Method and assembly for inspecting an insulation
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2024-05-24
- Publication Date
- 2026-04-08
AI Technical Summary
Existing insulation monitoring devices for electrically operated vehicles, such as eHighway trucks, are not designed to handle voltage levels above 1000 V, posing a challenge as system voltages are expected to increase due to high power requirements.
A method and arrangement that utilize a circuit arrangement with a voltage divider, comprising resistors, to limit the voltage applied to insulation monitoring devices, allowing them to operate safely up to higher voltages by accounting for internal resistance and external capacitance, enabling continued use of existing devices and preserving component production volumes.
Enables insulation monitoring for voltages above 1000 V while reducing costs and maintaining operational safety, allowing existing devices to be retrofitted or used with minimal changes, optimizing circuit performance and reducing thermal stress on components.
Smart Images
Figure EP2024064331_02012025_PF_FP_ABST
Abstract
Description
[0001] Description
[0002] Procedure and arrangement for insulation monitoring
[0003] The invention relates to a method for insulation monitoring according to the preamble of claim 1 and to an arrangement for insulation monitoring according to the preamble of claim 10.
[0004] The use of electrically powered vehicles, such as electrically powered rail vehicles such as trams and trains, or road vehicles, in particular trucks (lorries), operated according to so-called eHighway technology, is known.
[0005] It is also known that electrically powered vehicles require some form of electrical insulation monitoring to ensure operational safety.
[0006] An insulation monitor, also known as an insulation monitoring device (IMM), is designed to monitor the insulation condition in IT systems, including IT networks. IT systems are local low-voltage networks that do not have a functionally grounded neutral point. The insulation monitor alerts as soon as the insulation resistance falls below the minimum level.
[0007] An IT system, also known as "Isole Terre" (French), refers to a specific implementation of a low-voltage network within an electrical installation for the supply of electrical power. The most outstanding feature of this network type is the earth connection at the power source and the electrical equipment. In the IT system, there is no direct electrical connection between the active conductors and the earthed components; it is generally designed in such a way that an initial fault that may occur in the system does not lead to an electrical hazard. An immediate shutdown of the power supply is therefore not absolutely necessary.
[0008] For vehicles with overhead line operation, it may even be necessary to use several insulation monitoring systems.
[0009] The problem is that in order to reduce the current that occurs due to the high power requirements of the vehicles, the system voltages in electrically operated vehicles will be increased in the future.
[0010] For non-rail vehicles, insulation monitoring devices with operating voltages of up to approximately 1000 V are available and certified on the market.
[0011] These devices are not specified for higher overhead line and vehicle voltages, which will result from the prospective increase, and can therefore no longer be used.
[0012] The object underlying the invention is to provide a technical solution which overcomes the disadvantages of the prior art, in particular to provide an arrangement and a method which enable insulation monitoring for voltages above 1000 V.
[0013] This object is achieved by the method for insulation monitoring starting from the features according to the preamble of claim 1 by its characterizing features and by the arrangement for insulation monitoring starting from the features according to the preamble of claim 10 by its characterizing features.
[0014] In the method according to the invention for insulation monitoring based on at least one first insulation monitoring device which can be connected to a first and second measuring connection in a supply of an electrically driven vehicle with electrical energy by means of a supply voltage, in particular via an overhead line, wherein the insulation monitoring device is designed to be connectable to the supply circuit via the first and second measuring connection and is designed for operation up to a predetermined maximum permissible nominal voltage peak value, an electrical circuit arrangement is electrically conductively connected between the supply and the insulation monitoring device, which circuit arrangement is dimensioned such that at a first value of the supply voltage which is above a second value of the nominal voltage,the voltage applied to the insulation monitoring device is limited to the second value and, when dimensioning the circuit arrangement, at least the resistance value of the internal resistance of the insulation monitoring device resulting from the connection of the supply is taken into account in such a way that the measuring time for measuring an insulation resistance occurring in the event of a fault cannot exceed a specified maximum time.
