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
  • H01T1/14—Means structurally associated with spark gap for protecting it against overload or for disconnecting it in case of failure
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H37/00—Thermally-actuated switches
  • H01H37/02—Details
  • H01H37/32—Thermally-sensitive members
  • H01H37/52—Thermally-sensitive members actuated due to deflection of bimetallic element
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H9/00—Details of switching devices, not covered by groups H01H1/00 - H01H7/00
  • H01H9/30—Means for extinguishing or preventing arc between current-carrying parts
  • H01H9/32—Insulating body insertable between contacts

Definitions

• the present invention relates to the general technical field of devices for protecting electrical equipment or installations, of the electrical appliance, circuit or distribution network type, against disturbances of electrical supply.
• the present invention relates more particularly to a device for protecting electrical equipment against voltage disturbances, such as overvoltages, in particular due to lightning.
• the present invention relates to a device for protecting electrical equipment against overvoltages
• a protection unit connected to electrical equipment via a connection circuit, said circuit comprising a first connector connected to electrical equipment, a second connector connected to the protection unit, as well as a means for interrupting electric current movable between a return position corresponding to the opening of the circuit and a position for closing the circuit, said interruption means comprising a rod extending between a first end provided with a stop means and a second end, said rod being mounted in elastic axial sliding between a first stop and return position, corresponding to the opening of the circuit, and a second stop position, corresponding when the circuit is closed, said stop means cooperating with a blocking means to hold the rod in s its second stop position, said device also comprising a bimetallic strip.
• surge protector or surge arrester The purpose of such devices, which are sometimes designated by the name surge protector or surge arrester, is to drain lightning currents to the earth, and to clip induced overvoltages at levels compatible with the behavior of the equipment and materials connected in downstream of protective devices.
• these protection devices are generally connected between the phase or phases supplying the equipment to be protected and the earth.
• these devices In normal operation, these devices have a very high impedance so as not to cause a short circuit between the phase supplying the equipment to be protected and the earth.
• the impedance of the device drops to a very low value, which allows the lightning current to flow to earth.
• the device When the overvoltage episode is over, the device automatically returns to its initial high impedance.
• varistors that is to say electrical resistances or impedances, the resistance or impedance value of which varies greatly as a function of the applied voltage.
• MOV metallic oxide varistors
• these varistors have a very high impedance as long as the voltage at their terminal does not reach a threshold value; beyond this threshold, the impedance drops sharply.
• the impedance of the varistor is high enough for the current flowing through it to flow to the ground, called leakage current, to be negligible (for example of an intensity lower than one milliampere).
• the internal components of the known protection devices are generally assembled by welding.
• the critical varistor temperature when the critical varistor temperature is reached, only the solder of the thermal disconnector must melt, which implies that the melting point of this solder must be lower than that of the other welds used for assembly purposes in the device.
• This requires the use of low temperature solders, which in addition to their higher price, are very delicate to use and generally close up polluting materials such as lead or cadmium.
• welding which in general is a complex process, proves to be particularly difficult to implement in the case of low temperature welds. Thus, it is almost impossible in practice to obtain good quality welds with a very low melting temperature. Therefore, the temperature limits allowed by the thermal disconnector are far from optimal.
• the objects assigned to the invention therefore aim to remedy the various drawbacks listed above and to propose a new device for protecting electrical equipment against overvoltages which allows precise and rapid thermal disconnection.
• Another object of the invention is to propose a new device for protecting electrical equipment against overvoltages which is of a particularly simple and reliable design.
• Another object of the invention is to propose a new device for protecting electrical equipment against overvoltages, the manufacture of which is simple and inexpensive.
• Another object of the invention is to propose a new device for protecting electrical equipment against overvoltages the safety level of which is reinforced.
• Another object of the invention is to propose a new device for protecting electrical equipment against overvoltages whose use and maintenance are facilitated.
• a device for protecting electrical equipment against overvoltages comprising a protection unit connected to the electrical equipment via a connection circuit, said circuit comprising a first connector connected to electrical equipment, a second connector connected to the protection unit, as well as a means of interrupting electric current movable between a return position corresponding to the opening of the circuit and a position for closing the circuit, said interrupting means comprising a rod extending between a first end provided with a stop means and a second end, said rod being mounted in elastic axial sliding between a first stop and return position, corresponding to the opening of the circuit, and a second stop position, corresponding to the closing of the circuit, said stop means cooperating with block means age to maintain the rod in its second stop position, said device also comprising a bimetallic strip and being characterized in that the second end of the rod is provided with a contact element establishing electrical contact between the first and second connectors when the rod is in the second stop position, the bimetal strip being arranged on the one hand in the device to be sensitive
• FIG. 1 illustrates, in a schematic view, a first alternative embodiment of a device for protecting electrical equipment according to the invention, in a configuration where the temperature of the protection unit is below the critical value thermal disconnection.
