Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H1/00—Details of emergency protective circuit arrangements
  • H02H1/0007—Details of emergency protective circuit arrangements concerning the detecting means
  • H02H1/003—Fault detection by injection of an auxiliary voltage
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
  • G01R19/02—Measuring effective values, i.e. root-mean-square values
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
  • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
  • G01R27/20—Measuring earth resistance; Measuring contact resistance, e.g. of earth connections, e.g. plates
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
  • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
  • G01R27/20—Measuring earth resistance; Measuring contact resistance, e.g. of earth connections, e.g. plates
  • G01R27/205—Measuring contact resistance of connections, e.g. of earth connections
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H5/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection
  • H02H5/10—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to mechanical injury, e.g. rupture of line, breakage of earth connection
  • H02H5/105—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal non-electric working conditions with or without subsequent reconnection responsive to mechanical injury, e.g. rupture of line, breakage of earth connection responsive to deterioration or interruption of earth connection

Definitions

• Electrical measuring device for measuring the resistance of an earth electrode of an electrical installation.
• the invention relates to the field of electrical installations of electrical power distribution networks, including devices for measuring the grounding resistance of the masses of the electrical installation.
• the invention further provides an electrical measurement method for monitoring the evolution of the earth ground of the masses of the electrical installation and to issue an alert when the grounding resistance of the masses is not more appropriate for the protection of people.
• grounding material izes in its simplest expression by a metal portion which is driven into the ground to ensure an effective electrical connection with the earth (for example in the form of a metal stake planted in the ground or of buried metal cables).
• the earth electrode is a reference potential within the electrical installation which is used in particular to discharge electric charges of the installation such as the loads of a fault current.
• a fault current can be generated by an electrical anomaly in the installation (such as a localized insulation fault, for example).
• the fault current then flows via the earth electrode and it can be detected by means of protection associated with the earth electrode (such as a residual current circuit breaker (DDR) for example).
• DDR residual current circuit breaker
• the circuit breaker then goes into a "triggered" position (opening of the electrical circuit) to prevent any electrical hazard.
• the cooperation of the earth electrode and a residual differential circuit breaker thus makes it possible to avoid dangerous elevations of potential of the masses that can be touched by an individual.
• the electrical resistance of the earthing of the masses must not exceed a well-defined threshold resistance.
• This threshold resistance is a function of the type of power supply (according to AC current) and the surrounding humidity conditions.
• the maximum voltage during indirect contact with an individual must be 50 V in AC, with a fault current of a maximum of 0.5 A (which is usually the value of the rating of the branch differential circuit breaker (NFC 14-100) associated with earth grounding).
• the resistance of the earth electrode must not exceed a threshold resistance of 100 ⁇ .
• the variation of the humidity level (emanating from water damage, for example); and or
• Regular monitoring of the grounding can be done using portable devices known to perform a point measurement of earth grounding.
• the resistance obtained during a measurement is a cumulative resistance of the earthing of the masses and the neutral of the transformer. Since the resistance of the ground of the neutral of the transformer is relatively low, it is considered that the measurement of resistance obtained corresponds to a current value by excess of grounding of the masses.
• there are also devices for measuring the grounding which require the disconnection of the earth ground of the masses of the installation and the implantation in the ground of stakes near the grounding of the masses.
• the implanted stakes allow current injections and potential measurements to determine the current grounding resistance of the masses.
• these devices are intended to perform only spot checks of the earthing of the masses. They also have the disadvantages of requiring: the occupation of a socket outlet of the installation (requiring, in particular, the possible disconnection of an electrical device to carry out the verification), or
• binding implementation operations for each action to be taken disconnect of the grounding of the electrical installation, which earth connection of the masses is often difficult to access, and implantation of stakes in the ground, which does not is not always possible for example in urban areas;
• the second detector which requires the disconnection of the earthing of the masses of the installation can not ensure that the connection of the protective conductors of all the socket-outlets of the installation is connected to the earthing of the masses.
• the present invention improves the situation.
• the invention proposes in particular an electrical measuring device which regularly or even continuously carries out measurements of the grounding resistance of the masses for an accurate monitoring of its evolution (ie state of grounding of the masses during its aging) .
• the device and the method proposed are furthermore designed to alert a user and / or an operator when an electrical risk has been proved from the measured value of earth grounding.
• a first aspect of the invention relates to an electrical measuring device which comprises at least:
• a regulated and controlled alternating current generator for injecting alternating current on the first electrical connection
• control unit adapted for:
• o comparing the determined resistance with a predetermined threshold; and o issuing a first warning instruction when said compared resistance exceeds said predetermined threshold.
• the voltage generated between the first and second links can be measured:
• the measuring device makes it possible to warn of a predetermined threshold overrun. A user or an operator can thus be warned by the alert issued of an inappropriate value of the resistance of the earthing of the masses, which value can lead to a risk situation for users.
