阅读说明：本技术 电仪表热性能监测 (Electrical instrument thermal performance monitoring ) 是由 伊恩·杰克逊·戴维斯 于 2019-09-06 设计创作，主要内容包括：本发明涉及一种监测电仪表(2)的功能状态的方法,该方法包括以下步骤：生成至少一个温度信号,根据该至少一个温度信号可以得出电仪表(2)的实际温度值(T)；确定实际温度值(T)和/或该实际温度值的梯度(Gm)是否超过至少一个阈值(L),该至少一个阈值是根据至少一个预定义温度曲线(T300)得出的,该至少一个预定义温度曲线表示电仪表(2)根据电仪表(2)的经建模的热行为的随时间变化的预定义温度值(T)。此外,本发明涉及用于监测电仪表(2)的功能状态的计算机程序(4)。此外,本发明涉及其上存储有根据本发明的计算机程序(4)的计算机可读数据载体(5),并且涉及承载根据本发明的计算机程序(4)的数据载体信号(6)。此外,本发明涉及电仪表(2),该电仪表被配置成实施根据本发明的计算机程序(4)。最后,本发明涉及电计量系统(1),特别是高级计量基础设施(AMI),其包括被配置成实施根据本发明的方法的至少一个电仪表(2)和/或至少一个管理设备(3)。(The invention relates to a method for monitoring the functional state of an electrical instrument (2), comprising the following steps: generating at least one temperature signal from which an actual temperature value (T) of the electrical meter (2) can be derived; it is determined whether the actual temperature value (T) and/or the gradient (Gm) of the actual temperature value exceeds at least one threshold value (L) which is derived from at least one predefined temperature curve (T300) which represents a predefined temperature value (T) of the electrical meter (2) as a function of time according to a modeled thermal behavior of the electrical meter (2). Furthermore, the invention relates to a computer program (4) for monitoring the functional status of an electrical meter (2). Furthermore, the invention relates to a computer-readable data carrier (5) on which a computer program (4) according to the invention is stored, and to a data carrier signal (6) carrying a computer program (4) according to the invention. Furthermore, the invention relates to an electrical meter (2) configured to implement the computer program (4) according to the invention. Finally, the invention relates to an electrical metering system (1), in particular an Advanced Metering Infrastructure (AMI), comprising at least one electrical meter (2) and/or at least one management device (3) configured to implement the method according to the invention.)

1. A method of monitoring the functional status of an electrical meter (2), comprising the steps of:

generating at least one temperature signal from which an actual temperature value (T) of the electrical meter (2) can be derived;

determining whether the actual temperature value (T) and/or the gradient (Gm) of the actual temperature value exceeds at least one threshold value (L) which is derived from at least one predefined temperature curve (T300) representing time-dependent predefined temperature values (T) of the electrical meter (2) from a modeled thermal behavior of the electrical meter (2).

2. The method according to claim 1, characterized in that the method further comprises the steps of: generating a trigger signal (S) if the actual temperature value (T) and/or the gradient (Gm) of the actual temperature value exceeds the at least one threshold value (L).

3. The method according to claim 1 or 2, characterized in that the method further comprises the steps of: -selecting the temperature profile (T300) from a set of predefined temperature profiles (T300) according to a specific operating state of the electrical meter (2) and/or according to a specific operating condition of the electrical meter, and/or-adjusting the at least one temperature profile (T300).

4. Method according to one of the preceding claims, characterized in that the method further comprises the step of: identifying at least one point of interest in the at least one temperature profile (T300).

5. Method according to one of the preceding claims, characterized in that the resistance (R) in the main current path within the meter is associated with the at least one predefined temperature curve (T300) and/or is derived from the actual temperature value (T) and/or the gradient (Gm) of the actual temperature value.

6. Method according to one of the preceding claims, characterized in that the method further comprises the step of: establishing at least one thermal model for modeling the thermal behavior of the electrical meter (2), the at least one thermal model comprising the at least one predefined temperature curve (T300).

7. Method according to claim 6, characterized in that at least one parameter of the thermal model is automatically adjusted by machine learning upon identification of a specific error, trend, pattern or correlation between the actual temperature value (T) and/or the gradient (Gm) of the actual temperature value and the at least one predefined temperature curve (T300).

8. The method according to claim 6 or 7, characterized in that the step of establishing said at least one thermal model comprises the step of defining at least one equilibrium state (Q302, Q303) assumed by the electrical meter (2) during operation, said at least one equilibrium state (Q302, Q303) being representative of a thermal equilibrium of the electrical meter (2) which depends on at least one electrical load (A) passing through the electrical meter (2) and on environmental conditions present in the environment (100) of the electrical meter (2).

9. The method according to claims 6 to 8, wherein the step of establishing the at least one thermal model comprises the steps of: defining at least one heating behavior and/or at least one cooling behavior of the electrical meter (2) based on at least one functional step response (C) of the electrical meter (2) to a change of a functional state and/or an operational state of the electrical meter (2).

10. Method according to one of claims 6 to 9, characterized in that the step of establishing the thermal model comprises a step of determining at least one thermal resistance value (Rth) of the electrical meter (2) and/or a step of determining at least one thermal capacitance value (Cth) of the electrical meter.

11. Method according to one of claims 6 to 10, characterized in that the step of establishing at least one thermal model is performed for at least two different types of operating conditions of the electrical meter (2) and/or at least two different types of electrical meters (2).

12. A computer program (4) for monitoring a functional status of an electrical meter, the computer program comprising instructions which, when the computer program (4) is executed by an electrical meter (2) and/or a management device (3) in an electrical metering system (1), cause the electrical meter (2) and/or the management device (3) to carry out the steps of the method according to one of claims 1 to 11.

13. A computer-readable data carrier (7) on which a computer program (4) according to claim 12 is stored.

14. A data carrier signal (5) carrying a computer program according to claim 12.

15. An electrical meter (2) configured to implement the method according to one of claims 1 to 11.

16. An electrical metering system (1), in particular an Advanced Metering Infrastructure (AMI), comprising at least one management device (3) configured to implement the method according to one of claims 1 to 11 and/or at least one electrical meter (2) according to claim 15.

Technical Field

The invention relates to a method for monitoring the functional state of an electrical meter. Furthermore, the invention relates to a computer program for monitoring the functional status of an electrical meter. Furthermore, the invention relates to a computer-readable data carrier on which a computer program according to the invention is stored, and to a data carrier signal carrying a computer program according to the invention. Furthermore, the invention relates to an electrical meter configured to implement the computer program according to the invention. Finally, the invention relates to an electrical metering system, in particular an Advanced Metering Infrastructure (AMI), comprising at least one electrical meter according to the invention.

Background

Methods for monitoring the functional state of an electrical meter are known from the prior art. Such methods are commonly used to monitor whether the electrical meter is functioning properly. In particular, a fault condition of the electrical meter should be identified to prevent a dangerous event. Fault conditions may occur, for example, due to overload or malfunction in the microelectronic circuitry of the electrical meter, due to excessive current or malfunction in the main internal bus bars and associated electrical terminals of the electrical meter, or due to self-heating of the electrical meter caused by environmental effects of the electrical meter (e.g., excessive temperatures around the electrical meter, which may be due to sunlight or other heat sources (e.g., pipes of a heat generating system, etc.).

WO 2013006901 a1, representative of the applicant of the present invention, describes a method and apparatus for monitoring the condition of a utility meter by: obtaining a temperature value associated with a meter; determining whether the temperature value exceeds a threshold value; if the threshold is exceeded, an action is triggered. In another form, temperature may be used as a fault parameter to determine the condition of the utility power meter.

WO 2016066373 a1, which represents the applicant of the present invention, relates to a method of determining a reduction in the remaining useful life of an electrical device during a specific time period. A measurement system is provided that includes a temperature measurement device, a current measurement device, and a voltage measurement device. The temperature value, the voltage value, and the current value are measured by using a measuring device. The harmonic load is determined based on the current value. A reduced maximum operating temperature is determined based on the harmonic load. The amount of over voltage transient is determined based on the voltage value. A transient aging factor is determined based on the amount of transient overvoltage. A temperature dependent aging factor is determined based on the temperature value and the reduced maximum operating temperature. Finally, a reduction in remaining useful life is determined based on the specific time period, the transient aging factor, and the temperature-dependent aging factor.

Furthermore, US 6,847,300B 2 describes an electric power meter comprising a temperature sensor and a controller. The controller may operate based on the temperature reported from the temperature sensor to generate an alarm when the temperature exceeds a certain alarm threshold, and activate the power disconnect switch when the temperature exceeds a disconnect threshold, thereby disconnecting power to the customer premises. The controller is operable to activate the power disconnect switch to not pay a fee for electricity, which complies with a secondary standard based on regulatory requirements. The customer terminal may be used to notify the customer of an alarm condition, provide information regarding power usage or provide information regarding power disconnection.

EP 1980862 a2 describes a meter having an interface connected to a temperature sensor (i.e. a temperature dependent resistor) by a wireless transmission circuit. The processor includes a saving unit for saving temperature data, which is provided with time information, into the memory at preset time intervals or based on events registered in the processor. If the maximum temperature value is exceeded, the processor generates an alarm signal which is applied to the interface or the interface contacts.

US 7,716,012B 2 relates to a process monitoring method that aggregates monitoring devices and optional sensors into one or more groups each related to a process of a utility system. The monitoring devices are organized into a monitoring system hierarchy either manually or automatically. The processing algorithm determines from the hierarchy which monitoring devices are connected to the load. Monitoring data from a pair of monitoring devices connected to the load is correlated to produce a correlation coefficient, which is compared to a correlation threshold selected between 0 and 1. When the correlation coefficient exceeds a threshold, the device pairs are grouped into a processing group. Other pairs of devices that exceed the threshold are also grouped into processing groups. A processing algorithm may be utilized to determine the plurality of processes. Sensors may also be manually grouped using a processing group containing monitoring devices, which may include virtual monitoring devices. Alarms associated with monitoring devices and sensors are aggregated into one process alarm.

The method for monitoring the functional state of an electrical meter according to the prior art has the following disadvantages: these methods rely on the evaluation of temperature differences and gradients relative to some predefined threshold. This makes the known methods and the devices and systems implementing such methods rather inflexible.

Disclosure of Invention

The object of the present invention is to solve or at least mitigate the disadvantages of the methods for monitoring the functional status of an electrical meter according to the prior art. In particular, it is an object of the present invention to provide a method for monitoring the functional status of an electrical meter and a corresponding device and system, which can be easily adapted to the respective operating conditions.

This object is achieved by a method, a computer program, a computer readable data carrier, a data carrier signal, an electrical meter and an electrical metering system according to independent claims 1, 12, 13, 14, 15 and 16, respectively.

In particular, according to the invention, this object is achieved by a method of monitoring the functional status of an electrical meter, wherein the method comprises the steps of:

-generating at least one temperature signal from which an actual temperature value of the electrical meter can be derived;

-determining whether the actual temperature value and/or its gradient exceeds at least one threshold value, the at least one threshold value being derived from at least one predefined temperature curve representing time-varying predefined temperature values of the electrical meter according to the modeled thermal behavior of the electrical meter.

This object is achieved with a computer program for monitoring a functional state of an electrical meter, wherein the computer program comprises instructions which, when the computer program is executed by an electrical meter and/or a management device in an electrical metering system, cause the electrical meter and/or the management device to carry out the steps of the method according to the invention.

The computer-readable data carrier according to the invention has stored thereon a computer program according to the invention.

The data carrier signal according to the invention carries the computer program according to the invention.

The object is achieved by an electrical meter according to the invention, wherein the electrical meter is configured to carry out the method according to the invention.

This object is achieved by an electrical metering system, in particular an AMI, wherein the electrical metering system comprises at least one electrical meter according to the invention and/or at least one management device configured to implement the method according to the invention.

