Detection of defective clamping

Abstract

An electric meter (1) comprises: at least one input terminal (Ui), at least one voltage sensor, and at least one current sensor; a processor unit (11) arranged to: collect voltage measurements and current measurements and detect a first time period during which a source current is less than a first predefined current threshold and a second time period during which the source current is greater than a second predefined current threshold; collect a first voltage measurement value during the first time period and a second voltage measurement value during the second time period; and detect a defective clamping between at least one wire and the input terminal when at least one detection value representing a difference between the first voltage measurement value and the second voltage measurement value is greater than or equal to the voltage threshold.

Description

Technical Field

[0001] The present invention relates to the field of electricity meters. Background Art

[0002] When installing an electric meter at a subscriber's premises (whether private or commercial), the installer may improperly clamp one or more of the power transmission wires (phase or neutral). Poor clamping may cause problems long after installation.

[0003] Specifically, defective clamping of wires to the input terminals of the meter can result in heating, which in turn can cause the meter to catch fire.

[0004] It is therefore natural to propose to detect defective clamping and alert the installer and / or administrator of the network by including a temperature sensor inside the meter to measure the temperature near the input terminals. However, this solution is not entirely satisfactory.

[0005] Specifically, this solution requires the inclusion of at least one new sensor and its associated measurement components and is therefore relatively complex and expensive to implement.

[0006] Furthermore, while the abnormal temperature rise detected by the temperature sensor in the meter may be caused by defective clamping, it may also have some other causes, such as heating of a disconnecting component connected to the phase line within the meter. There is no distinction between heating attributed to the disconnecting component and heating attributed to a bad clamping line, which means that the exact cause of heating cannot be detected. Furthermore, this solution therefore cannot determine which input terminal is poorly clamped.

[0007] Purpose of the Invention

[0008] One object of the invention is to enable a detection of a bad clamping of a cable in the input of a meter which is rapid, simple, cheap to perform and unequivocal as to the cause of the fault. Summary of the invention

[0009] To achieve this object, there is provided an electric meter arranged for measuring electric energy supplied by a source, the electric meter comprising:

[0010] at least one input, each input being arranged to be connected to said source by a respective electrical wire;

[0011] at least one voltage sensor and at least one current sensor arranged to operate from within the meter to perform voltage measurements to estimate a source voltage supplied by the source and to perform current measurements to estimate a source current supplied by the source;

[0012] A processor unit arranged to:

[0013] collecting voltage measurements and current measurements and detecting at least one predefined sequence, the at least one predefined sequence comprising a first period of time during which the source current is less than a first predefined current threshold and a second period of time during which the source current is greater than a second predefined current threshold, the second predefined current threshold itself being greater than the first predefined current threshold;

[0014] For each predefined sequence, acquiring at least one first voltage measurement during a first time period and at least one second voltage measurement during a second time period;

[0015] A defective clamping between at least one electrical wire and an input connected to said electrical wire is detected when during at least one predefined sequence at least one detection value representing a difference between a first voltage measurement value and a second voltage measurement value is greater than or equal to a voltage threshold.

[0016] The electric meter of the present invention requires no additional hardware components to detect defective clamping, making the present invention simple and inexpensive to implement.

[0017] The detection criterion is based on how the measured source voltage (coming upstream from the input) changes when the source current changes from low to high level and vice versa. This change depends on the impedance of the input, which in turn depends on how well the wire is clamped. Therefore, there is no dispute about the cause of the observed fault. Defective clamping can be detected immediately after a predefined sequence and is therefore very fast.

[0018] There is also provided an electricity meter as described above, wherein the processor unit is arranged to detect the predefined sequence only if the duration between the first period and the second period is less than a predefined time threshold.

[0019] There is also provided an electricity meter as described above, wherein the voltage threshold is defined as a function of both a first current measurement taken during the first time period and a second current measurement taken during the second time period.

