DE102020214614B3 - Circuit arrangement for voltage testing and partial discharge detection - Google Patents

Abstract

Circuit arrangement for voltage testing and partial discharge detection in a single or multi-phase medium or high voltage system, with one or more conductor signal inputs (1), each of which is set up for coupling to a capacitive coupling electrode (2) which is connected to a conductor (L1, L2 , L3) of the single- or multi-phase medium or high-voltage system is coupled to a voltage testing unit (3) which is coupled on the input side to the assigned conductor signal input of the circuit arrangement and is set up for threshold-based voltage state detection with respect to the assigned conductor, at least one set up for partial discharge detection with respect to an assigned conductor Partial discharge detector unit (4) which has a partial discharge detector circuit (5) coupled on the input side to an assigned conductor signal input of the circuit arrangement and a Te According to the invention, the energy supply for the partial discharge detector unit (4) comprises a first energy supply circuit (8) which is used to supply the partial discharge detector circuit (4) with energy from the or one of the conductor signal inputs of the circuit arrangement is set up, and / or a second energy supply circuit (9) which is set up to supply the partial discharge display circuit (7) with energy from the or one of the conductor signal inputs of the circuit arrangement. Use for voltage testing and partial discharge detection in single or multi-phase medium or high voltage systems .

Description

The invention relates to a circuit arrangement for voltage testing and partial discharge detection in a single- or multi-phase medium or high voltage system according to the preamble of claim 1.

Single-phase or multi-phase medium or high voltage systems, in particular in the form of so-called medium or high voltage switchgear systems, are known to contain a number of voltage-carrying electrical lines corresponding to the number of phases, briefly referred to as conductors. In the common three-phase systems these are consequently three conductors, which are usually referred to as L1, L2 or L3 for short.

Said circuit arrangement is used in such systems on the one hand for threshold-based voltage testing, in particular in accordance with FIG IEC 61243-5 standard , and contains one or more conductor signal inputs, each of which is set up for coupling to a capacitive coupling electrode, which in turn is coupled to a conductor of the single or multi-phase medium or high voltage system. A voltage testing unit is coupled on the input side to the respective conductor signal input of the circuit arrangement and is set up for threshold-based voltage state detection with respect to the assigned conductor.

On the other hand, the circuit arrangement in such systems serves to detect partial discharges on a respective conductor and for this purpose contains at least one partial discharge detector unit set up for partial discharge detection with respect to the assigned conductor, which has a partial discharge detector circuit coupled on the input side to an assigned conductor signal input of the circuit arrangement and an input side coupled to a signal output of the partial discharge detector circuit Includes partial discharge indicator circuit. In addition, the circuit arrangement has a suitable power supply for the partial discharge detector unit.

New description pages 2 and 2a

Circuit arrangements of this type are known in different designs. A conventional embodiment is, for example, in the laid-open specification DE 101 34 790 A1 disclosed. Typically, these conventional circuit arrangements require auxiliary energy, that is to say electrical energy provided externally or additionally for coupling to the respective conductor of the medium or high voltage system, for feeding the partial discharge detector unit. For example, an amplifier unit is often used in the partial discharge detector circuit, which requires external energy for the supply. And the partial discharge display circuit is also often designed in conventional designs in such a way that it requires auxiliary energy. For example, in the patent EP 0 428 601 B1 and the disclosure document WO 97/07 411 A1 Circuit arrangements for partial discharge detection are disclosed which require external auxiliary power for signal processing of the partial discharge detection and / or for the display of the partial discharge information obtained.

The disclosure document WO 2017/144 091 A1 discloses a circuit arrangement for detecting partial discharge on an electrical object such as a cable connection between two high-voltage cables, whereby a battery or a power supply unit or a magnetic coil can be used to supply energy to the circuit arrangement, with which electrical energy is inductively tapped on one of the two high-voltage cables.

For so-called voltage detection systems, which are circuit arrangements only for threshold-based voltage state detection without partial charge detection, versions with and without auxiliary power are known and are described, for example, in the standards VDE0682T415 and IEC61243-5. The patent specification DE 103 04 396 B4 discloses such a voltage testing system which has energy supply means which can be operated by the user in order to be able to provide the system with user-operated auxiliary energy.

There are also various voltage detection systems for voltage testing in medium or high voltage systems known, which also have means for detecting a conductor break on the test signal connecting line from the capacitive coupling electrode to the conductor signal input of the test circuit, such as in the utility model documents DE 203 20 394 U1 , DE 297 24 824 U1 and DE 20 2004 012 789 U1 disclosed. In the utility model DE 20 2013 002 563 U1 installation monitoring means are proposed for this purpose, which are designed in such a way that they can detect a high-resistance fault both in the test signal connection line and in an earth connection.

The technical problem underlying the invention is the provision of a circuit arrangement of the type mentioned at the outset which, in particular with regard to its energy supply management, offers advantages over the prior art explained above.

The invention solves this problem by providing a circuit arrangement having the features of claim 1.

In this circuit arrangement according to the invention, the energy supply for the partial discharge detector unit comprises a first energy supply circuit which is set up to supply the partial discharge detector circuit with energy from the or one of the conductor signal inputs of the circuit arrangement, and / or a second energy supply circuit which is used to supply the partial discharge display circuit with energy from the or one of the conductor signal inputs of the circuit arrangement is set up.