These solutions according to the invention have the advantage over the monitoring techniques known from the prior art that not only the temperature differences and gradients with respect to certain predefined thresholds are monitored, but also an additional dimension is added to the monitoring process, wherein the temporal effects of the temperature in relation to the operating state and conditions of the electrical meter are taken into account. In other words, according to the present invention, the dynamic behavior of the temperature values and/or temperature gradients is monitored, instead of just monitoring whether the temperature values or temperature gradients exceed a certain nominal value according to the prior art, because the temperature values and/or temperature gradients are based on a temperature profile as a function of time corresponding to the respective thermal behavior of a specific type of electrical meter. Thus, the present invention allows early detection of overheating in electrical meters and possibly other electronic devices due to fault conditions.

By using at least one temperature profile according to the invention, it is possible to monitor the change of the respective temperature values over time depending on the individual performance of the electrical meter, since the individual performance of the electrical meter may change over time instead of assuming general or common performance parameters of the electrical meter as is done according to the prior art. The invention allows to take into account certain time spans of the process of temperature values and/or temperature gradients to be monitored, and thus to adapt the threshold values according to certain events, load conditions, operating conditions and/or environmental conditions of the electrical meter within these time spans.

Thus, in one aspect, the solution according to the invention enables an improved accuracy of the monitoring, since the dynamic consideration of the predefined temperature profile allows setting a threshold for the temperature values and/or gradients that may be more stringent than the static thresholds used according to the prior art. On the other hand, the solution according to the invention enables an improved accuracy of the monitoring, since the thermal behavior itself and thus the at least one predefined temperature profile can be readjusted over time, providing a moving or rolling threshold or limit for the respective temperature value and/or temperature gradient in a manner similar to applying a moving average or mean to the time series of data points. Thus, the flexibility and adaptability of the monitoring process is enhanced.

The solution is not limited to monitoring the electrical meter itself, but also for the detection of faulty wires or cables connected to the electrical meter. Such a situation may occur when the fixing element (e.g. screw) in the electrical terminal to which the wire is attached is too tight, not tight enough, or the insulation of the wire is not removed correctly. In case of over-tightening, the wire may be damaged, for example such that its diameter is significantly reduced and/or its strands are broken. In the case where the electric wire is insufficiently fastened or not sufficiently stripped, the contact area between the electric wire and the terminal may be significantly reduced. Both cases may lead to high resistance contacts, which may cause overheating, which may be detected by the solution according to the invention.

The solutions according to the invention can be combined as desired and can be further improved by the following embodiments, which are advantageous for them in each case. These embodiments can be easily combined with each other unless otherwise stated. The skilled person will readily understand that all the device features of the apparatus and system according to the invention may also be implemented as and/or constitute steps of the method and/or computer program according to the invention, and vice versa.

In a possible embodiment of the method according to the invention, the method further comprises the steps of: a trigger signal is generated if the actual temperature value and/or its gradient exceeds at least one threshold value. The trigger signal may be used to affect the operating state or operating condition of the electrical meter and may also be used to signal a fault condition of the electrical meter, for example by generating an error signal.

For example, the operating state may be influenced by cutting off an electrical load applied to the electrical meter to reduce heat generation in and/or around the electrical meter. The operating conditions of the electrical meter may be influenced, for example, by providing the electrical meter with an internal and/or external heat sink, for example in the form of a cooling fan, to reduce the actual temperature in and/or around the electrical meter to a desired value. Corresponding signals indicative of changes in operating state and/or operating conditions, as well as error signals, may be recorded in the electrical meter and/or sent to higher-level instance management equipment of the electrical metering System, such as a data concentrator or Head-End System (HES), for processing and use in data analysis and decision making. Alternatively or additionally, the electrical meter may send or receive information to or from, respectively, the higher-level instance device, such as instructions for changing operating states or operating conditions, adjusting temperature curves and/or thresholds, and the like. This contributes to further increasing the flexibility and accuracy of monitoring the functional status of the electrical meter.

Furthermore, the derivation and/or adaptation of the threshold value for the trigger signal according to the invention contributes to an improvement of the reaction time in solutions for monitoring the functional state of an electrical meter compared to the prior art. According to the prior art, the thresholds are set such that they allow the worst-case thermal performance of a properly functioning meter to be detected, so that the trigger signal is not generated until the worst-case normal condition is exceeded. In contrast, according to the present invention, the varying threshold is constantly calculated for any given moment. Thus, the present invention allows for earlier detection of fault conditions than the prior art when the measured performance of an electrical meter exceeds the expected performance of a given set of operating parameters of the electrical meter.

In a possible embodiment of the method according to the invention, the method further comprises the steps of: the temperature profile is selected from a set of predefined temperature profiles and/or at least one temperature profile is adjusted according to a specific operating state of the electrical meter and/or according to a specific operating condition of the electrical meter. The adjusting of the at least one temperature profile may comprise: an intermediate value between two adjacent predefined temperature curves is calculated. The different operating states may include various modes of operating the electrical meter, such as whether the electrical meter is in an idle mode, a standby mode, a standard mode, a data reception and/or transmission mode, a data processing mode, a firmware update mode, and the like. The different operating conditions may also comprise different environmental conditions of the electrical meter, in particular the ambient temperature, the air flow and/or the heat radiation around the electrical meter.

The operating state may also be distinguished from a fault state of the electrical meter (e.g., a fault state when an error in the hardware and/or software of the electrical meter occurs). In distinguishing the operating state from the fault state, the functional state of the electrical meter can be evaluated. By adjusting at least one temperature profile and/or selecting a temperature profile from a set of predefined temperature profiles, it may be determined whether a threshold value is exceeded or not based on a specific temperature profile representing a respective operating state and/or a respective operating condition. The threshold for determining whether the electrical meter has entered a fault state may be adjusted accordingly. This helps to further improve the accuracy and reliability of monitoring the functional status of the electrical meter.

In a possible embodiment of the method according to the invention, the method further comprises the steps of: at least one point of interest in the at least one temperature profile is identified. The points of interest may be related to specific operating conditions of the electrical meter, such as steady state, load changes, heating or cooling conditions, and large changes in thermal energy generation. In defining the points of interest, the specific thermal behavior of the electrical meter may be closely monitored, for example by an increased density of predefined temperature values of the at least one predefined temperature curve and/or an increased rate of sampling the temperature signal, which facilitates better definition and detection of certain thermal phenomena in a differentiated manner. Therefore, the accuracy and reliability of monitoring the functional state of the electric meter can be further improved.

In a possible embodiment of the method according to the invention, the resistance in the main current path within the meter is associated with at least one predefined temperature profile and/or is derived from the actual temperature value and/or its gradient. The main current path may include busbars, shunts, switches, etc. A resistance in the main current path determines heat generation along the main current path in dependence on a respective electrical load on the main current path. Thus, when associating the at least one predefined temperature profile with the resistance in the main current path, the at least one predefined temperature profile may be a function of the electrical load on the main current path at the respective resistance. The actual temperature value and/or its gradient may be used to determine the resistance of the main current path. Thus, the critical resistance of the main current path can be identified. This contributes to further increase the accuracy and reliability of monitoring the functional status of the electrical meter, since temperature anomalies (e.g. overheating) in the high current mains connected equipment may be the first indicator of a fault that may lead to a fire or to equipment disassembly.

In a possible embodiment of the method according to the invention, the method further comprises the steps of: at least one thermal model for modeling thermal behavior of the electrical meter is established, the at least one thermal model including at least one predefined temperature profile. Such a thermal model may be implemented in any kind of computer software, e.g. firmware of an electrical meter and/or operating software of a management device in an electrical metering system. The thermal model is used to model the thermal behaviour of an electrical meter or any other electrical device and may comprise one or more thermally active elements or components of the electrical meter, the thermal behaviour of which is modeled to estimate the power consumption and thus the amount of both heating due to the microelectronic circuitry and heating due to currents in the main current path. Machine learning may then be applied to the output of the model to adjust the configuration parameters of the thermal model to adapt the thermal model to the particular operating conditions and operating states of the electrical meter.

For example, the input parameters of the thermal model include the following:

-heat generation due to heat generation in the microelectronic circuit;

-heating based on current in the main current path and resistance;

heating due to the surrounding environment (e.g. other heat generating facilities or equipment in the vicinity of the electrical meter, or direct sunlight onto the electrical meter);

-the currently measured absolute actual temperature or temperature gradient; and/or

-estimating (or measuring) the external ambient temperature.

For example, the output parameters of the thermal model include the following:

-a predefined temperature, temperature gradient and/or temperature profile; and/or

The time span until the electrical meter or its thermally active element or component reaches a point of interest in the temperature curve, such as certain thermal states (e.g. steady state, etc.).

Such output of the thermal model is preferably calculated continuously (e.g., every tenth of a second, every second, and/or every minute). Due to the variability of the estimated input parameters, the thermal model may be calculated multiple times with different possible minimum and maximum values to determine the range of possible output parameters. The output parameters may be used to perform certain actions in determining whether the actual temperature value and/or its gradient exceeds at least one threshold.

For example, based on a comparison between a measured or estimated actual temperature gradient and a predefined temperature gradient, it may be determined that:

-whether the electrical meter or a component or part thereof is faulty;

-whether the model parameters of the thermally active element or component need to be adjusted;

-whether the measured or estimated external ambient temperature needs to be adjusted; and/or

Whether the temperature sensor needs to be adjusted.

For example, based on a comparison between a measured or estimated actual temperature value and a predefined temperature value, it may be determined that:

-whether the electrical meter or a component or part thereof is faulty;

-whether the model parameters of the thermally active element or component need to be adjusted;

-whether the measured or estimated external ambient temperature needs to be adjusted; and or

Whether the temperature sensor needs to be adjusted.

For example, when the electrical meter is in a steady state with a low load condition, it may be determined that:

-whether the model parameters of the thermally active element or component need to be adjusted;

-whether the measured or estimated external ambient temperature needs to be adjusted; and/or

Whether the temperature sensor needs to be adjusted.

Any deviation or difference between the actual value and the predefined value (i.e. between the model output parameter and the measured and/or estimated value of the respective parameter) may be indicative of a modeling error and/or a fault condition of the electrical meter and is tracked over time, preferably over a long period of time, to determine whether any kind of trend, pattern or correlation implication of a particular modeling, software and/or hardware error can be identified based on further processing of the parameters.

In a possible embodiment of the method according to the invention, the at least one parameter of the thermal model is automatically adjusted by machine learning upon identification of a specific error, trend, pattern or correlation between the actual temperature value and/or its gradient and the at least one predefined temperature curve. Preferably, during the identification, errors due to fault conditions are distinguished from incorrectly set configuration parameters or external influences and operating conditions (e.g. heating caused by sources outside the electrical meter). For example, logic implemented for identifying and distinguishing specific errors, trends, patterns, or correlations from one another in a machine learning process, implemented as part of a method according to the present invention, may be based on the following:

-considering certain astronomical and seasonal influences corresponding to a certain time of day and a certain time of year, respectively;

-determining whether a low load condition exists;

-comparing the parameters and values with corresponding historical parameters and values, in particular with the transient thermal response of the electrical meter;

-determining whether an operating state related to the main current path has changed, in particular due to a change in the metered electrical load;

-determining whether an operational state related to the microelectronic circuit has changed; and/or

-determining whether a cooling effect is imminent, for example due to a drop in the electrical load metered and/or applied to the microelectronic circuit.

When the process of identifying and distinguishing specific errors, trends, patterns, or correlations from one another determines success, the machine learning process will involve adjustments and/or changes to the parameters of the model in a manner that reduces the corresponding errors or unwanted trends.

Whenever a machine learning process is applied, the respective system implementing the machine learning process should be avoided from drawing conclusions of errors, i.e. accepting the fault state or condition as a new specification or reference. Erroneous conclusions can be avoided by setting range limits on the model configuration parameters. If an attempt is made in the machine learning process to modify a particular configuration parameter beyond its limits, an abnormal condition may be indicated, and/or an alarm condition may be raised. Thus, a machine learning monitoring logic is implemented that runs in parallel with the main logic that triggers an alert when the model output error exceeds certain thresholds.

