Method for testing wiring of an electrical device

Abstract

The invention relates to a method (200) for testing wiring of an electrical device (100) comprising a plurality of circuits. In a method (100), a plurality of test signals (160-162) are generated. Each of the plurality of test signals (160-162) has a signal shape that is asymmetric in the time domain and also has a combination of harmonics from a predefined set of harmonics. The combinations of harmonics of the plurality of test signals (160-162) are different. A plurality of test signals (160-162) is fed into a plurality of first connections (142-144) assigned to a plurality of circuits at a first point (141) of the electrical device (100). A plurality of measurement signals is detected at a second point (145) of the electrical device (100) at a plurality of second connections (146-148) assigned to the plurality of circuits. Based on the fed test signal (160-162) and the detected measurement signal, an allocation between a first connection of the plurality of first connections (142-144) and a second connection of the plurality of second connections (146-148) is determined.

Description

Technical Field

[0001] The present invention relates to a method for testing the wiring of an electrical device, and in particular to a method for testing the wiring of an electrical device having a plurality of circuits (eg a power engineering electrical device in a substation or a power plant). Background Art

[0002] Wiring errors can occur during the installation, repair or expansion of electrical installations, for example in transformer substations or power plants. In particular in installations with multiple circuits and / or multiple phases, for example for three-phase alternating current, conductors can be mixed up; for example, two outer conductors can be mixed up or an outer conductor can be mixed up with a neutral conductor. Furthermore, for example, when connecting transformers, the polarity can be reversed. Therefore, before an electrical installation is put into service or recommissioned, the wiring is usually tested to identify incorrectly connected conductors and reversed polarity.

[0003] For example, a test signal can be injected continuously into the individual phases at an injection point, and a measurement signal can be acquired at a measurement point remote from said injection point, at which the effect of the test signal should appear if the wiring is correct. If the expected effect of the test signal is not detected at the measurement point, there may be a wiring error. This procedure is relatively time-consuming, as multiple measurements must be made to check multiple circuits and phases, and the measuring device must be connected to the measurement point and injection point for each measurement accordingly. In addition, although such measurements can be used to determine the presence of a wiring error, it is not possible to directly determine the type of wiring error, for example, whether the conductors have been mixed up or not connected.

[0004] Many power engineering systems use a three-phase current system. Likewise, many test devices have at least three current or voltage outputs. Thus, these test devices can be used to inject test signals in parallel in one operation and test the wiring of all phases. For example, test signals with different amplitudes for different phases can be used for this purpose. In particular, the amplitudes of current and voltage can be used here, the combination and / or subtraction of these amplitudes will produce new amplitudes that would not otherwise appear.

[0005] Example:

[0006] L1=3 L1+L2=8 L1-L2=-2 L1+L2+L3=17

[0007] L2=5 L1+L3=12 L1-L3=-6 L1+L2-L3=-1

[0008] L3=9 L2+L3=14 L2-L3=-4 L1-L2+L3=7

[0009] -L1+L2+L3=11

[0010] This enables detection of wiring errors based on the measured amplitude, for example if the return conductor of a phase is incorrectly connected.

[0011] However, in order to be able to make an unambiguous division, there must be a relatively large difference in the current or voltage amplitudes. Therefore, it is not always possible to work with amplitudes close to the nominal range of the device (e.g. 1A, 5A or 100V). In practice, multiple parallel connections or ground connections often occur. In these cases, the current division or voltage division is achieved based on the individual resistors. In this case, unambiguous phase detection is not possible. Summary of the invention

[0012] There is a need for improved options for testing the wiring of electrical installations having multiple circuits that can be performed quickly and reliably using simple methods.

[0013] According to the invention, a method for testing the wiring of an electrical device having a plurality of circuits and a testing device for testing the wiring of an electrical device having a plurality of circuits are provided, as defined in the independent claims. The dependent claims define embodiments of the invention.

[0014] The method for testing the wiring of an electrical device having a plurality of circuits according to the present invention comprises generating a plurality of test signals. Each of the plurality of test signals has a waveform that is asymmetric in the time domain and a combination of harmonics from a predefined group of higher harmonics. The waveform that is asymmetric in the time domain can be the same for all the plurality of test signals.

[0015] The following names are used in this description. The fundamental wave of frequency f is called the first harmonic. Double frequency oscillation (2f) is called the second harmonic. Generally speaking, oscillation of n times frequency nf is the nth harmonic. Higher harmonics refer to all harmonics except the first harmonic. The nth harmonic is referred to as the (n-1)th higher harmonic here.

[0016] Waveforms that are asymmetric in the time domain include the first harmonic (fundamental). The waveform is periodic with the frequency of this fundamental. Being asymmetric in the time domain means that the waveform plotted as a signal level over time cannot be mapped to itself by mirroring on an axis perpendicular to the time axis. An example of such a waveform that is asymmetric in the time domain is a ramp or sawtooth oscillation, where, for example, the rising edge has a small slope and the falling edge has a large (but negative) slope in terms of amplitude.

[0017] The combinations of harmonics of the multiple test signals are different, that is, each test signal has its own unique combination of harmonics.

