).
• the overvoltage protection device 1 will now be described with reference to FIGS. 1 to 5.
• the overvoltage protection device 1 is adapted to provide protection according to the common and differential modes, that is to say it must be able to be used either in common mode or in differential mode, and this without it is necessary to modify the device in any way, and in particular the nature and the mounting of the protective components constituting it.
• the protection device 1 comprises at least one electrically insulating housing 2, that is to say advantageously made from a non-conductive material of electricity.
• the protection device 1 also comprises at least one electrical binomial, formed by a varistor called phase-earth PT, disposed between a first phase L1 to be protected and the earth T and a varistor called phase-neutral PN, arranged between said first phase L1 to be protected and neutral N.
• a varistor called phase-earth PT disposed between a first phase L1 to be protected and the earth T
• a varistor called phase-neutral PN arranged between said first phase L1 to be protected and neutral N.
• phase-to-ground varistor PT is arranged to protect the electrical installation in common mode (ie between an active conductor and the ground), while the phase-to-neutral varistor PN is arranged to provide protection in differential mode (ie between two active conductors).
• the housing 2 is specifically adapted to receive the electrical binomial formed by the phase-earth varistors PT and phase-neutral PN, that is to say that it is designed to receive a maximum of two varistors.
• the phase-earth varistors PT and phase-neutral PN forming the electrical binomial are mounted next to each other within the housing 2 so as to form a mounting binomial 3.
• the protection device 1 thus designed advantageously has a reduced bulk, the phase-earth varistors PT and phase-neutral PN no longer being, as in the devices of the prior art, mounted in individual boxes but grouped together in the same box 2 .
• each phase-earth varistor PT or phase-neutral PN is advantageously provided with its own disconnection means, preferably of the thermal type so that the thermal runaway is stopped sufficiently early in the event of aging of the varistors.
• the disconnection means can be formed by a disconnection blade 4 which extends between two ends 4A, 4B, one of said ends 4A being preferably fixed using a hot-melt solder on one of the poles of the associated varistor.
• the end 4A of the disconnection blade 4 is thus preferably welded under stress, so that heating of the varistor at the end of life leads to the fusion of the solder which, once broken, allows the release of the disconnection blade 4 and therefore the disconnection of the associated varistor from the electrical installation.
• the housing 2, provided with phase-earth varistors PT and phase-neutral PN provided with their disconnection means 4, then advantageously forms a "double" motor, that is to say a motor provided with two varistors.
• the box 2 could be formed by a simple support, not necessarily closed, but specifically adapted to receive the electrical binomial formed by the pair of phase-earth varistors PT and phase-neutral PN.
• the protection device 1 thus designed can be easily adapted to be in a withdrawable version.
• the protection device 1 advantageously comprises a base 6, preferably fixed, that is to say permanently connected to the electrical installation to be protected (FIG. 6).
• each box 2 is then provided with plug-in / draw-out means 7 (FIG. 2) adapted to allow the removable electrical connection of the box 2 relative to the base 6.
• the racking-in / racking-out means 7 are advantageously formed by four studs 8A, 8B, 9A, 9B allowing the housing 2 to be plugged into the base 6.
• the poles of the phase-to-earth PT and phase-neutral PN varistors are thus advantageously connected respectively to the pads 8A, 8B on the one hand and 9A, 9B on the other hand.
• the base 6 is preferably provided with a housing 10 arranged to receive the housing 2, and on the bottom 10A of which are formed four openings 8'A, 8'B, 9'A, 9'B specifically adapted for receive the pads 8A, 8B, 9A, 9B respectively.
• the box 2 provided with its racking-in / out tools 7 constitutes an interchangeable cartridge 11.
• the user can remove the cartridge 11 relative to the base 6, in order to replace it. This operation is made particularly easy and logical because of the unequivocal connection existing between the cartridge 11 and the phase to be protected.
• the protection device 1 is designed to ensure the protection of a single-phase network.
• the protection device 1 comprises at least one housing 2 (in dotted lines in FIG. 4) provided with a mounting pair formed by a phase-earth varistor PT and a phase-neutral varistor PN, said mounting pair being electrically connected to the L1 phase to be protected.
• the phase-earth varistor PT is electrically connected between the phase L1 to be protected and the earth T, thus ensuring protection in common mode
• the phase-neutral varistor PN is connected between the phase L1 and the neutral point N so as to provide protection in differential mode.
• the protection device 1 is designed to protect a three-phase network and for this purpose comprises at least three boxes 2A, 2B, 2C (dotted on FIG. 5) each provided with a mounting pair electrically connected to one of the phases L1, L2, L3 to be protected.
• the housing 2A contains a phase-earth varistor PT connected between the first phase L1 to be protected and the earth, and a phase-neutral varistor PN connected between said phase L1 and the neutral point N.
• the box 2B comprises a phase-earth varistor PT connected between the second phase L2 to be protected and the earth, and a phase-neutral varistor PN connected between the second phase L2 and the neutral point N.