In a possible embodiment of the method according to the invention, the step of establishing the at least one thermal model comprises the step of defining at least one equilibrium state that the electrical meter assumes during operation, the at least one equilibrium state being representative of a thermal equilibrium of the electrical meter that depends on at least one electrical load passing through the electrical meter and on environmental conditions present in an environment of the electrical meter. The at least one equilibrium state may be based on a certain operational state of the electrical meter, e.g. based on a power condition of the electrical meter for a certain current flowing through the electrical meter at a certain phase and voltage. The environmental condition may particularly refer to the temperature surrounding the electrical meter and/or the thermal radiation to which the electrical meter is exposed or emitted from the electrical meter. The at least one temperature profile may then be adjusted according to the at least one equilibrium state. In particular, an equilibrium temperature corresponding to at least one equilibrium state may be identified and/or defined. The threshold to be monitored may then be defined based on the respective equilibrium temperatures. This helps to further adapt the threshold values to the respective operating conditions of the electrical meter and thus increases the flexibility and accuracy of monitoring the functional status of the electrical meter.

In a possible embodiment of the method according to the invention, the step of establishing at least one thermal model comprises the steps of: at least one heating behavior and/or at least one cooling behavior of the electrical meter is defined based on at least one functional step response of the electrical meter to a change of an operating state and/or a functional state of the electrical meter. The step response occurs in particular when the operating conditions of the electrical meter change suddenly, for example when the power applied to the electrical meter rises or falls suddenly, or when the electrical load to be measured by the electrical meter changes, or when the electronic circuits of the electrical meter itself perform certain operations including powering on or powering off. Thus, at least one heating action is typically associated with a rise in power, while at least one cooling action is associated with a decrease in power applied to the electrical meter. When taking these actions into account, the respective threshold values to be monitored can be adjusted, which contributes to further increasing the flexibility and accuracy of monitoring the functional state of the electrical meter.

For example, the at least one functional step response is related to a change in electrical load on a busbar of the electrical meter. The busbars or busbars of electrical meters carry the electrical power to be metered and are therefore exposed to relatively high maximum currents and voltages. The busbar is therefore a critical component to be monitored, since, due to the relatively high loads, faults on the busbar and the associated terminals may cause dangerous conditions, including overheating, melting, arcing, etc. of the individual components, which on the one hand may cause electrical faults and on the other hand may cause fire. Therefore, including the change in the electrical load on the busbar in the temperature model helps to further improve the accuracy and reliability of monitoring the functional state of the electrical meter.

In a possible embodiment of the method according to the invention, the step of establishing the thermal model comprises the step of determining at least one thermal resistance value of the electrical meter and/or the step of determining at least one thermal capacity value of the electrical meter. The at least one thermal resistance value is used to define a temperature difference across the structure of the electrical meter and to model thermal behavior of the electrical meter, such as heat dissipation behavior, and the ability of the electrical meter to conduct thermal energy in reaction to exposure to thermal energy generated within or in the surroundings of the electrical meter. The at least one thermal capacity value helps to define the thermal mass of the electrical meter and helps to model the electrical behavior of the electrical meter, in particular its ability to store thermal energy. At least one thermal resistance value and/or at least one thermal capacitance value may be applied to each thermally active element or component of the electrical meter as respective modeling parameters of the thermal model to be established. Thus, the at least one thermal resistance value and the at least one thermal capacitance value contribute to refine the thermal model of the electrical meter to provide an accurate understanding of the thermal behavior of the electrical meter and thus generate the at least one predefined temperature curve. Therefore, the at least one thermal resistance value and the at least one thermal capacitance value contribute to further improving the accuracy and reliability of monitoring the functional state of the electric meter.

In a possible embodiment of the method according to the invention, the step of establishing at least one thermal model is carried out for at least two different types of operating conditions of the electrical meter and/or for at least two different types of electrical meter. The at least two different types of operating conditions may be related to different load conditions and operating states of the electrical meter and/or to different functional states of the electrical meter. Under different load conditions, different electrical loads of the electrical meter may be taken into account. As mentioned above, the different operating states may comprise various modes of operating the electrical meter, such as an idle mode, a standby mode, a standard mode, a data receiving and/or transmitting mode, a data processing mode, a firmware updating mode, etc., and may also comprise different environmental conditions of the electrical meter, in particular the temperature, airflow and/or heat radiation around the electrical meter. The operating state should be distinguished from a fault state of the electrical meter (e.g., a fault state when an error in the hardware and/or software of the electrical meter occurs). This contributes to further improving the accuracy and reliability of monitoring the functional status of the electric meter.

Further, establishing at least one thermal model for at least two different types of electrical meters may include: a generic thermal model is established for at least two different types of electrical meters. Alternatively or additionally, a separate thermal model may be established for each of the at least two different types of electrical meters. Thus, both collective and individual behavior of the electrical meters can be taken into account when building the thermal model. In one aspect, this helps to improve the accuracy and reliability of monitoring the functional status of the electrical meter. In another aspect, the efficiency of building the thermal model may be improved.

Based on at least one thermal model established for at least two different types of operating conditions of the electrical meter and/or at least two different types of electrical meter, a set of predefined temperature profiles may be generated, including temperature profiles for respective different operating conditions and/or different electrical meters. Each predefined temperature profile of the set of predefined temperature profiles may represent a specific thermal behavior of the electrical meter or of different electrical meters under respective operating conditions. Thus, by selecting a predefined temperature profile from a set of predefined temperature profiles, the monitoring of the functional status of the electrical meter can be easily adapted to the respective operating conditions of the electrical meter or to different types of electrical meters. This contributes to further increasing the flexibility and accuracy of monitoring the functional status of the electrical meter.

Drawings

In the following, the invention will be described in more detail in an exemplary manner using advantageous embodiments and with reference to the accompanying drawings. However, the described embodiments are only possible configurations, wherein the individual features as described above may be provided independently of one another or may be omitted.

In the drawings:

FIG. 1 illustrates a schematic diagram showing an exemplary schematic architecture of an electrical metering system including an electrical meter, shown in schematic elevation view, according to an embodiment of the present invention;

FIG. 2 shows a schematic cross-sectional side view of an electrical meter according to an embodiment of the invention in an operating environment of the electrical meter;

FIG. 3 illustrates an exemplary thermal performance diagram of a thermal model for modeling thermal behavior of an electrical meter in accordance with the present invention;

FIG. 4 illustrates an exemplary graph showing the effect of thermal resistance in a thermal model for modeling thermal behavior of an electrical meter according to the present invention;

FIG. 5 illustrates an exemplary graph showing the effect of heat capacity in a thermal model for modeling thermal behavior of an electrical meter in accordance with the present invention;

FIG. 6 illustrates an exemplary graph showing the effect of resistance in the main current path of an electrical meter considered in a thermal model for modeling thermal behavior of an electrical meter according to the present disclosure;

FIG. 7 illustrates an exemplary graph showing modeling bias that may occur when building a thermal model for modeling thermal behavior of an electrical meter according to the present invention;

FIG. 8 illustrates an exemplary flowchart showing steps for establishing a thermal model for modeling thermal behavior of an electrical meter in accordance with the present invention;

FIG. 9 illustrates an exemplary flowchart showing steps of a runtime logic of an electrical meter when creating a thermal model for modeling thermal behavior of the electrical meter according to the present invention;

FIG. 10 illustrates an exemplary flowchart showing steps of a design time-course thermal model discovery process in creating a thermal model for modeling thermal behavior of an electrical meter in accordance with the present invention;

FIG. 11 illustrates an exemplary flowchart showing steps of an installation time course thermal model discovery process when building a thermal model for modeling thermal behavior of an electrical meter in accordance with the present invention; and

fig. 12 shows an exemplary diagram illustrating the actual temperature curves of three different electrical meters to be simulated with a thermal model according to the present invention.

Detailed Description

Fig. 1 shows a schematic diagram illustrating an exemplary schematic architectural front view of an electrical metering system 1 comprising an electrical meter 2 according to an embodiment of the present invention. The electricity metering system 1 further comprises a management device 3, for example a data concentrator or a head-end system (HES) in the form of a computer or the like, which management device 3 serves to manage and control the electricity metering system 1. The control and management of the electrical metering system 1, in particular the electrical meter 2 and the management device 3, is performed by means of a computer program 4.

The computer program 4 may be provided on a computer-readable data carrier 5, which computer-readable data carrier 5 is configured to be accessed by the electrical meter 2 and/or the management apparatus 3. Alternatively or additionally, the computer program 4 may be arranged to be carried on a data carrier signal 6. A data carrier signal 6 or any other type of data and/or information can be exchanged between the electrical meter 2 and the management device 3 via an energy and/or information transmission line 7. The energy and/or information transmission line 7 may be established in a wired and/or wireless manner. For receiving and sending data and information via the energy and/or information transmission line 7, the electrical meter 1 is provided with transmission means 8 in the form of a wired or wireless communication line, an antenna or the like. Furthermore, the electrical metering system 1 comprises an electrical wire 9 in the form of a cable or wire for transmitting the electrical power to be metered by the electrical meter 2.

The electrical meter 2 comprises a housing 10 in the form of a shell, casing, shell for accommodating therein the various components of the electrical meter 1. At the bottom 11 of the housing 10, the electrical meter 2 is provided with electrical terminals 12 for connecting the electrical wires 9 to the electrical meter 2 in an electrically conductive manner. In particular, the active input terminal 12a is configured to be connected to the phase input line 9a, the neutral input terminal 12b is configured to be connected to the neutral input line 9b, the active output terminal 12c is configured to be connected to the phase output line 9c, and the neutral output terminal 12d is configured to be connected to the neutral output line 9 d. The terminals 12 are mounted on a terminal block 13 of the electric meter 2. The terminal block 13 is held by the housing 10, and is formed of a highly insulating material and supports the terminals 12.

A busbar 14 having a high current carrying capacity and a low resistance is provided within the electrical meter 2 as a main current path for conducting an electrical load from the input terminals 12a, 12b to the output terminals 12c, 12 d. The busbar 14 has an active input 14a, an active link 14b, an active output 14c and a neutral link 14 d. The active input portion 14a connects the active input terminal 12a to the resistive shunt 15. The active link 14b connects the resistive shunt 15 to the supply disconnect switch 16, in particular to its switch input line 16 a. The active output 14c connects the supply disconnect switch 16, and in particular its switch output line 16b, to the active output terminal 12 c. The neutral link 14d connects the neutral input terminal 12b to the neutral output terminal 12 d.

The metering unit 17 of the electrical meter 2 comprises a metering device in the form of a microelectronic device, the metering unit 17 being connected to the busbar 14 in the region of the resistive shunt 15 for measuring the current flowing through the busbar 14 by converting the current into a proportional voltage. In particular, the metering input line 17a of the metering device 17 is connected to the resistive shunt 15 near the location where the active input 14a is connected to the resistive shunt 15. The meter out line 17b is connected to the resistive shunt 15 near the location where the active link 14b is connected to the resistive shunt 15.

The processing unit 18 of the electrical meter 2 comprises at least one microelectronic main processor, a memory, an oscillator and/or supporting circuitry. The communication unit 19 comprises communication microelectronics, such as at least one transceiver or radio transmitter, for communication via the transmission means 8. The power supply unit 20 of the electrical meter 2 comprises power supply circuitry and microelectronics for converting the mains supply voltage to a voltage suitable for operating the internal meter circuitry and components, such as the supply disconnect switch 16, the metering device 17, the processing unit 18 and the communication unit 19.

A temperature sensor 21 is provided for generating a temperature signal and/or a temperature value. The temperature sensors 21 include a remote sensor 21a, an external sensor 21b, an internal top sensor 21c, an internal front sensor 21d, an internal back sensor 21e, an internal side sensor 21f, a terminal area sensor 21g, a terminal block sensor 21h, a supply line sensor 21i, an input section sensor 21j, an output section sensor 21k, a link section sensor l, a switch sensor 21m, a metering unit sensor 21n, a processing unit sensor 21o, a communication unit sensor 21p, and/or a power supply unit sensor 21 q.

