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    • 专利摘要:
    Device for detecting a fault current flowing in a current line (5) of an electrical installation comprising: - a magnetic circuit (11) traversed by the current line (5), comprising a secondary winding (12) - a generator (13) connected to the winding (12) for delivering an electrical signal, - a current measuring circuit (14) flowing in the winding (12), - a processing circuit (15) for providing a fault signal when the current in the winding (12) exceeds a determined threshold. The device comprises a control circuit (22) arranged to provide a second fault signal (25) in case of saturation of the magnetic circuit (11) or failure of the generator (13). The invention also relates to a differential protection apparatus and the assembly of a plurality of differential protection devices.
    公开号:FR3050081A1
    申请号:FR1653183
    申请日:2016-04-12
    公开日:2017-10-13
    发明作者:Farid Allab；Jiri Stepanek；Yvan Cadoux
    申请人:Schneider Electric Industries SAS；
    IPC主号:
    专利说明:

    TECHNICAL FIELD The invention relates to a device for detecting a fault current flowing in a current line of an electrical installation. The invention also relates to an electrical differential protection apparatus comprising such a detection device and a set of differential protection devices.
    STATE OF THE ART
    The devices for detecting an alternating fault current are used very widely in electrical installations powered by alternative networks. Their function is to detect any fault current, also called leakage current, generally flowing between the power grid and the earth or the mass of the installation. A fault current is the manifestation of an insulation fault of the network with respect to the earth and must be eliminated before damage can take place. These devices are part of industrial or domestic electrical installations.
    With the development of electronic loads, for example electric vehicle charging stations or the production of electricity by photovoltaic panels, the nature of the fault currents has changed: the presence of electronic rectifiers, voltage converters or frequency converters is at the origin of the appearance of continuous or pulsed fault currents. The purely alternating fault current detection devices are not sufficiently sensitive to DC or pulsed currents. In electrical installations in which electronic loads are installed, it is therefore necessary to install protective devices adapted to the detection of any type of alternating current, continuous or pulsed.
    An implementation constraint of these protection devices is the need to detect a relatively low fault current, for example 30 mA, in an electrical installation where currents flow from a few amps to several tens of amperes. For this, the use of a torus summator is particularly interesting since the magnetic circuit of the torus performs the summation of the magnetic fields generated by the currents flowing in each conductor of the current line. The resulting field is only the image of the current imbalance of all phases. A winding wound on the magnetic circuit makes it possible to measure this current imbalance, called differential current.
    An important difficulty is to measure a direct current with a core consisting of a magnetic circuit. Different ways are used to solve this problem.
    The patent application EP 0 069 655 A1 describes a protection device that can permanently detect grounding of the neutral and AC / DC phase-to-earth fault currents by detecting an offset of the magnetic state of the toroid. wherein an oscillator generates an alternating magnetic field.
    Patent Application EP 1 533 880 A1 describes a differential protection device and method that is sensitive to continuous differential currents or that comprises a DC component, while avoiding undesirable tripping for certain fault current frequencies. For this, the fault detection must be confirmed for different excitation frequencies of the magnetic circuit.
    The patent application EP 1 267 467 A2 uses two current transformers: a first to generate a first magnetic field on which is superimposed the magnetic field created by a fault current, a second current transformer, connected to the first transformer of current by a circuit in which is inserted a circuit producing a phase rotation of about 180 °, this circuit being arranged as a high-pass filter. The use of two current transformers is interesting since the resulting field is always minimized and therefore is not very sensitive to the saturation of the magnetic circuits. However, a significant drawback is the size and the cost induced by the use of two magnetic circuits.
    The operating principle of known devices using a single magnetic circuit requires a suitable dimensioning of the magnetic circuit so that it is not saturated for a fault current equal to the highest tripping threshold. In addition, for reasons of high dispersion of the characteristics of the magnetic materials and to be sure of a product operation at the highest tripping threshold, the magnetic circuit is generally oversized. This therefore has the disadvantage of being more bulky and more expensive. The object of the invention is to detect an alternating, continuous or pulsed fault current using a single magnetic circuit as well as the detection by an inexpensive and space-saving means of the saturation of said magnetic circuit. The invention is particularly suitable for use in a differential protection device of a low voltage electrical installation.
    SUMMARY OF THE INVENTION
    According to the invention, a device for detecting a fault current flowing in a current line comprises: a current sensor formed by a magnetic circuit traversed by the current line, the latter forming a primary, said sensor having a first secondary winding wound on the magnetic circuit; - a generator connected to the first secondary winding for delivering an alternating electric signal; - a measuring circuit for measuring a current flowing in the secondary winding; - a connected processing circuit; to the current measurement circuit, for supplying a first fault signal when said current measurement exceeds a threshold, and comprises a control circuit: - for controlling the electrical signal delivered by the generator, and - for providing a second fault signal when said electrical signal is representative of saturation of the magnetic circuit or in case of generator failure .