[0018] For example, each of the multiple test signals may have an asymmetric waveform in the time domain, which is formed by superimposing a first harmonic, a second harmonic, and a third harmonic, each having a corresponding amplitude factor. In this case, the asymmetric waveform in the time domain includes, for example, at least a second harmonic and a third harmonic in addition to the fundamental wave. In another example, the asymmetric waveform in the time domain may include only a second harmonic or a third harmonic in addition to the fundamental wave. The asymmetric waveform in the time domain thus formed may additionally have a combination of higher harmonics with corresponding amplitude factors superimposed thereon, such as a combination of a fourth harmonic and a fifth harmonic. In other words, in this case, the predefined group of high-order harmonics includes a fourth harmonic and a fifth harmonic. For example, a first combination assigned to a first test signal in a plurality of test signals may have a fourth harmonic without a fifth harmonic. Therefore, the first test signal includes the first, second, third, and fourth harmonics. For example, a second combination assigned to a second test signal in a plurality of test signals may include a fifth harmonic but not a fourth harmonic. Therefore, the second test signal includes the first, second, third, and fifth harmonics. For example, a third combination assigned to a third test signal of the plurality of test signals may have neither the fourth harmonic nor the fifth harmonic. Therefore, the third test signal only includes the first, second and third harmonics.

[0019] In general, for example, the combination of harmonics of a plurality of test signals is designed so that any linear combination of the plurality of test signals also has substantially the same asymmetric properties in the time domain as the individual test signals. This can be achieved, for example, in that the test signals differ from one another only in terms of higher harmonics (e.g., fourth and fifth harmonics) and are phase-synchronized relative to the fundamental. If the higher harmonics (e.g., fourth and fifth harmonics) are encoded accordingly, it is also possible to detect which individual signals appear in the sum signal (i.e., the linear combination). Thus, it is possible to detect individual signals, but for the sum signal it is also easy to determine the partial signals it contains.

[0020] At a first point of the electrical device, multiple test signals generated thereby are injected into multiple first connections assigned to multiple circuits of the electrical device. For example, the multiple circuits may include multiple phases of the electrical device. Different test signals among the multiple test signals are injected into each first connection of the multiple first connections. In other words, different test signals are injected into each circuit of the electrical device at the first point. At a second point of the electrical device, multiple measurement signals are acquired at multiple second connections assigned to the multiple circuits. For example, in the case of a substation, the first point may be at the input end of the substation, and the second point may be at one of the output ends of the substation. In another example, the first point may be on the first side of the transformer, and the second point may be on the second side of the transformer. The injected test signals and the acquired measurement signals are used as a basis for determining the allocation between the first connection in the multiple first connections and the second connection in the multiple second connections, respectively, so as to test the wiring of the electrical device, for example, based on the allocation. Since the injected test signals are different, it is possible to clearly determine which test signal leads to the corresponding measurement signal at which second connection, so that a clear allocation between the first connection and the second connection can be determined. For example, based on the test signals, confusion and interruption can be easily determined.

[0021] For example, in the case of a wiring error, an assignment may be determined that does not correspond to the expected or predefined assignment, or there may be no assignment, or an incomplete assignment (e.g. due to an interruption or coupling to a completely incorrect circuit). On the other hand, in the case of no errors, an assignment may be determined that corresponds to a predefined "target assignment".

[0022] Thus, the presence or absence of a particular harmonic, such as the fourth or fifth harmonic, results in a digital encoding of the test signal. Adding a sixth harmonic can increase the number of different combinations and thus the number of different test signals, for example to be able to test the wiring of an electrical installation with more than three phases or circuits, such as a test signal for testing two three-phase installation components, that is to say a total of six phases, or an installation component with multiple circuits, such as having six or more circuits.

[0023] A plurality of test signals can be injected into a plurality of first connections simultaneously. Likewise, a plurality of measurement signals can be acquired simultaneously. Since the test signals are encoded based on different combinations of harmonics contained in the test signals, a plurality of measurement signals acquired at a second point of the electrical device can be clearly assigned to the corresponding test signals even if the test signals are carried simultaneously by the electrical device. Thus, appropriate measurement wiring for injecting test signals and capturing measurement signals can be achieved at one point in time, and the wiring can be checked without changing the measurement wiring. Thus, the wiring can be tested quickly. Wiring errors can be avoided because the measurement wiring does not have to be changed in order to check the wiring of all circuits and / or phases.

[0024] According to one embodiment, the first harmonic (i.e., fundamental wave) of the waveform that is asymmetric in the time domain has a frequency that is not equal to the power frequency or the nominal frequency of the electrical device. The first harmonic of the waveform that is asymmetric in the time domain may, for example, have a frequency of 50 to 60 Hz, in particular a frequency of 51 to 55 Hz, for example a frequency of 52.63 Hz. Since the first harmonic of the test signal is not equal to the power frequency of the electrical device, interference from other device components in operation can be avoided. Device components in operation usually generate interference signals at the power frequency (that is, for example, 50 Hz or 60 Hz) and interference signals with higher harmonics. If the fundamental wave and higher harmonics of the test signal deviate from the power frequency and the corresponding higher harmonics, interference signals from other device components in operation can be easily detected and filtered out in the measurement signal. Since the frequency of the fundamental wave of the waveform that is asymmetric in the time domain does not deviate to a large extent from the nominal frequency of the electrical device, the test signal is suitable for transmission through the electrical device (e.g., through a current or voltage converter with a transformer and / or a capacitor).

[0025] In one embodiment, the amplitude of the nth harmonic of the group of higher harmonics has a 1 / n amplitude relative to the amplitude of the fundamental wave of the waveform that is asymmetric in the time domain. 2 Amplitude factor. The above-mentioned second and third harmonics may also have corresponding amplitude factors. Such an amplitude factor can achieve an asymmetric waveform in the time domain. The waveform including a combination of first to third harmonics and higher harmonics (such as fourth and / or fifth and / or sixth harmonics) has, for example, a sawtooth waveform having a steep rising edge and a gentle falling edge, so that the waveform is asymmetric in the time domain. In addition, the test signal generated in this way is generally free of DC components, so that saturation of the current or voltage converter in the electrical device can be avoided.