The remote sensor 21a is arranged and configured to measure the ambient temperature of the environment surrounding the electrical meter 2, and is therefore preferably not physically connected to the electrical meter 2, in order to avoid conductive thermal energy transfer between the remote sensor 21a and the electrical meter 2. The external sensor 21b is arranged and configured to measure the external temperature of the electrical meter 2, in particular of the housing 10. The internal sensors 21c to 21f are arranged and configured to measure the internal temperature of the electrical meter 2 at the top wall, front wall, rear wall and side walls (see fig. 3) of the interior of the housing 10, respectively. The terminal area sensor 21g is arranged and configured to measure the temperature near or around the electrical terminal 12 inside the housing 10. The supply line sensor 21i is arranged and configured to measure the temperature of the electrical line 9, in particular the phase input line 9 a. The terminal block sensor 21h is arranged and configured to measure the temperature of the terminal block 13. The input sensor 21j, the output sensor 21k and the link sensor 21l are arranged and configured to measure the temperature of the busbar 14, in particular the active input 14a, preferably in the vicinity of the resistive shunt 15, the active output 14c and the neutral link 14d, respectively. The switch sensor 21m, the metering unit sensor 21n, the processing unit sensor 21o, the communication unit sensor 21p and the supply unit sensor 21q are arranged and configured to measure the temperature of the supply disconnection switch 16, the metering unit 17, the processing unit 18, the communication unit 19 and the power supply unit 20.

Furthermore, the internal conductor 22 of the electrical meter is provided in the form of a cable, a wire, a conductive path, a conductor rail, a strip conductor or the like, in order to connect these components and elements of the electrical meter 2 to each other whenever information and/or energy needs to be exchanged between the transmission means 8, the busbar 14 (in particular the active input 14a and the neutral link 14d thereof), the supply disconnection switch 16, the metering unit 17, the processing unit 18, the communication unit 19, the power supply unit 20 and/or the temperature sensor 21 of the electrical meter 2. For the sake of clarity, an explicit illustration of the inner conductor 22 connected to the temperature sensor 21 is omitted in fig. 1.

Fig. 2 shows a schematic cross-sectional side view of the electrical meter 2 in an operating environment 100 of the electrical meter 2. It is apparent here that the housing 10 of the electric meter 2 includes a top wall portion 10a, a bottom wall portion 10b, a front wall portion 10c, and a rear wall portion 10 d. Further, the housing 10 is provided with or supplemented with a terminal cover 10e covering the electric terminals 12. In the terminal block 13, the electrical terminals 12 are each provided with at least one fixing element 13a, such as a terminal screw, a clamp, a latch or the like, for fixing the electrical wire 9 to the electrical terminals 12 while establishing electrical contact between the electrical wire 9 and the busbar 14.

The supply disconnection switch 16, the metering unit 17, the processing unit 18, the communication unit 19, and the power supply unit 20 are mounted on a substrate 23 such as a Printed Circuit Board (PCB). The base plate 23 is mounted to the housing 10, particularly the rear wall portion 10d thereof, by means of mounting elements 24. The mounting elements 24 may be embodied as mounting studs, spacer bolts, or the like.

The operating environment 100 generally includes a mounting structure 150 (e.g., a wall of a building structure, electrical cabinet, etc.), an air mass 160, and an external heat source 170 (e.g., the sun, pipes, ducts, exhaust pipes, etc.).

In order to build a thermal model of the method according to the invention, an envelope boundary 200 is defined for defining the thermal equilibrium of the electrical meter 2 with respect to the operating environment 100. For example, the envelope boundary 200 extends along a wall of the housing 10, in particular within a top wall portion 10a, a front wall portion 10c, a rear wall portion 10d and a terminal cover 10e enclosing the inner space 25 of the electrical meter 2.

With respect to the envelope boundary 200, certain thermal energy flows relating to the elements and components of the electrical meter 2 are defined for establishing the thermal model of the method according to the invention. In this example, the flow of thermal energy in the form of negative or positive conduction, convection and/or radiant heat transfer comprises: heat transfer 209 across envelope boundary 200 via electrical wires 9, heat transfer 210 from housing 10 across envelope boundary 200 to air mass 160 and operating environment 100, heat transfer 210d across envelope boundary 200 from rear wall 10d to mounting structure 150, heat transfer 214 within envelope boundary 200 from busbar 14 to interior space 25 of electrical meter 2, heat transfer 216 within envelope boundary 200 from supply disconnect switch 16 to interior space 25 of electrical meter 2, heat transfer 217 within envelope boundary 200 from metering unit to interior space 25 of electrical meter 2, heat transfer 218 within envelope boundary 200 from processing unit 18 to interior space 25 of electrical meter 2, transfer 219 within envelope boundary 200 from communication unit 19 to interior space 25 of electrical meter 2, transfer 220 within envelope boundary 200 from power supply unit 20 to interior space 25 of electrical meter 2, heat transfer 260 within envelope boundary 200 across envelope boundary 200 due to convection of air mass 160, and/or heat transfer 170 from external heat source 170 across envelope boundary 200 Heat transfer to meter 2 270.

FIG. 3 illustrates an exemplary thermal performance diagram 300 of a thermal model for modeling the thermal behavior of the electrical meter 2 in accordance with the present invention. A temperature curve T300 is determined on the basis of the thermal performance diagram 300, the temperature curve T300 representing, for example, an internal temperature T25 as the temperature of the air in the internal space 25 of the electrical meter 2. In a first phase 301 of the thermal performance diagram 300, the heat transfer from the internal microelectronic circuits of the electrical meter 2 (e.g. including the heat transfers 216, 217, 218, 219, 220 in connection with the supply disconnection switch 16, the metering unit 17, the processing unit 18, the communication unit 19 and/or the power supply unit 20, respectively) amounts to about 1.3W and results in a slow temperature rise T301 starting from an external ambient temperature T100 representing the temperature of the operating environment 100.

At the first transition C301 of the thermal performance diagram 300, the heat generation of the busbar 14 begins to rise abruptly due to the application of a current load of 100A to the busbar 14 and associated components and main current path of the electrical meter 2. Thus, in the second stage 302 of thermal performance diagram 300, a rapid temperature rise T302 occurs due to a corresponding heat transfer 214 of about 50W in addition to heat transfers 216, 217, 218, 219, 220. Towards the end of the second phase 302, after a period d302 of about 24s between the first step change C301 and the first steady state Q302, the first steady state Q302 is reached at a temperature of about 78 ℃, which represents a thermal equilibrium state between the electrical meter 2 and the operating environment 100.

At the second step-up C302, a sudden drop in the electrical load of the busbar 14 occurs as the current drops from 100A to 50A. Thus, the heat transfer 214 drops to about 12W, except for heat transfers 216, 217, 218, 219, 220. Thus, during the third phase 303 of the thermal performance map, a rapid temperature decrease 303 occurs from a temperature of about 78 ℃ in the first steady state Q302 to about 42 ℃ in the second steady state Q303.

Fig. 4 shows an exemplary diagram of the influence of heat capacity in a thermal model for modeling the thermal behavior of the electrical meter 2 according to the present invention. In the present example, based on thermal performance diagram 400, the modeled thermal behavior results in three different temperature profiles T410, T420, and T430, which are based on three different thermal resistance values Rth 0.5K/W, 1K/W, and 2K/W, respectively, assumed for electrical meter 2. In general, the thermal resistance value Rth is determined by the case 10 of the electric meter 2, and particularly by the thickness and material characteristics of the terminal cover 10e and the wall portions 10a, 10b, 10c, 10d having their specific heat transfer coefficients. The temperature curves T410, T420, and T430 represent, for example, an internal temperature T25 of the electric meter 2.

In a first phase 401 of thermal performance diagram 400, a total of about 3W of heat transfer from the internal microelectronic circuit of electrical meter 2, which again for example comprises heat transfers 216, 217, 218, 219, 220 associated with supply disconnection switch 16, metering unit 17, processing unit 18, communication unit 19 and/or power supply unit 20, respectively, results in slow warming T411, T421 and T431 of temperature curves T410, T420 and T430, respectively, starting from an external ambient temperature T100 of about 25 ℃ representing the temperature of operating environment 100.

At a first step change C401 of the thermal performance diagram 400, a sudden rise in heat generation of about 10W of the busbar 14 occurs as a result of the respective current loads applied to the busbar 14 and associated components in the main current path of the electrical meter 2. Thus, in second stage 402 of thermal performance diagram 400, rapid temperature increases T412, T422, and T432 in temperature curves T410, T420, and T430, respectively, occur due to a corresponding heat transfer 214 of about 10W in addition to heat transfers 216, 217, 218, 219, 220.

During the second phase 402, first steady states Q412, Q422 and Q432 representing a thermal equilibrium state between the electrical meter 2 and the operating environment 100 are reached at temperatures of about 31 ℃, 38 ℃ and 50 ℃ in the temperature curves T410, T420 and T430, respectively. The first steady states Q412, Q422, and Q432 are reached after periods d412, d422, and d432 of about 8s, 22s, and 40s, respectively, after the first step change 401. The difference in the temperatures reached at the first steady states Q412, Q422 and Q432 and the difference in the periods d412, d422 and d432 until the first steady states Q412, Q422 and Q432 are reached, respectively, is caused by the respective different thermal resistance values Rth of 0.5K/W, 1K/W and 2K/W assumed for the electric meter 2. It is evident that the heat dissipation performance of the electrical meter 2 decreases with increasing thermal resistance, i.e. the equilibrium temperature of the corresponding steady heat transfer 209, 210d, 260 towards the operating environment 100 by crossing the envelope boundary 200 is reached later and higher the thermal resistance value after the step change with rising heat generation. In other words, the lower the thermal resistance, the higher the heat transfer 209, 210d, 260 during periods d412, d422, and d 432.

At the second step-up C402, a sudden drop in the electrical load of the busbar 14 occurs. Thus, the heat transfer 214 drops to about 1.5W, except for heat transfers 216, 217, 218, 219, 220. Thus, during the third phase 403 of the thermal performance map, rapid cooling T413, T423, and T433 occur in the temperature curves T410, T420, and T430, respectively. In this example, for the temperature curves T410, T420, and T430, the temperature drops from a temperature of about 31 ℃, 38 ℃, and 50 ℃ at the first steady state Q412, Q422, and Q432, respectively, to a temperature of about 28 ℃, 31 ℃, and 38 ℃ at the second steady state Q413, Q423, and Q433, respectively. After the first step change C401, second steady states Q413, Q423, and Q433 are reached after periods d413, d423, and d433 of 9s, 18s, and 24s, respectively.

Thus, similar to the effect of the different thermal resistance values Rth of 0.5K/W, 1K/W and 2K/W, respectively, on the heat dissipation behavior of the electric meter 2, it is evident that the heat source performance of the electric meter 2 based on the heat transfer 209, 210d, 260 across the envelope boundary 200 towards the operating environment 100 decreases with increasing thermal resistance, i.e. the higher the thermal resistance value, the later the equilibrium temperature is reached and the higher the equilibrium temperature is after a step change with decreasing heat generation. Accordingly, the lower the thermal resistance, the higher the heat transfer 209, 210d, 260 during time periods d413, d423, and d 433.

Fig. 5 shows an exemplary diagram illustrating the effect of heat capacity in a thermal model for modeling the thermal behavior of the electricity meter 2 according to the present invention. In the present example, based on thermal performance diagram 500, the modeled thermal behavior results in three different temperature curves T510, T520, and T530, which are based on three different assumed thermal capacitance values Cth2J/K, 5J/K, and 10J/K, respectively, for electrical meter 2. The temperature curves T510, T520, and T530 represent, for example, an internal temperature T25 of the electric meter 2. In the present example, it is assumed for the modeled thermal behavior that a thermal resistance Rth of 1K/W results in three different temperature curves T510, T520 and T530. Thermal performance plot 500 and temperature curve T520 are the same as thermal performance plot 400 and temperature curve T420, respectively, shown in fig. 4.