[0020] There is also provided an electric meter as described above, wherein the following applies:

[0021] SV = a*(I2-I1);

[0022] Where SV is the voltage threshold, a is a parameter, I1 is a first current measurement value obtained during a first period of time, and I2 is a second current measurement value obtained during a second period of time.

[0023] There is also provided an electricity meter as described above, wherein parameter a is defined as a function of both the first predefined current threshold and the second predefined current threshold.

[0024] There is also provided an electricity meter as described above, wherein the processor unit is arranged to execute on a single predefined sequence to obtain a plurality of detection values, and when the number of those detection values ​​greater than the voltage threshold reaches a first predefined number, defective clamping is detected.

[0025] There is also provided an electricity meter as described above, wherein the processor unit is arranged to execute over a plurality of consecutive predefined sequences to obtain respective detection values, and when a plurality of those detection values ​​are greater than a voltage threshold, defective clamping is detected.

[0026] There is also provided an electric meter as described above, wherein the first predefined current threshold is within the range of 2.5 amperes (A) to 7.5A, and the second predefined current threshold is within the range of 20A to 60A.

[0027] There is also provided an electric meter as described above, the source having three phase lines, the electric meter being a three-phase electric meter comprising three input terminals, each input terminal being arranged to be connected to a respective phase line via a respective phase line, the electric meter comprising, for each phase line, a respective voltage sensor arranged to produce a voltage measurement value for evaluating a source voltage present on said phase line and a current sensor arranged to produce a current measurement value for evaluating a source current flowing in said phase line, and for each phase line a processor unit being arranged to detect, based on the voltage measurement value produced by the voltage sensor and the current measurement value produced by the associated current sensor, a defective clamping between said phase line and an input terminal connected to said phase line.

[0028] There is also provided an electric meter as described above, the source also having a neutral line, and the electric meter further comprising an input arranged to be connected to the neutral line via a neutral wire, the processor unit being arranged to:

[0029] When it detects a defective clamping between one or two phase wires and the corresponding input terminal connected to said phase wires, it determines that the defective clamping is actually located at said input terminal;

[0030] When it simultaneously detects defective clamping between all three phase wires and the three corresponding input terminals connected to the phase wires, it determines that the defective clamping is actually located at the input terminal connected to the neutral wire.

[0031] There is also provided an electric meter as described above, the source having a phase line and a neutral line, the electric meter being a single-phase electric meter comprising an input terminal arranged to be connected to the phase line via a phase wire and an input terminal arranged to be connected to the neutral line via a neutral wire, the electric meter comprising a voltage sensor arranged to produce a voltage measurement value for evaluating a source voltage present on the neutral wire and a current sensor arranged to produce a current measurement value for evaluating a source current flowing in the phase wire, the processor unit being arranged to detect a defective clamping based on the voltage measurement value produced by the voltage sensor and the current measurement value produced by the current sensor.

[0032] There is also provided an electricity meter as described above, the source being a network for distributing electrical energy.

[0033] There is also provided an electricity meter as described above, the source being a subscriber device that generates electrical energy.

[0034] There is also provided a detection method performed in a processor unit of an electric meter as described above, and the method comprises the following steps:

[0035] collecting voltage measurements and current measurements and detecting at least one predefined sequence, the at least one predefined sequence comprising a first period of time during which the source current is less than a first predefined current threshold and a second period of time during which the source current is greater than a second predefined current threshold, the second predefined current threshold itself being greater than the first predefined current threshold;

[0036] For each predefined sequence, acquiring at least one first voltage measurement during a first time period and at least one second voltage measurement during a second time period;

[0037] A defective clamping between at least one electrical wire and an input connected to said electrical wire is detected when during at least one predefined sequence at least one detection value representing a difference between a first voltage measurement value and a second voltage measurement value is greater than or equal to a voltage threshold.

[0038] A computer program is also provided, which comprises instructions for causing a processor unit of the electric meter as described above to execute the steps of the detection method as described above.

[0039] A computer-readable storage medium is also provided, which stores the above-mentioned computer program.