[0026] According to one embodiment, the allocation is determined by filtering the measurement signal using a bandpass filter, the center frequency of which corresponds to the frequency of the harmonics from a predefined group of higher harmonics. The filtered measurement signal is compared with a threshold value. The threshold value can be set according to the amplitude of the fundamental wave of the waveform that is asymmetric in the time domain. Since the harmonics of the test signal do not usually appear in electrical devices, the threshold value can be set to be relatively low, for example to one percent of the fundamental wave, so that even weak signals can be clearly allocated. The above-mentioned coding of the test signal can relatively easily perform the allocation between the measurement signal and the test signal, i.e. the allocation between the first connection part and the second connection part, by checking whether there is a signal level at the output end of the bandpass filter.

[0027] In another embodiment, the allocation is determined by determining the amplitude of the frequencies corresponding to the frequencies of the harmonics from the predefined group of higher harmonics in the measurement signal. These amplitudes can be determined, for example, by discrete Fourier transformation. The amplitudes determined in this way are each compared with a threshold value. As described in the previous embodiment, the threshold value can be set relatively low, for example to one percent of the fundamental wave, so that even small amplitudes can be clearly detected. The encoding of the above-mentioned test signal can relatively easily perform the allocation between the measurement signal and the test signal, i.e. the allocation between the first connection part and the second connection part, by checking whether there is a signal level at the frequency of the corresponding harmonic.

[0028] The encoding of the test signal by adding a combination of higher harmonics to a waveform that is asymmetrical in the time domain will be described in detail below in the form of three embodiments.

[0029] In one embodiment, the predefined group of high-order harmonics includes the fourth harmonic and the fifth harmonic. As described above, the combinations for various test signals are selected as follows: the first combination includes the fourth harmonic, but does not include the fifth harmonic. The corresponding digital representation of the combination can be represented by 10, wherein the first digit represents the presence (1) or absence (0) of the fourth harmonic, and the second digit represents the presence (1) or absence (0) of the fifth harmonic. The second combination includes the fifth harmonic, but does not include the fourth harmonic. The corresponding digital representation of this combination is 01. The third combination includes neither the fourth harmonic nor the fifth harmonic, and the corresponding digital representation of this combination is 00. Therefore, by a combination of only two harmonics, a sufficient number of test signals can be provided to test an electrical device having three phases.

[0030] In another embodiment, the predefined group of higher harmonics includes the sixth harmonic in addition to the fourth harmonic and the fifth harmonic. Combinations for various test signals can be selected as follows, and for simplicity, only the corresponding digital representations of these combinations are listed. In the digital representation, the first digit represents the presence (1) or absence (0) of the fourth harmonic, the second digit represents the presence (1) or absence (0) of the fifth harmonic, and the third digit represents the presence (1) or absence (0) of the sixth harmonic. The first combination is, for example, 100, the second combination is, for example, 010, and the third combination is, for example, 001. Through these combinations, a sufficient number of test signals can be provided to test an electrical device having three phases, and the Hamming distance between the three combinations is 2, so that these combinations can be reliably detected even in the case of noisy signals or interfered signals.

[0031] In yet another embodiment, the predefined group of higher harmonics includes the fourth harmonic, the fifth harmonic and the sixth harmonic. The combinations for various test signals can be selected as follows, and for simplicity, only the corresponding digital representations of these combinations are listed again. The first combination is, for example, 001, the second combination is, for example, 010, the third combination is, for example, 011, the fourth combination is, for example, 100, the fifth combination is, for example, 101, and the sixth combination is, for example, 110. Through these combinations, a sufficient number of test signals can be provided to test electrical devices having two three-phase or up to eight circuits.

[0032] In another embodiment, the predefined group of higher harmonics also includes an amplitude factor that can be assigned to the higher harmonics. The explicit combination of harmonics assigned to the corresponding test signal can additionally include one or more amplitude factors from the predefined group. For example, a first combination can have a specific higher harmonic (e.g., the fourth harmonic) with a first amplitude factor (e.g., with an amplitude factor of 1 / 16). A second combination in a different combination can have the same higher harmonic (i.e., the fourth harmonic) with a second amplitude factor (e.g., an amplitude factor of 1 / 24). A third combination in a different combination can have the same higher harmonic (i.e., the fourth harmonic) with a third amplitude factor (e.g., an amplitude factor of 1 / 48). It should be noted that the amplitude factors (i.e., the first amplitude factor, the second amplitude factor, and the third amplitude factor in the example) are different. Another combination can be based on, for example, another higher harmonic (e.g., the fifth harmonic). By appropriate encoding, the phases of multiple multi-phase systems (e.g., multiple three-phase systems or multiple circuits) can be distinguished, and therefore their wiring can be tested simultaneously.

[0033] According to another embodiment, the method further comprises determining the polarity of the acquired measurement signal so as to test the wiring of the electrical device according to the determined polarity. In particular, the waveform of the test signal which is asymmetric in the time domain allows for a simple and reliable determination of the polarity. For example, if the wiring of the transformer is incorrect, for example the connections on one side of the transformer are mixed up, the polarity of the measurement signal will be opposite to the polarity of the corresponding test signal. In the case of an asymmetric waveform in the time domain, the opposite polarity can be easily detected. For example, if the test signal has a steep rising edge and a gentle falling edge, the measurement signal with the opposite polarity has a gentle rising edge and a steep falling edge. Therefore, the corresponding error in the wiring can be determined.

[0034] In order to determine the polarity of the acquired measurement signal, for example, for a corresponding measurement signal of the acquired measurement signal, a derivative of the measurement signal can be determined and a comparison signal can be generated by comparing the derivative with a threshold value. For example, for a range of derivatives with a positive slope above the threshold, the comparison signal can have positive values ​​and for a range of derivatives with a negative slope above the threshold, can have negative values ​​of equal absolute value. If an average value of the comparison signal is subsequently determined, for example as a sliding average value or over a period of time of the fundamental of the test signal, the polarity of the measurement signal can be determined based on the average value of the comparison signal.