In a first phase 501 of the thermal performance diagram 500, a total of about 3W of heat transfer from the internal microelectronic circuit of the electrical meter 2, which again for example comprises heat transfers 216, 217, 218, 219, 220 in connection with the supply disconnection switch 16, the metering unit 17, the processing unit 18, the communication unit 19 and/or the power supply unit 20, respectively, results in slow temperature increases T511, T521 and T531 at temperature curves T510, T520 and T530, respectively, which slow temperature increases T511, T521 and T531 start from an external ambient temperature T100 of about 25 ℃ representing the temperature of the operating environment 100. Since the difference in the slow warming T511, T521 and T531 is significant, the effect of the different heat capacity values Cth2J/K, 5J/K and 10J/K has become apparent based on the relatively low heat transfer from the internal microelectronic circuits of the electric meter 2 only. During the slow ramp-up T511, T521 and T531, the temperature rises from T100 at 25 ℃ to about 25.5 ℃, 26 ℃ and 27 ℃, respectively, reflecting the strong influence of the heat capacity on the thermal behavior of the electrometer 2 with respect to the temperature gradient (i.e. the slope of the temperature curve).

At a first step change C501 in the thermal performance diagram 500, a sudden rise in heat generation of, for example, about 10W of the busbar 14 occurs due to the respective current loads applied to the busbar 14 and associated parts and main current path of the electrical meter 2. Thus, in the second stage 502 of thermal performance diagram 500, rapid temperature increases T512, T522, and T532 of temperature curves T510, T520, and T530, respectively, occur due to a corresponding heat transfer 214 of about 10W in addition to heat transfers 216, 217, 218, 219, 220.

During the second phase 502, first steady-states Q512, Q522 and Q532 representing a thermal equilibrium state between the electrical meter 2 and the operating environment 100 are reached at temperatures of about 38 ℃ in the temperature curves T510, T520 and T530, respectively. After the first step change C501, first steady states Q512, Q522, and Q532 are reached after periods d512, d522, and d532 of about 8s, 22s, and 37s, respectively. The differences in the periods d512, d522 and d532 until the first steady-state Q512, Q522 and Q532, respectively, is reached are caused by the respective different heat capacity values Cth2J/K, 5J/K and 10J/K assumed for the electric meter 2. It is evident that the thermal buffer performance of the electrical meter 2 improves with increasing heat capacity, i.e. after a step change with rising heat generation, the higher the heat capacity value, the later the equilibrium temperature is reached with a corresponding stable heat transfer 209, 210d, 260 across the envelope boundary 200 towards the operating environment 100. In other words, the lower the heat capacity, the higher the heat transfer 209, 210d, 260 during the time periods d512, d522, and d 532.

At the second step-up C502, a sudden drop in the electrical load of the busbar 14 occurs. Therefore, the heat transfer 214, except for heat transfer 216, 217, 218, 219, 220, drops to about 1.5W. Thus, during the third phase 503 of the thermal performance map, rapid cooling T513, T523, and T533 occur in the temperature curves T510, T520, and T530, respectively. In this example, for the temperature curves T510, T520, and T530, the temperature drops from a temperature of about 38 ℃ in the first steady state Q512, Q522, and Q532, respectively, to a temperature of about 31 ℃ in the second steady state Q513, Q523, and Q533. After the first step change C501, the second steady states Q513, Q523, and Q533 are reached after periods d513, d523, and d533 of about 11s, 18s, and 24s, respectively.

Thus, by the influence of the respective different heat capacity values Cth2J/K, 5J/K and 10J/K on the thermal buffer behavior of the electrical meter 2, it is evident that as the heat capacity increases, the heat storage performance of the electrical meter 2 increases based on the heat transfer 209, 210d, 260 across the envelope boundary 200 towards the operating environment 100, i.e. after a step change with decreasing heat generation, the higher the heat capacity value Cth, the later the equilibrium temperature is reached. Accordingly, the lower the heat capacity value Cth, the lower the heat transfer 209, 210d, 260 during the time periods d513, d523, and d 533.

Fig. 6 illustrates an exemplary graph showing the effect of resistance in the main current path of the electric meter 2 considered in the thermal model for modeling the thermal behavior of the electric meter 2 according to the present invention. In the present example, the simulation is based on three thermal performance maps 610, 620 and 630, which are based on three different capacitance values R0.0002 ohm, 0.001 ohm and 0.005 ohm, respectively, assumed for the main current path of the electrical meter 2. The modeled thermal behavior results in three different temperature curves T610, T620 and T630 relating to capacitance values R of 0.0002 ohm, 0.001 ohm and 0.005 ohm, respectively. The temperature curves T610, T620, and T630 represent, for example, an internal temperature T25 of the electric meter 2.

In the first phases 611, 621 and 631 of the thermal performance diagrams 610, 620 and 630, respectively, an equal heat transfer amounting to about 3W from the internal microelectronic circuits of the electrical meter 2, which heat transfer for example also comprises the respective heat transfers 216, 217, 218, 219, 220 relating to the supply disconnection switch 16, the metering unit 17, the processing unit 18, the communication unit 19 and/or the power supply unit 20, respectively, leads to a uniform slow warming T611, T621 and T631 in the temperature curves T610, T620 and T630, respectively, which uniform slow warming T611, T621 and T631 starts from an external ambient temperature T100 of about 25 ℃ representing the temperature of the operating environment 100.

At the first transitions C611, C621 and C631 in thermal performance maps 610, 620 and 630, a sudden rise in heat generation of, for example, about 2W, 10W and 50W of busbar 14, respectively, occurs due to the respective current loads applied to busbar 14 of electrical meter 2 and the associated parts in the main current path. Thus, in second stages 612, 622, and 632 of thermal performance maps 610, 620, and 630, respectively, rapid temperature increases T612, T622, and T632 of temperature curves T610, T620, and T630, respectively, occur due to corresponding heat transfers 214 of approximately 2W, 10W, and 50W in addition to heat transfers 216, 217, 218, 219, 220.

During the second phases 612, 622 and 632, first steady states Q612, Q622 and Q632 representing thermal equilibrium conditions between the electrical meter 2 and the operating environment 100 are reached at temperatures of about 29 ℃, 38 ℃ and 78 ℃ in the temperature curves T610, T620 and T630, respectively. After the first step change C601, first steady states Q612, Q622, and Q632 are reached after periods d612, d622, and d632 of about 12s, 18s, and 37s, respectively. The difference in the time periods d612, d622 and d632 until the first steady states Q612, Q622 and Q632, respectively, are reached is caused by the respective different heat transfers 214 of about 2W, 10W and 50W. As the resistance increases, the heat generation performance of the electrical meter 2 increases, i.e. after a step change with rising heat generation, the higher the resistance value R, the later the equilibrium temperature is reached and the higher the temperature of the equilibrium temperature is, with a corresponding steady heat transfer 209, 210d, 260 across the envelope boundary 200 towards the operating environment 100.

At the second step-up C602, a sudden drop in the electrical load of the busbar 14 occurs. Thus, heat transfer 214, except heat transfer 216, 217, 218, 219, 220, drops to approximately 1.5W, 2W, and 12W in thermal performance maps 610, 620, and 630, respectively. Accordingly, during the third stages 613, 623, 633 of thermal performance maps 610, 620, 630, rapid cooling T613, T623, T633 occurs in temperature curves T610, T620, T630, respectively. In this example, for the temperature curves T610, T620, and T630, the temperature drops from a temperature of about 29 ℃, 38 ℃, and 78 ℃ in the first steady states Q612, Q622, and Q632, respectively, to a temperature of about 29 ℃, 28 ℃, and 42 ℃ in the second steady states Q613, Q623, and Q633, respectively. After the first step change C601, the second steady states Q613, Q623, and Q633 are reached after periods d613, d623, and d633 of about 9s, 18s, and 24s, respectively.

Thus, as the resistance of the main current path increases, the heat generation performance of the electrical meter 2 increases based on the heat transfer 209, 210d, 260 across the envelope boundary 200 towards the operating environment 100, i.e. the higher the resistance value of the main current path, the higher and later the equilibrium temperature is reached after a step change with decreasing heat generation. Correspondingly, the lower the resistance value, the lower the heat transfer 209, 210d, 260 and the corresponding equilibrium temperature.

Fig. 7 shows an exemplary diagram illustrating modeling deviations that may occur when building a thermal model for modeling thermal behavior of the electricity meter 2 according to the present invention. In the present example, based on thermal performance diagram 300 (see fig. 3), the modeled thermal behavior results in three different temperature curves T710, T720 and T730, which are based on nominal parameters of thermal resistance and thermal capacity assumed for electrical meter 2, respectively, thermal mis-resistance and thermal mis-capacity. For example, the temperature curves T710, T720, and T730 each represent an internal temperature T25 of the electric meter 2.

In a first phase 301 of thermal performance diagram 300, a total of about 3W of heat transfer from the internal microelectronic circuits of electrical meter 2, which again for example comprises heat transfers 216, 217, 218, 219, 220 in connection with supply disconnection switch 16, metering unit 17, processing unit 18, communication unit 19 and/or power supply unit 20, respectively, results in slow temperature increases T711, T721 and T731 in temperature curves T710, T720 and T730, respectively, which slow temperature increases T711, T721 and T731 start from an external ambient temperature T100 of about 25 ℃ representing the temperature of operating environment 100. Since the difference in the slow warming T711, T721 and T731 is apparent, the effect of having a wrong heat capacity value has become apparent based on the relatively low heat transfer from the internal microelectronics of the electric meter 2 only. During the slow temperature increases T711, T721 and T731, the temperature rises from T100 at 25 ℃ to about 27 ℃ and 27.5 ℃, respectively, reflecting the strong influence of the heat capacity on the thermal behavior of the electrometer 2 with respect to the temperature gradient (i.e. the slope of the temperature curve).

At a first step change C301 in the thermal performance diagram 300, a sudden rise in heat generation of, for example, about 50W of the busbar 14 occurs due to the respective current loads applied to the busbar 14 and associated parts and main current paths of the electrical meter 2. Thus, in the second stage 302 of thermal performance diagram 700, rapid temperature increases T712, T722, and T732 occur in temperature curves T710, T720, and T730, respectively, due to a corresponding heat transfer 214 of about 50W in addition to heat transfers 216, 217, 218, 219, 220.

During the second phase 302, first steady-states Q712, Q722 and Q732 representing a thermal equilibrium state between the electrical meter 2 and the operating environment 100 are reached at temperatures of about 78 ℃,71 ℃ and 78 ℃ in the temperature curves T710, T720 and T730, respectively. After the first step change C301, the first steady states Q712, Q722, and Q732 are reached after periods d712, d722, and d732 of about 24s, 20s, and 12s, respectively. The difference in the periods d712, d722 and d732 until the first steady states Q712, Q722 and Q732, respectively, are reached reflects the deviation from the nominal values assumed for the thermal resistance Rth and the thermal capacity Cth of the electric meter 2.

At the second step-up C302, a sudden drop in the electrical load of the busbar 14 occurs. Therefore, the heat transfer 214, except for heat transfer 216, 217, 218, 219, 220, drops to about 12W. Accordingly, during the third phase 303 of thermal performance diagram 300, rapid temperature reductions T713, T723, and T733 occur in temperature curves T710, T720, and T730, respectively. In this example, for the temperature curves T710, T720, and T730, the temperature drops from a temperature of about 78 ℃,71 ℃, and 78 ℃ in the first steady-state Q712, Q722, and Q732, respectively, to a temperature of about 40 ℃, 38 ℃, and 40 ℃ in the second steady-state Q713, Q723, and Q733, respectively. After the first step change C701, the second steady states Q713, Q723 and Q733 are reached after time periods d713, d723 and d733 of about 11s, 18s and 24s, respectively.

It is apparent that the deviation of the thermal resistance causes the following two deviations: a different temperature difference dT with respect to the temperature assumed for the nominal parameter; and the difference in the time period between the step change and the reaching of the next equilibrium state, while deviations of the heat capacity from the nominal parameters only lead to the latter.