[0015] The method according to the invention makes it possible, despite a given trend to continually increase the supply voltage for electrically powered vehicles, in particular above a current maximum rated voltage of 1000 V, to still use the insulation monitoring device already designed for the current dimensioning, in particular 1000 V maximum rated voltage, and for the insulation monitoring devices currently produced for this dimensioning, so that costs can be reduced, wherein the restriction also includes or is defined in such a way that this second value may be temporarily exceeded, depending on the national standard, for a time specified in accordance with the standard by an amount that is also specified, in particular corresponding to the permitted rated voltage peak value.Firstly, because the previously used insulation monitoring devices can continue to be used by retrofitting them with the circuit arrangement according to the invention, and secondly, because the production volumes of the currently available components, such as the insulation monitoring device, are at least maintained, thus enabling cost-effective purchasing. Furthermore, the invention also encompasses and allows for the circuit arrangement according to the invention to be integrated into the finished product during the manufacture of new insulation monitoring devices of the current dimensions, thus producing it directly as an insulation monitoring device according to the invention.With the continued use of the insulation monitoring device for current requirements, dimensioning of the nominal voltage, in particular a maximum of 1000V, there is also the technical advantage that production remains almost unchanged and the dimensioning of the circuit of the insulation monitoring device will, at the latest through experience from use, have a lead over newer circuits in terms of optimization.
[0016] In the inventive arrangement for insulation monitoring based on at least one first insulation monitoring device connectable to a first and second measuring connection in a supply of an electrically driven vehicle with electrical energy by means of a supply voltage, in particular via an overhead line, wherein the insulation monitoring device is designed to be connectable to the supply circuit via the first and second measuring connection and is designed for operation up to a predetermined maximum permissible nominal voltage peak value, means are provided for carrying out the method and / or one of its developments.
[0017] The inventive arrangement for insulation monitoring is characterized in that it comprises means for carrying out the method for insulation monitoring and / or one of its embodiments and further developments.
[0018] In this way, it contributes to the implementation and, mutatis mutandis, to the realization of the advantages mentioned in connection with the method. Further advantageous embodiments and developments of the invention are specified in the subclaims.
[0019] If the method according to the invention is further developed in such a way that the consideration is given to the circuit arrangement being operated in such a way that the resistance value of at least parts of the resistors of the circuit arrangement is determined in each case as a function of the internal resistance of the insulation monitoring device, the circuit arrangement is adjusted in an optimized manner to the electrical properties, in particular the resistive load, of the insulation monitoring device.
[0020] The advantage of adjusting to the electrical properties of the insulation monitoring device is also achieved if, alternatively or additionally, according to a further development of the method according to the invention, the consideration is given in such a way that the circuit arrangement is operated in such a way that the resistance value of at least parts of the resistors of the circuit arrangement is determined in each case as a function of capacitance external to the insulation monitoring device and resulting from circuit components connected to it, this further development in particular resulting from the wiring of the insulation monitoring device with the circuit arrangement according to the invention with regard to.the insulation monitoring and circuit arrangement acting externally, in particular as a capacitance connected in parallel to the common circuit of the insulation monitoring device and the circuit arrangement, is taken into account in such a way that this time delay caused by internal current sources of the insulation monitoring device can be limited in the measurement provided for the insulation monitoring by the inventive selection of the resistance value(s).
[0021] The limitation according to the invention is particularly advantageously implemented if the method according to the invention is further developed in such a way that the consideration is given in such a way that, in the event that the insulation monitoring device is operated in such a way that the monitoring is carried out on the basis of a so-called "Earth-Lift" switch, the circuit arrangement is operated in such a way that the resistance value of at least parts of the resistors of the circuit arrangement is determined in each case as a function of a maximum voltage permissible at the Earth-Lift switch in the event of a fault.As a result, on the one hand, a conventional insulation monitoring device is taken into account according to the invention, so that the inventive idea of enabling the further use of conventional insulation monitoring devices is continued to be taken into account and the invention also takes into account the properties of an earth-lift switch, which lie, among other things, in the consideration of the breakdown voltage of the switch, which is usually designed as a semiconductor, which must be limited, which can also be achieved by additionally incorporating it into the dimensioning of at least parts of the resistors in the circuit arrangement, and thus the voltage applied to the earth-lift switch, which determines the power at the resistor and thus heating, can be limited, so that the thermal load on the resistors is also limited.