• the device thus makes it possible to follow rigorously the variations in the earthing of the masses in time, and the connection of the device to this earth electrode, and to alert a user or an operator as soon as the grounding of the earths masses no longer conform to a safe state (ie resistance within a safe range). With this rigorous monitoring, a quick detection as soon as the fault appears is possible. An intervention can thus be carried out quickly to repair the connection to the earthing of the masses or to check and possibly build a new earth ground and thus reduce its value below the predetermined threshold.
• the safety range may be based in particular according to the requirements defined by NFC standards 15-100 and / or IEC 60364.
• the device ensures that the electrical safety of the device, the user and the installation is durable.
• the device is particularly adapted to be installed in a low voltage electrical installation performed according to a ground connection scheme in TT mode.
• an electrical appliance connected to the electrical installation such as a television-type equipment, computer, washing machine, refrigerator, or an electrical panel of the installation.
• the device may further comprise a power supply cutoff switch of an electrical apparatus connected to the installation, the control unit being adapted to open the switch when the compared resistance exceeds the predetermined threshold.
• the electrical apparatus in question may be equipment connected to the installation or the electrical panel of this installation. In an open position, the bipolar switch opens the single-phase power supply circuit. The electrical apparatus is therefore no longer supplied with electricity. In fact, if this device has an insulation fault, the conductive grounds of this device or of this installation are no longer powered by the active conductors (phase or neutral), which avoids any risk of electrification or electrocution. an individual with the device in question.
• the measuring device By being installed or delivered with the electrical device, the measuring device is thus directly implanted fixedly in the electrical installation. Monitoring the evolution of the connection of the device with the earthing of the masses of the installation makes it possible to ensure that the electrical apparatus is properly connected. This monitoring makes it possible to:
• the safety of the user is therefore increased since the device is powered only if the grounding resistance of the masses of the installation makes it possible to protect it from an electrical hazard dangerous to humans (if not power to the device is cut off by the switch that is placed in the open position).
• the device may further comprise an autonomous source of power supply.
• a power supply can be taken upstream of the bipolar switch to allow the device to recharge the backup battery in case of loss of power to the device and thus continue to operate by generating including a warning set.
• the switch goes to the open position, cutting off the power received by the device, the device issues an alarm.
• the injected current is regulated in time according to at least a first level of current and a second level of current successively injected, the first and second current levels being distinct.
• the device may further comprise a third electrical connection to a phase conductor of the network.
• the control unit can also be adapted to:
• the required voltage range may be between 200 volts and
• control unit can prevent voltage measurements and issue an alert, in particular to propose an intervention of an operator of the power distribution network to restore a supply voltage expected by the device.
• the control unit therefore conducts voltage measurements when the electrical conditions allow stable current injections by the generator.
• the device may further comprise a non-volatile memory capable of storing data such as data relating to the predetermined threshold, to the measured voltage, to said measured true rms voltage and / or to the determined resistance.
• the data of the predetermined threshold and the values of measured voltages and the determined resistance values are thus stored durably within the device.
• the resistance compared to the predetermined threshold may be an average grounding resistance value of the masses calculated by the control unit from data stored in the memory.
• the memory may further be adapted to store data relating to the calculated average resistance value.
• the determined average value can be based on resistance values measured at specific times. This average is a representative value of the state of grounding of the masses over a given period of time. This weighted average makes it possible to integrate any non-homogeneous calculated resistance values due to a possible instability observed in the measurements of the voltages between the neutral conductor and the ground, since the injected current is considered stable if the generator regulates the current under the above-mentioned required voltage range (which may be between 200 volts and 250 volts).
• the average value may be a weighted average of the resistance values measured each hour during a day.
• the average obtained is therefore representative of the state of grounding of the masses for the day in question.
• the average value may in particular be compared with the predetermined threshold to determine whether the resistance of the earthing of the masses is, during a given period of time, in a state generally suitable for the installation or requires the emission of an alert to report a dangerous situation.
• the average value recorded thus makes it possible to have a good representation of the evolution of the grounding of the masses in time, without requiring the processing of a very large number of measured values at each post processing of the archived data.
• the data archived in the device can be horo dated when stored in the memory.
• the stored and time stamped data can be used in post-processing or by the control unit to establish a history of the measurements and to trace the variations of measured voltages and resistances over time encountered by the earth electrode. masses.
• the predetermined threshold may in particular be an electrical resistance value of between 25 and 100 ⁇ .
• the electrical resistance value can thus be set according to the requirements of the NFC 15-100 standard (or the European standard IEC 60364).
• the value of the predetermined threshold is:
• the predetermined threshold can be initialized according to is a value slightly lower than the limits prescribed by the standard, such as 5% lower than the above values.
• the value of the predetermined threshold can also be initialized according to a value that may exceed 100 ⁇ (800 ⁇ for example in Spain with a branch circuit breaker of ⁇ 30 mA), provided that this value ohmic does not expose a user to a voltage greater than 50 Volts with a branch circuit breaker ⁇ 500 mA, in case of indirect contact.