Fig. 8 shows an exemplary flowchart illustrating the steps of establishing a thermal model for modeling the thermal behavior of the electricity meter 2 according to the present invention. In a first step S1, the heat generation within the electrical meter 2 is calculated. In particular, in the first sub-step S1a, the heat generation in the microelectronic components and units, for example the heat transfers 216, 217, 218, 219, 220 in connection with the supply disconnection switch 16, the metering unit 17, the processing unit 18, the communication unit 19 and/or the power supply unit 20, respectively, is calculated on the basis of the communication state COM, the configuration state CON and the CPU load CPU of the electrical meter 2. In the second substep S1b, the heat generation of the busbar 14 and associated parts and the main current path of the electrical meter 2 is calculated taking into account the current load a applied to the busbar 14, the temperature T of the busbar 14 and/or the internal temperature T25 of the electrical meter 2, and the resistance R of the main current path. As output values of the first and second substeps S1a, S1b, heat dissipation from the electrical meter 2 due to heat transfer 210 across the envelope boundary 200, etc. is calculated for both the microelectronic components of the electrical meter 2 and the main current path. In addition, the heat dissipation and/or absorption due to heat transfer 209 across the envelope boundary 200, etc. is calculated for the main current path of the electrical meter 2.

In a second step S2, based on the thermal modeling and the measured gradient Gm with the temperature sensor 21, the output value of step S1 is calculated as a calculated or simulated gradient Gc together with the ambient temperature T100 and the minimum and maximum values of the heat transfer 270 from the external heat source 170, the temperature gradient characterizing the thermal behavior of the electrical meter 2. The output values of the second step are the minimum and maximum values of the calculated gradient Gc and the measured gradient Gm.

In a third step S3, the respective temperature gradient and/or temperature value errors and/or deviations are calculated using the minimum and maximum values of the calculated gradient Gc and the measured gradient Gm as input values.

In a fourth step S4, the temperature gradient error and/or deviation calculated in the third step S3 is checked against the corresponding error range and/or threshold value used as limit L. If such a limit L is exceeded, in a fifth step S5 a respective trigger signal S is generated, such that a respective event is recorded, an alarm is triggered, and/or the supply disconnection switch 16 is actuated.

The fourth step S4 is followed by a sixth step S6 if it has been determined in the fourth step S4 that the respective limit L has not been exceeded. Then, in a sixth step S6, it is checked, for example by taking into account the configuration state CON, the CPU load CPU and the communication state COM and any required temperature value T derived from the temperature sensor 21, whether any temperature gradients and/or temperature value errors and/or deviations are due to self-heating of the electrical meter 2, for example due to heat generated in the microelectronic component by the heat transfer 216, 217, 218, 219, 220. If in the sixth step S6 it is determined that the temperature gradient and/or the temperature value error and/or deviation is due to self-heating of the electrical meter 2, in a seventh step S7 the respective parameter used as input value in step 1, in particular the heat transfer 216, 217, 218, 219, 220, the configuration state CON, the CPU load CPU and/or the communication state COM, is adjusted accordingly.

The sixth step S6 is followed by an eighth step S8 if it has been determined in the sixth step S6 that the temperature gradient and/or temperature value error and/or deviation is not due to self-heating of the electrical meter 2. Then, in an eighth step S8, it is determined whether any temperature gradient and/or temperature value error and/or deviation is due to heating of the main current path, in particular the busbar 14 of the electrical meter 2, for example by taking into account any of the respective heat transfer 214 and the temperature sensor 21 associated with the busbar 14. If in the eighth step S8 it is determined that the temperature gradient and/or the temperature value error and/or deviation is due to heating of the main current path, in particular the busbar 14, in a ninth step S9 the value of the resistance R associated with the main current path, in particular the busbar 14, which is used as input value in step 1, is adjusted accordingly.

If it has been determined in the eighth step S8 that the temperature gradient and/or the temperature value error and/or deviation is not due to heating of the main current path of the electrical meter 2, in particular the busbar 14, the eighth step S8 is followed by a tenth step S10. Then, in a tenth step S10, it is determined, in particular by using the respective temperature sensor 21 associated with the external heat source 170, whether any temperature gradients and/or temperature value errors and/or deviations are due to heat transfer 270 from the external heat source 170. If in the eighth step S8 it is determined that the temperature gradient and/or the temperature value error and/or deviation is caused by heating the heat transfer 270 from the external heat source 170, in an eleventh step S11 the value considered for calculating the respective heat transfer 270, in particular the outside temperature T, used as input value in step 1 is adjusted accordingly.

If it has been determined in the eighth step S8 that the temperature gradient and/or the temperature value error and/or deviation is not due to heating of the main current path of the electrical meter 2, in particular the busbar 14, the eighth step S8 is followed by a tenth step S10. Then, in a tenth step S10, it is determined, in particular by using the respective temperature sensor 21 associated with the external heat source 170, whether any temperature gradients and/or temperature value errors and/or deviations are due to heat transfer 270 from the external heat source 170. If in a tenth step S10 it is determined that the temperature gradient and/or temperature value error and/or deviation is due to heat transfer 270 from the external heat source 170, in an eleventh step S11 the values considered for calculating the respective heat transfer 270 are adjusted accordingly.

The tenth step S10 is followed by a twelfth step S12 if it has been determined in the tenth step S10 that the temperature gradient and/or temperature value error and/or deviation is not due to heat transfer 270 from the external heat source 170. Then, in a twelfth step S12, it is determined, in particular by using the respective temperature sensor 21 associated with the electrical wire 9, whether any temperature gradients and/or temperature value errors and/or deviations are due to the heat transfer 209 via the electrical wire 9. If in a twelfth step S12 it is determined that the temperature gradient and/or temperature value error and/or deviation is due to heat transfer 270 from the external heat source 170, in a thirteenth step S13 the values considered for calculating the respective heat transfer 209 are adjusted accordingly.

In a fourteenth step S14 following the fifth step S5, the seventh step S7, the ninth step S9, the eleventh step S11, the twelfth step 12 and/or the thirteenth step 13, the process shown in fig. 8 is terminated and/or repeated again from the beginning of the first step S1.

Fig. 9 shows an exemplary flowchart illustrating the steps of the runtime logic of the electrical meter 2 when establishing a thermal model for modeling the thermal behavior of the electrical meter 2 according to the present invention. The runtime logic is computer readable instructions, such as software and/or firmware, constituting at least part of the computer program 4, which are executed by the supply disconnection switch 16, the metering unit 17, the processing unit 18, the communication unit 19 and/or the power supply unit 20.

In a first runtime step RS1, the instantaneous temperature value T and the calculated temperature gradient value Gc are continuously generated using the formula for the heat capacity Cth and the heat resistance Rth to model the electrical meter 2, using readings from at least one of the temperature sensor 21, the measurement of the current load a and/or the microelectronic heat estimation (in particular for the heat transfers 216, 217, 218, 219 and 220 in connection with the metering unit 17, the processing unit 18, the communication unit 19 and/or the power supply unit 20, respectively).

The thermal model is based on the following three equations for calculating the temperature T as a function of time T:

T(t)＝T₀×(1-e^(-t/λ)) (1)，

wherein, T (t) [ K ]]Is the instantaneous temperature, T, during the heating phase of the electric meter 2₀[K]Is the final steady-state instantaneous temperature of the electrical meter 2, and λ [1/s ]]Is a time constant obtained by multiplying the thermal resistance Rth and the thermal capacity Cth;

T(t)＝T₀×(e^(-t/λ)) (2)，

wherein, T (t) [ K ]]Is the instantaneous temperature, T, during the cooling phase of the electric meter 2₀[K]Is the initial instantaneous temperature of the electric meter 2, and λ [1/s ]]Is a time constant obtained by multiplying the thermal resistance Rth and the thermal capacity Cth; and

ΔT＝Q×R_th (3)，

where Δ T [ K ] is the temperature difference between two points of an object, such as the electrical meter 2 and its parts, elements or components, Q [ W ] is the heat flow through the object, and Rth [ K/W ] is the thermal resistance between two defined points of the object for which the thermal performance is simulated.

In a second runtime step RS2, a plurality of results of small variations of model parameters (e.g. heat capacity Cth, heat resistance Rth, resistance R and/or microelectronic heat factor, in particular for heat transfer 216, 217, 218, 219 and 220 in relation to the metering unit 17, the processing unit 18, the communication unit 19 and/or the power supply unit 20, respectively) within the range of potential model parameters are calculated.

In a third runtime step RS3, the error and/or deviation between the measurement and the model result (i.e. its measured temperature gradient and the simulated temperature and temperature gradient) is calculated.

In a fourth runtime step RS4, the model parameters are identified, yielding the minimum error/deviation between the measurement results and the simulation results.

In a fifth runtime step RS5, small incremental changes are made to the model parameters identified in the fourth runtime step RS4 in the direction that produces the smallest error or deviation and in proportion to the identified model parameters. For such adjustments, filtering may be used, for example, by applying a finite impulse response filter and/or an infinite impulse response filter.

In a sixth runtime step RS6, the identified and adjusted model parameters from the runtime step 5 are compared with preconfigured range limits to detect when the established thermal model is normalized to indicate a specific thermal model in case of an error or fault condition, such as an excessive resistance in the main current path, in particular the busbar 14, and/or a fault in the microelectronic component.

In a seventh run-time step RS7, it is determined whether the parameters of the particular thermal model from the sixth run-time step RS6 indicating an error or fault condition are outside of a particular parameter range. Thus, the respective model results are compared to the respective threshold values. If the respective model parameter exceeds the respective threshold, an error, fault and/or alarm event is logged and/or further measures are taken, such as actuating the supply disconnect switch 16 and the like.

In a ninth runtime step RS9, following the seventh runtime step RS7, points of interest, such as steady state, heating conditions, cooling conditions and/or any relatively large changes in thermal energy generation, are determined.

In a tenth runtime step RS10, when a point of interest is identified in the ninth runtime step RS9, then corresponding information is recorded, including basic thermal model parameters such as instantaneous temperature T and temperature gradient G, current load a, microelectronic heating estimation, etc.

In an eleventh runtime step RS11, the information and parameters characterizing the points of interest recorded during the tenth runtime step RS10 are used to adjust the model parameters and the weighting of the respective filter values of the applied finite impulse response filter and/or infinite impulse response filter. For example, starting from a certain steady state, the sudden step change of the load current a is close to zero and the associated cooling provides an excellent opportunity to adjust the heat capacity Cth without any error in the estimated resistance R in the main current path. Alternatively or additionally, the steady state condition provides an opportunity to adjust the thermal resistance Rth without being affected by the heat capacity Cth that complicates the calculation. Furthermore, a change in the temperature T may be indicative of a thermal change in the operating environment 100 during a specific steady state in which the load current a and the heating due to the microelectronic heating factors (in particular the heat transfers 216, 217, 218, 219 and 220 in relation to the metering unit 17, the processing unit 18, the communication unit 19 and/or the power supply unit 20, respectively) are relatively stable over time T.

In a twelfth runtime step RS12, the thermal model results are calculated again as in the first runtime step RS1, but now based on the information and parameters recorded in the runtime step R10 during the point of interest (if applicable), as adjusted in the eleventh runtime step RS 11. Similarly, in a twelfth runtime step RS12, the corresponding error and/or deviation between the measurement and the simulation results (i.e. their measured temperature gradient and the simulated temperature and temperature gradient) is calculated, similar to what was done in the third runtime step RS 3.

In a twelfth operating step RS12, small incremental changes are made to the model parameters recorded in the tenth operating step RS10 and/or set in the eleventh operating step RS11, as in the fifth operating step RS5, in the direction of the smallest errors or deviations and in proportion to the identified model parameters. For such an adjustment, for example when applying a finite impulse response filter and/or an infinite impulse response filter, adjusted filter values obtained by weighting the individual filter values in the runtime step 11 may be used. In other words, information and parameters may be fed back from the twelfth runtime step RS12 to the first runtime step RS1, the third runtime step RS3 and/or the fifth runtime step RS5, so that these steps are performed in an iterative manner.

In a thirteenth runtime step RS13, the model parameters obtained in the previous runtime step, in particular in the twelfth runtime step RS12, are recorded as historical values of the model parameters.

In a fourteenth runtime step RS14, the historical model parameters recorded in the thirteenth runtime step RS13 are scanned to identify any large responses or suspected values and/or parameter changes.

In a fifteenth runtime step RS15, the range limits of the model parameters are incrementally adjusted using the changes in the historical model parameters recorded in the fourteenth runtime step RS 14. The respective adjusted range limits may be fed back to the sixth runtime step RS6 to detect an error or fault condition based on the respective range limits.

