DE102022211027A1 - Ageing test for low voltage components - Google Patents

Abstract

The invention relates to checking the aging of a low-voltage component which is designed to be introduced into an electrical circuit. In this case, a first item of temperature information relating to the low-voltage component is determined for a first point in time, a second item of temperature information relating to the low-voltage component is determined for a second point in time, and with the aid of the two items of temperature information, a first item of information is determined which represents a measure of the heating between the points in time. This first item of information is compared with a second item of information which represents a measure of a comparable heating between the points in time for a corresponding low-voltage component in a known state. With the aid of the difference between the first and the second item of information, a statement is then derived on the aging of the low-voltage components. The invention allows a low-effort and efficient check of the aging of a low-voltage component.

Description

The invention relates to a method for checking the aging of a low-voltage component which is designed to be introduced into an electrical circuit, a device for carrying out a method according to the invention and a computer program product with a computer program which carries out the calculation steps of a method according to the invention when it runs on a processor.

In particular, current-carrying low-voltage components are subject to an ageing process in which the ageing depends not only on the external conditions but also on the loads during operation.

An example of such low-voltage components are fuse links, which age during operation at high ambient temperatures, with frequently occurring alternating loads and in overload operation. This ageing results in a change in the tripping characteristics, up to the point of tripping during nominal operation.

Advanced security solutions are sometimes equipped with sensors and communication devices to monitor consumption information, for example.

Fuses with integrated measuring function are e.g. in the WO2020/127486A1 , the WO2020/127488A1 , the WO2020/148015A1 and the DE 102018213522 A1 disclosed.

There is a need to replace such fuses and generally low-voltage components when they have reached the end of their service life. Although the components should be replaced before they fail in order to avoid longer interruptions in operation, replacing them too early would be a waste of resources. A check for ageing is therefore desirable.

The invention aims to make a contribution to this.

This object is achieved by a method according to claim 1, a device according to claim 13 and a computer program product according to claim 17.

According to the invention, a check of the aging of a low-voltage component is proposed, which is designed to be introduced or looped into an electrical circuit (e.g. by means of corresponding connection terminals and a current path running in the low-voltage component). This low-voltage component can be used to monitor or interrupt the electrical circuit.

Here and in the following, the conjunction "or" is always to be understood as a non-exclusive "or". In particular, this should also include the conjunction "and", i.e. in the above case, the low-voltage component can also be used for monitoring and interruption.

In particular, the low-voltage component can be a fuse, a low-voltage switch or a measuring device for energy monitoring - often also referred to as a PMD or power measurement device.

According to the invention, a first item of temperature information relating to the low-voltage component is determined for a first point in time (and preferably also at this point in time). This first item of temperature information is, for example, a temperature characteristic of the low-voltage component. This temperature can be a temperature measured by a temperature sensor of the low-voltage component. However, it is also conceivable, for example, that the low-voltage component has a plurality of temperature sensors spaced apart from one another, the measured values of which are linked to form the first item of temperature information.

Furthermore, a second piece of temperature information relating to the low-voltage component is determined for a second, typically later point in time (and preferably also at this point in time). The determination is preferably carried out in the same way as for the first piece of temperature information in order to ensure comparability. Using the two pieces of temperature information, a first piece of information is determined which represents a measure of the heating between the points in time. If the two pieces of temperature information represent temperature values, this first piece of information can be the difference between these temperature values. In addition, a second piece of information is determined which represents a measure of a comparable heating between the points in time for a corresponding low-voltage component in a known state. The known state of a corresponding low-voltage component can be the end of its service life or new condition, i.e. the aim is to make a comparison with a corresponding low-voltage component at the beginning or at the end of its service life. Using the difference (e.g. in the form of a difference between two values) between the first and the second piece of information, a statement is derived on the aging of the low-voltage components. For example, values for the heating between the points in time can be determined. It is also possible, for example, to use heating to calculate temperature values at the second point in time and to compare them.

Since the current in most circuits with corresponding low-voltage components is not even close to constant and the heating depends on the current flow, it is usually sensible to take this into account. Therefore, in one design, the low-voltage component is provided with at least one current measuring device, and a current value is determined for checking the aging using current measurement by the current measuring device. This is a suitable value, which can be, for example, a measured current value (possibly for a DC current) or an average of measured current values (e.g. RMS value for AC current). The second piece of information is then determined depending on this current value.

