Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H83/00—Protective switches, e.g. circuit-breaking switches, or protective relays operated by abnormal electrical conditions otherwise than solely by excess current
  • H01H83/10—Protective switches, e.g. circuit-breaking switches, or protective relays operated by abnormal electrical conditions otherwise than solely by excess current operated by excess voltage, e.g. for lightning protection
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
  • H01H83/00—Protective switches, e.g. circuit-breaking switches, or protective relays operated by abnormal electrical conditions otherwise than solely by excess current
  • H01H83/20—Protective switches, e.g. circuit-breaking switches, or protective relays operated by abnormal electrical conditions otherwise than solely by excess current operated by excess current as well as by some other abnormal electrical condition

Definitions

• the invention relates to a surge protection module intended to be connected to an electrical breaking device via mechanical actuation means.
• Said module comprises at least one varistor mechanically connected to mobile drive means by a first thermal separator. The melting of the first thermal separator in the event of heating of the varistor releases the displacement of the mobile drive means to act on the mechanical actuation means.
• Said first thermal separator comprises a first melting time constant and a first melting temperature
• the invention also relates to an overvoltage protection assembly comprising a protection module and comprising a breaking device.
• an overvoltage protection device comprising an overvoltage limiter with variable non-linear elements with the voltage with an electrical switching device actuated by an actuating mechanism.
• the surge protector and the electrical cut-off device are connected in series.
• the electrical breaking device can adopt a trigger position and a latching position respectively corresponding to the open state and the closed state of the electrical contacts.
• a tripping circuit cooperates with the actuating mechanism to cause the displacement of the contacts of the disconnection device to the open state especially in the event of destruction of the surge protector, especially at the end of life of said non-linear elements.
• the surge limiter including a varistor connected to a separator thermal. In case of overheating of the varistor due to a malfunction, the melting of the thermal separator acts directly on the actuating mechanism and causes the opening of the electrical contacts of the electrical breaking device.
• the thermal separator is placed in an environment of the varistor and heats by indirect conduction.
• Indirect conduction means that the thermal separator is not crossed by the electric current flowing through the varistor.
• direct conduction is meant that the thermal separator is traversed by an electric current.
• the use of a thermal separator which is heated, in particular by indirect conduction sometimes has disadvantages. Calibration of the thermal separator in thermal baths of choice of material and thermal of volume of material used to make the separator is binding.
• the thermal separator is generally calibrated to melt following heating of the varistor which is traversed by leakage currents.
• this same thermal separator is not intended to melt when the varistor heats up following a lightning strike. In case of melting of the thermal separator following a lightning shock would result in unavailability of the surge arrester for future lightning strikes, the latter situation is not desirable.
• a control kinematic chain comprising a plurality of mechanical means such as transmission shafts or rods.
• the use of this kinematic control system has the disadvantage of complicating the implementation of the protection device.
• TOV Temporal Over Voltage
• the fault current resulting from a TOV causes also a heating of the varistor detected by a thermal separator.
• the amplitude of the fault current is in this case much greater than in the case of leakage current due to the aging of the varistor.
• This thermal separator must then theoretically intervene with a relatively short time constant (a few seconds) to counter the influence of TOV and with a relatively long time constant (a few minutes or even a few hours) to counter the defect of the generating varistor. low leakage currents.
• this thermal separator must not intervene in the presence of lightning shock.
• the invention therefore aims to overcome the disadvantages of the state of the art, so as to provide a device for protection against overvoltages and having protection means adapted to problems related to TOV (Temporary Over Voltage).
• Said at least one varistor of the protection module according to the invention is mechanically connected to the drive means by a second thermal separator, the melting of the second thermal separator in case of heating of the varistor releasing the displacement of the drive means mobile, said second thermal separator having a second melting time constant and a second melting temperature, the second melting temperature being greater than the first melting temperature, and the first melting time constant being greater than the second melting constant. melting time.
• the protection module comprises elastic means providing a displacement force for moving the drive means from a first position the armed position to a trigger position, the means of driving being mechanically retained in the armed position by said first and second thermal separators, the fusion of one of the two thermal separators releasing the displacement of the drive means.
• the first thermal separator and the second thermal separator exert respectively a first and a second retaining forces on the drive means, said retaining forces acting in series on the drive means.
• the fusion of a thermal separator successively causes the cancellation of one of the retained forces and the release of the displacement of the drive means.
• the two retaining forces are respectively greater than the displacement force.