• the device may further comprise a communication unit transmitting to a remote entity the first and / or the second alert issued.
• the measurement device can issue the alerting instructions to a remote entity such as a management center or a communicating equipment of a user such as a mobile phone (typically a smartphone). Therefore, when a risk situation is detected or the voltage supplied to the device is outside the required range, the instruction is sent directly to the management center or to the user so that a rapid intervention can be implemented. to repair or replace the earthing of the masses, or restore a correct power supply of the device (according to a voltage of about 230 Volts typically). The safety of individuals is thus further improved.
• the communication unit may also be able to transmit, on request, data stored in said memory.
• the determined resistance data, the measured voltage data and / or the predetermined threshold value can be transmitted, on request from a remote entity or a user (via an application on his Smartphone for example).
• This communicated data notably allows the deployment of remote monitoring services of the grounding failures of the device and its power supply.
• the device may further comprise a local alarm module emitting a signal when one of the first and second alerting instructions is issued.
• the local alarm module can include:
• a loudspeaker emitting an audible signal when the predetermined threshold is exceeded and / or the device is not powered by a voltage within the required voltage range;
• a light source such as an LED emitting for example a color light signal
• the electrical measuring device may further comprise a display screen displaying the nature of the alert when an alert instruction is issued, or the date and time when this instruction was issued.
• the display screen can also show the last average resistance and network voltage.
• the invention relates to a domestic electrical appliance connected to an electrical installation connected to a general electrical network, which installation is provided with a grounding ground,
• the electrical appliance is connected to the earth electrode of masses and is equipped with a measuring device electric as described above.
• This electrical device can be a type of equipment such as television, computer, washing machine, refrigerator, or other, or an electrical panel of the installation.
• the invention relates to an electrical measurement method via an electrical measuring device.
• the method comprises at least the steps of:
• the method may further comprise a step of cutting a power supply of an electrical appliance connected to the installation when the resistance compared exceeds said predetermined threshold.
• the resistance compared with said predetermined threshold is a weighted average value calculated from measured values of the grounding resistance of the masses.
• the current injection step comprises a regulation of the current in time according to at least a first level of current and a second level of current injected successively, the first and second levels being distinct.
• the method may furthermore comprise steps of:
• the method may furthermore comprise:
• a step of initialization of the threshold according to an electrical resistance value and a step of storing data relating to the threshold in a non-volatile memory.
• the method may further comprise a step of time stamping and storage in the data memory relating to the measured voltage and the determined resistance.
• the resistance compared with the predetermined threshold is an average grounding resistance value of the masses calculated by the control unit from data stored in the memory.
• the method may comprise a step of communicating with an entity that is distant from the first and / or the second alert setpoint sent.
• the steps a) and b) can be repeated successively according to a first frequency
• the step c) can be repeated according to a second frequency
• the steps d) and e) can be repeated successively according to a third frequency.
• the first, second and third frequencies may respectively be of decreasing frequency value.
• the first frequency may be a so-called high frequency in a regular manner (every 500 ms for example), or even continuously.
• the second frequency may be a frequency so as to perform regularly (typically every minute or every hour) the weighted average value calculation of the grounding resistance of the masses according to the values of the resistances calculated over the period considered.
• This weighted average makes it possible to integrate any non-homogeneous calculated resistance values due to a possible instability observed in the measurements of the voltages between the neutral conductor and the ground, since the injected current is considered stable if the generator operates under the range. aforementioned voltage requirement.
• the third frequency can be a frequency adapted to the monitoring of the evolution of grounding masses over time such as a daily or weekly frequency.
• This lower frequency can be adapted to calculate the differences between two weighted averages during a day, a week or a month, and to deduce the possible growth of the resistance of the grounding over this period.
• the invention further relates to a computer program for storage in a memory of an electrical measuring device.
• This computer program comprises instructions readable by a processor of a control unit of the device, the processor implementing the method described above when said instructions are executed by the processor
• the invention further relates to a computer program for storage in a memory of an electrical measuring device.
• This computer program includes instructions readable by a processor of a control unit of the device, the processor implementing the method described above when said instructions are executed by the processor.
• FIG. 1a shows an example of an electrical installation which comprises an electrical appliance incorporating the electrical measuring device according to the invention
• FIG. 1b shows an example of an electrical installation which comprises a low-voltage electrical panel integrating the electrical measuring device according to the invention
• FIG. 2a shows a first embodiment of the electrical measuring device
• FIG. 2b shows a second embodiment of the electrical measuring device
• FIG. 3a is a flowchart representing a first example of a succession of steps of the electrical measurement method according to the invention.
• FIG. 3b is a flow chart showing a second example of a succession of steps of the electrical measurement method according to the invention.
• the dimensions of the various elements shown in these figures are not necessarily in proportion to their actual dimensions.
• identical references correspond to identical elements for the various embodiments shown.