    Preferably, the device detects a saturation of the magnetic circuit representative of a fault current of amplitude greater than a saturation threshold.
    Advantageously, the control circuit measures the amplitude of the current of the electrical signal delivered by the generator and provides the second fault signal representative of a saturation of the magnetic circuit when said amplitude is greater than or equal to a high threshold.
    According to one embodiment, the control circuit measures the voltage of the electrical signal across the secondary winding and provides the second fault signal representative of a saturation of the magnetic circuit when said voltage is less than or equal to a low threshold.
    Preferably, the control circuit measures the frequency of the electrical signal delivered by the generator and provides the second fault signal representative of a saturation of the magnetic circuit when said frequency is located in a predefined frequency band.
    Preferably, the control circuit measures the amplitude of the current of the electrical signal delivered by the generator and supplies the second fault signal representative of a fault of the generator when said amplitude is lower than a predefined low threshold.
    According to another embodiment, the control circuit measures a flux variation as a function of time in the magnetic circuit and provides the second fault signal representative of a saturation of the magnetic circuit when said flux variation is lower than a low threshold. predefined.
    The measurement of the flux variation in the magnetic circuit is preferably carried out by means of a second secondary winding wound on the magnetic circuit.
    Preferably, the device comprises a current limiter limiting the amplitude of the current of the electrical signal delivered by the generator to a predefined high value.
    The generator is preferably self-oscillating.
    Advantageously, the device comprises an inductance connected in series between the generator and the first secondary winding for setting the frequency of oscillation of the generator in the predefined frequency band when the magnetic circuit is saturated.
    Advantageously, the second fault signal activates a fault signaling device, a control relay or a communication module. The invention also relates to an electrical differential protection device comprising: - elements for connection to an electrical network and connection elements to one or more electrical charges, - a cutoff device of the current line disposed between the elements of connection to the electrical network and the connection elements of the electrical load or charges, said cut-off device comprising electrical contacts, - a mechanism for controlling opening of the electrical contacts, and - a device for detecting a fault current such as as previously defined and such that the contact opening control mechanism is activated by the first fault signal or by the second fault signal. The invention also relates to a differential protection assembly comprising: - elements of connection to the electrical network and connecting elements to one or more electrical charges, - a cutoff device of the current line disposed between the connecting elements to the electrical network and the connection elements of the electric charge or charges, said cut-off device comprising electrical contacts; a mechanism for controlling opening of the electrical contacts, said assembly being formed by an assembly of: a first device for detecting a fault current as previously defined; - a second differential protection device arranged to provide a fault signal, and such that the contact opening control mechanism is activated by the first fault signal or by the second fault signal of the first device or by the fault signal of the second device tif differential protection.
    BRIEF DESCRIPTION OF THE DRAWINGS Other advantages and features will emerge more clearly from the following description of particular embodiments of the invention, given by way of non-limiting examples, and represented in the accompanying drawings, in which: FIG. 1 shows a block diagram of a fault current detection device according to a first embodiment of the invention; - Figures 2a, 2b, 2c show current signals in the device respectively in the absence of a fault current, in the presence of a fault current and saturation of a magnetic circuit; FIG. 3 represents a detailed diagram of a differential protection apparatus comprising a fault current detection device according to the first embodiment of the invention; FIG. 4 represents a block diagram of a fault current detection device according to a second embodiment; FIG. 5 represents a detailed diagram of a differential protection apparatus comprising a fault current detection device according to the second embodiment of the invention; - Figure 6 shows a block diagram of a differential protection assembly comprising a differential protection apparatus according to one embodiment of the invention.
    DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
    FIG. 1 represents a block diagram of a fault current detection device according to a first embodiment of the invention. A power supply network 1 supplies one or more loads 3 by means of a current line 5 formed of at least one current conductor. The power supply network 1 may be a three-phase public distribution network, for example of 400 Volt and 50 Hz frequency, the neutral is connected to a ground 2 and distributed with the phases as shown in Figure 1. The current line 5 comprises in this case four current conductors. When the neutral conductor is not distributed, the current line has three current conductors. The network 1 can also be a voltage or frequency converter. The network 1 can also be a photovoltaic source of DC voltage. In this case, the current line 5 comprises two current conductors, a positive polarity conductor and a negative polarity conductor. The load 3 can be an industrial electrical receiver such as a motor associated with a variable speed drive or represent a set of electrical charges present in an industrial building or residential. In order to ensure the protection of persons against electrical defects, the shell of the load 3 is connected to a ground 4. The earth 2 and the earth 4 are at the same electrical potential.
    In case of fault isolation of the load 3, a fault current may flow into the earth. This fault current will follow a loop: power supply 1, power line 5, load 3, earth link 4, and return to the power supply via the earth link 2. The device for detecting a fault current is for detecting this fault current and providing a fault signal or controlling a mechanism for opening the electrical connection between the supply network 1 and the load 3.