[0040] The present invention may be better understood in light of the following description of certain non-limiting embodiments of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] With reference to the accompanying drawings, in which:

[0042] [ Figure 1 ] Figure 1The electric meter in the first embodiment of the present invention is shown, which is a three-phase electric meter with a four-wire configuration; [ Figure 2 ] Figure 2 yes Figure 1 Circuit diagram of the meter (only one phase is shown);

[0043] [ Figure 3 ] Figure 3 An electric meter in a second embodiment of the present invention is shown, which is a three-phase electric meter in a three-wire configuration;

[0044] [ Figure 4 ] Figure 4 The electric meter in the third embodiment of the present invention is shown, and the electric meter is a single-phase electric meter;

[0045] [ Figure 5 ] Figure 5 yes Figure 4 Circuit diagram of the electric meter; DETAILED DESCRIPTION

[0046] refer to Figure 1 The electric meter 1 in the first embodiment of the present invention is a three-phase electric meter, which is arranged in a direct-connected four-wire configuration under standard circumstances, and which can be used for civil or commercial purposes.

[0047] The electricity meter 1 is used to measure electrical energy delivered by a source, in particular an electricity distribution network 2 , to a subscriber electrical installation 3 .

[0048] The power distribution network 2 has three phase lines Ph1, Ph2, and Ph3 and one neutral line N. An electric meter 1 is connected to the phase lines and the neutral line of the network 2 to perform measurements thereon.

[0049] A circuit breaker 4 is located at the boundary between the distribution network 2 and the installation 3. The circuit breaker 4 (operable by the subscriber) is used in particular to protect the installation 3 by opening in the event of a surge current in the distribution network 2, for example due to a short circuit downstream of the circuit breaker 4. In this example, the term "downstream" refers to the side of the installation 3, while the term "upstream" refers to the side of the distribution network 2.

[0050] The electricity meter 1 has three input terminals U1, U2 and U3 each connected to a respective one of the phase lines Ph1, Ph2 and Ph3 of the network 2 by means of phase wires C1, C2 and C3, and an input terminal UN connected to the neutral line N through a neutral wire CN.

[0051] The electricity meter 1 also has four outputs U′ 1 , U′ 2 , U′ 3 and U′N connected to a circuit breaker 4 , itself connected to the installation 3 .

[0052] refer to Figure 2, the electricity meter 1 has a neutral conductor 5 connected to the input terminal UN. The neutral conductor 5 is connected to the electrical ground 7 of the electricity meter 1.

[0053] For each phase line Phi (i being in the range 1 to 3), the electricity meter 1 has a respective phase conductor 8 connected to a corresponding input terminal Ui.

[0054] The electricity meter 1 also comprises disconnection means 9 comprising, for each phase conductor 8, a respective different switch 10 connected in said phase conductor 8. The disconnection means 9 are used in particular to remotely interrupt or re-establish the electricity supply to the installation 3 (which may be represented as a load), for example in the event of cancellation of a subscription or non-compliance with a subscription contract.

[0055] The electric meter 1 also has an application part and a measurement part.

[0056] The application part includes an application microcontroller (not shown).

[0057] The measurement part comprises a metering microcontroller 11 , the main function of which is to generate measured values ​​of a certain number of parameters which enable the electricity consumption of the installation 3 to be evaluated.

[0058] The microcontroller 11 is also adapted to execute instructions of a program for performing the detection method as described below. The instructions of the program are stored in a memory 12 included in or connected to the microcontroller 11 .

[0059] The microcontroller 11 includes a first analog-to-digital converter (ADC) 14 , a second ADC 15 , a voltage measurement module 16 , and a current measurement module 17 .

[0060] For each phase line Phi, the measuring section comprises a voltage sensor arranged to produce voltage measurement values ​​for evaluating the source voltage Vphi present on the phase line Ci.