[0022] The method according to the invention is preferably further developed such that the circuit arrangement is operated such that the supply voltage is fed to a resistor network which is functionally connected and operated such that at least part of the circuit arrangement functions as a voltage divider, wherein the voltage divider is dimensioned and functionally connected and operated with the insulation monitoring device such that the value of the resulting voltage does not exceed the value of the nominal voltage. This provides a very simple but at the same time extremely suitable measure for limiting the nominal voltage.
[0023] If the method according to the invention is further developed in such a way that the voltage divider is operated at least by means of a first resistor, a second resistor and a third resistor, such that the first measuring connection of the insulation monitoring device is connected to the supply circuit via the first resistor, that the second measuring connection of the insulation monitoring device is connected to the supply circuit via the second resistor and the first measuring connection and the second measuring connection are connected via the third resistor, a particularly preferred further development is provided.
[0024] This further development makes it possible for the supply voltage limiting the nominal value to be applied to the third resistor and not to be exceeded, in particular due to the possible short-term permissible reaching of a maximum nominal voltage intermediate value during standardization, otherwise it is limited to only this short-term exceeding, because this limits the first two together with the third resistor by the resistance values dimensioned according to the invention, wherein the first and the second resistor also ensure a defined voltage potential at the two measuring terminals connected to the supply voltage.
[0025] If the determination is made in such a way that the resistance value of the first resistor and the resistance value of the second resistor are determined by the same amount x, which is determined as a function of the amount y of the internal resistance and an amount z which correlates with an extension of the time period until the insulation monitoring device is triggered in the event of a fault condition, in particular which corresponds to a fixed percentage value, such that z = x / y, a development of the method according to the invention is provided, with which an optimal voltage divider circuit is provided which can be set to the wiring of the insulation monitoring device, in which, among other things, both the limitation to the nominal voltage, adjustment to maximum heat development or.Limitation of the voltage load in the event of a fault, as well as equal potentials at the measuring terminals are guaranteed, since the value of the first two resistors is determined to be the same and the limitation to a delay resulting from the external capacitance is taken into account and can be set by a concrete determination of the values adapted to the respective implementation.
[0026] For common insulation monitoring devices with a nominal voltage of 1000 V, i.e. according to the invention up to a maximum permissible voltage of 1000 V, the development of the method according to the invention is suitable, in which the circuit arrangement is dimensioned and operated in such a way that, for a given parameterization such that at least the value x of the internal resistance is 1.2 MΩ, a nominal voltage of the insulation monitoring device of 1000 V and a supply voltage with a value up to a maximum of 1950 V and / or a setting of the parameter maximum measuring time duration with a value which is 10% longer than a time given without the circuit arrangement for triggering the insulation monitoring device in the event of a fault, the resistance value determined for the first resistor and the resistance value determined for the second resistor is determined from a value range around 120 kΩ, in particular determined by tolerances, and for the third resistor a resistance value from a,In particular, the value range around 190 kΩ is determined by tolerances. This enables the implementation of an insulation monitoring arrangement according to the invention based on the conventional insulation monitoring device, which operates with an acceptable time delay.
[0027] The method according to the invention can be further developed in such a way that, in the event of deviations of individual or all predetermined values of the parameterization, the resistance range of the first resistor, the second resistor and / or the third resistor is determined by a resistance value which deviates from the determined value as a function of the deviation, so that at least optimal wiring of the insulation monitoring device is always possible by adjusting individual or all of the determined values mentioned in the previously described development accordingly to a change, wherein the dependencies of the circuit according to the invention lead to the fact that, for example, a change in one of the resistance values results in an adjustment of further values corresponding to the dependency ratio.For example, a combination which is essentially independent of the measurement timeout but which is aimed at minimizing the power loss and which also meets the inventive approach is given by a value of 180kQ for the first and second resistors and 150kQ for the third resistor.