According to a further development of the invention, it is taken into account that the current value used is typically not constant between the two points in time. In principle, it would be possible to track the change in this value and incorporate it into the determination of the second piece of information. However, it is less complex and easier to handle to assume a sufficiently constant current value, i.e. to determine the second piece of information only as a function of a current value. According to one embodiment of the invention, a corresponding procedure is followed, whereby a criterion for a sufficiently constant current value is checked and the second piece of information is only determined if the criterion is met. In concrete terms, for example, a current value is determined by the current measuring device at points in time relevant to the method for determining aging (e.g. at the first and second points in time, but possibly also for points in time in between). A measure based on these current value determinations is then used for the change in the current between the points in time (e.g. the amount of the difference in the current value at the first and second points in time). The procedure is then only carried out or the results of the procedure are only output as relevant aging information if a criterion related to this measure of the change in the current (e.g. a threshold criterion for the amount of the difference in the current value at the first and second point in time) is met for a small change in the current.

According to a development of the invention, a value is determined as the second piece of information which represents a measure of comparable heating between the points in time for a corresponding low-voltage component at the end of its service life, and a value is determined as the third piece of information which represents a measure of comparable heating between the points in time for a corresponding new low-voltage component. The difference between the second and third pieces of information is then used as a criterion for the significance of the statement on the aging of the low-voltage components or for information on aging. If this difference is too small (e.g. of the same order of magnitude as the intrinsic inaccuracies due to measurements, approximations, etc.), the results may not be meaningful. This is checked according to the development. In this development, a current value can be determined for checking aging by means of current measurement by the current measuring device (suitable value, e.g. RMS value for alternating current) and the third piece of information can be determined depending on this current value (preferably then also the second piece of information).

According to one embodiment of the invention, the low-voltage component is provided with at least one temperature sensor and the first or second temperature information is determined by measuring the temperature using the at least one temperature sensor. The difference between the measured temperatures is then used as the first information, which represents a measure of the heating between the points in time.

According to one embodiment of the invention, the first temperature information is the temperature of the first low-voltage component at the first point in time, and to determine the second information or the third information, the temperature of a comparable low-voltage component in the known state is determined, which it would assume based on the temperature of the first low-voltage component after a period of time given by the time difference between the first and second points in time with comparable current flow (as a criterion for comparable current flow, it can be checked, for example, whether the current value is sufficiently constant between the two points in time). To determine the second or third information, the ambient temperature at the first or second point in time can be measured outside the low-voltage component (e.g. at a central location in a distribution box or by a central communication unit responsible for several low-voltage components) and transmitted to the low-voltage component.

According to one embodiment, the determination of the second or (if provided) third information is carried out by means of a formula-based description of the heating, a table or a neural network. The determination of the second or third information can be carried out using a formula-based description of the heating, for which a final temperature or final heating is assumed to be dependent on the current flow (which can be assumed to be constant) and an empirical approach is established for this final temperature or final heating and the approach behavior.

The invention also relates to a device that can comprise the low-voltage component. The low-voltage component can be provided with at least one current measuring device (e.g. Rogowski coil, shunt, current transformer ...) and with at least one temperature sensor. In addition, the low-voltage component can have a receiver for receiving an ambient temperature measured outside (possibly centrally) the low-voltage components.

Furthermore, the subject matter of the invention relates to a computer program product with a computer program that carries out the calculation steps of a method according to the invention when it runs on a processor.

• 1: eine Sicherung mit einem Temperatursensor,
• 2: ein Ablaufdiagramm für ein erfindungsgemäßes Verfahren,
• 3: einen Vergleich von dem Erwärmungsverhalten einer neuen Sicherung und dem Erwärmungsverhalten einer baugleichen gealterten Sicherung und
• 4: die Abhängigkeit der Enderwärmung einer Sicherung vom Laststrom.

The invention is explained in more detail below within the framework of an embodiment.

• 1 : a fuse with a temperature sensor,
• 2 : a flow chart for a method according to the invention,
• 3 : a comparison of the heating behaviour of a new fuse and the heating behaviour of an identical aged fuse and
• 4 : the dependence of the final heating of a fuse on the load current.

In 1 a fuse 1 is shown schematically. The fuse has a protective housing 2 and a further housing 12, which are arranged one behind the other in the longitudinal direction L and reach the total height H of a standardized NH fuse.