[0061] In this example, the voltage sensor comprises a voltage divider bridge comprising a first measuring resistor R1 and a second measuring resistor R2. The first measuring resistor R1 has a first end connected to the phase conductor 8 near (and downstream of) the input terminal Ui. The second measuring resistor R2 has a first end connected to the electrical ground 7. The second ends of the first measuring resistor R1 and the second measuring resistor R2 are connected together and to an input of a microcontroller 11, which is also connected to an input of a first ADC 14. The first ADC 14 thus has (at least) three inputs, namely one input per phase line Phi.

[0062] The voltage Vm1 measured by the first ADC 14 is a voltage that is a mirror image of the input voltage Ve (ie, the voltage of the input terminal Ui and downstream thereof), and it enables the source voltage Vphi to be estimated.

[0063] The level of the voltage Vm1 is adapted (by means of the voltage divider bridge R1 , R2 ) in order to avoid saturating the first ADC 14 and in order to apply a signal at a meaningful level (corresponding to the input range of the first ADC 14 ) to the input of the first ADC 14 .

[0064] The first ADC 14 thus digitizes the voltage Vm1. Based on the samples generated by the first ADC 14, the voltage measurement module 16 generates a measurement value for evaluating the root mean square (RMS) voltage of the input voltage Ve. The microcontroller 15 uses the voltage measurement value to evaluate the source voltage Vphi provided by the network 2, even if the input voltage Ve is not exactly equal to the source voltage Vphi, as described below.

[0065] For each phase line Phi, the measurement section further comprises a respective current sensor arranged to produce a current measurement value representative of the source current Iphi flowing in the phase conductor Ci.

[0066] The current sensor comprises a ring 20 mounted on the phase conductor 8 upstream of the switch 10 of the disconnection means 9. Across the output terminals of the ring 20 a third measuring resistor R3 is connected.

[0067] The measuring assembly further comprises a current measuring circuit 21 presenting a known gain. The current measuring circuit 21 is connected to one of the ends of a third measuring resistor R3, the other end of the measuring resistor being connected to ground 7.

[0068] The output of the current measurement circuit 21 is connected to an input of the microcontroller 11 which has connected thereto a second ADC 15. The second ADC 15 thus has (at least) three inputs, namely one for each phase line Phi.

[0069] The voltage vm2 at the output from the current measurement circuit 21 is an image of the source current Iphi.

[0070] The level of the voltage Vm2 is adapted (by means of the gain of the current measurement circuit 21 ) in order to avoid saturating the second ADC 15 and in order to apply a signal at a meaningful level (corresponding to the input range of the second ADC 15 ) to the input of the second ADC 15 .

[0071] The second ADC 15 thus digitizes the voltage Vm2. From the samples generated by the second ADC 15, the current measurement module 17 generates measurement values ​​making it possible to estimate the source current Iphi.

[0072] In this example, both the voltage measurement module 16 and the current measurement module 17 generate measurement values ​​for each phase line once per second.

[0073] The manner in which the electricity meter 1 detects a defective clamping between a phase conductor Ci and an associated input terminal Ui is described more precisely below.The following description is valid for each of the phases Ph1, Ph2, Ph3.

[0074] When the phase line Ci is correctly clamped on the input terminal Ui, the input terminal Ui generally presents an impedance of about 1 milliohm (mΩ). When the phase line Ci is poorly clamped or loose, the input terminal Ui generally presents an impedance of about 10 mΩ.

[0075] For a given source voltage Vphi (supplied by network 2 upstream of input terminal Ui), when source current Iphi changes from a low value to a high value, the input voltage Ve measured by meter 1 (downstream of input terminal Ui) therefore varies in different ways depending on whether the phase wire Ci is clamped correctly or not.

[0076] When the phase wire Ci is clamped correctly, the voltage variation is low, whereas when the phase wire is poorly clamped, the voltage variation is high.

[0077] Therefore, for a source voltage of 230V RMS, when the phase line Ci is properly clamped to the input terminal Ui, the input voltage Ve drops by about 0.04V RMS, while when the phase line Ci is poorly clamped to the input terminal Ui, the voltage drop is greater than or equal to 0.4VRMS.