[0028] The further development of the insulation monitoring arrangement according to the invention, in which the circuit arrangement is designed such that the supply voltage is fed to a resistor network which is designed such that at least part of the circuit arrangement is designed as a voltage divider, wherein the voltage divider is dimensioned and functionally connected to the insulation monitoring device such that the value of the resulting voltage does not exceed the value of the nominal voltage, provides one of the possible implementations which realizes the corresponding one of the above-mentioned further developments of the method according to the invention. This enables the realization of the advantages of this further development of the method according to the invention.
[0029] This applies equally to the further development of the insulation monitoring arrangement according to the invention in such a way that the voltage divider is designed at least by means of a first resistor, a second resistor and a third resistor in such a way that the first measuring connection of the insulation monitoring device is connected to the supply circuit via the first resistor, that the second measuring connection of the insulation monitoring device is connected to the supply circuit via the second resistor and the first measuring connection and the second measuring connection are connected via the third resistor.
[0030] With the development of the insulation monitoring arrangement according to the invention in such a way that the resistance value of the first resistor and the resistance value of the second resistor have the same amount x, which is determined as a function of the amount y of the internal resistance and the amount z which correlates with an extension of the time period caused by the circuit arrangement until the insulation monitoring device is triggered in the event of a fault condition, in particular corresponding to a fixed percentage value, such that z = x / y, an optimal wiring is provided as stated in the above evaluation of the advantages of the corresponding development of the method according to the invention.
[0031] Furthermore, the same advantages are achieved as stated in the above-mentioned development of the method according to the invention if the insulation monitoring arrangement according to the invention is developed in such a way that the circuit arrangement is designed in such a way that for a given parameterization such that at least the value x of the internal resistance is 1.2 MΩ, a nominal voltage of the insulation monitoring device of 1000 V and a supply voltage with a value up to a maximum of 1950 V and / or a setting of the parameter maximum measuring time duration with a value which is 10% longer than a time given without the circuit arrangement for triggering the insulation monitoring device in the event of a fault, the resistance value determined for the first resistor and the resistance value determined for the second resistor from a, in particular determined by tolerances,A value range of around 120 kΩ is given, and for the third resistor, a resistance value from a value range of around 190 kΩ, determined in particular by tolerances. Exemplary embodiments of the invention are explained in more detail below with reference to Figures 1 to 3. In Figures 1 to 3, identical or functionally equivalent elements are provided with the same reference numerals, unless otherwise indicated. They show:
[0032] Fig. 1 schematically shows an exemplary structure of an insulation monitoring device with an earth-lift switch known from the prior art,
[0033] Fig. 2 schematically shows an embodiment of the method according to the invention and schematically shows an embodiment of the arrangement according to the invention.
[0034] The embodiment explained below in Figure 2, based on the insulation monitoring device shown in Figure 1 according to the prior art, represents preferred embodiments and developments of the invention.
[0035] In particular, the exemplary embodiments presented and / or discussed below merely show exemplary implementation possibilities of how such implementations of the teaching according to the invention could look like, since it is impossible and also not expedient or necessary for understanding the invention to name all of these implementation possibilities.
[0036] In particular, a (relevant) person skilled in the art, with knowledge of the independent claims, will of course be aware of all the possibilities customary in the prior art for realising the invention, so that in particular there is no need for an independent disclosure in the description.
[0037] In the embodiments, the described components of the embodiments each represent individual features of the invention that are to be considered independently of one another, which also further develop the invention independently of one another and are therefore to be regarded as part of the invention, either individually or in a combination other than that shown.
[0038] Furthermore, the described embodiments can also be supplemented by further features of the invention already described.
[0039] The same reference symbols have the same meaning in the different figures.
[0040] Figure 1 shows an insulation monitoring device (also called isometer) ISO-W according to the state of the art.