The circuit arrangement according to the invention can be implemented in a single device which enables a combined voltage test and partial discharge detection. The detection and display of partial discharges on a respective conductor of the medium or high voltage system is possible with the presence of the first energy supply circuit without auxiliary energy for the partial discharge detector circuit and with the presence of the second energy supply circuit without auxiliary energy for the partial discharge display circuit. Auxiliary energy is to be understood as any electrical energy that is not taken from the respective conductor signal input of the circuit arrangement, but is provided in some other way, e.g. by a battery or a mains voltage connection of a device containing the circuit arrangement. Compared to using auxiliary energy in this way, this has the advantage that no maintenance-intensive batteries are required and no interference signals have to be taken into account that could be incorrectly interpreted as partial discharge signals and are often caused by switched-mode power supplies that are used to connect such devices to the mains voltage .

The circuit arrangement according to the invention enables the electrical energy required for the operation of the partial discharge detector unit and in particular of its partial discharge detector circuit and its partial discharge display circuit to be taken from the measurement signal present at the associated conductor signal input of the circuit arrangement, in particular from its low-frequency signal component. The circuit arrangement is suitable for both single-phase and multi-phase, in particular three-phase, medium / high voltage systems.

Furthermore, the circuit arrangement according to the invention offers the advantage that an active partial discharge detection, consisting of the evaluation of the incoming input signal and the display of the evaluation result, is automatically limited to the only periods of interest in which the measurement signal is effectively applied to the relevant conductor signal input of the circuit arrangement, which means What is meant is that the measurement signal is present in a signal size or signal strength sufficient for the voltage test by the voltage test unit. In inactive periods in which this active measurement signal is not available, which reflects a corresponding voltage carrying activity on the associated conductor of the medium or high voltage system, no partial discharge detection is required. Since, according to the invention, the partial discharge detector circuit and / or the partial discharge display circuit is / are energetically supplied via the first or second power supply circuit from the measurement signal present at the conductor signal input of the circuit arrangement, one or both of these components for the partial discharge detection automatically remain inactive due to insufficient energy supply as long as none there is an active measurement signal at the conductor signal input.

As a result of this energetic supply of the partial discharge detector unit from the same measurement signal that is fed to the voltage test unit, the energy supply for the detection and display of partial discharges via the first or second energy supply circuit can consequently be kept in an adjustable dependence on the size or strength of the measurement signal for the voltage test so that, for example, below a minimum threshold for the presence of the voltage detected by the voltage testing unit, the detection and display of partial discharges is automatically omitted. This also protects against false partial discharge detection due to high-frequency interference signals or interference injections into the conductor signal input of the circuit arrangement, the frequency of which is well above the usual network frequency of the normal, low-frequency measurement signal. Because if there is no active measurement signal, the partial discharge detector unit remains inactive due to a lack of sufficient energy supply and thus insensitive to these interfering signals. In other words, by supplying the partial discharge detection with energy from the measurement signal for the voltage test, the invention makes it possible to evaluate the partial discharge detection exclusively for signals that are coupled to a specific low-frequency mains frequency signal with regard to partial discharge, while high-frequency interference injections without a low-frequency signal component do not result in a partial discharge indication.

In order to keep the energy requirement for the partial discharge detection low, the evaluation of the partial discharge detection by appropriate design of the partial discharge detector unit can simply consist in specifying and determining a plurality of discrete different partial discharge level levels and correspondingly reporting or displaying which of these level levels is currently in use is present. In In the simplest embodiment, it can be a purely binary, two-stage message and display that only indicates whether a partial discharge is present or not.

In a corresponding embodiment, the circuit arrangement according to the invention is able to carry out the voltage test and the partial discharge detection within the framework of a combined multiphase test and display system. In particular, the circuit arrangement can have the associated voltage testing unit for each of several conductors of the medium or high voltage installation to be monitored, or for only some of all conductors of this installation. Analogously, the circuit arrangement can have the respectively assigned partial discharge detector unit for each of several conductors of the medium or high voltage system or for only one conductor or only a part of all conductors of the system, as required. Using the partial discharge detector unit on only one of several phases of a multiphase system minimizes the circuit complexity and the energy requirement. Using the partial discharge detector unit on several or all phases increases the circuit complexity, but can, if necessary, improve the reporting or display selectivity with regard to partial discharges.

When dimensioning the circuit arrangement, it is useful if the energy-consuming components of the partial discharge detector unit, i.e. the partial discharge detector circuit and the partial discharge indicator circuit, have a sufficiently high resistance so that their presence leaves the response behavior of the voltage testing unit largely unchanged. In addition, such a high-resistance design of the partial discharge detector unit contributes to a minimal energy requirement of the same, which can easily be covered by the measurement signal at the relevant conductor signal input via the first and / or the second energy supply circuit.

In a further development of the invention, the first energy supply circuit is coupled to the same conductor signal input of the circuit arrangement as the partial discharge detector unit or to another of several conductor signal inputs of the circuit arrangement. The first-mentioned alternative is given for single-phase systems and can also be provided for multi-phase systems if required if the power supply circuit for the partial discharge detector unit does not want access to a conductor other than the one monitored by the partial discharge detector unit. The other alternative can be advantageous in multi-phase systems, for example in order to distribute the energy consumption by the circuit arrangement as evenly as possible over several conductors of the medium / high voltage system.