    The device for detecting a fault current is based on the principle of a magnetic circuit sensor. It comprises a current sensor 10 preferably consisting of a magnetic circuit 11 of substantially toroidal shape traversed by the conductors of the current line 5. The conductors of the current line 5 thus behave as the equivalent of a primary winding . The magnetic circuit 11 comprises a secondary winding 12. A generator 13 is connected across the secondary winding 12. Said generator can be self-oscillating or fixed frequency. It delivers an electrical frequency signal Pose creating an Ig current that is applied in the secondary winding 12. Figure 2a shows an example of such a current Ig in the absence of a fault current. The current Ig induces a magnetic field in the magnetic circuit 11.
    The electrical signal delivered is preferably an alternating signal that is to say alternately applied in one direction and then in the opposite direction, symmetrically, at the frequency Pose. Said electrical signal is preferably of rectangular shape but it can also be of square, sinusoidal or trapezoidal shape.
    The sizing of the magnetic circuit 11, the secondary winding 12 and the signal generated by the generator 13 are such that the magnetic circuit 11 follows a magnetization phase PI then saturates after a time which is a function of the value of the inductance of the secondary winding, series resistors of the generator 13 and the secondary winding 12. At the saturation point P2, the inductance of the magnetic circuit 11 decreases and the current Ig increases strongly.
    In the presence of a fault current flowing in the current line, there is a shift of the magnetic field in the magnetic circuit 11 which is manifested by a component, proportional to the fault current, superimposed on the current Ig. Figure 2b shows such an asymmetrical current.
    In the case of using a self-oscillating generator, the generator 13 inverts the polarity of the signal generated as soon as the saturation detection is detected at the point P2, that is to say when the current Ig increases strongly. When the magnetic circuit is saturated by a field that is not related to the operation of the generator 13, the magnetization phase PI disappears. It follows an increase in the frequency of said generator. Figure 2c shows such a current. This increase in frequency is thus a representative indicator of saturation of the magnetic circuit 11. The dimensioning of the magnetic circuit is adapted so that it is not saturated for a fault current equal to the highest tripping threshold. A detection of the saturation of the magnetic circuit will therefore be an indication representative of the presence of a fault current higher than the highest trigger threshold.
    In the case of using a fixed frequency generator, the generator 13 waits for the end of each half-period to invert the polarity of the generated signal. This last variant is simpler to achieve than in the self-oscillating case but does not allow the variation of the frequency to be used as an indicator of the saturation state of the magnetic circuit 11.
    According to the block diagram of FIG. 1, a first circuit 14 makes a measurement of the current Ig. The measuring circuit 14 is connected to a processing circuit 15 which preferably performs a low pass filtering 16 in order to attenuate the high frequency components contained in the current signal Ig, in particular the component at the oscillation frequency. then makes a comparison between the current value obtained and a threshold determined by means of a comparator 17. If the threshold is exceeded, the comparator 17 provides a first fault signal 18 indicating the presence of a fault current.
    The cut-off frequency Fc of the low-pass filter 16 is preferably 150 Hz.
    The switching threshold of the comparator 17 is determined for a fault current in the upper current line, for example at 30 mA or 100 mA or 500 mA, these values being nonlimiting.
    Preferably, the oscillation frequency Pose is chosen to be greater than the frequency of the power supply network 1, for example of the order of 2 kHz, this value being non-limiting. In the case of the choice of a self-oscillating generator 13, the oscillation frequency Pose is mainly a function of the value of the inductance of the secondary winding 12 and the sum of the series resistances of the generator 13 and the secondary winding. 12. These components are chosen so that the self-oscillation frequency Pose is that desired in the absence of fault current.
    Above a given amplitude fault current Uat in the current line 5, for example 10 A, the magnetic circuit 11 becomes saturated and the current Ig generated by the generator 13 is not sufficient to create a magnetic field capable of compensating for the magnetic field generated by the fault current. In this case, the inductance inductance of the winding 12 decreases sharply and the self-oscillation frequency increases to reach a frequency located in a frequency band Fsat much higher than the pitch. For example, Fsat = 30 to 50 kHz whereas Fosc = 2 kHz. Figure 2c shows such a current. Consequently, since the current Ig is a current whose frequency is situated in the frequency band Fsat, the signal at the output of the low-pass filter 16 does not have the amplitude sufficient to switch the comparator 17. The processing circuit 15 is therefore not able to provide a first fault signal 18. The object of the invention is therefore to remedy this drawback and concerns the detection of this change in the operating mode of the oscillator and the detection of the saturation of the magnetic circuit 11 to provide a second fault signal 25.
    A sensor 21 measures the current Ig. The sensor 21 is connected by a link 210 to a control circuit 22. The control circuit 22 is arranged to perform one or more treatments of the measurement of the current Ig: a measurement of the frequency of the current Ig, if the frequency of the current Ig is located in the frequency band Fsat, it is an indication representative of a saturation of the magnetic circuit and the control circuit provides the second fault signal 25, - a comparison of the current Ig to an Igmin threshold , for example 10 mA, if the current Ig is less than Igmini, it is an indication representative of a defect of the generator 13 or a rupture of the winding 12 or a rupture of the connection between the generator 13 and the winding 12, the control circuit then supplies the second fault signal 25, a comparison of the current Ig with an Igmaxi threshold, for example 30 mA, if the current Ig is greater than Igmaxi, it is is an indicat representative ion of a disturbance coming from the electrical network and transmitted by the magnetic circuit 11, the control circuit supplies the second fault signal 25.
