Patent Application
20230088430
The invention relates to the field of networks for the transmission and/or distribution of high-voltage direct current, generally referred to by the acronym HVDC. The invention particularly relates to mechanical current cut-off paparatuses intended for such networks.
HVDC networks are in particular contemplated as a solution for the interconnection of disparate or non-synchronous electricity production sites. The HVDC networks are in particular envisaged for the transmission and distribution of energy produced by offshore wind farms rather than AC technologies, due to lower line losses and to absence of impact of the parasitic capacitances of the network on long distances. Such networks typically have voltage levels on the order of 100 kV and more.
In the present text, for a device in which a direct current circulates, either a “high-voltage A” device in which the nominal operating voltage is greater than 1,500 V in direct current but less than or equal to 75,000 V (75 kV), or a “high voltage B” device when the nominal operating voltage is greater than 75,000 V (75 kV) in direct current, is considered as a high-voltage device. Thus, the field of high DC voltage includes the field of “high-voltage A” and that of “high-voltage B”.
The direct current cut-off in such networks is a crucial issue directly conditioning the feasibility and development of such networks.
The evolution of these networks today tends towards the interconnection of infrastructures to lead to mesh networks, that is to say networks including several possible pathways between two given points in the network. In these networks, there are electrical installations, including in particular electrical stations or electrical substations, in which there is at least one electric circuit cut-off apparatus within an electric circuit.
In an electric circuit, there is generally at least one voltage source, and at least one voltage user, which can comprise any apparatus or set of apparatuses or any network having such apparatuses that use the electrical energy to transform it into another form of energy, for example into mechanical, and/or calorific, and/or electromagnetic energy, etc.
In an electric circuit, there is generally at least one electric circuit cut-off apparatus for interrupting the circulation of the electric current in the circuit, generally between the voltage source and the voltage user, or between the voltage source and the ground.
Different types of electric circuit cut-off apparatuses are known. For example, circuit breakers are known, which are mechanical cut-off apparatuses of the electric circuit and which are designed and dimensioned to authorize in particular a charge or fault mode opening of the electric circuit in which they are interposed. However, the circuit breakers are complex, expensive and bulky apparatuses, and they are intended for network protection functions. Electric circuit cut-off apparatuses, of simpler design are further known, such as disconnectors which are generally not designed to cut off circuits in charge, but rather to ensure, in a circuit where the circulation of current is already interrupted by another cut-off apparatus, the safety of property and people during interventions, by ensuring electrical insulation of a predetermined high level between an upstream portion of the circuit, linked for example to the voltage source, and a downstream portion of the circuit.
In a mechanical cut-off apparatus, the current cut-off is obtained only by the opening of a mechanical switch element. Such a mechanical switch element includes two contact-making conductive parts which are in mechanical and electrical contact when the switch element is closed and which mechanically separate when the switch element is open. These mechanical cut-off apparatuses have several drawbacks when they are traversed by high currents.
In the presence of a current and/or a high-voltage, the mechanical separation can result in the establishment of an electric arc between the two conductive parts, due to the high energies accumulated in the network that the apparatus protects. As long as the electric arc remains established through the mechanical separation, the cut-off apparatus does not perform the electrical cut-off since a current continues to circulate through the apparatus due to the presence of the arc. The electrical cut-off, in the sense of the effective interruption of the circulation of the electric current, is sometimes particularly difficult to achieve in a context of direct current and high voltage, these conditions tending to maintain the electric arc. Furthermore, this electric arc degrades, on the one hand, by erosion, the two contact-making conductive parts, and on the other hand, by ionization, the environment surrounding the conductive parts in which the arc is established. This requires maintenance operations of the cut-off apparatus which are restrictive and costly.
The high-voltage direct currents (HVDC) cut-off is more complex to achieve than the alternating currents (AC) cut-off. Indeed, upon cut-off of an alternating current, we take advantage of a zero crossing of the current to perform the electrical cut-off, which we cannot benefit from with a direct current, in particular HVDC.
Furthermore, it is known to use, in particular, for high-voltage circuits, apparatuses called “metal-cased” apparatuses where the active cut-off members are enclosed in a sealed enclosure, sometimes called tank or a metal casing, filled with an insulating fluid. Such fluid can be a gas, commonly sulfur hexafluoride (SF6), but liquids or oils are also used. This fluid is chosen for its insulating nature, in particular so as to have a dielectric strength greater than that of dry air at equivalent pressure. The metal-cased apparatuses can in particular be designed in a more compact manner than the apparatuses where the cut-off and the insulation are performed in the air.
A conventional “metal-cased” mechanical disconnector includes for example in particular two electrodes which are held, by insulating supports, in fixed positions remote from the peripheral wall of an enclosure, for example the metal casing, which is at ground potential. These electrodes are electrically linked to each other or electrically separated from each other depending on the position of a movable connection member forming part of one of the electrodes, for example a sliding tube actuated by a control. The tube is generally carried by a main body of one of the electrodes, to which it is permanently electrically linked, and the separation of the tube relative to the opposite electrode is likely to create an electric arc. A disconnector is generally located in an electrical substation. It is connected to the other elements of the substation, for example by connection bars. On each side of the disconnector, other elements of a substation can be found such as a power transformer, an overhead crossing, etc.
A mechanical disconnector traditionally comprises two pairs of electrical contacts. For example, for each pair, one of the contacts is carried by the sliding tube forming part of one of the electrodes and the other contact of the same pair is carried by the electrode which does not include this sliding tube. A pair of main contacts is the pair through which the nominal current passes in the completely closed position of the apparatus. This current flow path, which will be called main electrical path, is a path of least electrical resistance, thus limiting the conduction losses in the steady state. This pair of main contacts is assisted by a second pair called pair of arc contacts or pair of secondary contacts. The two secondary contacts are intended to remain in sharp contact during the separation of the pair of main contacts, so as not to have any arcing phenomenon on the pair of main contacts, which avoids wear of the main contacts. Conversely, the contacts of the pair of secondary contacts separate lastly and the electric arc is established. They must resist this wear. Arrived at a sufficient arc length, and after a sufficient time, the electric arc is interrupted.
The use of such a mechanical disconnector without a specific device to facilitate the cut-off could cover the lowest stresses of the charging current transfer cases, but is unsuitable for circuits with high loop impedances.
Indeed, in this case, the opening can produce electric arcs likely to stretch to significant lengths and this can cause certain problems. An arc that is too long between the connection member and the opposite electrode can degenerate and develop into a short circuit. For example, in a metal-cased disconnector of the type described above, an arc can be established between the powered electrode and the grounded enclosure wall. In a less extreme case, the arc extinction times can be too long and damage the parts constituting it and thus jeopardize the insulation of the system.