In a sixteenth runtime step RS16, the maximum variation of each model parameter is recorded.

In a seventeenth runtime step RS17, the first to sixteenth runtime steps RS1 to RS16 as described above may be repeated in order to calculate thermal model results for a plurality of thermal models representing different parts, elements and/or components within the electrical meter 2. Preferably, a single thermal model comprising a single heat capacity Cth and a heat resistance Rth is necessary and should be sufficient to model the thermal behavior of the electrical meter 2. However, in order to increase the accuracy of the method for monitoring the functional status of an electrical meter 2 according to the present invention, the thermal behavior of different parts, elements and/or components within the electrical meter 2 may be modeled as described herein.

Fig. 10 shows an exemplary flowchart illustrating steps of a design-time-course thermal model discovery process when building a thermal model for modeling the thermal behavior of the electrical meter 2 according to the present invention. The steps shown in fig. 10 are used to provide initial parameters and values that will be implemented in the method steps described above with reference to fig. 8 and 9.

In a first design step DS1 of the design time course thermal model discovery process shown in fig. 10, the electrical meter 2 in an unpowered state (i.e., the electrical meter is not powered) is placed in a temperature controlled room (not shown) and allowed to reach a thermal equilibrium state relative to a temperature room having an ambient temperature T100.

In a second design step DS2, the meter is energized without any load applied to the main current path and with constant, i.e. stable, microelectronic behavior to ensure that the heating due to the microelectronic heating factors (in particular the heat transfer 216, 217, 218, 219 and 220 in connection with the metering unit 17, the processing unit 18, the communication unit 19 and/or the power supply unit 20, respectively) is relatively stable, preferably constant over time.

In a third design step DS3, a series of temperature readings is recorded from the point in time at which the microelectronic components of the electrical meter 2 are energized, performed in the second design step DS2, until the point in time at which the electrical meter 2 again reaches a state of thermal equilibrium with respect to the temperature chamber. Based on these temperature readings, the thermal resistance Rth and/or the thermal capacity Cth of the electrical meter 2 and, if desired, any parts, elements and/or components thereof are calculated.

In a fourth design step DS4, the microelectronic heating factors turned on in the second design step DS2, in particular the heat transfers 216, 217, 218, 219 and 220 in connection with the metering unit 17, the processing unit 18, the communication unit 19 and/or the power supply unit 20, respectively, are abruptly eliminated by de-energizing the electrical meter 2.

In a fifth design step DS5, the supply disconnection switch 16 is activated under various load conditions with varying magnitude and phase of the electrical power applied to the main current path, i.e. different load currents a are applied to the active input terminal 12a and the neutral input terminal 12b of the electrical meter 2. By applying various load conditions, the range of the respective relay contact resistance of the supply disconnection switch 16 is measured and/or derived therefrom.

In the sixth design step DS6, after each switching operation of the supply disconnection switch 16 performed in the fifth design step DS5, the impedance from the active input terminal 12a to the active output terminal 12c of the electric meter 2 through the main current path of the electric meter 2 is measured.

The first design step DS1 to the sixth design step DS6 as described above are then repeated.

In a seventh design step DS7, the electrical wire 9 is disconnected and reattached to the electrical terminal 12a plurality of times using different wire diameters of the electrical wire 9.

In an eighth design step DS8, the impedance through the main current path of the electrical meter 2 from the active input terminal 12a to the active output terminal 12c of the electrical meter 2 is measured after each change of the electrical wire 9 performed in the seventh design step DS 7.

In the ninth design step DS8, the impedance through the main current path of the electric meter 2 from the neutral input terminal 12b to the neutral output terminal 12d of the electric meter 2 is measured after each change of the electric wire 9 performed in the seventh design step DS7 and/or after each switching operation of the supply disconnection switch 16 performed in the fifth design step DS 5.

The first design step DS1 through the ninth design step DS9 as described above are then repeated.

In a tenth design step DS10, the temperature of the controlled temperature room, which represents the ambient temperature T100, is modified.

The first design step DS1 through the tenth design step DS10 as described above are then repeated.

In an eleventh design step DS11, a different external heat source 170 (e.g. direct radiation from light and/or a heat source for simulating solar radiation) and/or a controlled air flow is applied to the electrical instrument 2, in particular to the housing 10 thereof. Furthermore, the type of material of the mounting structure 150 to which the electrical meter 2 is attached and/or the specific location of the electrical meter 2 in the electrical cabinet and/or at the electrical switchboard, respectively, is modified.

The first design step DS1 through the eleventh design step DS11 as described above are then repeated.

In a twelfth design step DS12, the behavior of the microelectronic components of the electrical meter 2, in particular the heat transfer 216, 217, 218, 219 and 220 in relation to the metering unit 17, the processing unit 18, the communication unit 19 and/or the power supply unit 20, respectively, is varied. Such a change may be achieved, for example, by changing the sampling rate of the metering unit 17, changing the processing load, i.e., the CPU load, of the processing unit 18, and/or changing the communication frequency applied by the communication unit 19, etc.

Then, the first design step DS1 to the eleventh design step DS12 as described above were repeated for electric meter 2. In addition, after a desired number of repetitions of the first to eleventh design steps DS1 to DS12, these steps of the design time-course thermal model discovery process performed when establishing the thermal model for modeling the thermal behavior of the electrical meter 2 according to the invention may be performed for a plurality of different electrical meters 2 of the same kind and/or of different kinds, to provide respective model parameters and values for a range of the plurality of different electrical meters 2.

Fig. 11 shows an exemplary flowchart illustrating possible steps of an installation time course thermal model discovery process when building a thermal model for modeling the thermal behavior of the electrical meter 2 according to the present invention.

In a first mounting step IS1 of the installation-time thermal model discovery process when establishing the thermal model according to the invention, the impedance IS measured across the main current path of the electrical meter 2 from the active input terminal 12a to the active output terminal 12c of the electrical meter 2.

In the second mounting step IS2, the impedance IS measured across the main current path of the electrical meter 2 from the neutral input terminal 12b to the neutral output terminal 12d of the electrical meter 2.

In a third mounting step IS3, the type of wire 9 attached to the terminal 12 of the electrical meter 2 IS specified, e.g. recorded and/or selected from a predefined list of possible types and/or diameters of wires 9 enabled by the firmware of the electrical meter 2.

In a fourth installation step IS4, a type of installation of the electrical meter 2, i.e. the type of operating environment 100, mounting structure 150 and/or external heat source 170, e.g. in an electrical cabinet, on a wall, exposed to a radiation source, etc., IS specified-e.g. recorded and/or selected, respectively, from a predefined list of possible types of operating environment 100, mounting structure 150 and/or external heat source 170 enabled by the firmware of the electrical meter 2.

In a fifth installation step IS5, the current ambient temperature T100 IS recorded in the electrical meter 2 as enabled by the firmware of the electrical meter 2.

In a sixth installation step IS6, the current time, date and/or weather conditions at the installation site of the electrical meter 2 are recorded in the electrical meter 2, respectively, as enabled by the firmware of the electrical meter 2.

Fig. 12 shows exemplary diagrams showing the actual temperature curves TA, TB and TC of three different electrical meters 2a, 2b and 2c, respectively, to be simulated with a thermal model according to the invention. For example, assuming the same operating states for each of the electrical meters 2, namely current load a, configuration state CON, communication state COM, CPU load CPU, heat capacity Cth and heat resistance Rth, the three temperature curves TA, TB and TC are simulated in conformity with the method according to the invention by executing the individual method steps as described above. Any differences in temperature values and temperature gradients shown in fig. 12 should therefore be due to different resistances R and/or different environmental conditions of the current paths of the electrical meters 2a, 2b and 2 c.

Assuming that the electrical meters 2a, 2b and 2c are of the same type and are all in operation, respective ranges, limits and/or thresholds can be derived from the three temperature curves TA, TB and TC that can be considered acceptable for correct operation of the electrical meters 2a, 2b and 2 c. In particular, fig. 12 shows the maximum slope after a step change C occurs at a time t of about 2:01, i.e. simulated temperature gradients Gc 4.3 ℃/min (degrees celsius/minute), 4.5 ℃/min and 4.7 ℃/min, and maximum temperature rises dT 47.1 ℃, 49.2 ℃ and 47.5 ℃ simulated by the models of electrical meters 2a, 2b and 2℃, respectively.

Thus, it can be derived from these three temperature curves that, under the respective operating conditions, the acceptable range of the measured gradient Gm extends from 4.3 ℃/min to 4.7 ℃/min, 4.7 ℃/min constituting the upper range limit, both 4.7 ℃/min and 4.3 ℃/min constituting the threshold, i.e. the upper and lower thresholds, respectively, of the range of the maximum value of the simulated gradient dGc of 0.2 ℃/min. Accordingly, under the respective operating conditions, the acceptable range of temperature rise dT extends from 47.1 ℃ to 49.2 ℃, 49.2 ℃ constituting the upper range limit, and both 49.2 ℃ and 47.1 ℃ constituting the threshold values, i.e. the upper and lower threshold values, respectively, of the maximum range of simulated temperature difference dT 2.1 ℃. Then, if the respective measured gradient Gm and/or temperature T exceeds or falls below a threshold value based on the respective trigger signal S, an event may be recorded, measures may be taken, and/or an alarm may be generated by the electrical meters 2a to 2c and/or the respective management device 3.

In the alternative, it may be assumed by way of example that the three temperature curves TA, TB and TC shown in fig. 12 relate to the same electrical meter 2 having the same configuration state CON, communication state COM, CPU load CPU, heat capacity Cth and assumed thermal resistance Rth. For example, the temperature profile TA is based on a temperature measurement performed with at least one of the temperature sensors 21 after a specific load current a is applied to the main path of the electrical meter 2 at a step change C. The temperature profile TB may be a simulated temperature profile calculated for the alternative load current a, which is higher than the load current base temperature profile TA. The temperature curve TC may be a simulated temperature curve calculated for the same load current a base temperature curve TA.

Under these alternative assumptions, it is evident that, based on the threshold values derived from the temperature gradients and the range of temperature values between only two simulated temperature curves TB and the simulated temperature curve TC, the fault functional state or any prompt thereto cannot be detected, since the measured maximum temperature gradient Gm 4.5 ℃/min in the temperature curve TB is well within the simulated maximum temperature gradient Gc 4.3 ℃/min in the temperature curve TA and the simulated maximum temperature gradient Gc 4.7 ℃/min in the temperature curve TC, respectively. Furthermore, the maximum measured temperature rise dT 47.5 ℃ of the temperature curve A at time t of 4:20 lies well within the simulated temperature rise 47.1 ℃ of the simulated temperature curve TA at this point in time and the simulated temperature rise 49.2 ℃ of the simulated temperature curve TC at this point in time, respectively.

However, considering that under an alternative assumption the temperature curve TA is measured at the same current load a as the base simulated temperature curve TC, a higher measured temperature rise dT 47.5 ℃ of the temperature curve TA at a time of 4:20 than the simulated temperature rise dT 47.1 ℃ of the temperature curve TC at that point in time exceeds the relative temperature difference Δ T0.4 ℃ between the two temperature curves may imply a fault condition, or may at least indicate a trend towards a fault condition. Furthermore, if it is taken into account that at a point in time T of about 3:47, at which the measured temperature T almost reaches the temperature in the simulated temperature curve TB under the assumption of a higher current load a than the base temperature curve TA, a maximum relative temperature difference Δ T of about 4 ℃ between the temperature curve TA and the temperature curve TC, the deviation between the temperature curve TA and the temperature curve TC under the alternative assumption clearly indicates that certain parameters of the electrical meter 2 are out of range. It must then be evaluated by applying the above-mentioned method steps whether the deviation is based on modeling errors, whether the deviation is based on differences in ambient conditions, or indeed whether an excessive heat rise in the temperature curve TA indicates an increase in the electrical resistance R of the main current path and/or of the microelectronic component of the electrical meter, which increase may be due to a deterioration of the electrical connections within the main current path and/or the microelectronic component, respectively, and may thus constitute a fault state of the electrical meter 2.