The fuse 1 has two connection elements 3, which consist of an electrically conductive material, for example copper. The connection elements 3 each extend through an opening formed in the closure caps 4 into the cavity of the protective housing 2. In this cavity, at least one so-called fusible conductor 5 is arranged, which connects the two connection elements 3 to one another in an electrically conductive manner.

Elements 10 for monitoring consumption parameters are arranged in the further housing 12, comprising a current transformer 11 for measuring an electric current I flowing through the fuse 1 and a transmission device 13 for transmitting the measured value to a receiving device arranged outside the fuse 1 (not shown). In addition, a temperature sensor 15 is provided.

The total installation space required for the protective housing 2 and the additional housing 12 is just as large as the installation space of a standardized NH fuse, i.e. the installation space required by the protective housing 2 and the additional housing 12 corresponds in total to the predefined installation space of a standardized NH fuse, whereby the measuring device is now integrated in this installation space in addition to the actual fuse. In this way, the fuse 1 can also be used for retrofit applications as part of retrofitting or modernizing existing electrical systems, in which a conventional fuse without a measuring device is to be replaced by the fuse according to the invention.

The height H of the fuse 1 is divided into a first section with a first height H _D and a second section with a second height H _M. The first height H _D refers to the height of the pressure body 2, ie the actual protective body 2 of the fuse 1, the second height H _M refers to the height of the second housing 12 in which the measuring device 10 is arranged. This housing also has significantly lower requirements in terms of its mechanical stability.

The current transformer 11 and a temperature sensor 15 are connected to the processing device 14, which is 1 shown schematically as a circuit board, for transmitting the corresponding current or temperature measurement signals. The transmission device 13 is connected to the processing device 14 shown as a circuit board. The transmission device 13 can be an RFID module, for example, whereby both active RFID and passive RFID solutions are possible. Other - advantageously wireless - transmission technologies such as Bluetooth, Zigbee or Thread are also possible.

2 shows the sequence of a method according to the invention, as it can run, for example, in the processing device 14. The start of the method (step S1) is triggered, for example, by time information. It can be provided, for example, that an aging check is carried out at regular intervals, eg daily. For this purpose, a fuse according to. 1 date information from a timer or clock can be transmitted. Alternatively, the processing device comprises 1 a clock itself. Date information transmitted externally is useful if the backup has a sleep mode in which the processing device is not active. The date information is then compared with a target date for the next aging check and the check is carried out if the date of the check has been reached or exceeded.

Typically, a large number of fuses are installed in energy distribution systems (e.g. in a fuse box). It is usually sensible to carry out an ageing test for all relevant fuses, as the ageing behavior will usually differ due to structural deviations, different loads or different ages (e.g. due to replacement of individual fuses). In 2 This is illustrated by the loop in step S2. Different types of fuses are distinguished by an identifier (e.g. the MLFB or machine-readable product designation).

The heating behavior of the individual fuse types was tested at the factory and empirical formulas were determined.

For a new fuse, the heating can be described approximately as follows. Heating refers to a change in temperature, typically a rise in temperature. Heating is denoted by the letter T in the formulas below, while the Greek letter ϑ is used for temperatures, ie the heating during a period Δt = t ₂ - t ₁ would then be T (t ₂ - t ₁ ) = ϑ(t ₂ ) - ϑ(t ₁ ), whereby t ₁ = 0 and t ₂ = t are set where possible for the sake of simpler notation.

If a current I ₀ is applied, the fuse heats up. Immediately after the current is applied, the temperature of the fuse will not differ greatly from the ambient temperature. The temperature then rises and over time will approach a limit value that corresponds to the maximum temperature at a current I _0. Experience has shown that the rise or heating can be roughly described using an exponential function and is then proportional to (1 - exp (-t/τ)), where exp is the exponential function, t is the time and τ is a constant characteristic of the heating (thermal time constant). The final heating depends on the current I _0. An approximate formula can be set up for it by carrying out a Taylor expansion for the difference between the final temperature and the ambient temperature with respect to the current I _0. Let T _e (i;I ₀ ) denote the final heating for the fuse type i. If the Taylor series is terminated after the square term, the approximation applies $${\text{T}}_{\text{e}}\left({\text{i;I}}_0\right)={\text{a}}_{\text{e}\text{,i}}*{\text{I}}_0{}^2+{\text{b}}_{\text{e}\text{,i}}*{\text{I}}_0+{\text{c}}_{\text{e}\text{,i}}$$