In a further development of the invention, the second energy supply circuit is coupled to the same conductor signal input of the circuit arrangement as the partial discharge detector unit or to another of several conductor signal inputs of the circuit arrangement. Here, too, this measure can be advantageous for the second energy supply circuit in one or the other alternative, depending on the application, as explained above for the first energy supply circuit.

In one embodiment of the invention, the partial discharge detector unit, the first energy supply circuit and the second energy supply circuit are coupled to three different conductor signal inputs of the circuit arrangement. This design can be particularly advantageous for a three-phase system, whereby it even out the energy consumption from the various conductors and loads the voltage testing units, which are preferably provided for all three conductors, very evenly on all three conductors or phases. This contributes to the fact that an approximately uniform response threshold can be specified for the voltage test across all three phases or conductors without additional effort.

In a further development of the invention, the circuit arrangement has a variable capacitor at the respective conductor signal input for forming a capacitive voltage divider with the associated capacitive coupling electrode. With this variable capacitor, i.e. a capacitor with variably adjustable capacitance, the response threshold for the voltage test by the voltage test unit and the sensitivity for the partial discharge detection by the partial discharge detector unit can be variably set, i.e. adjusted, if required. The larger the capacitance of the variable capacitor, the more insensitive partial discharge detection becomes; if this capacitance is reduced, it becomes more sensitive. Since the response thresholds for the voltage test according to the IEC61243-5 standard for non-response or response of the voltage display have a relatively high tolerance, namely 10% to 45%, the capacitance of the variable capacitor can be used in a correspondingly large range to change the sensitivity the partial discharge detection can be varied without violating the response thresholds of the voltage display according to this standard.

In a further development of the invention, the partial discharge detector unit is designed to be adjustable in sensitivity. The adjustability of the sensitivity of the partial discharge detector unit can advantageously be used, for example, for a Set the response level for the partial discharge detection sufficiently high, depending on the given system, in order to avoid false displays, which can result from a background noise that is caused by high-frequency extraneous interference that often occurs in practice.

In one embodiment of the invention, the partial discharge detector unit for sensitivity adjustment comprises a circuit component which is coupled to the signal output of the partial discharge detector circuit and which has a variable capacitor or a potentiometer or an adjustable resistor network, i.e. a network of ohmic resistors with variably adjustable total ohmic resistance. In addition or as an alternative to the aforementioned arrangement of a variable capacitor at the conductor signal input, this represents an advantageous implementation option for the sensitivity adjustment with regard to partial discharge detection. The voltage testing unit remains unaffected by this variant of the sensitivity adjustment of the partial discharge detection, so that with this variant the partial discharge detection can also be sensitive in its sensitivity if required can be adjusted beyond the range that does not yet lead to a violation of the standard response thresholds for the voltage display of the voltage test with a corresponding adjustment of the capacitance of the variable capacitor at the conductor signal input.

In a further development of the invention, the partial discharge detector unit has a deactivation element by means of which it can be deactivated independently of the voltage test unit coupled to the same conductor signal input of the circuit arrangement. With this deactivation element, the partial discharge detector unit can be deactivated if necessary, while the voltage test unit can remain active. If desired, this enables voltage tests by the voltage test unit in periods in which the partial discharge detector unit is deactivated, so that the voltage test can be kept completely unaffected by the partial discharge detector unit.

In a further development of the invention, the partial discharge display circuit comprises a display unit and a controllable switch looped in between the display unit and the second power supply circuit, which switch is coupled with a control input to the signal output of the partial discharge detector circuit. This represents an advantageous circuit implementation for the partial discharge display circuit with regard to energy consumption and required display functionality, which requires only a small amount of circuitry.

In a further development of the invention, the circuit arrangement contains a ground connection, a detection information connection for transmitting detection information of the partial discharge detector unit to the outside and a controllable switch which is connected on the one hand to the ground connection and on the other hand to the detection information connection, a control input of the controllable switch with is connected to the signal output of the partial discharge detector circuit. Information relating to a detected partial discharge can be transmitted to the outside via the detection information connection.

In a further development of the invention, the circuit arrangement contains a diagnosis connection which is connected to the signal output of the partial discharge detector circuit. If a partial discharge is detected, the associated partial discharge signal at the signal output of the partial discharge detector circuit can be tapped via the diagnostic connection, e.g. to examine it externally using an oscilloscope for the purpose of diagnosing the cause of the partial discharge.

In a further development of the invention, the respective voltage testing unit comprises a voltage testing circuit coupled on the input side to the assigned conductor signal input of the circuit arrangement and a voltage status display circuit coupled on the input side to a signal output of the voltage testing circuit. The partial discharge display circuit of the partial discharge detector unit and the voltage status display circuit of the voltage test unit coupled to the same conductor signal input of the circuit arrangement have a common display unit. The voltage testing unit and the partial discharge detector unit therefore advantageously share a common display unit, which helps to keep the circuit complexity and the energy requirement for the circuit arrangement low.

In a further development of the invention, the circuit arrangement has a coaxial line with an inner conductor, which forms at least part of a connection line from the respective conductor signal input to the associated capacitive coupling electrode, and an outer conductor surrounding the inner conductor, which is grounded at a first end facing the coupling electrode, and a connection line. Monitoring circuit which can be coupled to a second end of the outer conductor facing away from the coupling electrodes and is set up to detect a potential deviation on the outer conductor. The connecting line monitoring circuit implements an installation monitoring means with which a high-resistance fault in the outer conductor can be detected can be caused in particular by a wire break in the coaxial line and which is typically also associated with high-resistance interference in the inner conductor and thus in the connecting line. as well as a high-resistance disturbance of a ground connection of the evaluation unit.