• FIG. 1a on which is illustrated an exemplary embodiment of the electrical measuring device DIS equipping a domestic electrical appliance AED of a low voltage electrical installation INS connected to a general power distribution network RG.
• This set forms a low voltage electrical system where the DIS device is integrated with the AED apparatus.
• the AED device is a device operating on a power supply provided by a low voltage domestic RED power grid.
• Such an appliance may be domestic electrical equipment (refrigerator, washing machine, dryer, etc.) or any other electrical housing equipment (domestic hot water system, radiators, air conditioner, etc.).
• the panel TE is intended to receive a power supply from a distribution transformer T or other installation of an electric power distributor.
• the distribution transformer T is here a three-phase star transformer with accessible neutral point, supplying electrical conductors L1, L2, L3 and whose accessible neutral point is connected to the earth ground of the neutral RN used as reference neutral point with the LN neutral electric conductor of the RG network.
• the power distribution network RG is arranged according to a ground connection scheme in TT mode. Also, the neutral of the distribution transformer T is grounded via the earth ground of the neutral RN and, as detailed below, the masses of the electrical equipment connected to the domestic electrical network RED, such as the apparatus AED, have their own connection to the GRO grounding of the INS installation via the PE conductor.
• the panel TE is thus connected: to the neutral of the distribution transformer T via a neutral conductor CN connected to the electrical conductor LN; to his own earth ground Ra via the PE conductor; and
• the power received from the transformer T by the panel TE is then distributed to different branches of the domestic electrical network RED.
• the panel distributes the conductors C3, CN and PE in the domestic network RED in order to supply the electrical appliances connected to the latter.
• a branch circuit breaker DB (typically a residual current circuit breaker (DDR) with a rating of 500 mA, denoted respectively ⁇ 500 mA) can be arranged upstream of the low-voltage switchgear TE to protect the distribution transformer T, the switchgear TE low voltage and RED network in case of failure.
• DDR residual current circuit breaker
• the panel TE is arranged at the head of the RED network and makes it possible to feed the various downstream RED power lines securely via circuit breakers D.
• the circuit breakers D are organized in the form of rows of circuit breakers.
• the circuit breakers D may in particular be residual differential circuit breakers (RCDs) calibrated so as to protect against electrical damage to the power lines associated with them (such as an electrical overload or a short circuit).
• RCDs residual differential circuit breakers
• the circuit breakers of a housing array TE are of a 30 mA rating (i.e. ⁇ of 30 mA).
• the electrical lines that they protect can consist of the phase conductor C3, the neutral conductor CN and the ground conductor PE.
• the PE conductor is connected to the earth ground GN of the INS installation.
• the grounding of the masses Ra of the INS installation can materialize in the form of:
• This grounding is usually located in the building with the INS facility or nearby.
• the power lines downstream of the panel TE are intended to supply the domestic electrical network RED and the electrical equipment (not shown in the figures) connected to it.
• the equipment is then connected to the neutral via the CN conductor of the corresponding power line, and to the power supply via the conductor C3 and to the ground via the PE conductor of this same line.
• the resistance of the earth electrode should not exceed a security threshold value.
• the NFC 15-100 standard defines that the resistance of the earth electrode must not exceed 100 ⁇ if the RED network is in AC supply in dry rooms.
• the AED device is also linked to:
• the power received by the AED apparatus is therefore a single-phase power supply.
• the AED device can be provided with additional conductors respectively connected to the L1 and L2 conductors via the RED network and the TE switchboard.
• the AED apparatus integrates the electrical measuring device DIS allowing the monitoring of the earth ground of the masses Ra and the PE link.
• the AED apparatus may integrate the DIS device in situ or may be equipped with such a device. Since the AED apparatus is equipped with the DIS device, the AED apparatus is arranged so that the device is connected to at least:
• phase and neutral conductors can be crossed in the socket or the junction box that supplies the device. These same conductors can also be crossed in the plug of the power cable or on the terminal block of the device.
• the DIS device can be provided with an inverter switch that powers the GEN generator. This inverter switch is controlled in a first position by the unit UC if a voltage close to the nominal voltage (230 Volts for example) is measured between the conductors C3 and PE. Otherwise, the UC unit switches the switch to position 2.
• the DIS device that equips the device can therefore, according to possible embodiments, be installed on the AED device, outside the enclosure of the AED device or close to the device being connected to the device via a dedicated power line, or arranged as an interface between the RED network and the power cable of the device or arranged on the power cable of the device.
• the device DIS is integrated in the apparatus AED, arranged in intermediate position between the network RED and the terminal block BOR of the apparatus AED.
• FIG. 1b on which is illustrated an exemplary embodiment of the electrical measuring device DIS equipping the low-voltage electrical panel TE of an electrical installation INS connected to a general power distribution network RG.
• the power received by the panel TE is therefore a single-phase power supply.
• the panel TE can be provided with additional conductors respectively connected to the conductors L1 and L2.
• the panel TE integrates the electrical measuring device DIS allowing the monitoring of the resistance of the grounding points Ra, RN and the neutral conductor.