• the first thermal separator and the second thermal separator respectively exert a first and a second retaining forces on the drive means, said retaining forces acting in parallel manner on the drive means.
• the melting of a thermal separator successively causes the cancellation of one of the two holding forces, the cancellation of the other holding force and the displacement of the drive means.
• the retaining forces are respectively less than the displacement force.
• the second thermal separator comprises a second melting temperature lower than the maximum operating temperature of the varistor and greater than the temperature of heating of the varistor after a lightning strike type 10/350.
• the second thermal separator comprises a melting temperature having a value equal to 195 ° Celsius degrees plus or minus 25 °.
• the first thermal separator comprises a first melting temperature lower than the maximum tolerated temperature of the protection device reduced to level of the varistor.
• the first thermal separator fuse connection has a melting temperature of value equal to 125 degrees Celsius plus or minus
• the first melting time constant is at least five times greater than the second melting time constant.
• the first thermal separator is a pin made of plastic material.
• the second thermal separator is a low temperature weld.
• said at least one protection module comprises coding means intended to collaborate with the breaking device.
• the surge protection assembly comprises a protection module as defined above and comprises an electrical switching device comprising inputs intended to be connected to a line to be protected, main contacts controlled by a tripping mechanism, and outputs connected to the overvoltage protection module.
• the mechanical actuation means of said module are interconnected with the triggering means for actuating the opening of the main contacts.
• FIG. 1 and 2 show schematic views of a protection assembly according to one embodiment of the invention
• FIG. 3 represents a perspective view of a protection module of an overvoltage protection assembly according to FIG. 1;
• FIGS. 4 to 6 show detailed views of the operation of the protection module according to FIG. 2;
• FIG. 7 represents a side view of an embodiment of the protection module according to FIG. 3;
• FIG. 8 represents a perspective view of an embodiment of the protection module according to FIG. 3;
• FIG. 9 represents a heating curve of the protection module in the event of rapid heating, linked in particular to the presence of a TOV;
• FIG. 10 shows a heating curve of the protection module in case of lightning shock
• FIG. 11 shows a heating curve of the protection module in case of slow heating.
• the overvoltage protection assembly comprises at least one protection module 20 intended to be connected to an electric switching device 21 via mechanical actuation means 33.
• the overcurrent protection assembly 20 is intended to be connected between on the one hand at least one current line via at least one first connection terminal 22 placed upstream of the cut-off device 21 and, on the other hand, to earth via at least one connector 6 of the protection module 20.
• the cut-off device 21 comprises at least one second connection terminal 25A downstream intended to be connected to the connection terminal 25B to the protection module 20.
• the protection module 20 comprises at least one varistor 1 comprising at least one terminal connected to a terminal terminal 25B of the protection module 20 and a second terminal connected to a connector 6.
• Said at least one varistor is mechanically connected to moving drive means.
• Said drive means are connected to the mechanical actuation means 33 are intended to actuate a trigger mechanism 24 of the switchgear 21 in case of malfunction of the varistor 1.
• the trigger mechanism 24 of the switchgear 21 then actuates the opening of the electrical contacts 23.
• the overvoltage protection assembly comprises a four-pole cut-off device 21.
• the protection module 20 of said protection assembly then comprises four varistors 1 connected respectively to a pole of the breaking device 21.
• said at least one varistor 1 of the protection module is mechanically connected to moving drive means 10 by a first thermal separator P1.
• the melting of the first thermal separator P1 in the event of heating of the varistor releases the displacement of the moving drive means.
• the displacement of the drive means 10 is intended to act on the mechanical actuating means 33 and cause the opening of the electrical contacts 23 of the switchgear 21.
• the first thermal separator P1 is fixed on the one hand to the varistor 1 and on the other hand to a pivoting arm 11 of the drive means
• the pivoting arm 11 is mechanically held by the first thermal separator P1 in a first operating position, called the armed position.
• Elastic means 12 exert a displacement force Fd on the pivoting arm 11.
• the displacement force Fd is intended to cause the pivoting arm 11 to move in a second operating position in case of melting of the first thermal separator P1.
• the first thermal separator P1 exerts a first retention force Fr1 on the drive means 10. The melting of the first thermal separator P1 causes the rupture of a mechanical connection between the first separator P1 and the pivoting arm
• the first restraining force FR1 being null, under the action of the force of Fd displacement, said arm pivots about an axis of rotation 13 from the armed position to the second operating position, called trigger position.
• the rotation of the axis of rotation 13 acts on the mechanical actuating means 33.