In one embodiment of the invention, the circuit arrangement contains a common connector for the simultaneous detachable coupling of the connecting line monitoring circuit to the second end of the outer conductor and the conductor signal input to an end of the inner conductor facing away from the coupling electrode. In this way, for example, the error case can be ruled out that although the conductor signal input was connected to the inner conductor, however, it was forgotten to also connect the outer conductor to the connection line monitoring circuit.

In one embodiment of the invention, the connecting line monitoring circuit is connected to an earth potential via an earth connection and is set up to detect a potential deviation on the earth connection. In this implementation, the connecting line monitoring circuit can therefore also detect a high-resistance fault in its earth connection. The term "high-resistance interference" is to be understood here as a fault that significantly increases the electrical resistance of the connection line or the earth connection compared to its normal, error-free operating state, which in particular includes the case that the connection line or the earth connection is completely interrupted is.

• 1 ein schematisches Schaltbild einer Schaltungsanordnung zur Spannungsprüfung und Teilentladungserfassung in einer ein- oder mehrphasigen Mittel- oder Hochspannungsanlage und
• 2 ein schematisches Schaltbild einer Variante der Schaltungsanordnung von 1 mit zusätzlichem Diagnose-Anschluss und zusätzlicher Leiterbruchüberwachung.

Advantageous embodiments of the invention are shown in the drawings. These and further advantageous embodiments of the invention are explained in more detail below. Here show:

• 1 a schematic circuit diagram of a circuit arrangement for voltage testing and partial discharge detection in a single or multi-phase medium or high voltage system and
• 2 a schematic circuit diagram of a variant of the circuit arrangement of 1 with additional diagnostic connection and additional wire break monitoring.

The ones in the 1 and 2 The circuit arrangement shown in exemplary embodiments is designed for voltage testing and partial discharge detection in a single or multi-phase medium or high voltage system. For this purpose, it has one or more conductor signal inputs 1 on, each of which for coupling to a capacitive coupling electrode 2 is set up, which is coupled to a conductor of the single or multi-phase medium or high voltage system. The circuit arrangement in FIG 1 coupled to a conductor L1 shown. Two further conductors are only symbolic L2 , L3 with each coupled capacitive coupling electrode 2 indicated as they exist in the case of a three-phase medium or high voltage system. The circuit arrangement can then each have a further conductor signal input 1 to the respective coupling electrode 2 the other leader L2 , L3 be coupled. This is schematized in 2 shown.

The circuit arrangement shown contains one on the input side of the assigned conductor signal input 1 coupled voltage testing unit 3 for the threshold-based voltage state detection with regard to the assigned conductor L1 is set up. The voltage testing unit preferably has 3 for this purpose a circuit structure as is known per se for voltage testing units of this type, which work in accordance with the IEC61243-5 standard, which therefore does not require any further explanation here.

Furthermore, the circuit arrangement shown has at least one for partial discharge detection with respect to the assigned conductor L1 installed partial discharge detector unit 4th one on the input side to the assigned conductor signal input 1 coupled partial discharge detector circuit 5 and one on the input side to a signal output 6th the partial discharge detector circuit 5 coupled partial discharge display circuit 7th includes.

In addition, the circuit arrangement shown contains a power supply for the partial discharge detector unit 4th , this power supply being a first power supply circuit 8th and / or a second power supply circuit 9 includes.

The first power supply circuit 8th is to feed the partial discharge detector circuit 5 with energy from the or one of the conductor signal inputs 1 the circuit arrangement set up, and the second power supply circuit 9 is to feed the partial discharge indicator circuit 7th with energy from the or one of the conductor signal inputs 1 the circuit arrangement set up. In advantageous embodiments, this energy supply comprises both the first and the second energy supply circuit, as in the example shown 8th , 9 , in alternative versions, there is only one of these two power supply circuits 8th , 9 intended. The first and second power supply circuits 8th , 9 have a circuit structure that provides the functionality required in each case. Circuit implementations suitable in this regard are available to those skilled in the art Knowledge of this functionality specified here is known per se, which therefore does not require any further explanation here.

In the 1 and 2 is the circuit arrangement with its to the conductor L1 coupled components shown. Optionally, the circuit arrangement comprises, in a manner not shown, further circuit components, which are connected via the respective further conductor signal input 1 via the relevant coupling electrode 2 to the head L2 or to the head L3 are coupled, for example a further voltage testing unit each 3 and optionally also a further partial discharge detector unit 4th , as in 2 indicated. Since these other circuit components are identical to those shown, attach to the conductor L1 coupled circuit components can be executed, the description of the circuit components shown in the following is sufficient. In particular, it is possible in corresponding designs to use the voltage testing unit 3 for all three phases, ie three-phase, and the partial discharge detector unit 4th to be provided for only one phase, ie single-phase.

The voltage testing unit 3 In the corresponding versions, as in the example shown, it has an input side to the assigned conductor signal input 1 coupled voltage test circuit 16 , for example in the form of a suitable conventional threshold value detector, and one on the input side to a signal output 17th the voltage test circuit 16 coupled voltage status display circuit 18th , for example in the form of a liquid crystal (LCD) display known per se for this purpose. This can also be done on the input side via the conductor signal input 1 supplied measuring signal parallel to an external measuring point 19th the voltage testing unit 3 be performed as shown.