    The control circuit 22 is also arranged to make a measurement of the voltage across the secondary winding (12) by means of a sensor 23. The voltage measurement consists of measuring the potential difference between one of the ends VI of the winding 12 and the other end V2 of the winding 12. If the measured voltage is less than a threshold Vmin, for example 2 Volt, it is an indication representative of a saturation of the magnetic circuit , the self inductance of the winding 12 having greatly decreased. In this case, the control circuit supplies the second fault signal 25.
    The treatments carried out by the control circuit 22 can be carried out separately, in parallel or in combination. The control circuit 22 can be realized by means of discrete electronic circuits, functions programmed in a microprocessor or any other known technical means.
    Fig. 3 is a detailed diagram of a differential protection apparatus having a fault current detecting device according to the first embodiment of the invention. The apparatus comprises connecting elements 7 to the electrical network and connecting elements 8 to one or more electrical charges. These elements are preferably in the form of cage terminals but can also be lugs or welds. A cutoff device 50 of the current line is arranged between the connecting elements 7 and 8. The breaking device 50 comprises electrical contacts having the capacity to interrupt the current flowing between the connecting elements 7 and 8. The device cutoff 50 is actuated by an opening control mechanism of the electrical contacts 40 by means of a mechanical connection 41. The control mechanism 40 is preferably an electromagnetic actuator.
    The control mechanism 40 is activated by a state or a transition to an active state of the output 31 of the circuit 30. The circuit 30 performs a logical "OR" function between its two inputs connected to the first fault signal 18 and to the second fault signal 25. Thus, in the presence of the first or the second fault signal or in the simultaneous presence of the two fault signals, the output 31 activates the control mechanism 40, said control mechanism 40 actuating the cut-off device 50 of the current line 5. The fault current can no longer circulate between the electrical network 1 and the or loads 3. The safety of goods and people is ensured.
    Preferably, an inductor 131 is connected in series between the generator 13 and the winding 12 in order to control the frequency of the generator 13 in auto-oscillating mode, when the magnetic circuit 11 is saturated. When the magnetic circuit 11 is saturated, its inductance becomes negligible compared to the inductor 131. The self-oscillation frequency in the frequency band Fsat therefore depends on the value of the inductance 131 and the generator series resistors 13. and the secondary winding 12. The self-oscillation frequency is thus made controllable and can be set to a predefined value. The value of the inductance 131 is preferably of the order of 1 mH, this value being nonlimiting, so that the self-oscillation frequency is in the frequency band Fsat preferably between 30 kFlz and 50 kFlz.
    A current limiting circuit 130 is connected in series between the generator 13 and the secondary winding 12 to limit the current Ig delivered by the generator when the magnetic circuit 11 is saturated. Thus the current can not exceed an Igmaxi threshold which reduces the energy consumption of the device and limit internal heat. The current limiter 130 limits the current by adding an impedance in series when the current flowing through it tends to exceed the Igmaxi level. The value of Igmaxi is of the order of 30 mA, this value being non-limiting.
    The first current measuring circuit 14 preferably consists of a shunt or resistor. Alternatively, it may consist of a Hall effect sensor, giant magnetoresistance (GMR) or giant magneto-impedance (GMI). The processing circuit 15 comprises a filter circuit 16 consisting of an inductor 160 in series with a current-voltage converter 161. The inductor 160 preferably has a value of 10 mH. The preferential use of the current-voltage converter 161 makes it possible to guarantee very good rejection of the high frequencies, in particular the frequency Pose, because it has a minimum load impedance. Thus, the DC component and the low frequency components of the current Ig will flow mainly through the inductor 160 and the current-voltage converter 161 rather than in the shunt 14.
    The output of the current-voltage converter 161 is connected to an amplifier 170. The output of the amplifier 170 is connected to a positive input of the comparator 172. The comparator 172 compares the signal delivered by the output of the amplifier 170. and a fixed threshold 171. When the signal at the output of the amplifier 170 is greater than the threshold 171, the output of the comparator 172 switches to an active state which constitutes the first fault signal 18. The amplifier 170 makes it possible to adjust the signal level so that the emission of the first fault signal corresponds to a specific fault current, for example 30 mA or 300 mA or 5A, these values not being limiting.
    The components 170, 171 and 172 are part of the comparator circuit 17 providing the first fault signal 18.
    The circuits 16 and 17 can be realized by means of analog electronic circuits such as operational or digital amplifiers such as microprocessors.
