DE102019209588B3 - Method for determining the aging status of a surge arrester, the surge arrester being assigned a U / I characteristic curve and a derating curve, and a device for carrying out the method - Google Patents

Abstract

The invention relates to a method for determining the state of aging of a surge arrester (VAR), the surge arrester being assigned a U / I characteristic curve and a derating curve. The invention also relates to a corresponding device.

Description

The invention relates to a method for determining the aging status of a surge arrester, the surge arrester being assigned a U / I characteristic curve and a derating curve, and a device for carrying out the method.

background

Various surge arresters degrade. The degradation - also known as the aging process - is influenced by various features, in particular, however, pulse load, temperature and temporary overvoltages (e.g. due to faults in the supply network).

The consequences of such an aging process can e.g. If a varistor is used as a surge arrester, leakage currents can cause the surge arrester to overheat.

As a rule, this inadmissible heating should be caused by putting the surge arrester out of operation, e.g. by disconnecting or short-circuiting the surge arrester.

A status display can be provided so that the user is informed about this. The status display is typically coupled to the temperature-sensitive separation point, a distinction being made between a working state and a defect state. However, there are also surge arresters that have a warning state shortly before the end of their service life based on a temperature-sensitive material or a solder material with a slightly lower melting point than the separation point. However, these warning status displays are only able to provide a warning shortly before an expected end of the service life of the surge arrester. However, due to the large number of influences, this is difficult to assess, so that a generous safety margin is planned.

Exemplary devices are, for example, from the German utility model DE 20 2012 002 281 U1 of the applicant or the US patent application US 2012/0 239 321 A1 known.

Surge arresters should be checked, especially in larger electrical systems, in order to avoid system downtime. As a rule, replacement is therefore carried out at defined operating intervals or in the event of a failure.

Since surge arresters are rather expensive components, they should only be replaced if the surge arrester has already failed or a failure of the surge arrester is imminent. However, due to the safety margins, this is only insufficiently possible.

task

It would therefore be desirable to record the actual load on the surge arrester so that maintenance and repair of the surge arrester can be carried out in accordance with their load and not exclusively according to fixed service intervals.

Summary of the invention

The object is achieved by means of a method according to claim 1 or a device according to claim 6. Further advantageous embodiments of the invention are specified in the dependent claims, the description and in the figures.

Brief presentation of the figures

• 1 eine schematisches Flussdiagramm von Verfahren gemäß Ausführungsformen der Erfindung, und
• 2 eine schematische Darstellung von Elementen einer Vorrichtung gemäß Ausführungsformen der Erfindung zeigt.

The invention will be explained further below with reference to the figures, wherein

• 1 a schematic flow diagram of methods according to embodiments of the invention, and
• 2 shows a schematic representation of elements of an apparatus according to embodiments of the invention.

Detailed description

The invention will be illustrated in more detail below (with reference to the figures). It should be noted that different aspects are described that can be used individually or in combination. I.e. any aspect can be used with different embodiments of the invention, unless explicitly shown as a pure alternative.

Furthermore, for the sake of simplicity, reference will generally only be made to one entity in the following. Unless explicitly stated, the invention can also have several of the entities concerned. In this respect, the use of the words “a”, “an” and “an” is only to be understood as an indication that at least one entity is used in a simple embodiment.

As far as methods are described below, the individual steps of a method can be arranged and / or combined in any order, unless the context explicitly results in something different. Furthermore, the processes can be combined with one another - unless expressly indicated otherwise.

Figures with numerical values are generally not to be understood as exact values, but also include a tolerance of +/- 1% up to +/- 10%.

References to standards or specifications or norms are to be understood as referring to standards or specifications or norms that apply at the time of application and / or - if a priority is claimed - at the time of priority application. However, this is not to be understood as a general exclusion of applicability to the following or replacement standards or specifications or norms.

In the following, “neighboring” explicitly includes an immediate neighborhood relationship without, however, being restricted to this. In the following, “between” explicitly includes a position in which the intermediate part is in close proximity to the surrounding parts.

In a method according to the invention for determining the aging status of a surge arrester (VAR), the surge arrester (VAR) being assigned a U / I characteristic curve and a derating curve, which is exemplified in FIG 1 is a first step 100 the residual voltage U (t) at the surge arrester VAR measured over time t in the course of a discharge event.

The method steps outlined below can in particular be performed with a device according to the invention 1 to determine the aging condition of a surge arrester VAR. An exemplary device 1 has for this purpose a voltage measuring device Su in order to measure the residual voltage U (t) at the surge arrester VAR over the time t in the course of a discharge event.