[0041] It can be seen that the insulation monitoring device ISO-W has a first measuring connection A1 and a second measuring connection A2.
[0042] One or more of these ISO-W insulation monitoring devices can be installed in the supply system of an electrically powered vehicle via these two measuring connections A1...A2.
[0043] The installation can be carried out on the battery / drive side and, particularly when using an overhead line truck, a so-called eHighway vehicle, also on the infrastructure side, via the overhead line voltage.
[0044] It can also be seen that the insulation monitoring device ISO-W, as a representation of the basic structure, generally has a resistor network RO, which connects one of the two measuring connections A1...A2 to an internal current source QI of the insulation monitoring device, which can be connected to the electrical ground connection MASSE via a so-called earth-lift switch ELS. The earth-lift switch ELS gets its name from the fact that it allows galvanic isolation of the circuit of the insulation monitoring device ISO-W. This is generally advantageous when several insulation monitoring devices ISO-W are connected, since the galvanic isolation prevents any falsification of the insulation measurement by the other insulation monitoring devices ISO-W.The earth lift switch is therefore advantageous for alternately operating several ISO-W insulation monitoring devices (IMDs) in the same network without them affecting each other. When it is open, in the event of a fault, the overhead line voltage can be present across the connections, depending on the structure of the respective IMD, if they are designed according to the invention, i.e. A1...A2. It can be designed as an electrical or mechanical switch. For the exemplary embodiment of the invention, it is an electrical semiconductor switch using MOS-FET technology.
[0045] ISO-W insulation monitoring devices, as shown, must not exceed a specified voltage during operation. Therefore, they are designed and certified for operation at a specified nominal voltage.
[0046] Currently, these insulation monitoring devices are available with a maximum nominal voltage of 1000 V, with the resistor network R0 having a resistance value of approximately 1.2 MΩ, which can be regarded as the internal resistance of the ISO-W insulation monitoring device. This resistance is the total resistance resulting from the parallel connection of the internal resistance of the supply voltage and the internal resistance of the unconnected ISO-W insulation monitoring device, both of which are approximately 2.4 MΩ. However, it is foreseeable that devices with significantly higher nominal voltages will have to be used, the peak values of which can be reached during operation can also be significantly higher, in particular up to 1950 V.An embodiment of the method according to the invention which addresses this situation given in the prior art, as well as an embodiment of the insulation arrangement according to the invention which is a result of the embodiment of the method according to the invention for insulation monitoring, are illustrated by the schematic representation shown in FIGURE 2 and the explanations given below.
[0047] It can be seen that the insulation monitoring device ISO-W according to the prior art is used as the basis of the embodiment of the insulation arrangement according to the invention, which according to the embodiment of the method according to the invention is connected to a circuit arrangement which, according to the embodiment of the insulation monitoring device according to the invention, is implemented by a voltage divider formed by a first resistor R1, a second resistor R2 and a third resistor R3, which according to the embodiment of the method according to the invention are functionally connected and operated with one another in such a way that the third resistor R3 is connected between the first measuring terminal A1 of the insulation monitoring device ISO-W and the second measuring terminal A2 of the insulation monitoring device ISO-W, such that the voltage applied to the third resistor R3 is also applied to the insulation monitoring device ISO-W,so that it forms a parallel circuit with the third resistor.
[0048] It can also be seen that, according to the exemplary embodiment of the insulation monitoring arrangement according to the invention, the first resistor RI, the second resistor R2 and the third resistor R3 are connected in series in such a way that the two-pole first resistor RI is connected on the input side to the first measuring terminal A1 and on the input side to the two-pole third resistor, and the second resistor R2, also two-pole, is connected on the input side to the output of the third resistor R3. The resistors R1...R3 of the voltage divider are therefore functionally connected and operated in such a way according to the exemplary embodiment of the method according to the invention that the output of the first resistor RI forms a first terminal A1* modified according to the invention and the output of the second resistor R2 forms a second terminal A2* modified according to the invention.