[0078] The microcontroller 11 thus acquires current measurements and current measurements and it attempts to detect at least one predefined sequence comprising a first period during which the source current Iphi is less than a first predefined current threshold and a second period during which the source current Iphi is greater than a second predefined current threshold, which is itself greater than the first predefined current threshold.

[0079] The first predefined current threshold SI1 typically lies in the range of 2.5 A to 7.5 A and in this example is equal to 5 A. The first predefined current threshold SI1 is programmable.

[0080] The second predefined current threshold SI2 typically lies in the range of 20 A to 60 A and in this example is equal to 40 A. The second predefined current threshold SI2 is programmable.

[0081] For each predefined sequence, the microcontroller 11 acquires at least one first voltage measurement value during a first period of time and at least one second voltage measurement value during a second period of time.

[0082] The microcontroller 11 detects a defective clamping between the phase line Ci and the input terminal Ui when, during at least one predefined sequence, at least one detection value representing the difference between the first voltage measurement value and the second voltage measurement value is greater than or equal to a voltage threshold value. In this example, the detection value is equal to the difference.

[0083] The voltage threshold SV is typically in the range of 0.2 V RMS to 0.6 V RMS and is equal to 0.4 V RMS in this example. The voltage threshold SV is programmable.

[0084] It should be noted that the RMS voltage is usually measured in electricity meters to within 0.1% or better (corresponding to 0.2V RMS at 230V).

[0085] In this example, the microcontroller 11 confirms the detection of a defective clamping by means of a plurality of measurements.

[0086] The microcontroller 11 operates on a single predefined sequence to obtain a plurality of detection values, and detects defective clamping when the number of those detection values ​​that are greater than the voltage threshold reaches a first predefined number.

[0087] In this example, the first predefined number is equal to three.

[0088] More precisely, the microcontroller 11 acquires (at least) one first voltage measurement value during a first period, and then acquires (at least) three second voltage measurement values ​​during a second period. The microcontroller 11 calculates (at least) three detection values, each detection value being equal to the difference between a respective one of the second voltage measurement values ​​and the first voltage measurement value, and it detects a defective clamping at the input Ui when at least three detection values ​​are greater than a voltage threshold. Thus, the detection of a defective clamping is confirmed within three consecutive seconds.

[0089] Alternatively, the microcontroller 11 may perform operations on a plurality of consecutive predefined sequences to obtain respective detection values, the number of consecutive sequences being a second predefined number, and when a plurality of those detection values ​​are greater than a voltage threshold, a defective clamping is detected.

[0090] In this example, the second predefined number is equal to three. Thus, the detection of a defective clamping is confirmed over three consecutive predefined sequences.

[0091] It should be observed that the microcontroller 11 detects the predefined sequence when the duration between the first period and the second period is less than a predefined time threshold.

[0092] Specifically, for the applicable criteria to apply, the time interval between the end of the low current period (first period) and the beginning of the high current period (second period) must be less than a predefined time threshold so that it can be assumed that the source voltage upstream of meter 1 does not change significantly between the low current period and the high current period.

[0093] The predefined time threshold T typically lies in the range of 30 seconds (s) to 90 seconds, and in this example it is equal to 60 seconds. The predefined time threshold T is programmable.

[0094] As mentioned above, the voltage threshold SV is programmable and, by way of example, it is equal to 0.4 V RMS, ie a constant value.

[0095] Alternatively, the voltage threshold SV may be dependent on a first current measurement (taken during a first time period) and a second current measurement (taken during a second time period).

[0096] For example:

[0097] SV = a*(I2-I1);

[0098] Where SV is the voltage threshold, a is a parameter, I1 is a first current measurement acquired during a first period, and I2 is a second current measurement acquired during a second period. Naturally, if multiple measurements are taken during each cycle, I1 and I2 are obtained from said measurements (e.g. by averaging). Advantageously, each of the first and second current measurements is obtained from at least two consecutive measurements that are stable (the current is stable for at least two seconds).

[0099] Parameter a is programmable.

[0100] The parameter a may be defined as a function of the first predefined current threshold and the second predefined current threshold.