[0035] Alternatively or additionally, determining the polarity of the measurement signal for acquisition of the corresponding measurement signal may include determining a correlation coefficient, in particular a correlation factor, based on the corresponding measurement signal and the waveform that is asymmetric in the time domain. The polarity of the corresponding measurement signal may be determined based on the correlation factor. In the case of identical polarities, the correlation factor is positive and has, for example, a value close to 1. In the case of opposite polarities, the correlation factor is negative and has, for example, a value close to -1.

[0036] The test device for testing the wiring of an electrical device having multiple circuits according to the present invention includes a test signal generating device, an injection device, an acquisition device and a processing device. The test signal generating device is configured to generate multiple test signals. Each of the multiple test signals has a waveform that is asymmetric in the time domain and a combination of harmonics from a predefined group of higher harmonics. The combination of harmonics of the multiple test signals is different. The injection device is configured to inject multiple test signals into multiple first connections at a first point of the electrical device. Multiple first connections are assigned to multiple circuits of the electrical device. Different test signals in the multiple test signals are injected into each first connection of the multiple first connections. Since the test signal is based on different combinations of harmonics, the test signals injected into the multiple first connections at the first point are different. The acquisition device is configured to acquire multiple measurement signals at a second point of the electrical device, at multiple second connections assigned to multiple circuits. The first point and the second point are different points of the electrical device. For example, multiple circuits may include multiple phases of the electrical device. For example, the first point may be on one side of a transformer of the electrical device, and the second point may be on the other side of the transformer. The acquisition device is configured to determine an assignment between first connections of the first plurality of connections and second connections of the second plurality of connections, respectively, based on the injected test signal and the acquired measurement signal.

[0037] The test signal generating device may include a plurality of single-phase devices, each of which generates only one test signal. The plurality of single-phase devices may be configured so that each of them generates one of the plurality of test signals based on different combinations of harmonics. Alternatively or additionally, the test signal generating device may include a plurality of multiphase devices, such as two three-phase devices, so as to generate six test signals, using which six circuits or phases can be tested simultaneously. In this case, the devices may be connected to achieve the same phase, which simplifies the detection of the superimposed signal. However, when the devices are not coupled, the detection of the individual phases also works.

[0038] The testing device may be specifically designed to carry out the above method or one of its embodiments and thus also include the advantages described above in connection with the method. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] The present invention will be explained in more detail below with reference to embodiments based on the accompanying drawings. In the accompanying drawings, the same reference numerals represent the same elements.

[0040] Figure 1 A testing device for testing a connection of an electrical device having a plurality of phases according to an embodiment is schematically shown.

[0041] Figure 2A method for testing wiring of an electrical device having multiple phases according to one embodiment is shown.

[0042] Figure 3 A plurality of test signals according to an embodiment are schematically shown, which have a combination of asymmetric waveforms and high-order harmonics in the time domain.

[0043] Figure 4 Schematically shows the Figure 3 The time derivatives of multiple test signals.

[0044] Figure 5 A comparison signal formed by comparing a derivative of a test signal with a threshold value is schematically shown.

[0045] Figure 6 Another testing device for testing wiring of an electrical device having a plurality of circuits according to one embodiment is schematically shown. DETAILED DESCRIPTION

[0046] The present invention is explained in more detail based on embodiments with reference to the accompanying drawings. In the accompanying drawings, the same reference numerals represent the same or similar elements. The accompanying drawings are schematic representations of various embodiments of the present invention. The elements shown in the accompanying drawings are not necessarily shown to scale. On the contrary, the various elements shown in the accompanying drawings are presented in a manner that a person skilled in the art can understand their functions and purposes.

[0047] The connections and couplings between the functional units and elements shown in the drawings may be implemented as direct or indirect connections or couplings. The connections or couplings may be implemented in wired or wireless forms.

[0048] Figure 1 A portion of an electrical device 100 is schematically shown, to which a test device 150 for testing the wiring of the electrical device 100 is connected. The electrical device 100 is a multi-phase electrical device. Many power engineering systems use a three-phase current system. Figure 1In the example shown, the electrical device 100 is a three-phase system. For example, the electrical device 100 may include a high voltage device or a part thereof. The electrical device 100 includes an electrical component 110, on which two three-phase connections are arranged. The electrical component 110 may include, for example, a three-phase circuit breaker, a three-phase transformer, a plurality of transformers, a capacitor, a current and voltage converter, or an intermediate converter. On a first side 112, the electrical component 110 has a connection portion of an outer conductor 120 to 122 connected to a three-phase power line 125. On a second side 114, the electrical component 110 has a connection portion of an outer conductor 130 to 132 connected to a second three-phase power line 135. The electrical component 110 may have additional connections, such as additional connections for grounding or for a neutral conductor of a star-connected three-phase system, but for clarity, these additional connections are not shown. Wiring errors may occur when installing the electrical component 110. For example, two outer conductors (e.g., outer conductors 120 and 121) may be connected to the first side 112 of the electrical component 110 in a wrong manner. Therefore, after installing or repairing the electrical device 100 , the wiring may need to be checked.

[0049] To check the wiring, Figure 1 The illustrated testing equipment 150 may be electrically coupled to both sides 112 , 114 of the electrical component 110 .