• the third box 2C includes a phase-earth varistor PT, connected between the third phase L3 to be protected and the earth, and a phase-neutral varistor PN connected between said third phase L3 and the neutral point N.
• the protection device 1 may be adapted to ensure the protection of a polyphase network comprising a number N of phases.
• the protection device 1 will advantageously include a number of boxes 2 at least equal to the number N of phases, each box 2 being provided with a mounting pair 3.
• the protection device 1 is said to be " multipolar ”.
• the protective device 1 comprises, when it is multipolar, insulating means 30, arranged between two mounting pairs 3 consecutive, that is to say juxtaposed, so as to electrically isolate one of the other.
• the insulating means 30 thus make it possible to avoid the formation of short circuits likely to occur between two consecutive mounting pairs 3 close together, due to their connection to active conductors and in particular to phases L1, L2, L3 of potentials. different. Thanks to the insulating means 30, it is possible to bring the mounting pairs 3 closer to one another, and therefore to reduce the overall size of the device, while avoiding the formation of short circuits between two consecutive mounting pairs 3.
• the insulating means 30 are formed by a screen made of electrically insulating material, interposed between two consecutive mounting pairs 3.
• the insulating means 30, and in particular the insulating screen are advantageously designed and dimensioned so as to increase the isolation distance between two consecutive mounting pairs 3, in order to prevent the formation of electric arcs between them while retaining a small spacing distance, less than the isolation distance, between the mounting pairs 3, so as to limit the size of the device.
• isolation distance here refers to the minimum distance that the electric arc must travel in the gaseous dielectric medium, by air example, separating the mounting pairs 3.
• the protection device 1 may include a varistor called neutral-earth NT, placed between the neutral and the earth, said varistor being mounted within an additional 2S box, as shown in FIGS. 4 and 5.
• the additional 2S box can either be arranged specifically to contain a single varistor, or be in all points similar to the box 2, with the difference ready that it will receive only a single neutral-earth varistor NT as illustrated in FIGS. 4 and 5. In the latter case, a part 2V of the additional box 2S will then be unused.
• the protection device 1 for networks whose connection diagram of neutral to earth is of the IT type (impedant neutral or isolated from earth), it suffices to remove or remove (in the case of a withdrawable version) the additional box 2S, the protection device 1 then comprising only a single box 2 in the case of a single-phase network and three boxes 2A, 2B, 2C in the case of a three-phase network.
• the protective device 1 according to the invention thus advantageously has a reduced overall size, with a maximum of two boxes 2, 2S in single phase and a maximum of four boxes 2A, 2B, 2C, 2S in three phase.
• the protection device 1 comprising only one housing 2, 2A, 2B, 2C (or motor) per active conductor, the manipulation of the plug-in versions of this device is particularly easy, the user intuitively associating a phase L1 , L2 or L3 to protect with a single corresponding cartridge 11.
• This aspect of the invention proves to be particularly interesting in the case of polyphase networks comprising a large number of active conductors.
• the higher the number of active conductors the more the protective device 1 according to the invention is advantageous compared to the devices of the prior art in terms of size and ease of use.
• the base 6 may include several housings, each housing being capable of receiving a cartridge 11, or even a single housing arranged to receive all of the cartridges 11 mentioned above.
• each phase-earth varistor PT, phase-neutral PN or neutral-earth NT is connected to the network using electrical connection means 15, the electrical connection to earth being carried out using other electrical connection means 16.
• the electrical connection means 15, 16 are, preferably and conventionally, of a wired nature.
• each phase-earth varistor PT comprises a so-called phase p terminal electrically connected to the phase L1, L2 or L3 to be protected, and a so-called earth terminal t, electrically connected to earth T.
• each phase-neutral varistor PN includes a so-called phase p terminal electrically connected to the phase L1, L2 or L3 to be protected and a so-called neutral n terminal electrically connected to neutral N.
• the phase-earth varistors PT and phase-neutral PN are arranged one next to the other within the housing 2, 2A, 2B, 2C.
• the neutral n and earth t terminals are not at the same potential so that if the latter are too close to one another, an electric arc is likely to form between said terminals n, t, thus short-circuiting the protection device 1.
• the protection device 1 advantageously includes electrical isolation means 20, adapted to electrically isolate the earth terminal t from the neutral terminal n and preferably arranged within the housing 2, 2A, 2B , 2C.
• the electrical insulation means 20 are advantageously arranged and arranged to form an insulating screen between said earth terminal t and said neutral terminal n.
• the electrical insulation means 20 may be formed by an electrically insulating partition 21, interposed between the earth terminal t and the neutral terminal n so as to guarantee the electrical insulation said earth t and neutral n terminals with respect to each other.
• the electrical insulation means 20 are designed and dimensioned to increase the insulation distance between the earth terminal t and the neutral terminal n, so that the insulation distance is greater than the separation distance real separating said earth t and neutral n terminals.
• the electrical insulation means 20 thus make it possible to shorten the distance between the neutral n and earth t terminals, thereby reducing the size of the device, while ensuring their electrical insulation, and this by increasing the distance d insulation between the neutral n and earth t terminals, that is to say the length of the path to be traveled by the electric arc between said neutral n and earth t terminals to circumvent the electrical isolation means 20.