Before the current flows, the temperature of the fuse corresponds to the ambient temperature. With the rise behavior mentioned above, the heating of the fuse can then be described as follows: $$\text{T}\left({\text{i;I}}_0\text{;t}\right)={\text{T}}_{\text{e}}\left({\text{i;I}}_0\right)*\left(1-\text{ex}\left(-\text{t}/\mathrm{\tau }\right)\right)$$

An empirical approach can also be used for the thermal time constant τ. This time constant will depend on the current I ₀ because the higher the current, the faster the heating occurs. Taking into account the linear dependence of τ on the current, the following approach is obtained: $$\mathrm{\tau }\left({\text{i;I}}_0\right)={\text{a}}_{\mathrm{\tau }\text{,i}}*{\text{I}}_0+{\text{b}}_{\mathrm{\tau }\text{,i}}$$

A central idea of the invention is that the course and the final heating of the fuse changes over time due to aging. This shows 3 , where the lower curve describes the heating behavior of a new fuse and the upper curve describes the heating behavior of an identical aged fuse. The final heating depends on the load current, as in 4 is shown.

An approach according to formula (1) can now also be used for the heating behavior at the end of the service life of a fuse. In the following, T _e,tot refers to the final heating of a fuse at the end of its service life. Then the following equation (1) applies: $${\text{T}}_{\text{e}\text{,dead}}\left({\text{i;I}}_0\right)={\text{a}}_{\text{dead}\text{,i}}*{\text{I}}_0{}^2+{\text{b}}_{\text{dead}\text{,i}}*{\text{I}}_0+{\text{c}}_{\text{dead}\text{,i}}$$

The coefficients of equations 1, 3 and 4 are determined by factory tests and are input for the procedure according to 2 . They are either already available in a backup storage facility upon delivery or are transferred to the backup facility by a central location before the procedure (the provision of the coefficients is in 2 step S3). In step S4, the charging current I ₀ and the current temperature ϑ _{a of} the fuse are measured. If the values of I ₀ and ϑ _a are available, a timer is set to zero (t=0, step S5). A load factor k is then calculated, which is defined as the quotient between the charging current I ₀ and the rated current I _r (steps S6 and S7). In the following step S8, it is checked whether the load factor is greater than 0.4. If not, it waits 10 seconds (step S9) and then continues with step S4. With a low load (here defined as k ≤ 0.4), the load factor drops in 3 shown is small, and the process reaches its limits due to tolerances and inaccuracies. It is therefore sensible to only carry out the process in steps S10 - S21 if the load has exceeded a threshold value. Of course, depending on the fuse and application scenario, threshold values other than k = 0.4 and waiting times other than 10 seconds may be conceivable or more favorable. If the load is high enough, the values of T _e , T _e,tot and τ are determined in steps S10 and S11 from the coefficients in step S3 using formulas (1), (3) and (4). Then wait 10s (step S12) and increment the timer accordingly (step S13) before the load current and fuse temperature and also the ambient temperature are measured again. The ambient temperature does not have to be measured by the fuse itself, but can be measured at a central location and transmitted to the fuse. The central measurement can be carried out, for example, by a communication module, as in the DE 202021000293 U1 described. The ambient temperature can also be measured centrally in a control cabinet with a plurality of fuses and then communicated from there to the fuses in the control cabinet. A data collector can also be responsible for a plurality of fuses, which transmits a value of the ambient temperature measured by itself or received from a measuring point to the plurality of fuses. This measurement or its time is referenced with the index 1 and the associated values of load current, ambient temperature and fuse temperature are designated I ₁ , ϑ _U1 and ϑ ₁ (steps S14 and S15). In step S16 it is checked whether the load current has changed significantly compared to the measurement of I ₀ , ϑ _a in step S4. The criterion for this is a deviation of less than 5%, i.e. 0.95*I ₀ < I ₁ > 1.05*I ₀ . If the deviation is too large, the system waits for 10 seconds (step S9) and then continues with step S4. Otherwise, values are calculated in step S17 to evaluate the aging of the fuse.