In the embodiment shown is the first power supply circuit 8th to the same conductor signal input 1 coupled to the circuit arrangement like the partial discharge detector unit 4th , especially to the head L1 leading conductor signal input 1 . In alternative embodiments of the circuit arrangement that are not shown, the first power supply circuit is 8th to another of several conductor signal inputs 1 coupled to the circuit arrangement like the assigned partial discharge detector unit 4th , whose partial discharge detector circuit 5 from the first power supply circuit 8th is fed.

The second power supply circuit is also in the exemplary embodiment shown 9 to the same conductor signal input 1 coupled to the circuit arrangement, as is the associated partial discharge detector unit 4th , their partial discharge display circuit 5 from the second power supply circuit 9 is supplied. In alternative embodiments, the second power supply circuit is 9 to another of several conductor signal inputs 1 coupled to the circuit arrangement like the relevant partial discharge detector unit 4th .

For example, in an advantageous implementation, the partial discharge detector unit 4th with a first leader L1 , the first power supply circuit 8th with a second conductor L2 and the second power supply circuit 9 with a third leader L3 be connected to a three-phase medium / high-voltage system, in particular in the event that only a single partial discharge detector unit for this three-phase system 4th is used. The voltage testing unit 3 is preferably present in threefold, once for each of the three conductors L1 , L2 , L3 .

In advantageous embodiments, the circuit arrangement includes a variable capacitor, as in the example shown 10 to form a capacitive voltage divider with the associated capacitive coupling electrode 2 . The associated conductor signal input 1 then forms the center tap of this capacitive voltage divider. The signal of the relevant phase or the relevant conductor is generated by the capacitive voltage divider L1 , L2 , L3 divided down to the measurement signal at the extra-low voltage level. The variable capacitor 10 can be used to set the response threshold for the voltage test unit 3 caused capacitive voltage display and at the same time, preferably in compliance with the response thresholds for the voltage display specified in the IEC61243-5 standard, the sensitivity of the partial discharge detection by the partial discharge detector unit 4th adjustable. By increasing the capacity of the variable capacitor 10 the partial discharge detection can be made less sensitive or more sensitive by reducing this capacity.

The partial discharge detector circuit 5 has a circuit structure as is known per se for the desired functionality, which does not require any further explanation here, for example using a high-pass or band-pass circuit. When by the partial discharge detection circuit 5 an existing partial discharge is detected, for example by reaching a predetermined partial discharge level, is indicated by the partial discharge detector circuit 5 at their signal output 6th a detection signal that the partial discharge display circuit 7th activated to generate a corresponding display information.

In advantageous implementations, the partial discharge display circuit comprises 7th as in the example shown, a display unit 13th and one between the display unit 13th and the second Power supply circuit 9 looped, controllable switch 14th , such as a semiconductor switch designed, for example, as a field effect transistor, this controllable switch 14th with a control input 15th to the signal output 6th the partial discharge detector circuit 5 is coupled.

In advantageous implementations of the circuit arrangement is the partial discharge detector unit 4th designed to be adjustable in sensitivity. For this purpose, the partial discharge detector unit comprises 4th in the example shown, one to the signal output 6th the partial discharge detector circuit 5 coupled circuit component 11 , which in the case shown has a potentiometer, alternatively a variable capacitor. This circuit component 11 enables a separate adjustment or adjustment of the sensitivity of the partial discharge detector unit 4th , ie a variable adjustment of their response threshold, independent of the setting of the response thresholds for the voltage test unit 3 by means of the variable capacitor 10 .

In advantageous embodiments, the partial discharge detector unit 4th as in the example shown, a deactivation element 12th by means of which it can be deactivated without also affecting the conductor signal input 1 voltage testing unit coupled to the circuit arrangement 3 is deactivated. In the example shown, it serves as a deactivation element 12th a user-operated switch between the signal output 6th the partial discharge detector circuit 5 and a ground connection 20th is looped in. In active operation of the partial discharge detector unit 4th the switch is open, and to deactivate the partial discharge detector unit 4th it can be closed by the user.

In corresponding implementations of the circuit arrangement, the partial discharge detector unit has 4th alternatively or as shown in addition to the controllable switch 14th via a controllable switch 21st , for example again a semiconductor switch. The desk 21st is on the one hand with the ground connection 20th and on the other hand, as shown, directly or, alternatively, indirectly via a coupling relay with a connection 22nd connected which, for example, enables connection to a telecontrol substation of a conventional type in order to transmit the partial discharge detection information by remote transmission, and in this way functions as a detection information connection. A control input of this switch 21st is from the output signal of the partial discharge detection circuit 5 applied.

In the embodiment shown, the display unit 13th for displaying the information on the partial discharge detection and the voltage status display circuit 18th designed as separate display units, preferably both in the form of suitable LCD display units. In alternative embodiments, the partial discharge display circuit 7th and the voltage status display circuit 18th a common display unit, again preferably an LCD display unit.