• the partition 21 may for example extend over a surface just sufficient to provide insulation between the earth terminals t and neutral n.
• the partition 21 will preferably be arranged inside the housing 2 so as to separate the latter into two housings 22, 23 substantially symmetrical with respect to the partition of separation 21, each housing 22, 23 being capable of receiving a varistor provided with its disconnection means. Even more preferably, and as shown in FIGS. 1 and 2, the partition 21 may extend outside the housing 2, so as to separate the pair of studs 8A, 8B associated with the phase-earth varistor PT, of the pair of pads 9A, 9B associated with the phase-neutral varistor PN.
• the base 6 will advantageously include a central housing 60, specifically adapted to receive the outgoing end of the partition 21 when the housing 2 is racked in on the base 6.
• Such a configuration makes it possible in particular to avoid the formation of electric arcs between the pads 8A, 9A of different potentials, connected respectively to the earth terminal t and to the neutral terminal n when plugging in.
• the phase-earth varistors PT and phase-neutral PN of the same mounting pair 3 have different operating voltages from one another.
• the phase-neutral varistor PN has a lower operating voltage than that of the phase-earth varistor PT, which makes it possible on the one hand to lower the level of protection of the arrester, and on the other hand to reduce the size of the electrical binomial.
• the phase-to-earth varistor PT may have an operating voltage of the order of 440 volts so as to withstand the voltage between phases (of the order of 400 volts) as required by French standards, the phase varistor - neutral PN with a lower operating voltage, of the order of 275 volts.
• each cartridge 11 will thus advantageously comprise a pair of varistors of different values, and this without creating any confusion in the mind of the user, since each active conductor remains associated with a single cartridge 11.
• the invention also relates to a method of manufacturing a device 1 for protection against overvoltages adapted to provide protection according to the common and differential modes, said method comprising the steps consisting in: - a) manufacturing at least one housing 2 electrically insulating, - b) manufacture at least one electrical binomial, formed by a varistor called phase-earth PT intended to be disposed between a first phase L1 to be protected and the earth T and a varistor called phase-neutral PN intended to be disposed between said first phase L1 to be protected and neutral N.
• the method also comprises the following steps: - c) specifically fitting the box 2 so that it can receive the electrical binomial, - d) associating the two varistors PT, PN in a mounting binomial 3 and mounting them one next to the other within the housing 2.
• the method also comprises a step in which the housing 2 is provided with racking-in / racking-out means 7 making it possible to connect said housing 2 removably to a fixed base 6.
• the phase-earth varistor PT comprising a phase terminal p electrically connected to the phase L1, L2 or L3 to be protected and a so-called earth terminal t, electrically connected to earth T
• the phase-neutral varistor PN comprising a so-called p-phase terminal, electrically connected to said phase L1, L2 or L3 to be protected and a so-called neutral n terminal, electrically connected to neutral
• the method also includes a step in which electrical isolation means are available 20 between earth terminal t and neutral terminal n.
• the method also advantageously comprises the following steps: - e) manufacturing a so-called neutral-earth varistor NT intended to be placed between neutral N and earth T, - f) mounting said neutral-earth varistor NT within an additional housing 2S, preferably withdrawable.
• the invention thus makes it possible to significantly reduce the dimensions and therefore the size of a protection device 1 of the common mode / differential mode type, while guaranteeing electrical insulation between the components of the device having different potentials.
• Another advantage of the invention is to allow an easy and intuitive removal of the protective components out of use, with a view to their replacement.
• Another advantage of the protection device 1 according to the invention is that it can be used whatever the connection scheme of the neutral to earth.
• protection device 1 requires a number of parts, and in particular of motors, reduced compared to the devices of the prior art, while ensuring the same functions.
• the solution offered by the invention is therefore more economical than existing solutions.
• Another advantage of the invention is that it makes it possible to rationalize the process for manufacturing the protection device 1 according to the invention, in particular by systematically using double motors.
• the invention finds its industrial application in the design and manufacture of protection devices against transient overvoltages.

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• Engineering & Computer Science (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Emergency Protection Circuit Devices (AREA)
• Thermistors And Varistors (AREA)

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• 2004
  • 2004-03-05 FR FR0402367A patent/FR2867318B1/fr not_active Expired - Fee Related
• 2005
  • 2005-03-04 BR BRPI0509002-4A patent/BRPI0509002A/pt not_active Application Discontinuation
  • 2005-03-04 MX MXPA06010057A patent/MXPA06010057A/es not_active Application Discontinuation
  • 2005-03-04 RU RU2006135132/09A patent/RU2006135132A/ru not_active Application Discontinuation
  • 2005-03-04 CN CNA2005800071133A patent/CN1930642A/zh active Pending
  • 2005-03-04 EP EP05736977A patent/EP1726019B1/de not_active Not-in-force
  • 2005-03-04 WO PCT/FR2005/000524 patent/WO2005086182A1/fr active Application Filing

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