    The control circuit 22 is arranged to control the electrical signal delivered by the generator 13 and to provide a second fault signal 25 in the event of disturbance of the electrical signal related to a saturation of the magnetic circuit 11 or a fault of the generator 13. According to the embodiment shown in Figure 3, the measurement of the current Ig is obtained by a connection to the sensor 14 by means of the link 210. This saves the cost and bulk of a current sensor 21.
    A control of the frequency of the electrical signal delivered by the generator 13 is carried out by a frequency measuring circuit 221 whose input is connected to the sensor 14 via the link 210 and whose output is connected to the input of a circuit Comparator 224. The output of the comparator 224 is connected to one of the inputs of a circuit 227 performing a logical "OR" of all its inputs. Output 25 of circuit 227 will be active if one or more of its inputs are active.
    The circuit 221 measures the frequency of the current Ig. The comparator 224 activates its output when the frequency of the current Ig is located in the frequency band Fsat which is representative of a saturation of the magnetic circuit 11. The output of the comparator 224 is connected to one of the inputs of the circuit 227 carrying out the OR >> logic of all its entries. When the comparator 224 activates its output, the output of the circuit 227 is therefore activated which provides the second fault signal 25.
    The control circuit 22 comprises a set of modules 222, 225 arranged to control the level of current emitted by the generator 13. The module 222 is a measuring circuit whose input is connected to the sensor 14 via the link 210 and whose output is connected to the input of a comparator circuit 225. In cases where the sensor 14 is a shunt, the current measurement is performed by measuring the voltage between the link 210 and a potential reference 9. This reference of potential 9 is also used by the various measuring and processing modules of the device. The output of the comparator 225 is connected to one of the inputs of the circuit 227 performing the logical "OR" of all its inputs. The module 222 performs the measurement of the current Ig over a wide frequency range. The module 225 compares the signal level measured by the module 222 with a minimum current threshold Igmini. When the current Ig is less than Igmini, it is a defect of the generator 13 or a rupture of the winding 12 or a rupture of the connection between the generator 13 and the winding 12. In this case the output of the comparator 225 is activated. The output of the comparator 225 is connected to one of the inputs of a circuit 227 performing the logical "OR" of all its inputs. When the output of the comparator 225 is activated, the output of the circuit 227 is therefore activated which provides the second fault signal 25. The value of Igmini is of the order of 10 mA, this value being non-limiting.
    It is possible to add other functions to the module 22 including a comparison of the measurement of the current Ig to a maximum current threshold Igmaxi representative of a disturbance coming from the electrical network and transmitted by the magnetic circuit 11. In this case, the module 22 provides the second fault signal 25. The value of Igmaxi is of the order of 30 mA, this value being non-limiting.
    The control circuit 22 comprises a voltage measuring module 223 whose one of the inputs is connected to one of the ends V2 of the winding 12 by the link 200 and whose other input is connected to the other of the ends VI of the The voltage measuring module 223 thus measures a differential voltage across the terminals of the winding 12. The output of the voltage measurement module 223 is connected to the input of a comparison module. a threshold 226. The output of the comparison module 226 is connected to one of the inputs of the circuit 227.
    When the voltage of the electrical signal at the terminals of the secondary winding (12) measured by the module 223 is less than a threshold Vmin, it is a saturation of the magnetic circuit characterized by a low inductance of the winding. 12. The requested current becomes greater than or equal to Igmaxi, the generator does not have the capacity to provide a sufficiently compensating current Ig, the current limiter 130 adds an impedance in series in order to limit the current to an Igmaxi level. In this case, the output of the comparison module 226 is activated and accordingly, the output of the circuit 227 is activated which provides the second fault signal 25.
    The processes carried out by the circuits 221, 222, 223, 224, 225, 226 of the control module 22 can be carried out separately, in parallel or in combination, by means of analog electronic circuits such as operational or digital amplifiers such as microprocessors.
    The different Igmaxi, Igmini, Fsat and Vmin thresholds are preferably fixed by device construction but can also be made parameterizable by adjustment in production, adjustment by means of adjustment knobs located on the front face of the device, or by means of a device. communication, for example NFC ("Near Field Communication"), not shown in Figure 3.
    The circuits 13, 16, 17, 21, 30, 40 are supplied with energy by a power module, not shown in FIG. 3, taking the energy preferentially on the current line 5.
    The fault signal 25 may be used to activate a fault signaling device such as a light or a siren, or a control relay to a signaling device or activate a wired or radio communication module to send a signal. message to a supervision device of the electrical installation. This mode of use is well suited to the case of the monitoring of a fault current in the earth link 2 inside a voltage transformer station located in an isolated site. In this case, the current line 5 comprises a single current conductor.