Depending on the requirements and application, the partial discharge detector circuit includes 5 a single threshold value detector with a predetermined threshold value or several threshold value detectors arranged in parallel with different threshold values. In the latter case, not only a binary display of the presence or absence of a partial discharge is possible, but also the detection or evaluation with regard to partial discharge threshold values of different levels, and by means of a correspondingly adapted design of the partial discharge display circuit 7th A separate display of the respectively present partial discharge threshold value or partial discharge level can then take place, ie a partial discharge display in more than two stages.

The circuit arrangement according to the invention enables the combined partial discharge detection and voltage testing by means of a single test device, for which purpose the circuit arrangement is, for example, in a common housing 23 can be accommodated, as in the 1 and 2 illustrated schematically. The circuit arrangement dispenses with a strict separation of the high-frequency and low-frequency components of the measurement signal on the respective conductor signal input 1 , which makes it easier to take from the low-frequency signal component the energy required for the evaluation of the high-frequency signal component for the purpose of partial discharge detection, as well as the energy required to display the detected information. A sufficiently high-resistance dimensioning of the partial discharge detector circuit is helpful here 5 , which also helps to improve the response of the voltage tester 3 by the presence of the partial discharge detector unit 4th not changed significantly.

In advantageous embodiments, the circuit arrangement has as in the example of FIG 2 a diagnostic connection 24 on, the one with the signal output of the partial discharge detector circuit 5 is connected, this connection is preferably carried out directly, that is, without intervening other circuit components. Via the diagnosis connection 24 which is like the detection information connector 22nd preferably accessible from the outside on the housing 23 and how it can be designed as a connection socket, if a partial discharge is detected, the associated signal output 6th the partial discharge detector circuit 5 Pick up pending partial discharge signal, e.g. to use it externally an oscilloscope or the like. To diagnose the cause of the partial discharge. In this case, the signal is behind the partial discharge detector circuit, designed as a high-pass filter, for example 5 tapped and can with 50Hz oscillations at the external measuring point 19th the voltage testing unit 3 be correlated. This shows the phase on which the partial discharge is generated. The diagnostic connection is missing in alternative versions 24 , as in the example of 1 , in this case the detection information connection if necessary 22nd can be used to access corresponding partial discharge information in order to examine it externally. The detection information connection is missing in further alternative versions 22nd , and the diagnostic connector 24 takes over the functions mentioned above.

In advantageous embodiments, the circuit arrangement for one, two or, as in the example of FIG 2 , one coaxial line for each of the three phases 31 with an inner conductor 32 , of at least part of a connecting line 30th from the respective conductor signal input 1 to the assigned capacitive coupling electrode 2 forms, and one the inner conductor 32 surrounding outer conductor 33 on, at a first end facing the coupling electrodes 33a is grounded, ie with a ground potential 36 connected is. In the example shown, there is also an end facing the coupling electrodes 32a of the inner conductor 32 together with the coupling electrode 2 via a stress-limiting predetermined breaking point 35 with the earth potential 36 connected. By using the coaxial line 31 the sensitivity of the partial discharge detection can be improved on the relevant phase.

Furthermore, in this case, the circuit arrangement has for at least one of the three phases or in association with at least one of the coaxial lines 31 a trunk monitoring circuit 38 to the end facing away from the coupling electrodes 33b of the outer conductor 33 can be coupled and is set up for a potential deviation on the outer conductor 33 to detect and thus to monitor the error-free connection status. For connecting the outer conductor (s) 33 , also known as screens, can have a common
Shield connection point 28 or a corresponding separate shield connection point can be used for each phase. So much for a phase to the outer conductor 33 of the respective coaxial line 31 no trunk monitoring circuit 38 is coupled, is the outer conductor 33 with its end facing away from the coupling electrodes 33b grounded by going to an earth potential 50 is led.

The trunk monitoring circuit 38 is capable of a high-resistance disturbance of the outer conductor 33 to detect, in particular due to a broken wire in the coaxial line 31 can be caused and with which typically also a high-resistance disturbance of the inner conductor 32 and thus the connecting line 30th goes hand in hand. The trunk monitoring circuit 38 can preferably together with the other mentioned components of the circuit arrangement, as in the example shown, in the common housing 23 be housed.

In corresponding implementations, an in 2 schematically indicated common connection plug 34 for the simultaneous detachable coupling of the connecting line monitoring circuit 38 to the second end 33b of the outer conductor 33 and the conductor signal input 1 to an end facing away from the coupling electrodes 32b of the inner conductor 32 intended. This avoids a false indication in an advantageously simple manner, which could result from the fact that the conductor signal input 1 to the inner conductor 32 has been connected, but the trunk line monitoring circuit 38 accidentally not on the outer conductor 33 was connected.

The trunk line monitoring circuit is in corresponding implementations 38 as in the example shown via an earth connection 49 with the earth potential 50 connected and set up for a potential deviation on the earth connection 49 to detect. This is the trunk line monitoring circuit 38 also capable of high impedance disturbance to their earth connection 49 detect.

In advantageous implementations, the trunk line monitoring circuit comprises 38 as in the example shown, a display element 41 and two switching transistors T1 , T2 on, with their respective switching path parallel between the display element 41 and a ground point 42 are looped in, which represents a circuit-side ground potential. The monitoring circuit 38 is supplied by an auxiliary power supply that can be activated by the user 43 fed, which can be, for example, in a manner known per se, a piezo element or some other element that converts mechanical energy into electrical energy. An actuation of this auxiliary voltage supply 43 by a user triggers a corresponding monitoring test process.