Document WO-2019/077269 describes a mechanical cut-off apparatus including two movable electrodes which, for a complete electrical closing position, allow the passage of a nominal electric current through the apparatus according to a main electrical path. The two electrodes form, for an intermediate position, a secondary electrical path through the apparatus, the main electrical path being interrupted. The apparatus includes, in the secondary electrical path, a surge protector in series with the pair of secondary contacts, and a controlled switch capable of switching a current circulating in the secondary electrical path either through the surge protector, or in a short-circuit of the surge protector. In one illustrated embodiment, the controlled switch is an electrically-piloted electronic switch, which requires, for the electronic switch, a control independent of the control of the electrodes. The electronic switch may present a significant additional cost, and the need to provide a pilot circuit for this electronic switch may increase the cost and complexity of the apparatus and its integration into an installation.
The invention aims to propose a cut-off apparatus of simpler design allowing a charge opening while limiting the arc risks.
The invention relates to a mechanical cut-off apparatus of a high-voltage electric circuit, the mechanical cut-off apparatus including:
an upstream terminal and a downstream terminal which are intended to be electrically linked respectively to an upstream portion and a downstream portion of the electric circuit;
in a main electrical path between the upstream and downstream terminals of the mechanical cut-off apparatus, a main mechanical switch having a pair of main contacts which are movable relative to each other between at least one open position corresponding to a mechanically open state of the main mechanical switch, and at least one closed position corresponding to a mechanically and electrically closed state of the main mechanical switch in which the main contacts establish a nominal electrical connection of the mechanical cut-off apparatus, said nominal electrical connection allowing the passage of a nominal electric current through the mechanical cut-off apparatus;
in a secondary electrical path which is electrically in parallel with the main mechanical switch between the upstream and downstream terminals of the mechanical cut-off apparatus, a secondary mechanical switch, having a pair of secondary contacts which are movable relative to each other between at least one open position, corresponding to a mechanically open state of the secondary mechanical switch, and at least one closed position corresponding to a mechanically and electrically closed state of the secondary mechanical switch;
a mechanical control of the main mechanical switch and of the secondary mechanical switch configured such that, in an electrical opening operation of the mechanical cut-off apparatus, the secondary mechanical switch is brought to its mechanically open state after the main mechanical switch has been brought to its mechanically open state.
The the apparatus includes a transition dipole comprising a capacitance, the transition dipole being electrically arranged in series with the pair of secondary electrical contacts in the secondary electrical path, and the apparatus includes a controlled switch which, in an electrically closed state, creates inside the mechanical cut-off apparatus a bypass that short-circuits the capacitance of the transition dipole.
The apparatus can further have either of the following characteristics, taken alone or in combination.
The transition dipole and the secondary electrical path are preferably devoid of a dedicated inductive component.
The the transition dipole can include a circuit for discharging the capacitance of the transition dipole.
The the transition dipole can include a voltage limiter arranged electrically in parallel with the capacitance in the transition dipole.
The voltage limiter can be designed as a surge protector.
The discharge circuit can include a discharge resistance which is arranged electrically in parallel with the capacitance and electrically in parallel with the voltage limiter of the transition dipole.
The controlled switch can be electrically arranged in parallel with the transition dipole, in the secondary electrical path, between the secondary mechanical switch and a terminal of the mechanical cut-off apparatus.
The controlled switch can be a tertiary mechanical switch having a pair of tertiary contacts which are movable relative to each other between an open position corresponding to a mechanically open state of the tertiary mechanical switch, and a closed position corresponding to a mechanically and electrically closed state of the tertiary mechanical switch.
The controlled switch is an electronic switch.
The controlled switch can be electrically arranged in parallel with the secondary electrical path, and be a tertiary mechanical switch having a pair of tertiary contacts which are movable relative to each other between at least one open position corresponding to a mechanically open state of the tertiary mechanical switch, and at least one closed position corresponding to a mechanically and electrically closed state of the tertiary mechanical switch.
The mechanical cut-off apparatus can be configured such that:
in an opening operation of the mechanical cut-off apparatus, the controlled switch is brought into an electrically open state after the main mechanical switch has been brought into its mechanically open state and before the secondary mechanical switch is brought into its mechanically open state;
in an electrical closing operation of the mechanical cut-off apparatus, the main mechanical switch and the secondary mechanical switch are brought into their mechanically and electrically closed state after the controlled switch has been brought into an electrically closed state.
The mechanical cut-off apparatus can include a mechanical control of the tertiary mechanical switch, and the mechanical control of the main, secondary and tertiary switches can be configured such that:
in an opening operation of the mechanical cut-off apparatus, the tertiary mechanical switch is brought into its mechanically open state after the main mechanical switch has been brought into its mechanically open state and before the secondary mechanical switch is brought into its mechanically open state;
in a closing operation of the mechanical cut-off apparatus, the main mechanical switch and the secondary mechanical switch are brought into their mechanically and electrically closed state after the switch controlled as a tertiary mechanical switch has been brought into its mechanically and electrically closed state.
In a closing operation of the mechanical cut-off apparatus, the secondary mechanical switch can be brought into its state mechanically and electrically closed after the main mechanical switch has been brought to its electrically and mechanically closed state.
In a closing operation of the mechanical cut-off apparatus, the secondary mechanical switch can be brought into its mechanically and electrically closed state before the main mechanical switch has been brought into its electrically and mechanically closed state.
The mechanical cut-off apparatus can include two electrodes:
which are electrically linked respectively to the upstream terminal and to the downstream terminal of the mechanical cut-off apparatus,
which each carry one of the contacts of the pairs of main, secondary and tertiary contacts,
and which are movable relative to each other along a relative opening movement and a relative closing movement, between at least one electrical opening position corresponding to an electrically open state of the mechanical cut-off apparatus and a complete electrical closing position corresponding to an electrically closed state of the mechanical cut-off apparatus in which the electrodes establish, through the pair of main contacts, the nominal electrical connection of the mechanical cut-off apparatus.
In such a case, on each of the two electrodes, the main contact and the tertiary contact have a fixed position on the considered electrode.
In such a case, for a given relative position of the two electrodes in their opening or closing movement, the main contact pair and the tertiary contact pair have a relative spacing between the contacts of the pair that is different, so that, in an opening operation of the mechanical cut-off apparatus to bring it from its closed state to its open state, for an intermediate position or a range of intermediate positions of the electrodes between the electrical opening position and the complete electrical closing position, the main electrical path is interrupted at the level of the pair of main contacts while an electrical path remains closed at the level of the pair of tertiary contacts;
In such a case, one at least of the contacts of the pair of secondary contacts is movable on the electrode which carries it, between an opening configuration adopted during the opening movement and a closing configuration adopted during the closing movement, the opening and closing configurations corresponding to a different relative spacing between the two contacts of the pair of secondary contacts for the same given relative position of the two electrodes, such that:
during the opening movement, the pair of secondary contacts separates after the pairs of main and tertiary contacts;
during the closing movement, the pair of secondary contacts comes into contact after the pair of tertiary contacts.