    FIG. 4 represents, in block diagram form, a fault current detection device according to a second embodiment of the invention. In this embodiment, the detection of the saturation of the magnetic circuit 10 is ensured by measuring the variation of flux Φg in said magnetic circuit by means of a flux sensor 20. Preferably, the flux sensor 20 is a winding wound on the magnetic circuit 11.11 comprises N20 turns, N20 being preferably equal to the number of turns N12 of the winding 12. Preferably N12 = N20 = 50. A variation of the flow Φg in the magnetic circuit 11 induces a voltage Eg across the second winding of the flux sensor 20 such that: Eg = N20 dΦg / dt (where Φg is the magnetic flux and t is the time). For example, a measurement of the peak value of the voltage Eg is representative of the flow variation Φg. The sensor 20 is connected by a link 200 to a control circuit 22. The control circuit 22 is arranged to perform one or more processing of the measurement of the voltage Eg such that: the measurement of the frequency of the voltage Eg, if said frequency is located in the frequency band Fsat, it is a saturation of the magnetic circuit, the control circuit 22 provides the second fault signal 25; the comparison to a threshold Egmini, if the voltage Eg is less than Egmini, it is the saturation of the magnetic circuit 11 or a defect of the generator 13 or a rupture of the winding 12 or a break of the connection between the generator 13 and the winding 12 and in this case, the control circuit 22 provides the second fault signal 25; the comparison with a threshold Egmaxi, if the voltage Eg is greater than Egmaxi, it is a disturbance coming from the electrical network, transmitted by the magnetic circuit 11, the control circuit 22 provides the second fault signal 25. Preferably the peak value of Egmini = 2 Volt.
    Preferably the peak value of Egmaxi = 4 Volts.
    The treatments carried out by the control circuit 22 can be carried out separately, in parallel or in combination. The control circuit 22 can be realized by means of discrete electronic circuits, functions programmed in a microprocessor or any other known technical means.
    The flow sensor 20 and the control circuit 22 are functionally independent of the circuits 14 and 15. Having no common circuit, this configuration of the device provides greater reliability.
    FIG. 5 represents a detailed diagram of a differential protection device according to the second embodiment of the invention.
    The flux sensor 20 is an additional winding wound on the magnetic circuit 11. Said sensor constitutes a flow sensor of the magnetic circuit 11 and the voltage Eg at its terminals is representative of the flow variation Φg. in the magnetic circuit. When the magnetic circuit 11 is saturated, the variation dΦg / dt is low, the voltage Eg is close to zero. The sensor 20 is connected to the alternating inputs of a diode bridge 224. The diode bridge 224 rectifies the alternating signal supplied by the sensor 20. A capacitor 225 is connected between the positive and negative outputs of the diode bridge 224. A resistor 226 connected in parallel on the capacitor 225 discharges said capacitor when the voltage Eg is low. The positive output of the diode bridge 224 is connected to the negative input of the comparator 223. Said comparator 223 compares the voltage between its negative input and its positive input connected to the threshold 222, equal to Egmini, and activates the output 25 when the voltage on its negative input is below threshold 222.
    Thus, when the magnetic circuit 11 is saturated, the voltage Eg is close to zero, the voltage across the capacitor 225 is close to zero, the output of the comparator 223 becomes active and provides the second fault signal 25.
    The operation of the device is identical if the generator 13 is in fault or in the case of a rupture of the winding 12 or a rupture of the connection between the generator 13 and the winding 12.
    The value of the resistor 226 is chosen so that the discharge time of the capacitor 225 is less than a time Td. Thus, when a fault current or an internal failure of the device occurs, the output of the comparator 223 becomes active after a maximum delay Td and, consequently, activates the control mechanism 40, said mechanism actuating the cutoff device 50 of the current line 5. The elimination of the fault current thus has a duration close to Td. The time Td is preferably determined to be in accordance with a maximum time of normative triggering. This time is preferably 40 ms.
    Alternatively, in order to reduce the cost of the device or its bulk, the diode bridge 224 can be replaced by a rectifying diode connected between one of the terminals of the sensor 20 and one of the terminals of the capacitor 225, the other terminal of the sensor 20 being connected to the other of the terminals of the capacitor 225.
    While being very simple, the control circuit 22 according to this embodiment makes it possible to detect a saturation of the magnetic circuit and therefore the presence of a large fault current in the current line 5 or allows the detection of an internal failure. of the device. The sensor 20 and the control circuit 22 being independent of the measurement circuits 14, filtering 16 and comparison 17, the reliability of the device is increased.
    FIG. 6 represents, in block diagram form, a differential protection assembly according to the invention. The assembly is composed of a first differential protection module 70 comprising a current sensor 71 in which the current line 5 composed of two electrical conductors, for example a phase conductor and a neutral conductor, passes, said sensor 71 being connected to a processing module 72. The processing module 72 measures the current level of differential fault and provides a fault signal 73 when the fault current level exceeds a threshold.
    The module 70 is preferably a module responsive to the pure alternating fault current or sensitive to the alternating and pulsed fault current. It is not very sensitive to the continuous fault current or the frequency fault current much lower than the frequency of the power supply network 1. The module 70 is preferentially self-powered to energy its sensor 71, the latter providing the necessary energy the operation of the processing module 72 and the activation of the fault signal 73.