This course measurement can e.g. can be started by exceeding a voltage value / current flow. The course can take place by repeatedly determining the current at predefined / predefinable intervals, the end of the course measurement being terminated when the voltage value / current flow is not reached. The start condition and the end condition can be designed differently. The interval between the individual measurements of a course can be made periodically. However, it would also be conceivable to set the distances as a function of a previously measured voltage value / current flow.

In a further step 200 the current amplitude I (t) is determined over time from the U / I characteristic curve of the surge arrester VAR by means of the measured curve of the residual voltage U (t) at the surge arrester VAR over time t.

An exemplary device 1 has for this purpose an evaluation device CPU to determine the current amplitude I (t) over time from the U / I characteristic of the surge arrester VAR by means of the measured curve of the residual voltage U (t) at the surge arrester VAR over time t. The evaluation device CPU can be a microcontroller, a microprocessor, an FPGA (Field Programmable Gate Array), an ASIC (application-specific integrated circuit) or the like. The steps can be hard-coded or specified in a program. The CPU can have an internal memory and / or an external memory MEM in order to store or temporarily store data from measurements, calculations, characteristics, derating curves, etc.

In a further step 300 the temporal course of the measured residual voltage U (t)) over the time t is assigned to a predetermined pulse shape. Different pulse shapes can be specified for this without restricting the generality. Well-known pulse shapes that are often used in data sheets, for example, are the test pulses 8/20 µs; 10/350 µs; 1.2 / 50 µs, as described in the standard DIN EN 61643-11: 2019-03; VDE 0675-6-11: 2019-03, VDE 0675-6-11: 2019-03. This does not exclude other pulse shapes, provided that derating curves are intended for them. This step 300 can also be understood as the assignment of an energy equivalent to a predetermined (eg normative) pulse shape.

The evaluation device CPU can correspondingly be set up to assign the time profile of the measured residual voltage U (t) over the time t to a predetermined pulse shape.

In a further step 400 the individual load I ² t is calculated from the determined current amplitude I (t) and the assigned pulse shape.

The evaluation device CPU can in turn be set up in a corresponding manner to calculate the individual load I ² t from the determined current amplitude I (t) and the associated pulse shape.

Then the in step 400 Calculated individual exposure I ² t to the previously determined individual exposure in one step 500 be added up, ie a sum is formed over the individual loads ∑I ² t.

The evaluation device CPU can in turn be set up in a corresponding manner to add up the individual loads (∑I ² t) over the discharge events.

Then the summed up individual loads ∑I ² t with the maximum possible load by means of one or more derating curve (s) in one step 600 be matched.

The evaluation device CPU can in turn be set up in a corresponding manner to compare the summed up individual loads ∑I ² t with the maximum possible load by means of one or more derating curve (s).

An indication of the state of the surge arrester VAR can then be provided in one step 700 can be made available, the information including a statement about the condition and / or an exchange recommendation.

The evaluation device CPU can in turn be set up in a corresponding manner to provide information relating to the state of the surge arrester VAR, the information including information about the state and / or a replacement recommendation.

State information can e.g. be that the surge arrester VAR still has a remaining service life corresponding to x discharge events corresponding to a predetermined pulse shape.

In one embodiment of the invention, the information is made available on a local display ANZ. The local display can e.g. be a light display, e.g. signals the status by means of a color change and / or flashing pattern. Alternatively or additionally, the local display can also comprise a digital display, e.g. in the form of a numeric display. The digital display can e.g. be an epaper display, so that a status display is possible even when the power is off.

Alternatively or in addition, it can also be provided that the information can be provided or accessed by means of a telecommunication device I / O. Such a telecommunication device I / O can e.g. based on a simple wire connection, but it can also be part of a bus system (fieldbus, Profibus, Interbus, etc.) or a data transmission system (Ethernet, WLAN, mobile communication (especially GSM, UMTS, LTE, Internet of Things), RFID, NFC , Zigbee Bluetooth, Infrared, etc.). The telecommunication device I / O can be implemented both wired and wireless. I.e. Cloud integration can also be implemented without further ado.

In a further embodiment of the invention the current amplitude is determined by means of a normalized U / I characteristic curve, the normalization e.g. based on the 1mA voltage. The evaluation device CPU can in turn be set up accordingly in a corresponding manner.