In one apparatus according to the invention, the relative closing and opening movements of the electrodes and the relative closing and opening movements between the two contacts of the pairs of main and tertiary contacts can be the same and can be translational movements, and the two configurations of the pairs of secondary contacts can correspond to two different relative positions of the two secondary contacts along the direction of translation for the same relative position of the electrodes.
The invention also relates to an electrical installation including at least one mechanical cut-off apparatus having any one of the preceding characteristics.
The invention also relates to an electrical installation, characterized in that it includes a first electric circuit between a first point and a second point, a second electric circuit, electrically in parallel with the first electric circuit between the first point and the second point, and a mechanical cut-off apparatus having any one of the characteristics above in at least one of the circuits for cutting off the electric current in the circuit.
The invention also relates to a method for cutting off a high-voltage electric circuit implementing a mechanical cut-off apparatus having an upstream terminal and a downstream terminal which are intended to be electrically linked respectively to an upstream portion and a downstream portion of the electric circuit, in which:
a main electrical path is mechanically and electrically opened, between the upstream and downstream terminals of the mechanical cut-off apparatus, which allows the passage of a nominal electric current, to switch the current in a secondary electrical path which is electrically in parallel with the main electrical path between the upstream and downstream terminals of the mechanical cut-off apparatus so as to charge a capacitance inserted into the secondary electrical path;
after expiry of a period following the opening of the main electrical path, the secondary electrical path is mechanically and electrically opened.
In such a method, during the opening of the main electrical path, the electric current can be first switched in a tertiary electrical path which is electrically in parallel with the main electrical path between the upstream and downstream terminals of the mechanical cut-off apparatus before switching it to the secondary electrical path.
In such methods, the voltage across the capacitance can be limited by the presence of a voltage limiter electrically in parallel with the capacitance in the secondary electrical path.
Each DC high-voltage network sub-portion 130 can for example include in particular a positive-potential DC high-voltage conductor 160 and a negative-potential DC high-voltage conductor 180 and generally a neutral-potential connection, for example a ground neutral-potential connection. In the example illustrated, each DC high-voltage conductor 160, 180 determines a DC high-voltage electric circuit. The DC high-voltage electrical network portion 110 includes, in the DC high-voltage electric circuits defined by the DC high-voltage conductors 160, 180, cut-off apparatuses 10 of an electric circuit each of which can be in an electrically open state in which it interrupts the electric current circulation in the considered electric circuit, or in part thereof, or in an electrically closed state in which it allows the circulation of an electric current in the considered electric circuit. Such a cut-off apparatus 10 is brought from its electrically closed state to its electrically open state by an opening operation, and it is brought from its electrically open state to its electrically closed state by a closing operation.
The cut-off apparatuses 10 of an electric circuit can be in particular of the disconnector type. The cut-off apparatuses of an electric circuit can in particular be mechanical apparatuses, in which the electrical cut-off is obtained by displacement, in particular by spacing, of two electrical contacts or several pairs of electrical contacts. In this case, the displacement of the electrical contacts is generally carried out by a mechanical control which preferably comprises at least one mechanical, pneumatic, hydraulic or electrical actuator, and possibly a transmission between the actuator and the electrical contacts. The transmission has a movement transmission kinematics which transforms a movement of the actuator into a relative movement of the contacts. This displacement can be electronically monitored, for example by an electronic monitoring unit piloting the actuator.
In a DC high-voltage network, for example of the type of the DC high-voltage network portion 110 described above, it may be necessary to conduct maneuvers of charge line current transfer by the disconnectors.
These transfer maneuvers occur to reorient the power flow between network portions while continuing to service all the clients of the network. In the diagram of
This is done by opening at least one or two of the cut-off apparatuses 10 in the electric circuits linking the network portions 143 and 142. For example, a cut-off apparatus 10 of the DC high-voltage network sub-portion is opened 130 which links the network portions 143 and 142.
The power supplied by the network portion 143 can continue to supply the network portions 141 and 142, but the flows are modified because there is no longer any power transiting directly between the network portions 143 and 142.
In other words, as illustrated in the equivalent wiring diagram of
Thanks to the invention, such transfer maneuvers can be carried out by an opening operation of a mechanical cut-off apparatus, in particular of the disconnector type, including when there is no circuit breaker in the electric circuit associated with this mechanical cut-off apparatus.
In the case contemplated within the scope of the invention, because there remains a parallel electric circuit, the voltage U10 across the mechanical cut-off apparatus 10.2, in this case the disconnector 10.2, after the opening operation of the mechanical cut-off apparatus 10.2, is equal to the voltage drop along the parallel circuit 1. This voltage drop is, in DC voltage, essentially equal to R1×I1, with R1 the equivalent resistance of the parallel electric circuit 1 and I1 the value of the electrical intensity in the parallel electric circuit 1 when the current I2 in the direct electric circuit 2 is zero. In an application of a network under “high-voltage B”, this voltage drop along the parallel circuit 1 is for example on the order of 1,000 volts, for example comprised between 500 and 5,000 volts.
In the exemplary embodiment, the mechanical cut-off apparatus 10 is a disconnector. In the example, the mechanical cut-off apparatus is provided to cut off a single electric circuit, but the invention could be implemented in an apparatus provided to cut off several electric circuits, then including, for example within the same enclosure, several cut-off devices in parallel.
The invention will more particularly be described within the framework of a mechanical cut-off apparatus of the “metal-cased” type. Such an apparatus is schematically illustrated in
A detail of one particular embodiment is illustrated in more detail, but still schematically, in
The mechanical cut-off apparatus 10 thus includes an enclosure 12 which delimits an internal volume 16 of the enclosure 12. Preferably, in operation of the apparatus, the enclosure 12 is sealed relative to the outside of the enclosure 12. The enclosure 12 can include one or several opening(s) (not represented) allowing, at least for maintenance or mounting operations, the access to the internal volume 16 from outside the enclosure, or allowing the volume 16 to be put into communication with another volume of another enclosure adjoined to the enclosure 12 around the opening. The openings are therefore intended to be obturated, for example by portholes or covers, or are intended to put the internal volume 16 of the enclosure 12 into communication with another enclosure itself sealed, by sealed correspondence of the opening with a corresponding opening of the other enclosure. Thanks to this sealing, the internal volume 16 of the enclosure 12 can be filled with an insulating fluid which can be separated from the atmospheric air. The fluid can be a gas or a liquid. The pressure of the fluid can be different from the atmospheric pressure, for example a pressure greater than 3 bars absolute, or can be a very low pressure, typically less than 1 millibar, possibly close to vacuum. The vacuum would be, within the meaning of the invention, assimilated to an insulating fluid. The insulating fluid can be air, in particular dry air, preferably at a pressure greater than the atmospheric pressure, in particular greater than 3 bars absolute. However, preferably, the fluid is chosen for its high insulating properties, for example by having a dielectric strength greater than that of dry air under equivalent temperature and pressure conditions. Thus, the fluid can be sulfur hexafluoride (SF6), under a pressure greater than 3 bar absolute.