[0049] The insulation device ISO-W connected to the circuit arrangement configured as a voltage divider thus provides an exemplary embodiment of the insulation monitoring arrangement according to the invention and shows how, by means of the exemplary embodiment of the method according to the invention, a conventional insulation monitoring device is converted into an insulation monitoring device according to the invention. The invention can also be used in the production of future insulation monitoring devices. This means that the circuitry can be integrated with the circuit of an insulation monitoring device according to an alternative exemplary embodiment of the insulation monitoring arrangement according to the invention and can be marketed and used as a unit.
[0050] All implementations of the invention have the advantage that it is possible to connect common ISO-W insulation monitoring devices or their circuitry to higher voltage supplies than those approved for the ISO-W insulation device, or to modify them for this purpose. The invention thus makes it possible to respond quickly to changes in requirements by a user and / or the manufacturer applying the procedure and arrangement according to the invention.
[0051] Furthermore, the invention can make this reaction possible in a cost-effective manner, since, especially when such requirements are rare or are just becoming widespread, insulation monitoring devices approved for these new requirements will be expensive. It can also be seen that an external capacitance C acting in the event of a fault, which is represented by the dashed lines, ext which in the event of a fault has an effect as if it were between the first modified terminal Al* and the ground MASSE as well as the insulation resistance Ri acting in the event of a fault, which is accordingly also shown in dashed lines. SO connected in parallel .
[0052] If the permissible nominal voltage of the insulation monitoring device ISO-W is 1000 V and its internal resistance resulting after connection to the supply voltage acts with an ohmic load of 1.2 MQ, an embodiment of the invention is specified which offers an optimal solution to the inventive problem with an inventive dimensioning of the circuit arrangement with Rl=R2=120kQ and R3= 190kQ.
[0053] As will be explained in more detail below, it also has some advantages and advantageous effects that can be generally attributed to the invention.
[0054] With this concrete inventive dimensioning of the embodiment of the invention, it is possible, for example, to use nominal voltages of 1200-1500 V in foreseeable projects, which can reach peak voltages of up to 1950 V.
[0055] Furthermore, the invention thus offers a ballast network which represents a cost-effective and timely solution to changing requirements, because this invention teaches a ballast network which makes it possible to use standard ISO-W devices in accordance with the specifications as regards the maximum permitted operating voltage, without restricting the actual function of these devices in such a way that they cannot fulfil their actual function or maintain the given optimised function. The invention also makes it possible to limit the voltage load of the earth-lift switch ELS in the open state, i.e. to limit it to <=1000 V given the parameters of the ISO-W insulation monitoring device.
[0056] Since this ISO-W device is technically designed as a semiconductor switch, it has a certain breakdown voltage, which is therefore always undershot according to the invention.
[0057] The current generated by the externally applied operating voltage of max. 1950 V through the internal resistor network R0 can be limited, particularly by the specific dimensioning mentioned above, so that thermal overload is excluded. This is possible thanks to the invention below the specified 1000 V.
[0058] Furthermore, the insulation resistance Riso , which is to be recognized as a fault in the event of a fault, continues to be recognized in a determined time by the circuit arrangement according to the invention despite the wiring according to the method according to the invention.
[0059] In addition, the possibly existing capacitance Cext is taken into account, which must be charged / discharged by the internal current source QI of the insulation monitoring device ISO-W in its measuring cycles in order to make an ohmic measurement possible at all.
[0060] The first series resistor RI or the second series resistor R2 added to the external network fundamentally increases this measuring time. According to the invention, a time period that is still acceptable for the protective function can now be defined. In the example shown, a maximum increase in the measuring time of 10% is accepted. The invention therefore provides that the first resistor RI and the second resistor R2 are each determined by a value that is 10% of the internal resistor network R0, which is therefore 120 kOhm for the specific dimensioning. With the resistors R1...R3 dimensioned in this way, a voltage divider is realized which limits the voltage between the two original high-voltage measuring terminals A1...A2 to the specified 1000 V and this limitation is also given in the event of a fault, i.e. with an insulation resistance of Riso = 0Q, the voltage load of the open earth lift switch is also given this value (1000 V).