The invention makes use of the fact that e.g. Depending on the surge current amplitude, varistors have an almost linear characteristic curve in relation to the residual voltage in their working range. Fluctuations of ΔU = 200 V due to the spread of the 1 mA voltage over the entire tolerance range of the varistor are recorded. In relation to the measured residual voltage, this can lead to load differences of 10 kA 8/20 µs.

When comparing two manufacturers, fluctuations / load differences of up to 20 kA can occur.

In order to compensate for the scatter of the measured residual voltages related to the manufacturer, the measured residual voltage can be normalized to the corresponding 1 mA point. This normalization leads to comparable residual stresses for a manufacturer, and thus to possible conclusions about the shock amplitude.

In a further embodiment of the invention, the assignable pulse shapes have at least one of the pulse shapes known from the standard DIN EN 61643-11: 2019-03; VDE 0675-6-11: 2019-03, VDE 0675-6-11: 2019-03, in particular 8/20 µs, 10/350 µs, 1.2 / 50 µs ... or an energy equivalent to the normative pulse shapes.

In a further embodiment of the invention, the U / I characteristic curve and / or the derating curve is read out by means of a second interface I / O ₂ from an element SE having the surge arrester VAR. For example, the surge arrester VAR can be part of a plug SE which is contained in a suitable socket in the device 1 is plugged in. The U / I characteristic curve and / or the derating curve can be contained, for example, in a read-out memory which is contactless or has contacts when the plug SE is inserted into the device 1 is read out. Alternatively or in addition, instead of the U / I characteristic curve and / or the derating curve, a reference, for example a URL to a remote database, can be made available from which the evaluation unit CPU uses the can retrieve relevant data. Without limiting the generality, further data, for example measurement data of the corresponding surge arrester VAR, can be read out or called up.

In a further embodiment of the invention, the surge arrester VAR is selected from a group comprising a varistor, transient voltage suppressor diode, gas-filled surge arrester, spark gap.

Without limiting the general hit, the device 1 and the surge arrester VAR can be integrated in one structural unit.

The invention thus makes it possible to draw conclusions about the actual load on the surge arrester VAR and thus enable maintenance and repair of the surge arrester VAR in accordance with its load. As a result, an exchange can take place in good time, so that an electrical system is protected while at the same time an early exchange is avoided, which saves costs for both the early exchange and the surge arrester VAR itself.

An evaluation of the surge arrester VAR by means of detection of the amplitude and the time profile of the voltage and / or the current is proposed. With the help of known parameters of the surge arrester VAR, such as 1 mA voltage and corresponding derating curves with regard to the pulse load of the surge arrester VAR, an analysis of the condition of the surge arrester VAR can be carried out. Information from this assessment about the load and condition of the surge arrester VAR can be provided to the user in different ways (e.g. by means of display, display, cloud, RFID, NFC, barcode, binary by closing several contacts, ...).

The acquisition of the measured values can take place via a voltage as well as a current measurement. The measurement can preferably be provided galvanically isolated (e.g. via a transformer).

The components for measuring the voltage and / or the current, for example the voltage measuring device Su (can also be used for current measurement by means of the residual resistance of the surge arrester VAR) can also be in the element SE and in the device 1 or in a structural unit consisting of a device 1 and surge arrester VAR can be integrated.

Alternatively, the voltage measuring device Su can also be provided as an independent unit, e.g. Can be inserted / snapped on / side-by-side on the VAR surge arrester.

• • Hersteller (optional)
• • 1mA Spannung (Realwert, optional)
• • 1mA Spannung (Nominalwert. optional)
• • 1mA Spannung Toleranzbereich (optional)
• • Derating Kurve des Überspannungsableiter VAR

For the evaluation of the recorded data, the following parameters with regard to the surge arrester VAR are preferably known:

• • Manufacturer (optional)
• • 1mA voltage (real value, optional)
• • 1mA voltage (nominal value. Optional)
• • 1mA voltage tolerance range (optional)
• • Derating curve of the surge arrester VAR

Although the elements of the device 1 as integrated elements have been described above, it is equally possible to provide them as individual elements. In this case, each of the connections then required to provide measured values / data / calculations / evaluations between the individual elements can be provided both wired and wirelessly, with different systems being able to be used for different connections. The connections can transmit the respective measured values / data / calculations / evaluations in an analog or digital manner, wired or contactless. Considerations relating to galvanic isolation can also be taken into account.