• the device DIS comprises in particular a connection to the PE conductor.
• the TE array may integrate the DIS device in situ or may be equipped with such a device. Since the TE board is equipped with DIS device, the TE array is arranged so that the device is connected at least:
• the DIS device that equips the board can therefore, in one possible embodiment, be installed on the board TE, outside the enclosure of the board or near the switchboard, being connected to the board via a line dedicated electric.
• the device DIS comprises, in particular, connections to the earth ground of the masses Ra, to the neutral conductor LN of the network RG and to a phase conductor L3 of the network RG via electrical connections such as:
• phase conductor C3 connected to the phase conductor L3.
• the DIS device further comprises:
• an LED light source (of the electroluminescent diode type);
• an autonomous BAT power supply (rechargeable battery type or other charge accumulator);
• the converter is intended to transform the AC power received by the device between the links C3 and CN into DC power supplies for powering the various electrical and electronic components of the DIS device mentioned above (including the unit UC, the screen ECR, GEN generator, etc.).
• grounding resistance measurement of the masses can be carried out in particular by means of a ground fault current loop technique consisting of:
• measuring a voltage generated between the CN and PE conductors by the injected current (by measuring an instantaneous difference of potential for peak values of the injected current when the latter is a sinusoidal alternating current, or else by measurement of true rms voltage ( RMS)).
• the resistance (Rdet) of the earth ground can be determined by the unit UC as a function of the value of the injected current (3 ⁇ 4) and the value of the voltage measured (U mes ).
• the generator GEN is regulated and controlled by the control unit UC to provide a stable alternating current in one or two levels (respectively 1 and 15 mA peak value for example), the alternating current being injected in phase with the power supply received from the C3 and CN conductors.
• this power range can be between minus ten percent (-10%) and plus six percent (+ 6%) of a nominal voltage of 230 volts.
• the unit UC can be adapted to measure the RMS value of the supply voltage between the conductors C3 and CN (being connected to an electronic circuit for measuring true RMS voltage connected between drivers C3 and CN for example).
• the CPU can prevent voltage measurements and transmit an alert (as detailed below).
• the alert issued may notably propose a intervention by an operator of the power distribution network to restore a supply voltage within the required voltage range. If the detected voltage is zero, the alert emitted indicates a power failure.
• the unit UC conducts voltage measurements only for a stable current injected by the generator GEN according to at least one regulated level.
• the unit UC can also be made to measure the voltage between the CN and PE conductors, generated by the current or currents injected into the PE conductor.
• the difference in potential can notably be measured according to:
• This potential difference or true rms voltage can be measured by the CPU unit via a digital analog converter type device connected to a voltage sensor disposed between the PE and CN conductors.
• the analog digital converter is driven by the unit.
• the determined resistance (Rdet) is a function of the injected current (I inj ) and a measurement of the instantaneous voltage (U mes ) performed simultaneously with the injection of the current.
• An excess value of the grounding resistance of the masses Ra is then obtained because the determined resistance (Rdet) therefore includes the grounding resistance of the neutral RN and the neutral conductors LN and CN.
• This calculation method determines a resistance Rdet which is an inaccurate resistance value by excess of the grounding resistance of the masses Ra. It has the advantage of having an excess value of grounding Ra which makes it possible to introduce a safety margin (since RN + LN + CN + Ra is of a value greater than the real resistance value of the grounding of the masses Ra). However, it can give rise to false alarms (resistance Ra taken in reality well below the threshold).
• the determined resistance is a function of a current injected according to two distinct levels of AC currents (I inj ), sinusoidal and in phase with the supply voltage of the device DIS received from the conductors C3 and CN. These current levels can be injected into the earth ground of the masses Ra.
• this differential calculation mode determines a resistance Rd e r which is also an excess resistance value of the grounding resistance of the masses Ra. Indeed, it takes into account the resistance of the ground of the neutral RN of the distribution transformer T. However, it has the advantage of subtracting the resistance of LN and CN conductors.
• the additional resistance RN being relatively small, the value of Ra by excess makes it possible to introduce a reasonable margin of safety (since RN + Ra is only slightly higher than the actual resistance value of the earth ground of the masses Ra ).
• the determined resistance (Rdet ”) is also a function of the injected current according to two distinct levels of AC currents (3 ⁇ 4), sinusoidal and in phase with the supply voltage of the device DIS received from the conductors C3 and CN.
• a mean M ( ⁇ U mes ) N is determined which corresponds to the homogeneous values obtained for N instantaneous voltage measurements synchronized with the peak values of the AC currents injections according to two levels .
• the average M ( ⁇ U mes ) N allows also to deduce the resistance (RN + Ra) by application of Ohm's law:
• This differential calculation mode determines a resistance Rdet "which is based on an average of homogeneous values of measured voltages, which values constitute a majority of representative values. This average of values makes it possible to avoid taking into account inherent bad values, for example Electrical instability encountered on the LN conductor during current injections and associated voltage measurements Resistance Rdet "is therefore determined in a more robust manner, avoiding nuisance alerts caused by momentary electrical instability during a measurement.