[0101] In this case, the following applies:

[0102] a=0.4 / (IS2-IS1)

[0103] =0.4 / (40-5)=0.01142857.

[0104] It should also be observed that the detection of a defective clamping is considered valid if and only if the source voltage Vphi has no anomalies (no voltage dips, no power outages, even short circuits, no inrush currents) when the measurement is made.

[0105] When the microcontroller 11 detects a defective clamping of the input terminal Ui, the microcontroller 11 displays an alarm message on a liquid crystal display (LCD) screen of the electricity meter 1 for the installer to see.

[0106] Alert messages are also sent to the network administrator's information system (IS).

[0107] To send the alarm message, the microcontroller 11 collaborates with communication means included in the electricity meter 1. As an example, the communication means 1 utilize power line communication (PLC), for example using the PLC-G3 standard, or radio communication via a cellular network (for example using the LTE-M protocol or the NB-IoT protocol), or any other technology capable of establishing remote communication.

[0108] When the microcontroller 11 detects a clamping defect between one or both phase wires Ci and the associated input terminals Ui, the microcontroller 11 determines that the defective clamping is actually present at each of the input terminals Ui.

[0109] In contrast, when the microcontroller 11 simultaneously detects a clamping defect between all three phase wires Ci and the three input terminals Ui, the microcontroller 11 corrects its abnormal position and determines that the defective clamping is actually located between the input terminals UN connected to the neutral wire CN (i.e., not at the input terminals Ui connected to the phase wires Ci).

[0110] The warning message thus contains both an indication that a defective clamping has been detected at at least one location and an indication that the defective clamping is localized at one or more specific inputs.

[0111] Advantageously, the defective clamping detection function can be "de-clutched", i.e. it can be deactivated (and reactivated) locally, for example by the installer (using a button provided for this purpose on the electricity meter 1, or using any other type of human-machine interface), or remotely, for example following instructions from a network manager (and for example using the above-mentioned communication means).

[0112] exist Figure 3 In the figure, an electric meter 101 in a second embodiment of the present invention can be seen. The meter 101 is a three-phase electric meter, arranged in a three-wire configuration.

[0113] The power distribution network 102 has three phase lines Ph1 , Ph2 , and Ph3 .

[0114] Circuit breaker 104 is located at the boundary between power distribution network 102 and subscriber facility 103 .

[0115] The electric meter has three input terminals U1 , U2 , and U3 , each of which is connected to a corresponding one of the phase lines through a cable having three phase wires C1 , C2 , and C3 , and three output terminals U′ 1 , U′ 2 , and U′ 3 connected to the circuit breaker 104 .

[0116] Figure 2 The circuit diagram is applicable to each phase of the electric meter 101.

[0117] exist Figure 4 In the figure, an electric meter 201 in the third embodiment of the present invention can be seen. The electric meter 201 is a single-phase electric meter.

[0118] The power distribution network 202 includes a phase line Ph and a neutral line N. The electricity meter 201 has two input terminals U and UN, one connected to the phase line Ph and the other connected to the neutral line N, and two output terminals U' and U'N.

[0119] Circuit breaker 204 is located at the boundary between power distribution network 202 and subscriber facility 203 .

[0120] refer to Figure 5 , the circuit diagram of the ammeter 201 is similar to Figure 2 Circuit diagram of the .

[0121] Therefore, we can see again Figure 2 Most of the components in Figure 5 The mark in has increased by 200.

[0122] However, in this example, the phase conductor 208 is connected to the electrical ground 207. The input voltage Ve is measured on the neutral conductor 205, i.e. the first measuring resistor R1 has a first end connected to the neutral conductor 205. In this example, the current sensor is a shunt 220 connected in the phase conductor 208, having a first end connected to the input terminal U and a second end connected to the cut-off element 209.

[0123] The microcontroller 211 detects defective clamping based on the voltage measurements produced by the voltage sensor and the current measurements produced by the current sensor.