In some embodiments, including the embodiment illustrated in
In the example illustrated, each electrode 20, 22 is fixed in the enclosure 12 via an insulating support 26. Outside the enclosure 12, the mechanical cut-off apparatus 10 includes, for each electrode, a connecting terminal 28, 30 which is electrically linked to the corresponding electrode 20, 22. One of the terminals is intended to be linked to an upstream portion of the electric circuit while the other of the terminals is intended to be linked to a downstream portion of the electric circuit. Arbitrarily, and without this having any particular meaning as to the polarity or direction of the current circulation, the upstream portion of the electric circuit will be referred to as the portion which is linked to the first electrode 20, by the connecting terminal 28, which can therefore be referred to as upstream terminal. Consequently, the downstream portion of the electric circuit is the portion which is linked to the second electrode 22, by the connecting terminal 30, which can therefore be referred to as downstream terminal.
In the example, each electrode 20, 22 is permanently electrically linked to the associated connecting terminal 28, 30, regardless of the open or closed state of the mechanical cut-off apparatus.
As indicated above, the mechanical cut-off apparatus 10 is intended to be included in an electrical installation 100 comprising a DC high-voltage electric circuit 2, one example of which is illustrated in
The main bodies of the two electrodes 20, 22 are disposed in the internal volume 16 in a fixed manner, spaced from the peripheral wall of the enclosure 12, and spaced from each other in such a way that an inter-electrode electrical insulation space is arranged along the direction of a central axis Al, between the portions facing their respective outer peripheral surfaces.
In the example illustrated, the movable connection member 24 of the second electrode of the mechanical cut-off apparatus can include a sliding tube, of axis Al, which is slidably guided along the central axis A1, which will be arbitrarily referred to as longitudinal, in the second electrode 22. In the example illustrated, the movable connection member 24 is preferably made of conductive material, for example metal. In the example illustrated, the movable connection member 24 is electrically linked to the main body 23 of the second electrode 22, therefore electrically linked with the associated connecting terminal 30 permanently, whatever the position of the movable connection member 24.
The connection member 24 is movable along an opening movement relative to the opposite electrode 20, between a relative complete electrical closing position, visible in
To reach its relative complete electrical closing position, the connection member 24 is moved longitudinally along the central axis A1 in the direction of the first electrode 20, across the inter-electrode electrical insulation space. In the remainder of the text, it is considered that the relative complete electrical closing position is the position of last electrical contact between the two electrodes through a pair of main contacts, one of which is carried by each electrode, in the direction of the opening of the mechanical cut-off apparatus. For this relative complete electrical closing position, a circulation of electric current is possible by conduction through a mechanical contact between the respective main contacts of the two electrodes. In some apparatuses, there may be a dead travel between an extreme electrical closing position and the last electrical contact position between the two electrodes, in the direction of the opening of the mechanical cut-off apparatus. On this dead travel, an electric current circulation is possible by conduction through a mechanical contact between the respective main contacts of the two electrodes.
In the example illustrated, in the complete electrical closing position of
In general, the main mechanical switch DS1 is electrically interposed in the main electrical path 2P without any other electrical switch, without a dedicated inductive component in the main electrical path between the two terminals 28, 30 of the mechanical cut-off apparatus 10. Any parasitic inductance or impedance in the main electrical path 2P will be of course reduced to the smallest possible value.
In this embodiment of the invention, the two electrodes 20, 22, 24 include a pair of secondary contacts 38, 39 which form, by their contact, for a range of intermediate positions of the electrodes between the electrical opening position and the complete electrical closing position, a secondary electrical path for the electric current through the mechanical cut-off apparatus.
In the particular embodiment illustrated in
In the example, the secondary contact 39 of the first electrode 20 is electrically linked to the body 21 of the first electrode, therefore to the upstream portion of the electric circuit 2. The secondary contact 38 of the second electrode 22 is electrically linked to the movable member 24, and therefore to the downstream portion of the electric circuit 2.
In the example, the secondary contact 39 of the first electrode 20 is fixed and extends along a tubular geometry of axis A1, so as to delimit an open inner bore along the axis A1. In the example, it can be designed as several conductive contact blades, which extend each in a radial plane containing the axis A1, disposed about the axis A1 following this tubular geometry, and all including a free contact end at the same radial distance from the axis A1. The secondary contact 38 of the second electrode 22, here carried by the movable connection member 24 and permanently electrically linked thereto, is configured, for all the positions of the range of relative intermediate positions of the electrodes for which the secondary electrical path is formed, to be engaged in the inner bore of the contactor 39 of the first electrode 20, ensuring electrical contact between the two secondary contacts. This is illustrated in
In the example illustrated, the secondary contact 38 of the second electrode is advantageously movable on the electrode which carries it, between an opening configuration of the mechanical cut-off apparatus 10 which is adopted during the opening movement (
The pairs of main 21, 25 and secondary 38, 39 contacts are designed and disposed so that, for a range of intermediate positions of the electrodes for which the secondary contacts are in contact with each other, the main contacts are spaced from each other to interrupt the main electrical path. In the example illustrated, for a relative opening position of the electrodes, the spacing “e1” between the two main contacts 21, 25 is greater than the spacing “e2” between the two secondary contacts 38, 39, in any case during an opening operation.
In the example illustrated, each of the pairs of main and secondary contacts includes a first contact 21, 39 carried by the first 20 of the two electrodes and a second contact 25, 38 carried by the second 22 of the two electrodes, in this case by its movable member 24. Thus, each of the pairs of main and secondary contacts has a relative closing movement and a relative opening movement between the two contacts which is the same as the relative opening and closing movements of the two electrodes 20, 22.
In these two diagrams, the pair of main contacts 21, 25 is represented as a switch DS1 inserted into the main electrical path 2P inside the mechanical cut-off apparatus 10. The pair of secondary contacts 38, 39 is represented as a switch DS2 inserted into the secondary electrical path 2S inside the mechanical cut-off apparatus 10. As represented, the main electrical path 2P and the secondary electrical path 2S are parallel electrical paths between the two terminals 28, 30 of the mechanical cut-off apparatus 10.
In the invention, the relative movements of the pair of main contacts 21, 25 and the pair of secondary contacts 38, 39 are temporally coordinated during an opening or closing operation of the mechanical cut-off apparatus. In the preferred embodiment, this time coordination is obtained by a mechanical link through which, for each of the two electrodes 20, 22, 24, the main contact and the secondary contact are secured to each other following a geometry which can take two configurations, a first configuration being implemented during opening operations and movements, and the other configuration being implemented during closing operations and movements. The time coordination thus corresponds, for the opening operations and movements, to a first time offset between the respective opening of the two pairs of contacts, and, for the closing operations and movements, to a second time offset between the respective closing of the two pairs of contacts, the second time offset being of different duration from the first time offset, the time offsets resulting from the different relative deviations between the contacts of the two pairs.