A control connection 44 of the first switching transistor T1 is at the end facing away from the coupling electrodes 33b of the outer conductor 33 the coaxial line 31 coupled, preferably as in the example shown via an optional coupling circuit 37 . A control connection 47 of the second switching transistor T2 is to the earth connection 49 coupled. The circuit-side ground point 42 is about one resistor each R1 , R2 with the control connection 14th , 17th of the first and the second switching transistor T1 , T2 connected.

The monitoring circuit implemented in this way 38 forms together with the outer conductor 33 the coaxial line 31 an installation monitoring means, through which both a high-resistance disturbance of the connection between the respective conductor L1 , L2 , L3 and the voltage testing unit 3 as well as the partial discharge detector unit 4th as well as a high-resistance fault in the grounding of the monitoring circuit 38 can be recognized. If there is no interference, the outer conductor is located 33 and thus also the control electrode 44 of the first switching transistor T1 firmly on earth potential 36 . The circuit-side ground point is also located 42 via the earth connection 49 the monitoring circuit 38 firmly on earth potential 36 or. 50 . The first switching transistor T1 thereby assumes its blocking state. The same applies to the second switching transistor T2 . When a monitoring test process is triggered by actuating the auxiliary voltage supply 43 therefore remains the display element 41 deactivated.

If, on the other hand, there is a line interruption in the coaxial line 31 or another high-resistance disturbance on the outer conductor 33 on, the ground for the control electrode goes 44 of the first switching transistor T1 lost, creating the first switching transistor T1 gets into its conductive state. This closes a current path between the monitoring display element 41 and the ground point 42 with the result that the monitoring indicator 41 activated when a surveillance test is triggered. On the activated monitoring indicator 41 it can be recognized that there is an installation error. The same error display arises in the event that the plug connection is through the connector 34 is not properly manufactured. Because in this case, too, is the control electrode 44 of the first switching transistor T1 not permanently connected to earth potential and remains floating, so that the first switching transistor T1 is switched conductive. In other words, the monitoring circuit recognizes 38 the interruption of the outer conductor 33 at a potential difference between the grounding points or ground potentials 36 and 50 .

Via the second switching transistor T2 can be recognized as a further installation error in the case that the monitoring circuit 38 with their earth connection 49 not or not properly connected to the earth potential 50 is coupled. In this case, the control electrode is permanently connected 47 of the second switching transistor T2 lost to ground potential, causing the second switching transistor T2 is placed in its conductive state and this now a display current path between the monitoring display element 41 and the ground point 12th provides.

The two switching transistors T1 , T2 work independently, which means that the monitoring circuit 38 is able to deal with the described installation errors with regard to the test signal connecting line 30th on the one hand and the grounding of the monitoring circuit 38 on the other hand to be recognized both individually and in combination and via the display element 41 to display. This concerns an incomplete installation due to a non-established connection via the connector 34 , an incomplete installation due to a missing or insufficient earth connection of the monitoring circuit 38 and a wire break or a high-resistance disturbance in the coaxial line 31 . The first transistor switch acts here T1 with the associated peripheral circuit part as test signal connection line monitoring circuit part, while the second transistor switch T2 functions with the associated peripheral circuit part as a ground connection monitoring circuit part. The outer conductor 33 acts as one along the inner conductor and thus the test signal connecting line 30th running monitoring line at its end facing the coupling electrodes 32a to the earth potential 36 is connected and at its other end 32b via the optional connector 34 and the optional coupling circuit 37 to the trunk monitoring circuit 38 is coupled.

The coupling circuit 37 contains a matching resistor in the example shown R3 for low-reflection high-frequency decoupling and an inductance 29 as a high-frequency filter to avoid a short circuit of the high-frequency partial discharge signal in the direction of the monitoring circuit 38 .

Although this has not been explicitly mentioned so far, it goes without saying that the voltage testing system shown can be designed in the usual way for voltage testing of three-phase high voltage and the monitoring and voltage testing described can be provided for each of the three phases. In this case, it is advantageous to have a common connection point for all three phases and the respective monitored coaxial cable shield or outer conductor 33 to be provided by an appropriately designed plug connection. The installation monitoring measure first determines whether there is an installation error. If there is no installation error, the voltage test unit can 3 Perform the normal voltage test for the high-voltage line to be monitored.

In the case of wire break detection by the monitoring circuit 38 As a rule, it can be assumed that a wire break in a three-phase voltage detection system is critical if all three test signal connecting lines 30th of a three-phase system are interrupted, because in this state a wire break would not be differentiated from the state "voltage free", while in the event of a wire break in a single connecting line the other connecting lines would still carry a signal and signal the state "voltage present". A three-phase system is only considered to be "de-energized" if all three phases are de-energized. For this reason, the monitoring of just one coaxial connection line is generally sufficient for wire break detection.

As the shown and the other embodiments explained above make clear, the invention provides a circuit arrangement that fulfills the known monitoring tasks of partial discharge detection and voltage testing on medium / high voltage systems in a very advantageous manner and with relatively little circuit complexity in a single , can implement these functions combining device and, if required, can do without any auxiliary energy for both voltage testing and partial discharge detection. The partial discharge detection can be automatically limited to the periods of interest in which there is an active measurement signal for the voltage test. In other periods of time, the partial discharge detection can be kept inactive due to a lack of energy supply due to the lack of the measurement signal. Optionally, wire break detection can also be provided as an integral part of the circuit arrangement, which can be implemented in a common device or device housing.