[0124] When the microcontroller 211 detects a defective clamp, it locates the defective clamp on all inputs (ie, the defective clamp may be at input P, ​​input N, or at both inputs).

[0125] Naturally, the invention is not limited to the embodiments described but covers any variant coming within the ambit of the invention as defined by the claims.

[0126] In each detected predefined sequence, a first period (low current) may precede a second period (high current), but this is not required.

[0127] The predefined sequence may be a sequence where a first time period precedes a second time period, or a sequence where a second time period precedes a first time period, or indeed a sequence having a first time period and a second time period regardless of the order in which the time periods arrive.

[0128] If the first period precedes the second period, the microcontroller will detect an abnormal drop in the input voltage in the case of defective clamping; if the second period precedes the first period, the microcontroller will detect an abnormal increase in the input voltage in the case of defective clamping.

[0129] The source providing the electrical energy measured by the meter is not necessarily the distribution network upstream of the meter.

[0130] The source can also be a user facility downstream of the meter. Then, this device will no longer be a "consumer", but a "producer", and it will provide electrical energy to the network.

[0131] The invention is then implemented in the same way, except that the input terminals are now terminals U'1, U'2, U'3 for a three-phase meter, and may be U'N, or U' and U'N for a single-phase meter.

[0132] For single-phase meters, the defective clamping is located at input U', at input U'N, or at both inputs.

[0133] For a three-phase meter with a neutral line, when one or two of the phases fail, the defective clamp is located at one or both of the input terminals U'i ( i 1 to 3), and when all three phases are faulty, the defective clamping is at the input terminal U'N.

[0134] For the "producer" device, it is assumed that the impedance caused by the cut-off components is negligible (on the order of a few hundred micro-ohms (μΩ) and not exceeding 500 μΩ).

[0135] The architecture of the electricity meter can naturally be different from the one described above.

[0136] Two ADCs are described as being included in the microcontroller. However, it is possible to utilize a single ADC included in the microcontroller.

[0137] One or more ADCs may also be located external to the microcontroller.

[0138] The microcontroller that executes the detection method is not necessarily a measurement microcontroller, but can be a different component, for example, it can be an application microcontroller of an application part.

[0139] More generally, the detection method can be performed in a processor unit comprising at least one processor component and a memory. The processor component is not necessarily a microcontroller, but it can be a different component, such as a conventional processor, a digital signal processor (DSP), or indeed a programmable logic circuit, such as a field programmable gate array (FPGA) or an application specific integrated circuit (ASIC).

Claims

1. An electric meter (1) arranged to measure electric energy provided by a source (2), the electric meter comprising: at least one input (Ui), each input being arranged to be connected to said source via a respective electric line (Ci); at least one voltage sensor and at least one current sensor arranged to operate from within the meter to perform voltage measurements to evaluate a source voltage (Vphi) supplied by the source and to perform current measurements to evaluate a source current (Iphi) supplied by the source; A processor unit (11) arranged to: collecting voltage measurements and current measurements and detecting at least one predefined sequence, the at least one predefined sequence comprising a first period of time during which the source current is less than a first predefined current threshold and a second period of time during which the source current is greater than a second predefined current threshold, the second predefined current threshold itself being greater than the first predefined current threshold; For each predefined sequence, acquiring at least one first voltage measurement during the first time period and at least one second voltage measurement during the second time period; A defective clamping between at least one electrical wire and an input connected to said electrical wire is detected when during at least one predefined sequence at least one detection value representing a difference between a first voltage measurement value and a second voltage measurement value is greater than or equal to a voltage threshold.

2. The electric meter according to claim 1, characterized in that The processor unit (11) is arranged to detect a predefined sequence only if a duration between the first period and the second period is less than a predefined time threshold.

3. An electric meter as claimed in any preceding claim, characterized in that The voltage threshold is defined as a function of both a first current measurement value taken during the first time period and a second current measurement value taken during the second time period.

4. The electric meter according to claim 3, characterized in that Applicable: SV = a*(I2-I1); Wherein SV is the voltage threshold, a is a parameter, I1 is a first current measurement value obtained during the first period, and I2 is a second current measurement value obtained during the second period.