• FIG. 2 illustrates, in a schematic view, the device of Figure 1, in a configuration where the temperature of the protection unit has reached or exceeded the critical value of thermal disconnection.
• FIG. 3 illustrates, in a schematic view, a second alternative embodiment of a protection device according to the invention, in a configuration where the temperature of the protection unit is below the critical value of thermal disconnection.
• FIG. 4 illustrates, in a schematic view, the protection device of Figure 3, in a configuration where the temperature of the protection unit has reached or exceeded the critical value of thermal disconnection.
• Figures 1 to 4 show a first and a second alternative embodiment of a device 1, 10 for protecting electrical equipment against overvoltages.
• electrical equipment is meant here any type of apparatus, instrument, installation, network, electrical or telecommunications circuit liable to be subject to electrical supply hazards from the point of view of voltage and in particular overvoltages due to the lightning.
• the protection device 1, 10 comprises a protection unit 2, 20, which is for example constituted by a varistor, that is to say a component whose impedance (or resistance) is variable depending on the voltage applied to the varistor.
• a protection unit 2, 20 which is for example constituted by a varistor, that is to say a component whose impedance (or resistance) is variable depending on the voltage applied to the varistor.
• the use of such components in a surge protection application is well known to those skilled in the art, and will therefore not be explained further.
• a protection unit 2, 20 will thus preferably comprise one or more metal oxide varistors (MOV).
• MOV metal oxide varistors
• the protection unit 2, 20 is connected to the electrical equipment to be protected (not shown) via a connection circuit 3, 30.
• connection circuit comprises at least two electrodes 3A, 3B, 30A, 30B, so as to be able to connect electrically, for example in parallel, a protection unit 2, 20 between a phase to be protected, and earth or neutral, or yet another phase.
• connection circuit 3, 30 comprises a first connector 3A, 30A electrically connected to the electrical equipment as well as a second connector 3C, 30C electrically connected to the protection unit 2, 20.
• the first and second connectors 3A , 3C, 30A, 30C are made of any conductive material well known to those skilled in the art.
• the connection circuit 3, 30 also includes an interruption means 4, 40 of electric current.
• Said means of interrupting 4, 40 of electric current is mounted movable relative to the rest of the device 1, 10 between a return position (shown in Figures 2 and 4) corresponding to the opening of the circuit 3, 30 and a closed position circuit 3, 30 (shown in Figures 1 and 3).
• the interrupting means 4, 40 is kept in the closed position of the circuit 3, 30 by a locking means 5, 50.
• the protection device 1, 10 also comprises means 6, 60 for opening the connection circuit 3, 30 when the temperature of the unit 2, 20 reaches a predetermined critical value, beyond which the heat given off by the protection unit 2, 20 may damage or set fire to the surrounding elements.
• the opening means 6, 60 thus forms a thermal disconnection means, which makes it possible to trigger the passage of the interrupting means 4, 40 in the open position. In this open position, the protection unit 2, 20 is no longer traversed by a current, and therefore ceases to heat, which eliminates the risk mentioned above.
• the opening means 6, 60 comprises means 6, 60 sensitive to the heat given off by the unit 2, 20, whether by radiation and / or conduction and / or convection.
• the heat-sensitive means 6, 60 is arranged in the device for directly detecting the achievement, by the unit 2, 20, of a predetermined critical temperature.
• the means 6, 60 sensitive to heat is functionally connected to an actuating means 6, 60 so that, when said critical predetermined temperature of the unit 2, 20 is reached, the means actuation 6, 60 produces a deactivation force of the locking means 5, 50, in order to move the interrupting means 4, 40 to the open position of the connection circuit 3, 30, as shown Figures 2 and 4.
• the actuating means 6, 60 exerts a positive action of triggering the means of interruption 4, 40 of electric current .
• the interrupting means 4 comprises a rod 4A extending axially between a first and a separate second end 4B, 4D.
• rod is meant here any element of the moving equipment or slider type, which does not necessarily have a slender geometry.
• the first end 4B is provided with a stop means 4C, formed for example by a flange, while its second end 4D is provided with a contact element 7, made of a conductive material of Electric power.
• the stop means 4C is distinct from the contact element 7.
• the stop means 40 preferably does not provide a current conduction function, while on the contrary, the contact element 7 preferably performs a single electrical conduction function.
• the rod 4A is mounted in elastic axial sliding, for example against a compression spring 8, between a first stop and return position, corresponding to the opening of the circuit 3 (shown in FIG. 2) and a second stop position (shown in Figure 1), corresponding to the closure of the circuit 3, in which the contact element 7 establishes electrical contact between the first and second connectors 3A, 3C.