Claims (14)

Circuit arrangement for voltage testing and partial discharge detection in a single or multi-phase medium or high voltage system, with - one or more conductor signal inputs (1), each of which is set up for coupling to a capacitive coupling electrode (2) which is coupled to a conductor (L1, L2, L3) of the single or multi-phase medium or high voltage system, - in each case one voltage testing unit (3) coupled on the input side to the assigned conductor signal input (1) of the circuit arrangement, which is set up for threshold-based voltage state detection with respect to the assigned conductor, - At least one partial discharge detector unit (4) set up for partial discharge detection with respect to an assigned conductor (L1, L2, L3), which has a partial discharge detector circuit (5) coupled on the input side to an assigned conductor signal input (1) of the circuit arrangement and an input side to a signal output (6) of the partial discharge detector circuit (5) coupled partial discharge display circuit (7) comprises, and - A power supply for the partial discharge detector unit (4), characterized in that - The energy supply for the partial discharge detector unit (4) comprises a first energy supply circuit (8) which is set up to supply the partial discharge detector circuit (5) with energy from the or one of the conductor signal inputs (1) of the circuit arrangement, and / or comprises a second energy supply circuit (9) which is set up to supply the partial discharge display circuit (7) with energy from the or one of the conductor signal inputs (1) of the circuit arrangement. Circuit arrangement according to Claim 1 , further characterized in that - the first energy supply circuit (8) is coupled to the same conductor signal input (1) of the circuit arrangement as the partial discharge detector unit (4) or to another of several conductor signal inputs (1) of the circuit arrangement and / or - the second energy supply circuit ( 9) is coupled to the same conductor signal input (1) of the circuit arrangement as the partial discharge detector unit (4) or to another of several conductor signal inputs (1) of the circuit arrangement. Circuit arrangement according to Claim 2 , further characterized in that the partial discharge detector unit (4), the first energy supply circuit (8) and the second energy supply circuit (9) are coupled to three different conductor signal inputs (1) of the circuit arrangement. Circuit arrangement according to one of the Claims 1 to 3 , further characterized in that it has a variable capacitor (10) at the respective conductor signal input (1) for forming a capacitive voltage divider with the associated capacitive coupling electrode (2). Circuit arrangement according to one of the Claims 1 to 4th , further characterized in that the partial discharge detector unit (4) is designed to be adjustable in sensitivity. Circuit arrangement according to Claim 5 , further characterized in that the partial discharge detector unit (4) for sensitivity adjustment comprises a circuit component (11) which is coupled to the signal output of the partial discharge detector circuit (5) and which has a variable capacitor or a potentiometer or an adjustable resistor network. Circuit arrangement according to one of the Claims 1 to 6th , further characterized in that the partial discharge detector unit (4) has a deactivation element (12) by means of which it can be deactivated independently of the voltage test unit (3) coupled to the same conductor signal input (1) of the circuit arrangement. Circuit arrangement according to one of the Claims 1 to 7th , further characterized in that the partial discharge display circuit (7) comprises a display unit (13) and a semiconductor switch (14) looped in between the display unit (13) and the second energy supply circuit (9), which has a control input (15) at the signal output (6) the partial discharge detector circuit (5) is coupled. Circuit arrangement according to one of the Claims 1 to 8th , further characterized by - a ground connection (20), - a detection information connection (22) for transmitting detection information of the partial discharge detector unit (4) to the outside and - a controllable switch (21), which is connected on the one hand to the ground connection (20) and on the other hand with the detection information connection (22), a control input of the controllable switch (21) being connected to the signal output (6) of the partial discharge detector circuit (5). Circuit arrangement according to one of the Claims 1 to 9 , further characterized by a diagnosis connection (24) which is connected to the signal output (6) of the partial discharge detector circuit (5). Circuit arrangement according to one of the Claims 1 to 10 , further characterized in that - the respective voltage testing unit (3) comprises a voltage testing circuit (16) coupled on the input side to the assigned conductor signal input of the circuit arrangement and a voltage status display circuit (18) coupled on the input side to a signal output (17) of the voltage testing circuit and - the partial discharge The display circuit (4) of the partial discharge detector unit and the voltage status display circuit of the voltage test unit coupled to the same conductor signal input of the circuit arrangement have a common display unit. Circuit arrangement according to one of the Claims 1 to 11 , further characterized by - a coaxial line (31) with an inner conductor (32) which forms at least part of a connecting line (30) from the respective conductor signal input (1) to the associated capacitive coupling electrode (2), and an outer conductor surrounding the inner conductor (32) (33) which is grounded at a first end (33a) facing the coupling electrode, and - a connecting line monitoring circuit (38) which can be coupled to a second end (33b) of the outer conductor (33) remote from the coupling electrode and is set up for a Detect potential deviation on the outer conductor (33). Circuit arrangement according to Claim 12 , further characterized by a common connector plug (34) for the simultaneous detachable coupling of the connecting line monitoring circuit (38) to the second end (33b) of the outer conductor (33) and the conductor signal input (1) to an end (32b) of the inner conductor (32) facing away from the coupling electrode ). Circuit arrangement according to Claim 12 or 13th , further characterized in that the connecting line monitoring circuit (38) is connected to a ground potential (50) via a ground connection (49) and is set up to detect a potential deviation on the ground connection (49).

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