[0050] The test device 150 comprises a test signal generating device 152 that generates a plurality of test signals. In order to test the three-phase electrical device 100, the test signal generating device 152 generates, for example, three test signals 160 to 162. The test device 150 further comprises an injection device 154, by which the test signals 160 to 162 are injected into a plurality of first connections 142 to 144 at a first point 141 of the electrical device 100 via respective lines 170 to 172. The injection device 154 can, for example, adapt the test signals from the test signal generating device 152 to the nominal range of the electrical component 110 and provide them at the three connections. A set of lines including the three lines 170 to 172 can be connected to the three connections of the injection device 154. At the first point 141, for example at a relatively accessible power distribution upstream of the electrical component 110, the line 170 can be connected to the outer conductor 120 so that the first test signal is injected into the outer conductor 120. Line 171 may be connected to outer conductor 121 to inject a second test signal into outer conductor 121. Line 172 may be connected to outer conductor 122 to inject a third test signal into outer conductor 121. Thus, a corresponding test signal is injected into each phase on first side 112 of component 110.

[0051] The test device 150 further comprises an acquisition device 156 which is connected via respective lines 180 to 182 to the three outer conductors 130 to 132 which are connected at a second point 145 of the electrical device 100 via respective second connections 146 to 148 to the second side 114 of the component 110. The second point 145 may be located on an easily accessible distribution network of the electrical device 100. Thus, a respective measurement signal can be acquired for each phase on the second side 114.

[0052] The test device 150 also includes a processing device 158. The processing device 158 includes, for example, an electronic controller (e.g., a microprocessor controller) that can, for example, execute a computer program. As will be described in detail below, the processing device 158 can be coupled to the test signal generating device 152 and the acquisition device 156 so as to drive them in a coordinated manner. In other examples, the processing device 158 is not connected to the test signal generating device 152, and the test signal generating device 152 generates the test signal independently of any control of the processing device 158. Therefore, it is clear that the test signal generating device 152, the injection device 154, the acquisition device 156 and the processing device 158 do not necessarily have to be formed in the same housing or a unit, but can include a spatially independent unit with its own housing. For example, the test signal generating device 152 can form a unit together with the injection device 154, which can be operated and set independently of any other unit including the acquisition device 156 and the processing device 158. Therefore, even in a large electrical installation where the first point 141 is far from the second point 145 , the test device 150 can be used without requiring correspondingly long lines 170 to 172 or 180 to 182 .

[0053] The following will refer to Figures 2 to 5 The manner in which the test device 150 operates is described in detail. Figure 2 A method 200 is shown having method steps 202 to 214 that can be performed by the test device 150 to test the wiring of the electrical installation 100 . Figure 2 At least some of the processing steps shown in may in particular be performed using the processing device 158 , for example by a computer program executed by the processing device 158 .

[0054] In step 202, a plurality of test signals are generated. Specifically, a separate test signal P is generated for each phase. p (t), the test signal has an asymmetric waveform in the time domain and a combination of harmonics from a predefined group of higher harmonics. Index p represents the test signal P p(t) expected phase. The combination of harmonics of the multiple test signals is different, so the test signals are also different. For example, the test signal can be based on a common signal P(t) having a waveform that is asymmetric in the time domain. The waveform of the common signal P(t) can be approximated by a sawtooth waveform. For this purpose, for example, sinusoidal signals with different amplitudes and frequencies can be used, which approximate the sawtooth waveform by Fourier synthesis. For example, according to the following equation, a signal can be used as the common signal P(t):

[0055]

[0056] Here, A represents the amplitude of the entire signal, k represents the number of harmonics used, and f g Indicates the fundamental frequency of a signal. The individual sine functions are weighted so that the overall approximation is a sawtooth waveform.

[0057] For example, A=1, k=3 and f g =52.63 Hz signal. In other examples, A may also be selected such that the root mean square (RMS) of the signal is approximately 1. For example, A ≈ 0.962 may be selected.

[0058] Test signal P p Each of the test signals P1(t) also includes higher harmonics. For example, the test signal P1(t) for the first phase also includes the fourth harmonic, the test signal P2(t) for the second phase also includes the fifth harmonic, and the test signal P3(t) for the third phase includes neither the fourth nor the fifth harmonic. In general, the test signals for the three-phase system are obtained according to the following equations and tables:

[0059]

[0060]

[0061] In this case, in principle the binary representation of the phase number p is used and the amplitudes of the fourth and fifth harmonics are adapted or coded accordingly:

[0062]

[0063] The test signal has a waveform that is asymmetric in the time domain, so that polarity can be distinguished, as described later. The fundamental frequency of the test signal can be selected to produce a time-varying signal that can be transmitted via the current or voltage converter of the device 100 (e.g., via a transformer and / or capacitor). In addition, the test signal has substantially no DC component, so saturation of the current or voltage converter can be avoided. The fundamental frequency of the test signal can be selected so that they are within the favorable transmission range of the current or voltage converter. For example, the fundamental frequency can be close to the nominal frequency of the converter, that is, close to the power supply frequency. On the other hand, the fundamental frequency of the test signal should not match the fundamental frequency or harmonics of the power supply frequency used or other frequencies appearing in the power engineering system as much as possible, so as to achieve optimal separation between the test signal and the interference. For example, the above-mentioned fundamental frequency of 52.63Hz meets these requirements of the device with a nominal frequency of 50Hz or 60Hz, as shown in the following table.

[0064] Baseband Second Harmonic Third harmonic Fourth Harmonic Fifth Harmonic Test signal 52,63Hz 105,26 157,89Hz 210,52Hz 263,15Hz 50Hz power frequency 50,00Hz 100,00Hz 150,00Hz 200,00Hz 250,00Hz 60Hz power frequency 60,00Hz 120,00Hz 180,00Hz 240,00Hz 300,00Hz

[0065] However, other frequencies greater than 50 Hz and less than 60 Hz may also be used.