As can be seen in
The capacitance 49 of the transition dipole 48 includes at least one dedicated capacitive component. A dedicated capacitive component is typically a capacitor. A capacitor includes two conductive plates (sometimes called “electrodes”) in total influence and separated by an insulator. One of the conductive plates of the capacitor is therefore linked to the first terminal 48a of the transition dipole 48 and the other of the conductive plates of the capacitor is therefore linked to the second terminal 48b of the transition dipole 48. The capacitance 49 of the transition dipole 48 can for example be designed as an assembly of several discrete capacitive components electrically arranged in series and/or in parallel and having a total electrical capacitance.
The transition dipole 48 is arranged in the secondary electrical path 2S either upstream of the secondary mechanical switch DS2 as illustrated schematically in
In the examples illustrated, the transition dipole 48 includes a voltage limiter 50 arranged electrically in parallel with the capacitance 49 in the transition dipole.
It could be envisaged not to have this voltage limiter, in particular for the case where the capacitance can withstand a significant voltage. However, the presence of a voltage limiter 50 arranged electrically in parallel with the capacitance 49 in the transition dipole allows implementing a capacitance that only has to withstand a relatively reduced voltage, for example on the same order as, but greater than, the voltage drop along the parallel circuit 1. Thus, it will be possible to implement a capacitance whose maximum voltage is comprised between 800 volts and 10,000 volts.
In the case of the presence of the voltage limiter 50, the transition dipole 48 thus includes two parallel branches, both inserted electrically in parallel with each other between a first terminal 48a and a second terminal 48b of the transition dipole 48, in the secondary electrical path 2S. The capacitance 49 is in a first branch. The voltage limiter 50 is in a second branch.
In a first example of electrical architecture illustrated in
In the second example of electrical architecture illustrated in
In both embodiments, and whether the transition dipole 48 is arranged upstream or downstream of the secondary mechanical switch, when the controlled switch DS3 is in a closed state, it creates, inside the mechanical cut-off apparatus, a bypass which short-circuits the capacitance 49 of the transition dipole 48, in the sense that a current circulating in the mechanical cut-off apparatus 10, between the two terminals 28, 30, does not pass through the capacitance 49. It is further noted that, in the electrical architecture of
In the embodiment of
However, in the two electrical architectures of
In the two electrical architectures of
In the exemplary embodiment of
In the example, the tertiary contactor 60 of the first electrode 20 is fixed and extends along a tubular geometry of axis A1, so as to delimit an open inner bore along the axis A1. It can be designed as several conductive contact blades, which extend each in a radial plane containing the axis A1, distributed about the axis A1 following the tubular geometry, and all including a free contact end at the same radial distance from the axis A1. In the example, the tertiary contactor 60 of the first electrode 20 extends coaxially around the secondary contact 39 which is carried by the same electrode 20.
The tertiary contact 62 of the second electrode 22, here carried by the movable connection member 24 and permanently electrically linked to the movable connection member, is configured, for all the positions of the range of relative intermediate positions of the electrodes for which the tertiary electrical path is closed, to be engaged in the inner bore of the contact 60 of the first electrode 20, by ensuring electrical contact between the two tertiary contacts 60, 62. One of these positions is illustrated in
When the mechanical cut-off apparatus 10 includes a controlled switch DS3 which, in an electrically closed state, creates inside the mechanical cut-off apparatus a bypass that short- circuits the capacitance 49, and which is designed as a tertiary mechanical switch, the apparatus also includes a mechanical control of the tertiary mechanical switch DS3 which ensures the relative displacement of the tertiary contacts between the open and closed positions of the tertiary mechanical switch DS3. In the example of
For the case where the mechanical cut-off apparatus includes a controlled switch which, in an electrically closed state, creates inside the mechanical cut-off apparatus a bypass that short-circuits the capacitance 49, and which is designed as an electronic tertiary switch, the control of the tertiary switch is an electronic control, which generally implements an electronic monitoring unit.
Advantageously, as will be seen later, the mechanical cut-off apparatus is configured such that, in an opening operation of the mechanical cut-off apparatus 10, the controlled switch DS3 is brought into an electrically open state after the main mechanical switch DS1 has been brought into its mechanically open state, but before the secondary mechanical switch DS2 is brought into its mechanically open state, which is illustrated by the sequence of
It will be seen that this sequencing allows ensuring the electrical opening of the mechanical cut-off apparatus by minimizing the appearance of an electric arc and by ensuring that the electric arc is extinguished when the mechanically open state of the mechanical cut-off apparatus is reached, to ensure electrical opening of the circuit.
On the other hand, the mechanical cut-off apparatus 10 is configured such that, in a closing operation of the mechanical cut-off apparatus 10, the main mechanical switch DS1 and the secondary mechanical switch DS2 are brought into their mechanically closed state after the controlled switch DS3 has been brought into its electrically closed state, which is illustrated by the sequence of
It could be provided that for each of the main mechanical switch DS1, of the secondary mechanical switch DS2 and of the controlled switch DS3 is provided with its own independent control to move from its mechanically open state to its mechanically and electrically closed state, and vice versa, independently. The controls can then be operated following a sequence to obtain the desired sequencing. It could also provided that, among the main mechanical switch DS1, the secondary mechanical switch DS2 and the controlled switch DS3, two of them are provided with a common control, and that the last one is provided with an independent control.
However, it is advantageous to provide a single control for both the main mechanical switch DS1, the secondary mechanical switch DS2 and the controlled switch DS3. In this case, the passage of the mechanical cut-off apparatus from the opening configuration to the closing configuration, and vice versa, is advantageously monitored by a passive mechanism that does not require independent control.
In the mechanical architecture illustrated in
On the other hand, in the example illustrated, one at least of the contacts of the pair of secondary contacts 38, 39 is movable on the electrode 20, 22, 24 which carries it, between an opening configuration adopted during the opening movement and a closing configuration adopted during the closing movement of the electrodes, in a closing operation of the mechanical cut-off apparatus 10. These opening and closing configurations correspond to a different relative spacing “e2” between the two contacts of the pair of secondary contacts 38, 39 for the same given relative position of the two electrodes, such that:
during the opening movement, the pair of secondary contacts separates after the pairs of main and tertiary contacts;
during the closing movement, the pair of secondary contacts comes into contact after the pair of tertiary contacts.
Preferably, during the closing movement, the pair of main contacts and the pair of secondary contacts come into contact after the pair of tertiary contacts.