Differences from the above described embodiments are possible within the scope of the invention.

The electrical metering system 1 may comprise any number and form necessary for operating, monitoring and/or controlling the electrical metering system 1, in particular any electrical meter 2, 2a, 2b, 2c thereof: electrical meters 2, 2a, 2b, 2c, management means 3, computer programs 4, computer readable data carriers 5, data carrier signals 6, power and/or information transmission lines 7, transmission means 8, and/or electrical lines 9, 9a, 9b, 9c, 9 d.

The electrical meter 2 may be provided with any number and form of sensors necessary for performing the desired function: a housing 10 having wall portions 10a, 10b, 10c, 10d, a terminal cover 10e, a bottom portion 11, electric terminals 12, 12a, 12b, 12c, 12d, a terminal block 13, a busbar 14 having portions 14a, 14b, 14c, 14d in a fixed element 13a, a resistive shunt 15, a supply disconnection switch 16, a switch input line 16a, a switch output line 16b, a metering unit 17, a metering input line 17a, a metering output line 17b, a processing unit 18, a communication unit 19, a power supply unit 20, temperature sensors 21, 21a to 21q, an internal conductor 22, a substrate 23, a mounting element 24, and/or an internal space 25.

Thus, the invention is not limited to an electrical meter 2 having electrical terminals 12, 12a, 12b, 12c, 12d as described herein, but may also be applied, for example, to a so-called socket meter having contact elements or terminals implemented as blades inserted into a socket being part of a base assembly fixed to a wall or electrical panel, which enables a quick change of such a socket meter and avoids cable adjustments. In such an arrangement, the invention may be implemented in a socket meter, a base assembly including a socket, or a combination thereof. The receptacle meter may experience high resistance contact on the blade and/or receptacle that interfaces with the receptacle meter. Similar problems with contact resistance and heat generation may arise for any part or element associated with the interface, as referred to herein with reference to the electrical wires 9, 9a, 9b, 9c, 9d, the electrical terminals 12, 12a, 12b, 12c, 12d, the respective fixing elements 13, e.g. contact springs, and the connections therebetween.

The management device 3, the transmission means 8, the metering unit 17, the processing unit 18, the communication unit 19, the power supply unit 20 and/or the temperature sensors 21, 21a to 21q may comprise any kind of electronic data processing, storage, interface and/or operating means in any number and form desired. The energy and/or information transmission line 7, the transmission means 8 and/or the inner conductor 22 may be implemented as any kind of wired and/or wireless means for transferring energy, in particular electrical energy and/or information (e.g. analog data and/or digital data), comprising any kind of computer software programs, interfaces, modules and/or functions, as well as communication systems, such as global system for mobile communication (GSM), DLMS/COSEM, Power Line Communication (PLC) etc.

The functions performed by the elements, units and modules of the metering system 1 may be implemented as hardware and/or software, to be performed by a single entity and/or a plurality of entities within the electrical meter 2 and/or the management device 3. Thus, the electrical meter 2 and/or the management device 3 may comprise at least one computer, (micro) processor or other type of processor, and at least one computer readable medium, such as a computer readable data carrier 5 which may be embodied as any kind of internal and/or external RAM and/or ROM storage device or data storage means and a corresponding permanent or non-permanent computer and/or machine readable medium, including but not limited to, for example, a cloud storage device, a microchip, a flash drive, an EEPROM, a disk, a card, a tape and drum, a punched card and paper tape, an optical disk, a barcode, a smart code and/or magnetic ink characters storing computer readable program code (e.g., software or firmware) such as computer program 4, which can be written by, for example, (micro) processor, Logic gates, switches, interfaces, gateways, transceivers, Application Specific Integrated Circuits (ASICs), programmable logic controllers, and/or embedded microcontrollers. In particular, the electrical meter 2 and/or the management device 3 may be configured to perform any kind of measuring, calculating, processing, generating, determining, deciding, monitoring and/or controlling steps as described herein.

The at least one thermal model according to the present invention may comprise a simplified thermal model and/or a complex thermal model required for modeling the thermal performance of the electrical meter 2 and/or elements, parts and/or components thereof and the operating environment 100 with the respective mounting structure 150, air mass 160 and/or external heat source 170. Depending on the complexity of the thermal model required, the envelope boundary 200 and the respective heat transfer 209, 210d, 214, 216, 217, 218, 219, 220, 260, 270 may be considered for any element, part and/or component in the electrical meter 2. For modeling the thermal behavior any kind of thermal performance map with corresponding phase, step change, steady state, time period and temperature values, gradients and temperature profiles (with corresponding temperature rise and/or temperature fall) can be used, while any combination of temperature profiles can constitute a set of temperature profiles.

Thus, the method according to the invention may comprise steps S1 to S14, design steps DS1 to DS12, installation steps IS1 to IS6 and/or runtime steps RS1 to RS17 as required and in any number and form necessary to model the thermal behavior of the electrical meter 2, 2a, 2b, 2c and the operating environment 100 to monitor the functional state of the electrical meter 2.

In addition to the electrical meter 2 as described herein, the method according to the invention and the corresponding system 1, including the management device 3, the computer program 4, the computer readable data carrier 5, the data carrier signal 6, the energy and/or information transmission line 7, the transmission means 8 and/or the electrical line 9, may be used for monitoring the functional status of any kind of electrical appliance, apparatus and/or device (e.g. household appliance, computer, transformer, generator, motor, etc.), in particular a device having a relatively large power input, throughput and/or output. The respective appliance, apparatus and/or device itself and/or the respective management device may be configured to perform the method according to the invention.

Reference numerals

1 electricity metering system

2 electric instrument

2a electric meter A

2B electric instrument B

2C electric meter C

3 management device

4 computer program

5 computer-readable data carrier

6 data carrier signal

7 energy and/or information transmission line

8 transmission device

9 electric wire

9a phase input line

9b neutral input line

9c phase output line

9d neutral output line

10 outer casing

10a top wall part

10b bottom wall part

10c front wall part

10d rear wall part

10e terminal cover

11 bottom part

12 electric terminal

12a active input terminal

12b neutral input terminal

12c active output terminal

12d neutral output terminal

13 terminal block

13a fixing element

14 bus bar/main current path

14a active input unit

14b active linking part

14c active output part

14d neutral Link

15 resistance shunt

16 supply disconnect switch

16a switch input line

16b switch output line

17 metering unit

17a metering input line

17b metering output line

18 processing unit

19 communication unit

20 power supply unit

21 temperature sensor

21a remote sensor

21b external sensor

21c internal top sensor

21d internal front sensor

21e internal backside sensor

21f internal side sensor

21g terminal area sensor

21h terminal block sensor

21i supply line sensor

21j input part sensor

21k output sensor

21l link sensor

21m switch sensor

21n metering unit sensor

21o processing unit sensor

21p communication unit sensor

21q supply unit sensor

22 inner conductor

23 base plate

24 mounting element

25 inner space

100 operating environment

150 mounting structure

160 air ball

170 external heat source

200 envelope boundaries

209 heat transfer

210 heat transfer

210d Heat transfer

214 heat transfer

216 Heat transfer

217 heat transfer

218 heat transfer

219 heat transfer

220 heat transfer

260 heat transfer

270 heat transfer

300 thermal performance diagram

301 first stage

302 second stage

303 third stage

400 thermal performance diagram

401 first stage

402 second stage

403 third stage

500 thermal performance diagram

501 first stage

502 second stage

503 third stage

610 thermal performance diagram

611 first stage

612 second stage

613 third stage

620 thermal performance diagram

621 first stage

622 second stage

623 third stage

630 thermal performance diagram

631 first stage

632 second stage

633 third stage

d302 period of time

Period d412

Period d422

Period d432

d413 time period

d423 time period

Period d433

d512 time period

Period d522

d532 time period

Period d513

Period d523

d533 period of time

d612 time period

d622 time period

d632 time period

d613 time period

d623 period of time

Period of d633 time

d712 time period

d722 time period

d732 time period

d713 time period

d723 time period

d733 time period

C301 first step transition

C302 second step transition

First step change of C401

C402 second step transition

C501 first step transition

C502 second step transition

C611 first step transition

C612 second step transition

C621 first step transition

C622 second step transition

C631 first step transition

C632 second step transition

Q302 first Steady/balance

Q303 second Steady/balance

Q412 first Steady/balance

Q422 first Steady/balance

Q432 first Steady/balance

Q413 second Steady/balance

Q423 second Steady/balance

Q433 second Steady/balance

Q512 first Steady/balance

Q522 first Steady/balance

Q532 first Steady/balance

Q513 second Steady/balance

Q523 second Steady/balance

Q533 second Steady/balance

Q612 first Steady/balance

Q622 first Steady/balance

Q632 first Steady/balance

Q613 second Steady/balance

Q623 second Steady/balance

Q633 second Steady/balance

Q712 first Steady/balance

Q722 first Steady/balance

Q732 first Steady/balance

Q713 second Steady/balance

Q723 second Steady/balance

Q733 second Steady/balance

Temperature in T25

T100 ambient temperature

T300 temperature curve

T301 slow temperature rise

T302 fast ramp

T303 rapid cooling

T410 temperature curve

T411 Slow temperature rise

T412 Rapid warming

T413 quick cooling

T420 temperature curve

T421 Slow heating

T422 Rapid temperature rise

T423 rapid cooling

T430 temperature curve

T431 Slow temperature rise

T432 Rapid ramp

T433 rapid cooling

T510 temperature curve

T511 Slow heating

T512 fast heating

T513 quick cooling

T520 temperature curve

T521 slowly increasing temperature

T522 Rapid ramp

T523 rapid cooling

T530 temperature curve

T531 Slow temperature rise

T532 rapid temperature rise

T533 rapid cooling

T610 temperature curve

T611 Slow heating

T612 Rapid temperature rise

T613 fast cooling

T620 temperature Curve

T621 slowly increasing temperature

T622 Rapid temperature rise

T623 Rapid Cooling

T630 temperature curve

T631 Slow temperature rise

T632 Rapid warming

T633 rapid cooling

T710 temperature curve

T711 Slow temperature increase

T712 Rapid warming

T713 Rapid Cooling

T720 temperature curve

T721 slowly increasing temperature

T722 fast ramp-up

T723 Rapid Cooling

T730 temperature curve

T731 Slow heating

T732 rapid temperature rise

T733 rapid cooling

First design step of DS1

DS2 second design step

Third design step of DS3

DS4 fourth design step

DS5 fifth design step

DS6 sixth design step

DS7 seventh design step

DS8 eighth design step

Ninth design step of DS9

Tenth design step of DS10

Eleventh design step of DS11

Twelfth design step of DS12

IS1 first installation step

IS2 second installation step

IS3 third installation step

IS4 fourth installation step

IS5 fifth installation step

IS6 sixth installation step

RS1 first runtime step

RS2 second runtime step

RS3 third runtime step

RS4 fourth runtime step

RS5 fifth runtime step

RS6 sixth runtime step

Seventh runtime step of RS7

RS8 eighth runtime step

Ninth runtime step of RS9

Tenth runtime step of RS10

Eleventh runtime step of RS11

Twelfth runtime step of RS12

Thirteenth runtime step of RS13

Fourteenth runtime step of RS14

Fifteenth runtime step of RS15

Sixteenth runtime step of RS16

Seventeenth runtime step of RS17

S1 first step

S1a first substep

S1b second substep

S2 second step

S3 third step

S4 fourth step

S5 fifth step

S6 sixth step

S7 seventh step

S8 eighth step

S9 ninth step

Tenth step of S10

Eleventh step of S11

Twelfth step of S12

S13 thirteenth step

S14 fourteenth step

A current load

C step change

CON configuration status

COM communication state

CPU load

Cth heat capacity

dT temperature difference/range

Time difference of dt

dG gradient difference/range

G gradient

Gc calculated/simulated gradients

Gradient of Gm measurement

L Limit/threshold

Q Heat transfer/Heat flux

R resistance

Rth thermal resistance

S trigger signal

T temperature

time t

TA temperature Curve Instrument A

TB temperature curve instrument B

TC temperature curve instrument A

Delta T relative temperature difference