• Said first thermal separator P1 comprises a first melting temperature T1 and a first melting time constant ⁇ 1.
• the first melting temperature T1 of the first thermal separator P1 is determined so as to be lower than the maximum temperature TmaxB tolerated at the outer surfaces of the housing of the protection module 20 brought to the level of the first thermal separator P1.
• the maximum temperature tolerated at the outer surfaces of the housing is usually set by standards. This temperature is for example equal to 120 degrees Celsius. This maximum temperature brought back to the level of the first thermal separator P1 placed inside the housing makes it possible to establish a first criterion for determining the first melting temperature T1.
• the first melting temperature T1 of the first thermal separator P1 is determined so as to be less than the maximum temperature of heating reached by the varistor 10 in the event of malfunction.
• the malfunction is for example related to the aging of the varistor, aging causing a start of short circuit. This heating of the varistor makes it possible to establish a second criterion for determining the first melting temperature T1.
• the first melting temperature T1 of value equal to 125 ° C degrees plus or minus 15 ° C.
• Melting time constant means a homogeneous quantity at a time characterizing the speed for a system studied to reach a melting temperature under system operating conditions.
• the time constant is often related to the response of the studied system to an instantaneous disturbance.
• the constant of fusion time ⁇ 1 is dependent on the architecture of the protection module 20 and in particular the position of the first thermal separator P1 with respect to the varistor 10, the nature of the material used to produce said separator, and also of its overall geometry. As shown in FIG. Figure 10, in the event of a lightning strike, heating of the first thermal separator P1 placed in the housing of the protection device reaches a maximum temperature after a time of about 25 seconds.
• the first curve C1 represents the heating curve of the first thermal separator P1 and the second curve C2 represents the heating curve of the second thermal separator P2.
• the first thermal separator P1 does not reach its melting point T1 in the event of a lightning strike.
• the third curve C3 theoretically represents heating of the varistor in the event of a lightning strike, particularly in the case of a 10/350 type shock.
• the first melting time constant ⁇ 1 is equal to 5 seconds.
• the first thermal separator P1 consists of a pin of plastic material.
• the displacement force Fd exerted by the elastic means 12 via the pivoting arm 11 of the drive means 10 then applies a shear force to said pin.
• the displacement force Fd exerted by the elastic means may apply a tensile force on said pin.
• heating of the first thermal separator P1 is by indirect conduction. According to a variant not shown, heating of the first thermal separator P1 is by direct conduction, the first thermal separator then being crossed by the electric current which passes through the varistor 1.
• the varistor 1 is connected to the drive means 10 by a second thermal separator P2.
• the melting of the second thermal separator P2 in the event of heating of the varistor 1 releases the displacement of the moving drive means 10.
• the displacement of the drive means 10 is intended to act on the mechanical actuating means 33 and cause the opening of the electrical contacts 23 of the switchgear 21.
• the second thermal separator P2 is fixed on the one hand to the varistor and is fixed on the other hand to the pivoting arm 11 of the drive means 10 mobile.
• the pivot arm 11 is mechanically held by the second thermal separator P2 in the armed position.
• Elastic means 12 exert a displacement force Fd on the pivoting arm 11.
• the displacement force Fd is intended to cause the pivoting arm 11 to move in a second operating position in case of melting of the second thermal separator P2.
• the second thermal separator P2 exerts a second retention force Fr2 on the drive means 10.
• the melting of the second thermal separator P2 causes the rupture of a mechanical link between said separator P2 and the pivoting arm 11. Under the action of the displacement force Fd, said arm pivots about an axis of rotation 13 from the armed position to the release position.
• the rotation of the axis of rotation 13 acts on the mechanical actuating means 33.
• Said second thermal separator P2 comprises a second melting temperature T2 and a second melting time constant ⁇ 2.
• the second melting temperature T2 of the second thermal separator P2 depends on three criteria. First, said second melting temperature T2 is determined to be less than the maximum operating temperature TmaxV supported by the varistor 1.
• the maximum permissible temperature TmaxV is an intrinsic characteristic of the component and is for example equal to 260 ° Celsius.
• the second melting temperature T2 of the second thermal separator P2 is determined so as to be greater than the temperature of heating reached by the varistor in the event of a lightning strike, in particular lightning strikes of the 10/350 type.
• the second melting temperature T2 of the second thermal separator P2 is determined so as to be less than the temperature of heating of the varistor 1 reached following a TOV type defect.
• the second a melting temperature T2 has a value equal to 195 ° Celsius plus or minus 25 ° C.