• the stop means 4C cooperates, for example in support or hooking, with the blocking means 5 to maintain the rod 4A in its second stop position, corresponding to the normal operation of the protection device.
• the interrupting means 4 is prestressed in the closed position (shown in FIG. 1) by the locking means 5.
• the heat-sensitive means and the actuation means are combined and are formed by a bimetallic strip 6.
• Bimetallic strips are elements well known as such. They are made by joining two metal blades with different expansion characteristics, so that at a certain temperature level, which here corresponds to the critical predetermined temperature, the bimetallic strip will deform to operate a deflection (shown in Figure 2).
• bimetallic strips thus make it possible to carry out a double function of thermal detection and actuation, via their deflection.
• the bimetallic strip 6 is specifically arranged, that is to say mounted and positioned in the device, to be sensitive to the heat given off by the unit 2, so as to detect the reaching by the latter of the predetermined temperature signifying a level of aging of the unit incompatible with safety requirements.
• the bimetallic strip 6 is thus mounted so as to be mainly sensitive to the heat of the unit 2, to the exclusion of other thermal phenomena.
• the bimetallic strip 6 is moreover designed, in particular from the point of view of its deflection capacity, to produce, by deflecting when the predetermined temperature is reached, a force for deactivating the locking means 5, causing the release of the rod 4A and by Consequently the passage of the interrupting means 4 from its closed position to its open position of the circuit 3.
• one of the ends 6A of the bimetallic strip 6 is mounted fixed relative to the first and second connectors 3A, 3C.
• this end of the bimetallic strip 6 is embedded in the second connector by a cold assembly process, of the clipping, crimping or riveting type.
• the other end 6B of the bimetallic strip 6 is free and provided with a stop 5 forming a locking means.
• the stop 5 is for example constituted by a plate attached to the free end 6B by any known means.
• the bimetallic strip 6 is chosen and arranged to deflect when the predetermined temperature is reached, this deflection producing the deactivation force making it possible to move the stop 5 away from the stop means 4C, and thus to interrupt the cooperation between the stop means 4C and the locking means 5.
• the interruption of the mechanical cooperation between the stop means 4C and the locking means 5 thus causes the rise of the rod 4A, which causes the contact element 7 to be disconnected from both the first connector 3A and the second 3C connector, simultaneously.
• the activation means formed by the bimetallic strip 6 produces a force which will move the locking means 5 away, which triggers the relaxation of the stress applied by the spring 8 to the rod 4A and the contact element 7.
• the bimetallic strip 6 is arranged so that its maximum deflection in the deflected position is located at the free end 6B of the bimetallic strip 6.
• the bimetallic strip 6 is not part of the connection circuit 3.
• its function in the context of this alternative embodiment is not to route the current to the protection unit 2.
• This current routing function is entirely assigned to the contact element 7, which establishes an electrical connection between the first and second connectors 3A, 3C.
• the bimetallic strip 6 fulfills only thermal detection and deactivation functions of the locking means 5. This design particularity thus allows the bimetallic strip not to undergo parasitic thermal influences which could come from its own resistive character, since it is not appreciably crossed by any current.
• the bimetallic strip 6 is not part of the connection circuit 3 makes it possible to avoid undesirable current loop effects, which could lead to the generation of mechanical forces damaging for the reliability and the operation of the device.
• the device presented in Figures 1 and 2 is identical, except for the fact that the bimetallic strip / locking means 6, 5 is replaced by a system comprising a thermistor (CTN or CTP) as heat-sensitive means, said thermistor being associated with electromechanical or electromagnetic means forming actuating means, via suitable processing electronics. It is also conceivable to use a thermocouple or any other temperature sensor well known to those skilled in the art as a means sensitive to heat. An example of embodiment in the context of this variant is as follows. A thermistor detects the critical predetermined temperature by strongly changing the resistance.
• This variation in resistance is analyzed and processed by an electronic circuit or an electrical device of the relay type, which functionally connects the thermistor to an actuating means, which is capable of providing a magnetic force sufficient to move a stop 5 away from the means of stop 4C.
• the deactivation force is thus of an electromagnetic nature, whereas in the case where a bimetallic strip 6 is used, this force is of a mechanical nature.
• FIGS. 1 and 2 Another embodiment of the protection device according to the invention will now be described. This embodiment is illustrated in Figures 3 and 4.
• the general architecture of the variant of Figures 3 and 4 is generally similar to that of the variant shown in FIGS. 1 and 2.
• the main differences lie in the production of the interrupting means 40.
• the locking means 50 comprises a conductive element 50, for example metallic, electrically connected to the second connector 30C.