• the memory MEM is also intended to store the data relating to the value of the threshold resistance not to be exceeded.
• the memory MEM can also archive the data relating to the resistance values determined by the device DIS. This memory is non-volatile in order to be able to preserve the archived data durably, even in the event of a power failure of the memory.
• the unit UC can be adapted to:
• the unit UC can send commands to the GEN generator to drive one or two AC current injections on the earth ground of the masses Ra (via the PE conductor).
• the sinusoidal current injections are in phase with the voltage measured between the conductors C3 and CN at the frequency of 50 Hz and are of a peak value intensity of 1 and 15 mA.
• the currents can be respectively injected successively at five and three periods.
• the maximum intensity of the injected AC current is chosen to be lower than the lowest tripping current of the circuit-breakers of the installation (which is typically 30 mA for a circuit-breaker D of the low-voltage switchboard TE) in order to avoid inadvertent tripping of the latter during measurements of the grounding resistance of the masses Ra. It should be noted that it is possible that the measurements cause the tripping of a circuit-breaker having a 30 mA si ⁇ if the circuit considered is already subject to a leakage current to the earth, to which is added that of the measurement . In this case, a search must be made on the installation to repair the faulty equipment.
• the unit UC may for example comprise an electronic circuit of the microprocessor type, micro controller, programmable logic circuit (FPGA, PLD or other).
• FPGA programmable logic circuit
• the unit UC can be connected to means known from the state of the art for measuring a potential difference or true rms voltage between the CN and PE conductors on the one hand, and the CN and C3 conductors on the other hand: voltage sensor, analog digital converter or other. Moreover, the unit UC can be realized so as to determine an average of:
• the determined resistance values compared to the predetermined threshold can therefore be a function of:
• the unit UC determines the weighted average of the absolute values of the ten and six voltage measurements to calculate the difference which remains always positive. From the distance obtained, it is then possible to determine the total resistance of the earths of the masses Ra and the neutral RN by applying Ohm's law with the stable current injected which is of known value (since controlled by the UC unit).
• the unit UC controls a current injection by the generator GEN according to a first level of maximum value of 1 mA and a current injection according to a second level of maximum value 15 mA, the unit UC knows the difference of the levels of injected currents (AIi nj ) which is 14 mA in maximum value.
• the unit UC calculates the value R + Ra then stimulates new injections of currents and voltage measurements in order to obtain new values of RN + Ra.
• the unit UC can perform the voltage measurements, determine the earth resistance values of the masses Ra by excess and compare the determined resistance values with the predetermined threshold at different frequencies (in particular according to the three frequencies described above. before).
• the second and third frequencies can be parameterized by the consumer or by an operator via the device's HMI interface, which notably comprises setting buttons.
• the values of these frequencies may furthermore be stored in the MEM memory of the DIS device.
• the generator GEN and the unit UC may be provided to detect that the current injected into the ground of the masses by the generator is zero. In this case, the electrical connection of the device or electrical panel TE may have been broken (dangerous situation for the user). The unit UC can then issue an alert for rapid intervention to be performed in order to restore the earth connection of the device masses and the table TE if necessary.
• the unit UC may comprise a calendar and an internal clock that allow time stamping the data relating to the measured voltages and to the determined resistance.
• the archived data make it possible to establish a history of measurements making it possible to establish the variations in time of the measured voltages (between the CN and PE conductors, and between the conductors C3 and CN) and the resistance of the earth electrode. Ra masses by excess.
• the unit UC can consult the measurement data stored in the memory MEM. From the data consulted, the unit UC can calculate a daily, monthly or even annual average value of the grounding resistance of the masses Ra (by excess).
• This average can also be stored in the memory MEM in order to give an overall representation of the state of the grounding of the masses Ra by excess over a given period.
• This average can for example be displayed on the ECR screen or transmitted to the user via the COM unit.
• the stand-alone BAT power source may be of the Lithium-ion battery type or a capacitor which is permanently charged by the power supply as long as it is present on the C3 and CN conductors.
• the device DIS then warns the user when a risk situation is detected by one or more measurements of the grounding of masses Ra by excess.
• This risky situation is reflected in particular by the cutting of the power supply of the apparatus (opening of the switch) and the issuance of an alarm instruction when the resistance of the earth ground of masses Ra by excess and the PE connection is too high (greater than 100 ⁇ for example).
• the user can be warned by means of different means emitting an alarm signal upon receipt of the alert instruction.
• the alarm signal can in particular be issued by:
• the LED light source passesage of a green light (if the grounding value of the masses Ra is constant and less than 100 ⁇ ) to a red light (if the grounding value of the masses exceeds 100 ⁇ )
• the LED source displays an orange light if the grounding value of the masses Ra is increasing but below the threshold
• the ECR screen (display of an alert message with the measured value) and / or - a remote entity that has received an alert notification via the COM unit.