[0061] It should be added that the arrangement defined by the invention and the method according to the invention can be used both in IT systems, i.e. a supply voltage principle of the overhead line that is completely isolated from earth, and in symmetrically earthed systems, as can be used, for example, in eHighway systems, and also in one-sided earthed systems.
[0062] A further advantage of the invention is that it can be used not only for voltages higher than the permissible voltage, but also for the use / integration of approved ISO-W insulation monitoring devices with lower voltages. This also ensures downward compatibility.
[0063] When using standard products that deviate from the principle explained with regard to ISO-W insulation monitoring devices, which, for example, operate according to the principle of cyclic measuring current injection, the invention is so flexible that a suitable, different configuration can be found that makes it usable for voltages above the permissible nominal voltage.
[0064] The resulting power loss as a result of the overhead line voltage between the two high-voltage measuring terminals A1...A2, which is in the single-digit watt range, can easily be taken into account in the design.
[0065] The invention is not limited to the described embodiments of the inventive method and the inventive arrangements that enable them. In particular, individual features or combinations of the embodiments or combinations thereof can be combined alternatively or additionally with individual features of the other embodiments or combinations thereof, mutatis mutandis.
[0066] The invention therefore encompasses all possible combinations of features that fall within the scope of the claims.
[0067] To the extent that expressions have been used above that indicate, imply or can be perceived as a grammatical gender and / or other characteristics suitable for distinguishing people, it is understood that these expressions have not been used in a divisive but inclusive manner, i.e. that all people - regardless of given, self-assumed or presumed individual characteristics - are considered to be of equal value.
Claims
Patent claims 1. Method for insulation monitoring based on at least one first insulation monitoring device connectable to a first and second measuring connection in a supply of an electrically driven vehicle with electrical energy by means of a supply voltage, in particular via an overhead line, wherein the insulation monitoring device is designed to be connectable to the supply circuit via the first and second measuring connection and is designed for operation up to a predetermined maximum permissible nominal voltage peak value, characterized in that an electrical circuit arrangement is electrically conductively connected between the supply and the insulation monitoring device, which is dimensioned such that at a first value of the supply voltage which is above a second value of the nominal voltage,the voltage applied to the insulation monitoring device is limited to the second value and, when dimensioning the circuit arrangement, at least the resistance value of the internal resistance of the insulation monitoring device resulting from the connection of the supply is taken into account in such a way that the measuring time for measuring an insulation resistance occurring in the event of a fault cannot exceed a specified maximum time.
2. Method according to the preceding claim, characterized in that the consideration is carried out in such a way that the circuit arrangement is operated in such a way that the resistance value of at least parts of the resistors of the circuit arrangement is determined in each case as a function of the internal resistance of the insulation monitoring device. 3 . Method according to one of the two preceding claims, characterized in that the consideration is such is carried out in such a way that the circuit arrangement is operated in such a way that the resistance value of at least parts of the resistors of the circuit arrangement is determined in each case as a function of the capacitance resulting from circuit components external to the insulation monitoring device and connected to it. 4 . Method according to one of the preceding claims, characterized in that the consideration is made in such a way that, in the event that the insulation monitoring device is operated in such a way that the monitoring is carried out on the basis of a so-called "Earth-Lift" switch, the circuit arrangement is operated in such a way that the resistance value of at least parts of the resistors of the circuit arrangement is determined in each case as a function of a maximum voltage permissible at the Earth-Lift switch in the event of a fault.
5. Method according to one of the preceding claims, characterized in that the circuit arrangement is operated in such a way that the supply voltage is fed to a resistor network which is functionally connected and operated in such a way that at least part of the circuit arrangement functions as a voltage divider, wherein the voltage divider is dimensioned and functionally connected and operated with the insulation monitoring device in such a way that the value of the voltage produced does not rise above the value of the nominal voltage. 6 . Method according to the preceding claim, characterized in that the voltage divider is operated at least by means of a first resistor, a second resistor and a third resistor, such that the first measuring terminal of the insulation monitoring device is connected to the supply circuit via the first resistor, that the second measuring terminal of the insulation monitoring device is connected to the supply circuit via the second resistor and the first measuring terminal and the second measuring terminal are connected via the third resistor.