5. The electric meter according to claim 4, characterized in that: The parameter a is defined as a function of both the first predefined current threshold and the second predefined current threshold.

6. An electric meter as claimed in any preceding claim, characterised in that The processor unit (11) is arranged to perform operations on a single predefined sequence to obtain a plurality of detection values, and to detect defective clamping when the number of detection values ​​greater than the voltage threshold reaches a first predefined number.

7. The electric meter according to any one of claims 1 to 5, characterized in that: The processor unit (11) is arranged to perform operations on a plurality of consecutive predefined sequences to obtain respective detection values, and to detect defective clamping when a plurality of those detection values ​​are greater than the voltage threshold.

8. An electric meter as claimed in any preceding claim, characterised in that The first predefined current threshold is within a range of 2.5 amperes (A) to 7.5A, and the second predefined current threshold is within a range of 20A to 60A.

9. An electric meter as claimed in any preceding claim, characterised in that The source (2) comprises three phase lines (Ph1, Ph2, Ph3), the electricity meter (1) being a three-phase electricity meter comprising three input terminals (U1, U2, U3), each input terminal being arranged to be connected to a respective phase line via a respective phase line (C1, C2, C3), the electricity meter comprising, for each phase line, both a respective voltage sensor and a current sensor, the voltage sensor being arranged to produce a voltage measurement value for evaluating a source voltage present on the phase line, the current sensor being arranged to produce a current measurement value for evaluating a source current flowing in the phase line, the processor unit being arranged, for each phase line, to detect a defective clamping between the phase line and an input terminal connected to the phase line based on the voltage measurement value produced by the voltage sensor and the current measurement value produced by the associated current sensor.

10. The electric meter according to claim 9, characterized in that The source further comprises a neutral line, and the meter further comprises an input arranged to be connected to the neutral line via a neutral wire, the processor unit being arranged to: When it detects a defective clamping between one or two phase wires and the corresponding input terminal connected to said phase wires, it determines that said defective clamping is actually located at said input terminal; When it simultaneously detects defective clamping between all three phase wires and three corresponding input terminals connected to the phase wires, it determines that the defective clamping is actually located at the input terminal connected to the neutral wire.

11. The electric meter according to any one of claims 1 to 8, characterized in that: The source has a phase line and a neutral line, the meter is a single-phase meter comprising an input arranged to be connected to the phase line via a phase line and an input arranged to be connected to the neutral line via a neutral line, the meter comprising a voltage sensor arranged to produce voltage measurements to estimate a source voltage present on the neutral line and a current sensor arranged to produce current measurements to estimate a source current flowing in the phase line, the processor unit being arranged to detect defective clamping based on the voltage measurements produced by the voltage sensor and the current measurements produced by the current sensor.

12. An electric meter as claimed in any one of the preceding claims, characterised in that The source is a network for distributing electrical energy.

13. The electric meter according to any one of claims 1 to 11, characterized in that: The source is a subscriber facility that generates electrical energy.

14. A detection method performed by a processor unit of an electric meter as claimed in any one of the preceding claims, the method comprising the following steps: collecting the voltage measurements and the current measurements and detecting at least one predefined sequence, the at least one predefined sequence comprising a first period of time during which the source current is less than a first predefined current threshold and a second period of time during which the source current is greater than a second predefined current threshold, the second predefined current threshold itself being greater than the first predefined current threshold; For each predefined sequence, acquiring at least one first voltage measurement during the first time period and at least one second voltage measurement during the second time period; A defective clamping between at least one electrical wire and an input connected to said electrical wire is detected when during at least one predefined sequence at least one detection value representing a difference between a first voltage measurement value and a second voltage measurement value is greater than or equal to a voltage threshold.

15. A computer program comprising instructions for causing a processor unit of an electricity meter according to any one of claims 1 to 13 to execute the steps of the detection method according to claim 14.

16. A computer-readable storage medium storing the computer program according to claim 15.

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