(Zum Zeitpunkt t=0 ist die Temperatur ϑ_a, zum Zeitpunkt t = ∞ ist die Temperatur ϑ_U1 + T_e, und der Verlauf der Erwärmung ab Zeitpunkt null hat ein Verhalten, das durch (1-exp(-t/τ)) beschrieben werden kann.)The starting point for the calculation according to step S17 are the values for the charging current I ₀ and the current temperature of the fuse ϑ _a obtained in step S4. The consideration is now that in the time t between step S4 and the measurement of the corresponding variables in step S14, the fuse has continued to heat up. This heating will depend on how much the fuse has aged. For a new fuse, the following approach can be used, which then _enables the calculation of a target temperature ϑ set. The starting point is then the temperature of the fuse _{ϑ a} measured in step S4 or at time zero. In the limit value t → ∞, the temperature of the fuse approaches a limit or end temperature. This limit temperature is made up of the ambient temperature and the final heating T _e . Formula (1) was given above for this difference T _e . Assuming that the heating from step S4 (time zero) exhibits a behavior according to (1 - exp (-t/τ)), the following is obtained for ϑ _set : $${\mathrm{\vartheta }}_{\text{should}}={\mathrm{\vartheta }}_{\text{a}}+\left({\mathrm{\vartheta }}_{\text{U1}}+{\text{T}}_{\text{e}}-{\mathrm{\vartheta }}_{\text{a}}\right)*\left(1-\text{ex}\left(-\text{t}/\mathrm{\tau }\right)\right)$$

(At time t=0 the temperature is ϑ _a , at time t = ∞ the temperature is ϑ _U1 + T _e , and the course of the heating from time zero has a behavior that can be described by (1-exp(-t/τ)).)

A fuse has a higher final temperature rise towards the end of its service life. Analogous to equation (2) we then obtain: $$\text{T}\left({\text{i;I}}_0\text{;t}\right)={\text{T}}_{\text{e}\text{,dead}}\left({\text{i;I}}_0\right)*\left(1-\text{ex}\left(-\text{t}/\mathrm{\tau }\right)\right)$$

A measure T _tot, which depends on the heating time t, is introduced for the difference in heating for the fuse i in new condition and at the end of its service life: $${\text{T}}_{\text{dead}}\left({\text{i;I}}_0\text{;t}\right)=\left({\text{T}}_{\text{e}\text{,dead}}-{\text{T}}_{\text{e}}\right)*\left(1-\text{ex}\left(-\text{t}/\mathrm{\tau }\right)\right)$$

definiert.In step S17 or S18 the size $$\Delta \text{T}={\mathrm{<figure-callout\; id="1"\; label="\theta "\; filenames="DE102022211027A1\_0012.png"\; state="\{\{state\}\}">\vartheta </figure-callout>}}_1-{\mathrm{\vartheta }}_{\text{should}}$$

Are defined.

und $$\Delta \text{T}\ge \mathrm{2,5}\text{ K}$$

ist. Das Kriterium (9) gilt der Frage, ob die Erwärmung auf ein Ende der Lebenszeit der Sicherung hinweist und das Kriterium (10) wurde eingeführt, um sicherzustellen, dass die Erwärmung signifikant genug ist, um eine Aussage über die Lebensdauer zu machen. Falls beide Bedingungen erfüllt sind, wird auf das Lebensdauerende geschlossen (Schritt S22) und das Verfahren beendet (Schritt S23). Es ist sinnvoll, das Lebensdauerende an eine zentrale Überwachungsstelle zu senden und ein Erfordernis des Austausches der Sicherung zu platzieren. Falls nicht beide Kriterien erfüllt sind, kann überprüft werden, ob das Kriterium (10) für sich erfüllt ist (Schritt S20), und in dem Fall eine Warnung ausgeben, dass eine signifikante Alterung der Sicherung besteht (Schritt S21). Anschließend wird wieder mit Schritt S12 weiterverfahren.This size is used in the query according to step S19, namely whether $$\Delta \text{T}\ge {\text{T}}_{\text{dead}}$$

and $$\Delta \text{T}\ge 2.5\text{K}$$

is. Criterion (9) addresses the question of whether the heating indicates the end of the fuse's service life, and criterion (10) was introduced to ensure that the heating is significant enough to make a statement about the service life. If both conditions are met, the end of service life is concluded (step S22) and the process is terminated (step S23). It is useful to send the end of service life to a central monitoring point and to indicate a requirement to replace the fuse. If both criteria are not met, it can be checked whether criterion (10) is met on its own (step S20), and in that case a warning can be issued that the fuse is significantly aging (step S21). The process then continues with step S12.