[0066] Due to the relatively small amplitude of the fourth and / or fifth harmonics, the asymmetric waveform changes only to a negligible extent. Lower harmonics (e.g., second and third harmonics) are less suitable for phase encoding because they significantly affect the asymmetry of the signal in the time domain and may therefore complicate detection, in particular the detection of polarity. Higher harmonics (especially seventh harmonics or higher) are also less suitable because current and voltage converters generally attenuate high frequencies to a greater extent, which may impair transmission and detection.

[0067] Figure 3 The waveforms of the test signals of phases 1, 2 and 3 and the sum of the test signals of phases 1, 2 and 3 divided by three are shown. Figure 3 It can be seen that the asymmetrical waveforms in the time domain are clearly identifiable for all test signals and also for the sum signal, ie, these signals basically have a relatively steep rising edge and a relatively gentle falling edge compared to the rising edge.

[0068] In step 204, the generated test signals 160 to 162 are injected into the outer conductors 120 to 122 at the first point 141 via the first connections 142 to 144. The test signals 160 to 162 can be injected simultaneously. The test signals injected in this way pass through the electrical component 110, which includes, for example, one or more transformers or capacitors or other power engineering equipment (e.g., circuit breakers). On the second side 114, due to the injected test signals, the electrical component 110 outputs output signals on three outer conductors 130 to 132. When the electrical component 110 is properly connected, for example, it is expected that the test signal injected into the outer conductor 120 will be substantially output to the outer conductor 130, and, for example, in the case of a transformer, the voltage will change. However, the expected waveform will be substantially unchanged. Similarly, when the electrical component 110 is properly connected, for example, it is expected that the signal injected into the outer conductor 121 will be substantially output to the outer conductor 131, and the signal injected into the outer conductor 122 will be substantially output to the outer conductor 132.

[0069] In the case of improper wiring, in which the outer conductors 121 and 122 are connected in a wrong manner, a signal injected into the outer conductor 121 is reversely output to the outer conductor 132 , and a signal injected into the outer conductor 122 is reversely output to the outer conductor 131 .

[0070] In step 206, a plurality of measurement signals are acquired at the second point 145. The plurality of measurement signals may be acquired simultaneously or sequentially. In the acquisition device 156, the acquired measurement signals may be optionally preprocessed (e.g., by filtering). For example, the measurement signals may be preprocessed using analog and / or digital filters, so as to suppress interference caused by resistance, inductance, or capacitance coupling, such as a resistance voltage drop caused by current flowing through a common return conductor. Such interference may affect the outer conductors 120 to 122 and 130 to 132, for example, from an adjacent system in operation. In addition, for example, a notch filter for a power supply frequency (e.g., 50 Hz, 60 Hz, or 16.7 Hz, or a combination thereof) may be used to filter out interference from an adjacent system. For higher harmonics of the power supply frequency, an additional notch filter may be used to filter the measurement signal. Alternatively or additionally, a low-pass filter may be applied to the measurement signal to remove higher harmonics and other interference. In this case, the cutoff frequency may be higher than the frequency of the highest harmonic used in the test signal. Finally, a high-pass filter can be applied to the measurement signal to remove low-frequency interference, where the cut-off frequency can be lower than the fundamental frequency of the test signal. Preprocessing of the measurement signal can improve the reliability of the wiring check and the sensitivity to interference from adjacent systems in operation.

[0071] In step 208, the assignment between the test signal and the measurement signal is determined. In other words, in step 208, the test signal is identified in the measurement signal. The individual test signals can be identified in the measurement signal by means of a narrowband filter or a discrete Fourier transform of the fourth and fifth harmonics. If the fundamental frequency f is appropriately selected as described above, g , for example 52.63 Hz, there is no overlap with the power supply frequency or higher harmonics of the power supply frequency.

[0072] By comparing the amplitude of the fundamental wave of the corresponding measurement signal with the amplitude of the higher harmonics (for example, with the amplitude of the fourth harmonic and the fifth harmonic), the waveforms P1(t), P2(t) and P3(t) can be distinguished. Since the relevant harmonics of the test signal do not appear in the power engineering device 100 during normal operation, a relatively low threshold value (for example, 1% or 4% of the fundamental wave) can be used for comparison. Therefore, even weak signals can be clearly assigned. The following table shows an example of detecting a test signal using a threshold value of 1%.

[0073] <![CDATA[H4]]> <![CDATA[H5]]> Detection signal <![CDATA[>1% H1 (existence)]]> <![CDATA[<1% H1 (not present)]]> <![CDATA[Phase 1 P1(t)]]> <![CDATA[<1% H1 (not present)]]> <![CDATA[>1% H1 (existence)]]> <![CDATA[Phase 2P2(t)]]> <![CDATA[<1% H1 (absent)]]> <![CDATA[<1% H1 (absent)]]> <![CDATA[Phase 3P3(t)]]> <![CDATA[>1% H1 (existence)]]> <![CDATA[>1% H1 (existence)]]> <![CDATA[Sum signal P S (t)]]>

[0074] For example, when the amplitude of the fourth harmonic is greater than 1% of the amplitude of the fundamental wave and the amplitude of the fifth harmonic is less than 1% of the amplitude of the fundamental wave, the test signal P1(t) is detected. When the amplitude of the fourth harmonic is less than 1% of the amplitude of the fundamental wave and the amplitude of the fifth harmonic is greater than 1% of the amplitude of the fundamental wave, the test signal P2(t) is detected. When the amplitude of the fourth harmonic is less than 1% of the amplitude of the fundamental wave and the amplitude of the fifth harmonic is less than 1% of the amplitude of the fundamental wave, the test signal P3(t) is detected. The sum signal of the three test signals P1(t), P2(t) and P3(t) contains both the fourth and fifth harmonics, so that when the amplitude of the fourth harmonic is greater than 1% of the amplitude of the fundamental wave and the amplitude of the fifth harmonic is greater than 1% of the amplitude of the fundamental wave, the sum signal P3(t) is detected. S (t).