• the conductive element 50 is mounted movable between on the one hand a closed position (shown in Figure 3) where it is in electrical contact with the first connector 30A to close the connection circuit 30 and on the other hand a position d opening (shown in FIG. 4) where it is distant from the first connector 30A so that the circuit 30 is open and the current no longer flows through the unit 20.
• the interruption means 40 comprises an insulating screen 40 mounted to slide freely relative to the first and second connectors 30A, 30C, for example in a slide formed in a frame 70.
• the screen 40 is made of an electrically insulating material. It can move by sliding between a first stop position (shown in FIG. 3) where it is in contact with the conductive element 50 when the latter is in the closed position, and a second stop and return position (shown in Figure 4) where it is interposed between the conductive element 50 and the first connector 30A, when the conductive element 50 is in the open position (as shown in Figure 4).
• the heat-sensitive means and the actuating means 60 are combined, and are formed by a bimetallic strip 60, one of the ends 60A of which is fixed, by any suitable means and for example by a cold assembly process. of the clipping, crimping or riveting type to the second 30C connector.
• Bimetallic strip 60 which is produced with conductive materials, is also electrically connected to the second connector 30C, which can be achieved by the simple assembly operation of the bimetallic strip 60 on the connector 30C.
• the other end 60B of the bimetallic strip is free and is integral with the conductive element 50, which is formed for example by a plate or a metal rod.
• the bimetallic strip is arranged to deflect when the critical predetermined temperature of the unit 20 is reached.
• the bimetallic strip 60 is arranged so that its maximum deflection in the deflected position is located at the free end 6B of the bimetallic strip 6.
• the bimetallic strip produces the deactivation force making it possible to distance the conductive element 50 of the first connector 30A, the conductive element 50 thereby releasing the insulating screen 40, which under the effect of gravity or of an elastic constraint means, of the spring type (not shown), falls and slides to abut in abutment against a support means 80 forming part of the frame, thereby coming to be interposed between the conductive element 50 and the first connector 30A (as shown in FIG. 4).
• the presence of the insulating screen 40 prevents any subsequent contact of the conductive element 50 and the first connector 30A, which could occur when the bimetallic strip 60 resumes a natural configuration (not deflected) once the unit 20 has cooled.
• an insulating screen 40 offers the advantage of preventing any risk of electric arc formation between the conductive element 50 and the connectors 30A.
• a thermistor or any other element making it possible to capture the temperature
• electromechanical or electromagnetic means in as a means of actuation.
• interruption means 4, 40 of heat-sensitive means 6, 60 and of actuation means 6, 60 given previously have been given purely for information, the single bimetallic strip being however preferred.
• an interrupting means mounted for rotation about an axis and comprising a torsion spring to operate in the manner of a ratchet, or even with an actuating means putting using an electric motor.
• the protection device according to the invention has a resettable nature.
• the thermal disconnection means used whether these are bimetallic strips or thermistors associated with electromechanical or electromagnetic means, have a reversible character, which allow them to resume their initial state when the temperature drops below the predetermined temperature. critical.
• Such a functionality was prohibited in the device of the prior art implementing a weld as a means of thermal disconnection, since the weld was precisely destroyed when the predetermined critical temperature was reached.
• the device according to the invention implements a positive action, in the form of a deactivation force, to achieve thermal disconnection, it also has a reversible character.
• connection means of the kind of contact and attachment means provided between each module make it possible to functionally associate, that is to say electrically and thermally, the modules in a removable manner.
• the invention finds its application in the design and manufacture of surge protection devices.

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• 2002
  • 2002-12-10 FR FR0215891A patent/FR2848353B1/fr not_active Expired - Fee Related
• 2003
  • 2003-12-10 US US10/538,308 patent/US20060145807A1/en not_active Abandoned
  • 2003-12-10 BR BR0317235-0A patent/BR0317235A/pt not_active IP Right Cessation
  • 2003-12-10 PL PL376529A patent/PL376529A1/pl not_active Application Discontinuation
  • 2003-12-10 WO PCT/FR2003/003659 patent/WO2004064213A1/fr not_active Application Discontinuation
  • 2003-12-10 EP EP03815110A patent/EP1579542A1/fr not_active Withdrawn
  • 2003-12-10 CN CNA2003801053345A patent/CN1723595A/zh active Pending
  • 2003-12-10 MX MXPA05006122A patent/MXPA05006122A/es not_active Application Discontinuation
  • 2003-12-10 RU RU2005121527/09A patent/RU2321930C2/ru active
  • 2003-12-10 AU AU2003296806A patent/AU2003296806A1/en not_active Abandoned
• 2005
  • 2005-07-12 ZA ZA200505573A patent/ZA200505573B/en unknown

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