The inventive approach is not limited to this embodiment, but can be used for other low-voltage components, e.g. the EN 10 2021 203 050 B3 described circuit breakers with temperature detection can be used. The calculation steps do not necessarily have to be carried out using the above formulas. Not only modifications to these formulas (e.g. taking into account more terms of the Taylor expansion of formula (1)) but also fundamentally different methods are conceivable. For example, it is possible to use a suitably trained neural network or pre-calculated or predetermined tables.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• WO 2020/127486 A1 [0005]
• WO 2020/127488 A1 [0005]
• WO 2020/148015 A1 [0005]
• DE 102018213522 A1 [0005]
• DE 202021000293 U1 [0038]
• DE 102021203050 B3 [0044]

Claims (17)

Method for checking the aging of a low-voltage component which is designed to be introduced into an electrical circuit, in which - a first piece of temperature information relating to the low-voltage component is determined for a first point in time, - a second piece of temperature information relating to the low-voltage component is determined for a second point in time, - a first piece of information which represents a measure of the heating between the points in time is determined using the two pieces of temperature information, - a second piece of information which represents a measure of a comparable heating between the points in time for a corresponding low-voltage component in a known state is determined, and - a statement on the aging of the low-voltage components is derived using the difference between the first and the second piece of information. Procedure according to Claim 1 , characterized in that the known condition of a corresponding low-voltage component is the end of its service life or as good as new. Procedure according to Claim 1 or 2 , characterized in that - the low-voltage component is provided with a current measuring device, - a current value is determined for checking the ageing with the aid of current measurement by the current measuring device, and - the second information is determined as a function of this current value. Procedure according to Claim 3 , characterized in that - by means of current measurement by the current measuring means, a current value is determined at points in time relevant to the method for determining ageing, - a measure of the change in current between the points in time based on these current value determinations is used, and - the method is only carried out or the results of the method are only output as relevant ageing information if a criterion for a small change in current related to this measure of the change in current is met. Method according to one of the preceding claims, characterized in that - as second information, a value is determined which represents a measure of comparable heating between the points in time for a corresponding low-voltage component at the end of its service life, - as third information, a value is determined which represents a measure of comparable heating between the points in time for a corresponding new low-voltage component, and - the difference between the second and third pieces of information is used as a criterion for the significance of the statement on the ageing of the low-voltage components or for information on the ageing. Procedure according to Claim 5 , characterized in that - for checking the ageing with the aid of current measurement by the current measuring device, a current value is determined, and - the third information is determined as a function of this current value. Method according to one of the preceding claims, characterized in that - the low-voltage component is provided with at least one temperature sensor, - the determination of the first or the second temperature information takes place by measuring the temperature by means of the at least one temperature sensor, and - the difference between the measured temperatures is used as the first information, which represents a measure of the heating between the points in time. Method according to one of the preceding claims, characterized in that - the first temperature information is the temperature of the first low-voltage component at the first point in time, - for determining the second information or the third information, the temperature or heating of a comparable low-voltage component in the known state is determined, which it would assume or experience starting from the temperature of the first low-voltage component after a period of time given by the time difference between the first and second points in time with a comparable current flow. Procedure according to Claim 8 , characterized in that for determining the second or third information, the ambient temperature is measured outside the low-voltage component at the first or second point in time and transmitted to the low-voltage component. Method according to one of the Claims 8 or 9 , characterized in that the determination of the second or third information is carried out by means of a formula-based description of the heating calculation, a table or a neural network. Procedure according to Claim 10 , characterized in that - the determination of the second or third information is carried out by means of a description of the heating based on formulas, - for this purpose a final heating which occurs depending on the current flow is assumed, and - an approach for this final heating and the approximation behaviour is established. Method according to one of the preceding claims, characterized in that the low-voltage component is a fuse, a low-voltage switch or an energy monitoring device. Device for carrying out a method according to one of the Claims 1 until 12 is trained. Device according to Claim 13 , characterized in that it comprises the low-voltage component. Device according to Claim 14 , characterized in that the low-voltage component is provided with a current measuring means and with at least one temperature sensor. Device according to Claim 14 or 15 , characterized in that the low-voltage component has a receiver for receiving an ambient temperature measured outside the low-voltage components. Computer program product comprising a computer program which implements the calculation steps of a method according to one of the Claims 1 until 12 when it runs on a processor.

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