• heating of the second thermal separator P2 placed in the housing of the protection module 20 reaches a maximum temperature after a time of about 5 seconds.
• the first curve C1 represents the heating curve of the first thermal separator P1 and the second curve C2 represents the heating curve of the second thermal separator P2.
• the third curve C3 theoretically represents heating of the varistor in the event of a lightning strike, particularly in the case of a 10/350 type shock.
• the second thermal separator P2 like the first separator P1, does not reach its melting temperature T2.
• the second melting time constant ⁇ 2 is equal to 1 second.
• heating of the second thermal separator P2 is preferably by indirect conduction.
• heating of the second thermal separator P2 is by direct conduction, the second thermal separator then being crossed by the electric current which passes through the varistor 1.
• the second thermal separator P2 is a low temperature weld.
• the thermal pin of the first thermal separator P1 is nested in a metal bracket. Said metal bracket is connected to the varistor 1 by the low temperature welding of the second thermal separator P2.
• the second melting temperature T2 is greater than the first melting temperature T1
• the first melting time constant ⁇ 1 is greater than the second melting time constant ⁇ 2.
• the first melting time constant ⁇ 1 is at least five times greater than the second melting time constant ⁇ 2.
• each pivoting arm 11 has a slot 16 in which is positioned a drive pin 14 fixedly secured to the axis of rotation 13.
• the displacement of a pivoting arm 11 in case of rupture of a thermal separator P1, P2 moves the drive finger 14 initially placed in abutment on an edge of the light 16 of said arm.
• the drive fingers 14 placed respectively in the lights of the other pivoting arm move freely in the lights, said other arms remaining stationary.
• the mechanical actuating means 33 comprise an actuating arm 35 guided in translation.
• the rotational movement of the axis of rotation 13 directly or indirectly, via a lever 36, the translation of the actuating arm 35.
• the actuating arm 35 has at one end a lug 34 projecting from a housing protection device. This lug 34 is intended to actuate a trip bar (not shown) of the switchgear 21.
• the operation of the protection module 20 against overvoltages according to the invention in case of rapid heating of the varistor 1 is as follows.
• the rapid heating is particularly related to the presence of a TOV.
• the first curve C1 in FIG. 9 represents the heating curve of the first thermal separator P1 and the second curve C2 represents the heating curve of the second thermal separator P2.
• the second thermal separator P2 will heat up quickly because of its low melting time constant ⁇ 2.
• the second curve C2 of heating of the second thermal separator P2 will quickly reach the second melting temperature T2.
• the temperature rise of the first thermal separator P1 is relatively low.
• the first thermal separator P1 is far from having reached its melting temperature at the moment when the second first thermal separator reaches its melting temperature T2.
• the operation of the protection module 20 against overvoltages according to the invention in case of slow heating of the varistor 1 is as follows.
• the first curve C1 in FIG. 11 represents the heating curve of the first thermal separator P1 and the second curve C2 represents the heating curve of the second thermal separator P2.
• the two thermal separators P1, P2 will heat up slowly.
• the first and second curves C1, C2 of heating of the two thermal separators P1, P2 are substantially parallel, or even merged.
• the first heating curve C1 of the first thermal separator P2 will reach the first melting temperature T1 before the case of the protection module has reached its maximum temperature TmaxB acceptable.
• the thermal protection of the protection module 20 is both operational for fast transient phenomena and slower phenomena.
• the operation of the thermal separators ensures a non-triggering of the device during a lightning strike.
• the holding forces of the first and second thermal separators P1, P2 are exerted in series on the drive means 10.
• the melting of a thermal separator successively causes the cancellation of one retained forces Fr1, Fr2 and the displacement of the drive means.
• the two retained forces Fr1, Fr2 are respectively of greater intensity than that of the displacement force Fd.
• said protection module 20 preferably comprises polarizing means intended to collaborate with the apparatus 21 of cutoff.
• the coding means comprise protuberances intended to fit into female fingerprints (not shown) placed in the cut-off device 21.

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• Thermally Actuated Switches (AREA)
• Lining Or Joining Of Plastics Or The Like (AREA)

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• 2009
  • 2009-07-02 FR FR0903252A patent/FR2947677A1/fr active Pending
• 2010
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  • 2010-06-10 WO PCT/FR2010/000423 patent/WO2011001040A1/fr active Application Filing
  • 2010-06-10 EP EP10734155A patent/EP2449570B1/fr active Active
  • 2010-06-10 CN CN201080029261.6A patent/CN102473562B/zh active Active
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