[0075] In the above examples, different combinations of the fourth harmonic and the fifth harmonic are used to generate the test signal. For example, in order to achieve greater robustness, other harmonics can be used. For example, the following table shows the use of the fourth, fifth and sixth harmonics with a Hamming distance of 2 and even parity for encoding.

[0076]

[0077] In another example, not only the presence or absence of harmonics can be used for encoding, but also the amplitude. For example, only the fourth harmonic can be used, but with different amplitudes for different test signals:

[0078]

[0079] The thresholds for detecting different amplitudes of the fourth harmonic need to be adapted accordingly. In the above examples, relatively small amplitudes were used for the fourth harmonic. The amplitudes of the harmonics (e.g. the fourth harmonic) can also be chosen to be larger, that is, for example, larger than 1 / 16. It should be noted here that the asymmetry in the time domain remains significant enough. Thus, by suitable encoding, not only individual phases can be distinguished, but also different phase combinations.

[0080] Based on the assignment between the test signal and the measurement signal determined in step 208, it can be easily determined whether the expected test signal is acquired at the corresponding outer conductor 130 to 132. If the assignment is not as expected, incorrect wiring can be determined.

[0081] In step 210, the polarity of the measurement signal acquired at the second point 145 is determined. The polarity is detected based on an asymmetric waveform in the time domain. For the measurement signal, which may be preprocessed as described above, a corresponding derivative is formed in the time domain. For example, the corresponding derivative may be determined by time-discrete numerical differentiation using the difference between the signal levels acquired in the time series, or implicitly by a suitably adapted filter structure (e.g. by using an analog operational amplifier as a differentiating circuit or a digital filter structure). Figure 4 The resulting measured signal M with phases p=1, 2 and 3 and the sum signal is shown. p The derivative of (t) dM p (t) / dt. For example, a corresponding auxiliary signal Q can be formed for each of the derivatives according to the following rule p (t):

[0082]

[0083] In this case, δ is a threshold used to suppress noise and other undesirable interference. Figure 5 By way of example, an auxiliary signal Q1(t) is shown for a test signal for phase 1. Based on the auxiliary signal Q p (t), calculate the corresponding average value within a certain period of time This average value can be calculated, for example, over discrete times (e.g. the duration T of a period of the fundamental of the test signal) or continuously via a low-pass filter. If this average value exceeds a defined positive threshold, a positive polarity is indicated (short rising edge and long falling edge). If the average value is below a defined negative threshold, a negative polarity is indicated (long rising edge and short falling edge). Thus, for each phase, a change in polarity that may occur, for example, due to incorrect wiring, can be easily determined.

[0084] In step 212 , the phase assignments and polarities determined in this way can be output, for example, on a display device of the user.

[0085] For example, a first test signal for phase 1 may be output on line 170, a second test signal for phase 2 may be output on line 171, and a third test signal for phase 3 may be output on line 172. If the electrical device 100 is wired correctly, the test device 150 indicates that the first test signal has been detected for line 180, the second test signal has been detected for line 181, and the third test signal has been detected for line 182. The test device 150 may also indicate that the test signals are each output and detected with positive polarity. Wiring errors, such as outer conductor confusion or incorrect wiring resulting in polarity reversal (e.g., at a transformer), can be identified by an operator based on the output.

[0086] Alternatively or additionally, in step 214 the detected phase assignment can be compared with a target assignment and / or the detected polarity can be compared with a target polarity, and if a deviation between the detected state and the target state has been determined, a warning can be automatically output.

[0087] The electrical device 100 may also have additional connections (e.g., additional three-phase connections), the wiring of which may be checked in the same manner as described above. For example, these connections may involve auxiliary circuits or control circuits, which may also be tested using the above method depending on the type of circuit.

[0088] If multiple circuits or phases are tested, they can use a common neutral conductor (N for L1, L2 and L3) or completely independent circuits (L1+N1, L2+N2, L3+N3). In this case, various wiring errors are also conceivable and can be detected using the method. In the event of a wiring error, multiple ground connections may occur. For example, a current clamp can be used to measure the current through the ground connection as one of several measurement signals. The described method can use an assignment to detect which test signals can be detected in the ground connection, so that desired and undesired ground connections can be identified.

[0089] Figure 6 Schematically, a part of a further electrical device 600 is shown, to which a test device 650 for testing the wiring of the electrical device 600 is connected. The electrical device 600 comprises a plurality of circuits which can be assigned to one or more phases. Figure 6In the example shown, the electrical device 600 includes two circuits 601 and 602 that are substantially separated from each other. However, the circuits 601 and 602 can also be assigned to one phase of a multi-phase system, that is, the same phase in a multi-phase system, or to a plurality of different phases in a multi-phase system, or can be connected to each other through their neutral conductors. In other examples, the electrical device 600 can include more than two circuits. For example, the electrical device 600 can include a high-voltage device or a portion thereof. Each of the circuits 601 and 602 can include one or more electrical components, such as current or voltage converters 610, 630, secondary wiring 612, 632, matching converters, test plugs 614-619, 634-639, test switches 611, 631, counters and / or protection devices (e.g., relays 613, 633).

[0090] After installing or repairing an electrical device 600, it may be necessary to check the wiring. To check the wiring, Figure 6 The illustrated testing equipment 650 may be electrically coupled to both circuits 601 and 602 .