    The module 60 is preferably a module comprising the device of the invention. It activates the fault signal 31 in the presence of a fault current exceeding a fixed threshold or in case of detection of the saturation of the magnetic circuit of the sensor 10. The power supply for the operation of the module 60 is made by a connection to the conductors of the current line 5 by means of the links 61.
    The fault signals 31 and 73 activate the opening control mechanism of the electrical contacts 50 by means of a mechanical connection 41.
    The connection of the current line 5 between the modules 60 and 70 can be made by wire connection, by connecting comb, by connector or be welded.
    Alternatively, a control mechanism 40 can be implanted in the module 60 and a second control mechanism 40 can be implanted in the module 70, each control mechanism 40 can actuate the mechanical link 41.
    In another variant, the module 60 may be a differential protection device according to the invention with which a module 70 for detecting pure alternating fault current or alternating and pulsed fault current is associated.
    This differential protection assembly has the advantage of providing protection against pure alternating currents, pure continuous currents and all pulsed currents by combining the properties of each of the differential protection devices that compose it. Its modularity makes it possible to reduce the number of commercial references since with a base of two sets, it is possible to produce three products with different characteristics.
    The device according to the invention is particularly intended for the protection of people and property against alternating differential fault currents in a wide frequency range including the frequency of the electrical network, and against the continuous or pulsed differential fault currents. The control circuit 22 allows the saturation detection of the magnetic circuit 11 of the current sensor 10. Thus, even in the presence of a very high level of fault current, the device according to the invention is able to provide the opening the electrical contacts 50 in order to cut off the fault current. Moreover, according to the preferred embodiment of the control circuit 22, any internal operating anomaly of the generator 13 is detected which generates a fault signal 22. The operating safety of the device is thus greater than that of the devices described in FIG. prior art.
    权利要求:
    Claims (14)
    [1" id="c-fr-0001]
    Apparatus for detecting a fault current flowing in a current line (5), comprising: - a current sensor (10) formed of a magnetic circuit (11) traversed by the current line (5), the latter forming a primary, said sensor comprising at least a first secondary winding (12) wound on the magnetic circuit (11), - a generator (13) connected to the first secondary winding (12) to deliver an alternating electric signal thereto, - a measuring circuit (14) for measuring a current flowing in the secondary winding (12), - a processing circuit (15), connected to the current measuring circuit (14), for providing a first fault signal ( 18) when said current measurement exceeds a threshold, characterized in that said device comprises a control circuit (22): - to control the electrical signal delivered by the generator, and - to provide a second fault signal (25) when said electrical signal is representative of a saturation of the magnetic circuit (11).
    [2" id="c-fr-0002]
    2. Device according to claim 1 characterized in that the device detects a saturation of the magnetic circuit (11) representative of a fault current amplitude greater than a saturation threshold (Uat) ·
    [3" id="c-fr-0003]
    3. Device according to one of claims 1 or 2 characterized in that the control circuit (22) measures the amplitude (Ig) of the current of the electrical signal delivered by the generator and provides the second representative fault signal (25). a saturation of the magnetic circuit when said amplitude (Ig) is greater than or equal to a high threshold (Igmaxi).
    [4" id="c-fr-0004]
    4. Device according to one of the preceding claims characterized in that the control circuit (22) measures the voltage of the electrical signal to the secondary winding terminals (12) and provides the second fault signal (25) representative of saturation of the magnetic circuit when said voltage is less than or equal to a low threshold (Vmin).
    [5" id="c-fr-0005]
    5. Device according to one of the preceding claims characterized in that the control circuit (22) measures the frequency of the electrical signal delivered by the generator and provides the second fault signal (25) representative of a saturation of the magnetic circuit when said frequency is in a predefined frequency band (Fsat).
    [6" id="c-fr-0006]
    6. Device according to one of the preceding claims characterized in that the control circuit (22) measures the amplitude of the current of the electrical signal delivered by the generator and provides the second fault signal (25) representative of a defect of the generator when said amplitude is lower than a low threshold (Igmini).
    [7" id="c-fr-0007]
    7. Device according to one of the preceding claims characterized in that the control circuit (22) measures a variation of flux as a function of time in the magnetic circuit (11) and provides the second fault signal (25) representative of a saturation of the magnetic circuit when said variation of flux is lower than a low threshold (Egmini) ·
    [8" id="c-fr-0008]
    8. Device according to claim 7 characterized in that the measurement of the flow variation in the magnetic circuit (11) is performed by means of a second secondary winding (20) wound on the magnetic circuit (11).
    [9" id="c-fr-0009]
    9. Device according to one of the preceding claims characterized in that it comprises a current limiter limiting the amplitude (Ig) of the current of the electrical signal delivered by the generator (13) to a high value (Igmaxi).