7. Method according to the preceding claim, characterized in that the determination is carried out in such a way that the resistance value of the first resistor and the resistance value of the second resistor are determined by the same amount x, which is determined as a function of the amount y of the internal resistance and an amount z which correlates with an extension of the time period until the insulation monitoring device is triggered in the event of a fault condition, in particular corresponding to a fixed percentage value, caused by the circuit arrangement, such that z = x / y. 8 . Method according to one of the preceding methods, characterized in that the circuit arrangement is dimensioned and operated in such a way that, for a given parameterization such that at least the value x of the internal resistance is 1.2 MΩ, a nominal voltage of the insulation monitoring device of 1000 V and a supply voltage with a value up to a maximum of 1950 V and / or a setting of the parameter maximum measuring time duration with a value which is 10% longer than a time given without the circuit arrangement for triggering the insulation monitoring device in the event of a fault, the resistance value determined for the first resistor and the resistance value determined for the second resistor is determined from a value range around 120 kΩ, in particular determined by tolerances, and for the third resistor a resistance value is determined from a value range around 190 kΩ, in particular determined by tolerances. 9 . Method according to the preceding claim, characterized in that in the event of deviations of individual or all predetermined values of the parameterization, the resistance range of the first resistor, the second resistor and / or the third resistor is increased by a value determined by the certain value depending on the deviation correspondingly different resistance value is determined.
10. Arrangement for insulation monitoring based on at least one first insulation monitoring device connectable to a first and second measuring connection in a supply of an electrically driven vehicle with electrical energy by means of a supply voltage, in particular via an overhead line, wherein the insulation monitoring device is designed to be connectable to the supply circuit for monitoring via the first and second measuring connection and is designed for operation up to a predetermined maximum permissible nominal voltage peak value, characterized by means for carrying out the method according to one of the preceding claims.
11. Isolationsmonitoring arrangement according to the preceding claim, characterized in that the circuit arrangement is designed such that the supply voltage is fed to a resistor network which is designed such that at least part of the circuit arrangement is designed as a voltage divider, wherein the voltage divider is dimensioned and functionally connected to the Isolationsmonitoring device such that the value of the resulting voltage is limited to the value of the nominal voltage.
12. Isolationsmonitoring arrangement according to the preceding claim, characterized in that the voltage divider is designed at least by means of a first resistor, a second resistor and a third resistor, such that the first measuring connection of the Isolationsmonitoring device is connected to the supply circuit via the first resistor, that the second measuring connection of the Isolationsmonitoring device is connected to the supply circuit via the second resistor. resistor is connected to the supply circuit and the first measuring terminal and the second measuring terminal are connected via the third resistor.
13. Isolation monitoring arrangement according to the preceding claim, characterized in that the resistance value of the first resistor and the resistance value of the second resistor have the same amount x, which is determined as a function of the amount y of the internal resistance and the amount z correlating with an extension of the time period caused by the circuit arrangement until the insulation monitoring device is triggered in the event of a fault condition, in particular corresponding to a fixed percentage value, such that z = x / y.
14. Isolation monitoring arrangement according to one of the preceding methods, characterized in that the circuit arrangement is designed in such a way that, for a given parameterization such that at least the value x of the internal resistance is 1.2 MΩ, a nominal voltage of the insulation monitoring is predetermined at 1000 V and a supply voltage with a value up to a maximum of 1950 V and / or a setting of the parameter maximum measuring time duration with a value which is 10% longer than a time given without the circuit arrangement for triggering the insulation monitoring device in the event of a fault, the resistance value determined for the first resistor and the resistance value determined for the second resistor is given from a value range around 120 kΩ, in particular a value range determined by tolerances, and for the third resistor a resistance value is given from a value range around 190 kΩ, in particular a value range determined by tolerances.