In practice, in the illustrated embodiment, the secondary contact 38 of the second electrode 22 is movable on the electrode which carries it, in this case movable on the movable connection member 24, between two distinct positions along the axis A1 relative to the movable connection member 24 which carries it, one position corresponding to the opening configuration and the other to the closing configuration. In the closing configuration position, the secondary contact 38 is retracted along the axis A1 relative to the movable connection member 24 to increase its spacing “e2” relative to the secondary contact 39 carried by the other electrode 20. In the opening configuration position, the secondary contact 38 is advanced along the axis A1 relative to the movable connection member 24 to reduce its spacing relative to the secondary contact 39 carried by the other electrode. It could be provided that it is the secondary contact 39 of the first electrode 20 that is movable on the electrode which carries it, or that the two secondary contacts 38, 39 of the first and second electrodes 20 are both movable each on the electrode which carries it. In the example, the contact rod 38 which forms the secondary contact is therefore movably mounted in translation along the axis A1 on the movable connection member 24. It is for example guided in translation along the axis A1 in a bore of the movable connection member 24.
In the example, the passage of the secondary contact from the opening configuration is controlled passively. Indeed, in the example, the secondary contact 38 is elastically returned to that of its positions which corresponds to one of the opening or closing configurations. In the example, the secondary contact 38 is elastically returned to its position which corresponds to the closing configuration. The elastic return is for example ensured by a return spring 64.
In the example, it is by mechanical cooperation with a member of the mechanical cut-off apparatus, here with the other secondary contact 39, that the secondary contact 38 is brought into its other position corresponding to the other of the open or closed configurations. In the example, it was seen that the secondary contact 38 is engaged in the inner bore of the contactor 39 of the first electrode 20, to ensure electrical contact between the two secondary contacts. In the example, the secondary contact 38 and the contactor 39 of the first electrode 20, are provided with complementary shapes which create a first peak of mechanical strength which prevents the loss of contact between the two below a threshold force in the direction of the opening. This first peak of mechanical strength is greater than the elastic return force, exerted in the example by the return spring 64, so that, before allowing the opening of the secondary mechanical switch DS2, the spacing movement of the electrodes, in the opening direction, causes the passage of the secondary contact 38 from its closing configuration to its opening configuration. In other words, from a certain position, the movement of the electrodes causes the displacement of the secondary contact relative to the movable connection member 24 which carries it, from the closing configuration to the opening configuration. When the secondary contact 38 reaches its opening configuration, it abuts in its relative movement relative to the electrode which carries it. It is noted that, for this position illustrated in
Other mechanisms could be provided to allow the passage of the mechanical cut-off apparatus 10 from its opening configuration to its closing configuration, including mechanisms comprising an actuator specific to the change of configuration. It is moreover noted that, in the example, the system is monostable, with only one stable configuration which is the closing configuration. However, a bistable system could be provided with a system which is elastically forced either into the opening configuration or into the closing configuration, and a control device which switches the system from one to the other, for example depending on the direction of movement of the electrodes.
In the invention, the voltage limiter can be or can comprise a surge protector 50, or voltage surge arester, and is a device which limits the voltage peaks across its terminals, and therefore in particular which limits the voltage peaks across the capacitance 49. The voltage limiter can be designed as an assembly of several discrete components electrically arranged in series and/or in parallel. Preferably, the assembly of several discrete components electrically arranged in series and/or in parallel has, from the point of view of the rest of the device, the behavior of a single surge protector having an equivalent transition voltage for the assembly and a protection voltage for the assembly. A surge protector generally comprises an electrical component which has a variable resistance as a function of the electrical voltage across its terminals. The variation of the resistance value is generally not linear with the electrical voltage across the surge protector. Generally, below a transition voltage across the surge protector, the resistance of the latter is high, with no or relatively small decrease in its resistance as a function of the increase in voltage, and the surge protector let pass only a leakage current, preferably less than 1 ampere (A), or less than 100 milliamperes (mA), or even less than or equal to 1 milliampere (mA). On the contrary, above the transition voltage across the surge protector, the resistance of the latter rapidly decreases as a function of the voltage increase, which reaches a peak clipping voltage value, or protection voltage, for which the resistance of the surge protector becomes low or even very low. In other words, the surge protector acts as a voltage limiter across its terminals over the current interval for which it has been chosen. It opposes the protection voltage when passing the highest current for which the surge protector has been dimensioned. Below the transition voltage, it tends to prevent the passage of the current. Beyond the transition voltage, it authorizes the passage of the current through the surge protector for a small increase in the voltage across its terminals. As known, the transition voltage is generally not a precise value but rather corresponds to a transition voltage range. However, in the present text, as a definition, the transition voltage of a surge protector will be the voltage for which the surge protector lets a current of 1 ampere (A) to pass therethrough. The protection voltage is the voltage across the surge protector when it is traversed by the highest current for which it has been dimensioned. Among the surge protectors, the surge arresters are known in particular, which may in particular comprise the varistors and the “TVS” (Transient Voltage Suppressor) diodes, such as the “Transil™” diodes. In particular, within the framework of the invention, a surge protector can comprise a metal oxide varistor (or MOV). The voltage limiter may be or may comprise a spark gap.
In the examples illustrated, a circuit for discharging the capacitance 49 of the transition dipole 48 is provided. In the examples illustrated, the discharge circuit is a passive discharge circuit, with no active component. In this example, the discharge circuit includes a resistance 51 which is arranged electrically in parallel with the transition dipole 48, therefore in parallel with the capacitance 49 of the transition dipole 48, and therefore in parallel with the voltage limiter 50 of the transition dipole 48 Preferably, the resistance 51 has a high electrical resistance value R51, for example comprised between 10 ohms and 1,000 ohms, more particularly between 50 ohms and 300 ohms, such that the dipole, which consists of the capacitance 49 of the transition dipole 48 and the resistance 51 arranged in parallel, has a significant time constant relative to an electrical cut-off period in the secondary mechanical switch DS2, for example a time constant greater than 100 milliseconds (ms), preferably greater than 500 milliseconds (ms). Conversely, this time constant must be sufficiently reduced so that the capacitance 49 is discharged in a relatively short time, so that the system is able to be operational again after a first implementation. Therefore, it will be advantageously provided that the time constant is less than 3 seconds, preferably less than or equal to 1 second. In this example, the time constant can be considered as being equal to the product R51×C49. Another type of discharge circuit, not illustrated in the drawings, could include a controlled switch. Thus, a discharge circuit could comprise a controlled switch which would be directly electrically arranged in series with the resistance 51, all of these two components being in parallel with the transition dipole 48. When the controlled switch would be switched in a closed state letting the current pass, a discharge circuit would be formed between the two plates of the capacitance 49 of the transition dipole 48. Preferably, the controlled switch would be a mechanical switch which would be similar to the main mechanical switch DS1 and to the secondary mechanical switch DS2, that is to say comprising a pair of contacts, one of which would be carried by one of the electrodes and the other by the other of the electrodes so as to open and close electrically in such a way temporally coordinated with that of the main mechanical switch DS1 and the secondary mechanical switch DS2 in particular. It can be considered that the circuit for discharging the capacitance 49 of the transition dipole 48 is integrated into the transition dipole 48, by forming a third parallel branch of this transition dipole 48.