• the ECR screen (which can be a typical LCD screen) can display different information like:
• a preventive message to carry out a control of the grounding of the masses Ra, - a request for intervention (which may be sent via the COM unit) to a repairer for verification or repair of the grounding of the masses Ra;
• an intervention request (which can be sent via the COM unit) to a service provider to measure the voltage and call on the network operator to carry out a distributed voltage adjustment if necessary.
• the user is therefore warned locally of a dangerous situation by the light signal emitted by the LED source, by the sound signal emitted by the speaker HP or by the information displayed on the screen of the DIS device.
• An acknowledgment button (present on the HMI interface for example) allows you to suppress the audible alarm.
• the user can also be remotely notified by receiving a notification sent by the COM unit on receipt of the alert instruction.
• This notification can be sent to the user via a web page, an e-mail message or a user's phone application.
• the COM unit may also receive a notification from a remote entity such as the mobile phone of the user, for example to acknowledge an alert.
• the COM unit may be a Wi-Fi, Bluetooth, GSM or other radio frequency communication module capable of transmitting data over the air to a remote entity (not shown in the figures).
• the unit COM allows in particular to issue instructions or alert notifications to a remote entity such as a management center or a communicating equipment of a user.
• the COM unit can access the data stored in the memory MEM and transmit it to the requesting entity.
• the requesting entity can exploit the transmitted data to know the precise variations over time of the resistance of the earth ground Ra or the network voltage.
• the interface HMI (which can materialize in particular in the form of buttons accessible to the user on the device DIS) can be adapted so as to be able to:
• the predetermined threshold and the choice of time intervals between each resistance measurement are stored in the MEM memory of the DIS device.
• This history makes it possible, for example, via a smartphone of the user for example, to represent a curve of the evolution of the voltages measured by the device and the evolution of the grounding of the masses Ra.
• This representation can allow the user to have a quick overview and a regular monitoring of the data measured and calculated by the device.
• the voltage monitoring provided to the device may enable the user to provide evidence to the energy distributor if the distributed voltage does not comply with the required voltage range (-10% / + 6% with respect to a nominal voltage 230 Volts).
• the memory MEM is adapted to store a computer program comprising instructions readable by a processor of the unit UC.
• the processor can also implement the method described below in the light of FIG. 3, and this when the instructions of the program are executed by this processor.
• the DIS device further comprises:
• the UC unit can be adapted to:
• the autonomous source BAT takes over so as to supply the converter CONV according to a power supply enabling to send an alarm setpoint to the alarm module ALM and to the communication module COM .
• the installer of the device or the user can adjust or update the value of the predetermined resistance threshold. It can also determine the time interval chosen between the different current injections or between two groups of several measurements (group of ten measurements, for example) of the grounding resistance of the masses Ra.
• a step M the data of the predetermined threshold and / or time intervals chosen and initialized in the INIT step are stored in the memory MEM.
• the unit UC can compare the supply voltage of the device DIS (supplied by the conductors C3 and CN) with a given nominal voltage range (between -10% and + 6% of 230 volts per second). example), a range corresponding to the expected requirements of the operator of the energy network and makes the generator GEN work properly.
• an ALERT step 1 provides for the issuance of a setpoint warning that the measurements of earth ground can not be made and that the nominal voltage is not respected. This alert can in particular propose to control the network voltage and to involve an operator of the power distribution network to regularize the situation and reduce the voltage in the power range expected by the DIS device. If the ALERTl step is triggered, a validation of an operator (via an acknowledgment button on the HMI of the DIS device or via a command received via the COM module) may be required to acknowledge the acknowledgment. alarm (especially local).
• a restart of the flowchart can only be performed by a specific button on the HMI of the DIS device or by a command received via the COM module and this to repeat the Tl step.
• the following steps of the method are therefore performed only when the received power supply makes it possible to obtain current injections in one or two stable and regulated levels, which subsequently makes it possible to calculate the grounding resistance of the masses Ra excessively depending on a single unknown, the value of the instantaneous voltage measured between the CN and PE conductors generated by the injected stable current (which voltage can however be disturbed during the measurement by variations of the neutral voltage, as this has been already quoted earlier in the text).
• step T1 if the supply voltage is correct at step T1 (included in the range -10% / + 6% with respect to the nominal voltage of 230 Volts), then the unit UC proceeds to a step A ( O arrow at the output of step Tl).
• the unit UC controls the current generator GEN to inject alternating current CA (L nj ) (in two distinct and successive sinusoidal levels for example) in phase with the supply voltage of the device DIS. These currents are injected into the earth ground of the masses Ra.
• an additional verification step may be performed (not shown in the figures), in which it is verified that the current injected into the earth ground of the masses is not zero. If necessary, an alarm instruction can be issued so that the ground connection of the device masses and the TE panel is controlled and repaired if necessary by a specialist.