List of reference symbols

VAR

Surge arresters

ANZ

local display

I / O

Telecommunication device

CPU

Evaluation device

MEM

Storage facility

SE

element

Su

Voltage measuring device

I / O ₂

Communication interface

100

Measurement of the residual voltage U (t) over time t in the course of a discharge event

200

Determination of the current amplitude I (t) over time from the U / I characteristic using the measured curve of the residual voltage U (t) over time t

300

Assignment of the time course of the measured residual voltage U (t) over time t to a predetermined pulse shape

400

Calculation of the individual load (I ² t) from the determined current amplitude I (t) and the assigned pulse shape

500

Summation of the individual loads (∑I ² t) over the discharge events

600

Comparison of the total individual loads (∑I ² t) with the maximum possible load using the derating curve

700

Providing an indication of the state of the surge arrester

Claims (13)

Method for determining the aging condition of a surge arrester (VAR), the surge arrester (VAR) being assigned a U / I characteristic curve and a derating curve, comprising the steps: • Measurement (100) of the residual voltage U (t) at the surge arrester (VAR) the time t in the course of a discharge event, • Determining (200) the current amplitude I (t) over time from the U / I characteristic of the surge arrester (VAR) using the measured course of the residual voltage U (t) on the surge arrester (VAR) via the Time (t), • assigning (300) the time course of the measured residual voltage U (t) over time t to a predetermined pulse shape (8/20; 10/350; 1.2 / 50), • calculating (400) the Individual load (I ² t) from the determined current amplitude I (t) and the assigned pulse shape, • Sum (500) of the individual loads (∑I ² t) over the discharge events, • Adjustment (600) of the summed up individual loads (∑I ² t) with the maximum possible load using the Derating curve, • Provision (700) of information relating to the state of the surge arrester (VAR), the information providing information about the state and / or a recommendation for replacement. Procedure according to Claim 1 , characterized in that the information is made available on a local display (ANZ). Procedure according to Claim 1 or 2 , characterized in that the information can be provided or called up by means of a telecommunication device (I / O). Method according to one of the preceding claims, characterized in that the current amplitude is determined by means of a standardized U / I characteristic, the normalization being carried out on the basis of the 1 mA voltage. Method according to one of the preceding claims, characterized in that the assignable pulse shapes have at least one of the 8/20 µs, 10/350 µs, 1.2 / 50 µs pulse shapes Device for determining the state of aging of a surge arrester (VAR), the surge arrester (VAR) being assigned a U / I characteristic curve and a derating curve, comprising: • A voltage measuring device (Su) to measure the residual voltage U (t) am in the course of a discharge event To measure surge arresters (VAR) over time t, • An evaluation device (CPU) to measure the current amplitude I (t) over time from the U / I characteristic of the surge arrester (VAR) using the measured curve of the residual voltage U (t) am To determine surge arresters (VAR) over time t, Whereby the evaluation device (CPU) is also set up to convert the temporal course of the measured residual voltage U (t) over time t to a predetermined pulse shape (8/20; 10/350; 1,2 / 50), • Whereby the evaluation device (CPU) is still set up to calculate the individual load (I ² t) from the determined current amplitude I (t) and the assigned pulse shape, • Whereby the evaluation device (CPU) is also set up to add up the individual loads (∑I ² t) over the discharge events, • The evaluation device (CPU) is set up to add the totalized individual loads (∑I ² t) with the maximum possible load using to match the derating curve, • The evaluation device (CPU) is also set up to provide information relating to the state of the surge arrester (VAR), the information indicating the state and / or a replacement recommendation. Device according to Claim 6 , characterized in that the information is made available on a local display (ANZ). Device according to Claim 6 or 7th , characterized in that the information can be provided or called up by means of a telecommunication device (I / O). Device according to one of the preceding Claims 6 to 8th , characterized in that the current amplitude is determined by means of a normalized U / I characteristic, the normalization being carried out on the basis of the 1 mA voltage. Device according to one of the preceding Claims 6 to 9 , characterized in that the assignable pulse shapes from at least one which have 8/20 µs, 10/350 µs, 1.2 / 50 µs pulse shapes. Device according to one of the preceding Claims 6 to 10 , characterized in that the information can be provided or accessed by means of a telecommunication device (I / O), the telecommunication device (I / O) providing a wireless communication interface. Device according to one of the preceding Claims 6 to 11 , characterized in that the U / I characteristic and the derating curve are read out from an element (SE) having the surge arrester (VAR) by means of a second interface (I / O ₂ ). Device according to one of the preceding Claims 6 to 12 , characterized in that the surge arrester (VAR) is selected from a group comprising a varistor, transient voltage suppressor diode, gas-filled surge arrester, spark gap.

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