In the examples illustrated, it is seen that each electrode 20, 22 has a conductive outer peripheral surface 32, 34 having an essentially convex geometry and devoid of protruding portions and, inside the casing defined by its conductive outer peripheral surface 32, 34, each electrode 20, 22 has an inner cavity 31, 33. The electrical transition dipole 48 can be advantageously housed inside the casing determined by the conductive peripheral surface 32, 34 of one of the two electrodes 20, 22, preferably by being entirely received inside said inner cavity 31, 33. However, it could also be provided that all or part of the electrical transition dipole 48 are arranged outside the casing defined by the conductive outer peripheral surface 32, 34 of the electrode 20, 22, while preferably remaining arranged inside the internal volume 16 of the mechanical cut-off apparatus.
In all cases, when the controlled switch DS3 is designed as a mechanical switch, a mechanical cut-off apparatus is obtained, the electrically open state of which can be observed visually, by visualizing the separation of the tertiary contacts, in addition to the separation of the main and secondary contacts.
It will now be described, with reference to
the intensity I1 in the first electric circuit 1;
the intensity I2 in the second electric circuit 2;
the intensity I2P of the electric current in the main electrical path 2P, therefore through the main mechanical switch DS1;
the intensity I2S of the electric current in the secondary electrical path 2S, therefore through the secondary mechanical switch DS2;
the intensity I2T of the electric current through the tertiary mechanical switch DS3;
the voltage U49 across the capacitance 49;
the voltage UDS3 across the controlled switch DS3;
the voltage UAB between the junction points A and B of the two parallel circuits 1 and 2.
The values indicated correspond to the following situation:
Current source delivering a nominal current of 2,000 A;
Voltage across the open mechanical cut-off apparatus 10: 1,000 V, corresponding to the voltage UAB across the two parallel circuits 1 and 2 when circuit 1 is closed and traversed by the nominal current, therefore corresponding to the voltage drop in the parallel circuit 1 under this nominal current;
capacitance value C49 of the capacitance 49: 4 millifarad;
resistance value R51 of the discharge resistance 51: 50 ohm.
In an initial state, it is considered that all the mechanical cut-off apparatuses 10 in the two circuits 1, 2 are in a complete electrical closing state, letting a current respectively I1 and I2 pass in each circuit. In the case envisaged above in which the two circuits have the same equivalent resistance and the same equivalent inductance, the initial values of the currents I1 and I2 are equal, for example equal to 1,000 A.
In this initial state, it is considered that all of the current I2 passing through the mechanical cut-off apparatus 10 circulates along the main electrical path 2P, in which therefore an electric current I2P is equal to the electric current I2 circulating in the second electric circuit 2. For this, the current which is likely to circulate, in this embodiment, in the tertiary electrical path 2T and which may present parasitic resistances and inductances, is neglected. Furthermore, the secondary electrical path 2S includes, in series, the transition dipole 48 which means that the impedance of the secondary electrical path 2S is higher, by several orders of magnitude, than that of the main electrical path 2P, so that it can be considered that no current passes in the secondary electrical path 2S. This initial state is represented in
The opening operation of the mechanical cut-off apparatus 10 begins with a step of opening the main electrical path 2P within the mechanical cut-off apparatus 10, by spacing of the main contacts 21, 25 of the main mechanical switch DS1. This step begins at an instant “tao” illustrated in
In the case of a mechanical cut-off apparatus as shown in
This switching is illustrated in
At an instant “tbo” following the instant “tao”, the opening operation of the mechanical cut-off apparatus 10 continues by the opening the controlled switch which is here designed as the tertiary switch DS3. The main mechanical switch DS1 remains electrically open, and the secondary mechanical switch DS2 remains electrically closed. In the case of a mechanical cut-off apparatus as shown in
When the voltage U49 across the capacitance 49 exceeds the transition voltage value of the voltage limiter 50, which substantially corresponds to the instant denoted “tco” in
The last step of the opening operation of the mechanical cut-off apparatus 10 consists in the opening of the secondary contacts 38, 39 of the secondary mechanical switch DS2 of the mechanical cut-off apparatus 10, at an instant “tdo” subsequent to the instants “tbo” and “tco”. Between the opening of the controlled switch, here designed as the tertiary mechanical switch DS3, and the opening of the secondary mechanical switch DS2, the current which circulates in the parallel circuit 2 drops due to the opposition of the voltage generated by the capacitance 49 of the transition dipole 48. During the opening of the secondary mechanical switch DS2, the current I2S through the secondary mechanical switch DS2 has become lower than the initial current, for example, less than 80%, preferably less than 60% of the initial current. In one example, it has been chosen to cause the opening of the secondary mechanical switch DS2 when the current I2S through the secondary mechanical switch DS2 has fallen to a value on the order of 600 amperes compared to an initial current of 1,000 A. A higher protection voltage of the voltage limiter 50, or a longer duration [tbo; tdo] between the opening of the tertiary mechanical switch DS3 and the opening of the secondary mechanical switch DS2, allows reducing the intensity of the current which must be cut by DS2, that is to say reducing the current that passes through the secondary mechanical switch DS2 upon its opening by separation of the secondary contacts 38, 39. If an arc is created between the secondary contacts at that time, it will have a lower arc voltage and a much shorter duration than what would be observed without the invention. For the example considered here, the calculations allow determining that, under the conditions described above, this arc would have the passage of an arc current of 580 amperes for a duration less than or equal to 60 milliseconds: This results in an amount of energy of about 110 joules. This amount of energy can be easily evacuated by the secondary contacts 38, 39 of the secondary mechanical switch DS2, recalling that it is, already according to the prior art, specially provided to absorb the arc energy at opening.
The current through the transition dipole 48 is completely canceled at an instant “teo” after a duration following the opening “tbo” of the controlled switch DS3 which, in the example, with the values indicated, is for example a few tens of milliseconds, easily less than 100 milliseconds, for example around 80 milliseconds. From the instant “teo”, it can be considered that the electric current is then entirely transferred to the first circuit 1. In the case of an entirely mechanical mechanical cut-off apparatus, it is possible to modify the mechanical structure of the apparatus in order to extend the time gap between the opening of the tertiary mechanical switch DS3 and the opening of the secondary mechanical switch DS2, so as to wait for the complete cancellation of the current through the capacitance 49 before proceeding with the opening of the contacts of the secondary mechanical switch DS2. This will reduce the wear on the contacts and increase the lifespan of the mechanical cut-off apparatus 10.
The capacitance 49 is then discharged through the discharge circuit, here designed as a discharge resistance 51 which is in parallel with the capacitance 49. The duration of this discharge depends directly on the value C49 of the capacitance 49 and resistance value R51 of the resistance 51. As a first approximation, it can be considered that we are dealing with the discharge of the capacitance 49 in the discharge resistance 51, therefore with a time constant equal to C49×R51. It can be considered that the capacitance is discharged at the end of a duration equal to 3 times the time constant or 5 times the time constant. The components will be advantageously chosen to have a discharge duration comprised between 1 and 10 seconds. In the example, the discharge duration is 3 s. At the end of this discharge duration, the voltage U49 across the capacitance 49 therefore becomes zero.