• the unit UC measures the voltage, ie the instantaneous voltage (U mes ) generated or the true rms voltage generated (U mes ), between the CN and PE conductors by the injected current (3 ⁇ 4).
• the data relating to the measured voltage values are temporarily stored in the RAM memory (which serves as a working memory for calculating the average of the voltages measured during a step C).
• Steps A, B and MRAM can be repeated at a predetermined frequency, for example every second to proceed at least:
• the unit UC determines the grounding resistance of the masses as a function of the injected current and the measured voltage.
• the CPU can extract the temporarily stored data into the RAM.
• the resistance can in particular be calculated on the basis of the resistors Rdet, Rdet 'or Rdet "described above.
• the data relating to the determined resistance values (Rdet, Rdef or Rdet ”) are archived and timestamped in the memory MEM.
• the unit UC can further store and time stamp the averages calculated by the unit UC in the memory MEM for post-processing.
• Steps C and MH may be repeated successively every minute or hour typically so as to determine a grounding resistance of the masses according to a weighted average of the resistance measurements already stored in the memory.
• the unit UC compares the determined value of resistance of the grounding of the masses (Rdet, Rdef or Rdet "), or the weighted average of this resistance, with the value of the predetermined threshold. For this comparison, the unit UC extracts from the memory MEM the necessary values.
• step END If the resistance or the weighted average resistance does not exceed the value of the predetermined threshold (arrow N at the output of step T2), the process ends (step END).
• a step ALERT2 foresees the emission of an instruction of alert to prevent from a risk situation (risk of electrification or even electrocution of an individual if indirect contact occurs).
• the step T2 (and the step ALERT2 if necessary) can be repeated at a frequency adapted to the monitoring of the evolution of earth ground masses over time such as a daily or weekly frequency.
• This lower frequency can be adapted to regularly calculate a weighted average of the resistances determined during a day, a week or a month, and to deduce a global value representative of the state of the taking of land over this duration.
• the process can remain stuck in the ALERT2 step until an operator intervention has been performed (validation by acknowledgment button or remote command), then go to the END step once the Grounding safety has been verified and validated by a second local or remote action.
• This embodiment makes it possible to restart the measurement cycle of the grounding of the masses Ra in safe electrical conditions.
• step END the steps of the flowchart can be successively repeated to perform a new measurement of the grounding resistance of the masses Ra.
• steps M, MRAM and MH steps for calculating the drift of the earthing of the masses (not shown in the figure) can also be implemented to control, for example, the orange LED source of the device.
• DIS and generate an alert setpoint to a remote entity in case of grounding of masses below the predetermined threshold but of increasing value over time.
• another step may consist in transmitting, on request, to a remote entity the data stored in the memory MEM in steps M and MH.
• the proposed device and method provide near real-time continuous monitoring of the ohmic value of the grounding of the excess masses Ra and the PE conductor, as well as that their possible drift in time compared to the threshold which can be 100 ⁇ (or more) or slightly lower than the limit value (95 ⁇ for example).
• step A the voltage between the conductors C3 and PE can be measured. If the measured voltage is close to the nominal voltage of 230 volts, then the unit UC controls the switch INT2 inverter in position 1. In the opposite case, the unit UC controls the switch INT2 inverter in position 2. Thus, it is ensured that the generator GEN receives well the phase of the supply provided by the RED network.
• a step OUV provides for cutting off the power supply of the AED device by commanding the passage of the switch INT1 in an open position.
• the ALERT2 step consists of issuing an alert instruction when the measured resistance exceeds the predetermined threshold in order to warn the user or an operator of a fault occurring at the device or at the grounding point.
• the unit UC issues an alert requesting an intervention on the installation so as to verify the fuses or the power breaker.
• the reappearance of the supply voltage on the conductors C3 and CN then restarts the process in step T1.
• the predetermined threshold may be of an electrical resistance value set in accordance with the requirements of NFC standards 15-100 and / or IEC 60364, such that:
• the predetermined threshold can be adjusted to a value slightly lower than the prescribed limits, for example 5% lower than the aforementioned values.
• the device and the method thus provide protection to users against indirect contact that is dangerous for humans, which device is in continuous operation, with continuous or at least regular measurements (and this without the need for any constraining steps). installation as in the prior art).
• the device therefore significantly improves the security of property and people, can also serve as a platform for the implementation of electrical safety services in housing and demand for intervention to repair the grounding of the masses and / or the connection of the device to this ground.
• the device can be integrated into a device as soon as it is manufactured or can be mounted on an existing device, the device then being connected to a dedicated electrical connection connected to the installation to which the device is connected.

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• 2015
  • 2015-01-08 EP EP15702543.8A patent/EP3092502A1/de not_active Withdrawn
  • 2015-01-08 US US15/110,588 patent/US20170110869A1/en not_active Abandoned
  • 2015-01-08 WO PCT/FR2015/050043 patent/WO2015104505A1/fr active Application Filing

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