    [10" id="c-fr-0010]
    10. Device according to one of the preceding claims characterized in that the generator (13) is self-oscillating.
    [11" id="c-fr-0011]
    11. Device according to claim 10 characterized in that it comprises an inductance (131) connected in series between the generator (13) and the first secondary winding (12) to set the frequency of oscillation of the generator (Pose) in the frequency band (Fsat) when the magnetic circuit (11) is saturated.
    [12" id="c-fr-0012]
    Device according to one of the preceding claims, characterized in that the second fault signal (25) activates a fault signaling device, a control relay or a communication module.
    [13" id="c-fr-0013]
    13. Electrical differential protection device comprising: - connection elements (7) to an electrical network and connecting elements (8) to one or more electrical loads, - a cutoff device (50) of the current line arranged between the connecting elements (7) to the electrical network and the connecting elements (8) of the electric charge or charges, said breaking device comprising electrical contacts, and - an opening control mechanism (40) of the electrical contacts , characterized in that it comprises a device for detecting a fault current according to one of claims 1 to 12 and that the contact opening control mechanism (40) is activated by the first fault signal ( 18) or by the second fault signal (25).
    [14" id="c-fr-0014]
    14. Differential protection assembly comprising: - connecting elements (7) to the electrical network and connecting elements (8) to one or more electrical loads, - a cutoff device (50) of the current line arranged between the connecting elements (7) to the electrical network and the connecting elements (8) of the electrical load or charges, said breaking device having electrical contacts, and - an opening control mechanism (40) of the electrical contacts, characterized in that said assembly is formed by an assembly of: - a first defect current detection device (60) according to one of claims 1 to 13, - a second differential protection device (70) , arranged to provide a fault signal (73), such that the contact opening control mechanism (40) is activated by the first fault signal (18) or the second fault signal (25) of the first er device (60) or by the fault signal (73) of the second differential protection device (70).
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    同族专利:
    公开号 | 公开日
    EP3232526A1|2017-10-18|
    ES2877123T3|2021-11-16|
    EP3232526B1|2021-06-02|
    CN107394744A|2017-11-24|
    FR3050081B1|2018-03-23|
    CN107394744B|2020-03-06|
    引用文献:
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    AT550819T|2001-06-12|2012-04-15|Doepke Schaltgeraete Gmbh|DEVICE FOR DETECTING ELECTRICAL DIFFERENTIAL FLOWS|
    FR2862423B1|2003-11-18|2005-12-30|Schneider Electric Ind Sas|DEVICE AND METHOD FOR DIFFERENTIAL PROTECTION AND ELECTRICAL APPARATUS COMPRISING SUCH A DEVICE|
    FR2887634B1|2005-06-24|2007-08-10|Schneider Electric Ind Sas|DIFFERENTIAL CURRENT MEASURING DEVICE, TRIGGER MODULE COMPRISING SUCH A MEASURING DEVICE AND CUTTING DEVICE HAVING SUCH A MODULE|
    DE102007003830B4|2007-01-25|2009-08-06|Robert Seuffer Gmbh & Co. Kg|Device for measuring an electrical current flowing through an electrical conductor|DE102018204047A1|2018-03-16|2019-09-19|Siemens Aktiengesellschaft|Residual current protection unit|
    FR3084932B1|2018-08-09|2020-10-09|Schneider Electric Ind Sas|DEVICE FOR DETECTION OF A DIRECT OR ALTERNATIVE ELECTRIC CURRENT, MODULE AND PROTECTION DEVICE INCLUDING SUCH A DEVICE|
    DE102019204272B4|2019-03-27|2021-10-07|Siemens Aktiengesellschaft|Residual current device and procedure|
    FR3108453A1|2020-03-19|2021-09-24|Schneider Electric Industries Sas|Electrical protection devices and associated processes|
    FR3111746A1|2020-06-23|2021-12-24|Hager-Electro Sas|Method for detecting leakage or fault currents in an electrical installation from a protection device providing at least differential protection and such a device suitable for the implementation of said process|
    法律状态:
    2017-04-06| PLFP| Fee payment|Year of fee payment: 2 |
    2017-10-13| PLSC| Publication of the preliminary search report|Effective date: 20171013 |
    2018-04-18| PLFP| Fee payment|Year of fee payment: 3 |
    2019-04-29| PLFP| Fee payment|Year of fee payment: 4 |
    2020-04-30| PLFP| Fee payment|Year of fee payment: 5 |
    2021-04-27| PLFP| Fee payment|Year of fee payment: 6 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1653183A|FR3050081B1|2016-04-12|2016-04-12|DEVICE FOR DETECTING A DEFAULT CURRENT|
    FR1653183|2016-04-12|FR1653183A| FR3050081B1|2016-04-12|2016-04-12|DEVICE FOR DETECTING A DEFAULT CURRENT|
    ES17154930T| ES2877123T3|2016-04-12|2017-02-07|Device for detecting a fault current|
    EP17154930.6A| EP3232526B1|2016-04-12|2017-02-07|Device for detecting a fault current|
    CN201710217737.2A| CN107394744B|2016-04-12|2017-04-05|Device for detecting fault current|
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