The opening operation of the mechanical cut-off apparatus 10 can be carried out with a speed of separation of the electrodes 20, 22, 24, and therefore of the contacts carried by these electrodes, which is for example comprised between 0.01 and 5 meters per second.
In general, the presence of the capacitance 49 modifies the impedance of the secondary electrical path 2S. The greater the capacitance value C49 of the capacitance 49, the more the impedance of the secondary electrical path 2S decreases and therefore the more the chances of successful switching increase since the switching from DS3 to DS2 is facilitated during the opening. On the other hand, a capacitance of a higher value and with reasonable dimensions may be difficult to find. Without the capacitance according to the invention, a conventional disconnector cannot carry out a line switching operation according to the desired performance because the arcing voltage created at the opening of the contacts is not sufficient to exceed/oppose the voltage of the parallel line. The addition of the capacitance thus allows circumventing this limitation. Indeed, at opening of DS3, the capacitance is charged and a voltage is thus created across its terminals. When this voltage exceeds the voltage UAB across the parallel circuit 1, it makes the switching from the circuit 2 to the parallel circuit 1 possible.
In general, the role of the voltage limiter 50 is to limit the voltage across the capacitance 49. The value of the protection voltage of the voltage limiter 50 thus determines the maximum value of the voltage across the transition dipole 48, therefore across the capacitance 49. By choosing a protection voltage of the voltage limiter of a greater value, the maximum voltage across the capacitance 49 and therefore the voltage U10 across the cut-off device 10 increase, so that the current switches more quickly from the second circuit 2 to the first parallel circuit 1 and the switching is then more likely to succeed. With the same duration between the opening of the tertiary mechanical switch DS3 and the opening of the secondary mechanical switch DS2, a greater protection voltage of the voltage limiter 50 leads the secondary mechanical switch DS2 to cut off a lower current. On the other hand, this increases the stresses on the capacitance 49 since it will in this case have to withstand a higher voltage across its terminals.
The capacitance 49 is chosen such that its capacitance value C49 allows a successful current switching from the tertiary electrical path 2T to the secondary electrical path 2S. Indeed, in order to allow the switching of current from the tertiary electrical path 2T to the secondary electrical path 2S, a necessary condition is to be able to create in the tertiary electrical path 2T a voltage greater than that in the secondary electrical path 2S.
At opening of the controlled switch DS3, the current I2S in the secondary electrical path 2S, solution of the differential equation which governs the branch, must exceed the value of the current I2 to be switched. This current I2S being in oscillatory mode, we will only be interested in its maximum amplitude. This results in the condition given by the following inequalition:
C49×w′o×(R3p×I2×Uarc)×exp[−PI/(2×w′o×T)]−I2>0
where:
w′o
2
=wo
2−(1/T2);
Uarc is the arc voltage across the controlled switch DS3 during its opening.
The condition above is taken from solving the following differential equation, which governs the variation of the current I2S in the secondary circuit as a function of the current I2 to be interrupted:
with Q=∫I2S dt, which therefore represents the charge accumulated in the capacitance 49.
In practice, this leads to capacitance values which are comprised between 1 millifarad and 10 millifarads, more preferably between 3 and 5 millifarads.
For example, for the following values:
Experimentally or by numerical simulation, it is for example possible to determine the value of the capacitance adapted to a given device starting from a low value in the ranges above, for example 1 millifarad, and by checking the success of the electrical cut-off in the mechanical cut-off apparatus 10. If the cut-off is not successful, the value of the capacitance is increased, for example by 0.5 millifarad and a new experiment or numerical simulation is carried out.
It will now be described, with reference to
In an initial state, for a closing operation, it is considered that an electric current respectively I1, having for example an intensity of 2,000 A, circulates in the first parallel circuit 1, and that the mechanical cut-off apparatus 10 in the second parallel circuit 2 is in an open state so that no electric current circulates in this second parallel circuit 2. In terms of numerical values, we remain in the particular case envisaged above in which the two circuits have the same equivalent resistance and the same equivalent inductance, but the operation would be similar if this were not the case. In this initial state, it is considered that no current passes through the mechanical cut-off apparatus 10. This initial state is represented in
The closing operation of the mechanical cut-off apparatus 10 begins with the closing of the controlled switch DS3. In the cases where this controlled switch is designed as a tertiary mechanical switch DS3, for example as described above, the tertiary contacts 60, 62 get closer to each other at a certain speed, which can for example be comprised between 0.01 and 5 meters per second. Initially, no electric arc is present between the tertiary contacts 60, 62.
During the closing movement, it is ensured that the secondary mechanical switch DS2 is in a closing configuration such that the main mechanical switch DS1 and the secondary mechanical switch DS2 are brought to their mechanically closed state after the controlled switch DS3 has been brought to its electrically closed state. Thus, during a closing operation of the apparatus, the operation of restoring the current in the high-voltage electric circuit, the secondary electrical path 2S and the main electrical path 28, 30 are electrically closed after the closing of the tertiary electrical path 2T. This is reflected for example in the fact that, in the examplary embodiment as illustrated espacially in
In the embodiment of
Still within the framework of one embodiment using the electrical architecture illustrated in
With the mechanical architecture of the embodiment illustrated in
Indeed, in all cases using the electrical architecture illustrated in
However, for the closing, in the cases using the electrical architecture illustrated in
This embodiment is very close to the one previously described in relation to
We find the characteristic according to which, on each of the two electrodes 20, 22, the main contact 21, 25 and the tertiary contact 60, 62 of the same electrode have a fixed position on the considered electrode. In addition, for a given relative position of the two electrodes 20, 22 in their opening or closing movement, the main contact pair 21, 25 and the tertiary contact pair 60, 62 have a relative spacing, respectively “e1” and “e3” between the contacts of the pair that is different, which is illustrated in
As in the example of
during the opening movement, the pair of secondary contacts 38, 39 separates after the pairs of main 21, 25 and tertiary 60, 62 contacts;
during the closing movement, the pair of secondary contacts 38, 39 comes into contact with each other after the pair of tertiary contacts 60, 62.
The secondary contact 38 of the second electrode is also movable on the electrode which carries it, between an opening configuration of the mechanical cut-off apparatus 10 which is adopted during the opening movement (
The difference between the two embodiments lies in the fact that the first contact position of the two secondary contacts 38, 39 during the closing corresponds to an even closer relative position of two electrodes, more particularly, in this embodiment, to a closer relative position of the movable connection member 24 relative to the first electrode 20, than the one prevailing for the embodiment of
It is noted that this embodiment follows the same opening sequence as that of
Within the framework of the electrical architecture illustrated in
The invention is not limited to the described and represented examples because various amendments can be made thereto without departing from its framework.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2001456 | Feb 2020 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2021/050260 | 2/12/2021 | WO |