[0091] The test device 650 includes a plurality of test signal generating devices that generate a plurality of test signals. Figure 6 Two test signal generating devices 652 and 654 are shown for generating two test signals. Multiple test signals can also be generated by a common test signal generating device. Each of the test signal generating devices 652 and 654 is assigned a corresponding injection device (not shown), by which the test signal is injected into the electrical device 600 via a corresponding line at a corresponding injection point. The injection device can, for example, adapt the test signal from the test signal generating device 652, 654 to the required nominal range at the corresponding injection point. Figure 6 In the example shown, the test signal from the test signal generating device 652 can be injected, for example, at the test plugs 616, 617 on the secondary side of the converter 610 (e.g., a current converter or a voltage converter). Alternatively, the test signal from the test signal generating device 652 can also be injected at the test plugs 614, 615 on the primary side of the converter 610, as shown in dashed lines. The injection on the primary side can additionally check the polarity and wiring of the converter 610. In the case of injection on the primary side, a correspondingly higher current may be required for the current converter, and a correspondingly higher voltage may be required for the voltage converter. Similarly, the test signal from the test signal generating device 654 can be injected, for example, at the test plugs 636, 637 on the secondary side of the converter 630. Alternatively, the test signal from the test signal generating device 654 can also be injected at the test plugs 634, 635 on the primary side of the converter 630, as shown in dashed lines, to additionally check the polarity and wiring of the converter 630.

[0092] The test device 650 also includes a plurality of acquisition devices for acquiring measurement signals. Figure 6 In the example of , the test device 650 includes two acquisition devices 651 and 653, which are respectively coupled to the first circuit 601 and the second circuit 602 via corresponding lines. For example, the acquisition device 651 can be coupled to the test plugs 618 and 619 at the test switch 611 to acquire the voltage at the test switch 611 as a measurement signal. As an alternative, as shown by the dotted line, the acquisition device 651 can be coupled to the test plugs 616 and 617 to acquire the voltage on the secondary side of the converter 610, or coupled to the current clamp 620 to acquire the current through the wiring 612. In the same way, the acquisition device 653 can be coupled to the second circuit 602. As shown in FIG. Figure 6 As shown, the acquisition device 653 can be coupled to the test plugs 638, 639 at the test switch 631 to acquire the voltage at the test switch 631 as a measurement signal. Alternatively, the acquisition device 653 can be coupled to the test plugs 636, 637 to acquire the voltage on the secondary side of the converter 630, or coupled to the current clamp 640 to acquire the current through the wiring 632.

[0093] The testing device 650 also includes a processing device 655, which is Figure 6 653. In other examples, the processing device 655 may also be designed to be integrated with the test signal generating device 652, 654 or one of the detection devices 651, 653. The processing device 655 includes, for example, an electronic controller (e.g., a microprocessor controller), which can, for example, execute a computer program. As will be described in detail below, the processing device 655 may be coupled to the test signal generating device 652, 654 and the acquisition device 651, 653 to drive them in a coordinated manner. In other examples, the processing device is not connected to the test signal generating device 652, 654, and the test signal generating device 652, 654 generates a test signal independently of any control of the processing device 655. The test signal generating device 652, 654, the acquisition device 651, 653 and the processing device 655 do not have to be formed in the same housing or a unit, but may include a spatially independent unit with its own housing. For example, the test signal generating device 652, 654 can each form a unit that can be independently operated and set. The further units may comprise acquisition devices 651, 653 and processing devices 655 and are coupled to the test signal generating devices 652, 654. Thus, even in large electrical installations where the injection points are far from the measuring points, the test device 650 can be used without correspondingly long lines between the test signal generating devices 652, 654 and the respective injection points.

[0094] As mentioned above Figures 1 to 5 As described in detail, the way in which the test device 650 works substantially corresponds to the way in which the test device 150 works. As described above, Figure 2 The method 200 shown in FIG. 6 may be performed by a test device 650 to test wiring of an electrical device 600 .

[0095] In step 202, two test signals are generated in this case. A separate test signal P is generated for each circuit 601, 602. p (t), the test signal has an asymmetric waveform in the time domain and a combination of harmonics from a predefined group of higher harmonics. Index p represents the test signal P p (t) is targeted at the circuit, for example, for circuit 601, p=1, for circuit 602, p=2. The combination of harmonics of multiple test signals is different, so the test signals are also different. For example, the test signal can be based on a common signal P(t), which has an asymmetric waveform in the time domain. The waveform of the common signal P(t) can be approximated to a sawtooth waveform. To this end, for example, sinusoidal signals with different amplitudes and frequencies can be used, which approximate the sawtooth waveform by Fourier synthesis. For example, according to the following equation, a signal can be used as the common signal P(t):

[0096]

[0097] Here, A represents the amplitude of the entire signal, k represents the number of harmonics used, and f g Indicates the fundamental frequency of a signal. The individual sine functions are weighted so that the overall approximation is a sawtooth waveform.

[0098] For example, A=1, k=3 and f g =52.63 Hz signal. In other examples, A may also be selected such that the root mean square (RMS) of the signal is approximately 1.

[0099] Test signal P p Each of the test signals 601 and 602 also includes higher harmonics. For example, the test signal P1(t) also includes the fourth harmonic and the test signal P2(t) also includes the fifth harmonic. In general, the test signals for the two circuits 601 and 602 are obtained according to the following equations and tables:

[0100]

[0101]

[0102] In this case, in principle the binary representation of the circuit number p is used and the amplitudes of the fourth and fifth harmonics are adapted or coded accordingly:

[0103]

[0104] If additional circuits are to be included in the check, the higher harmonics can be adapted accordingly using the corresponding binary representation. In the case of more than four circuits, additional harmonics, such as H6(t) and / or H7(t), can be used. The test signal has a waveform that is asymmetrical in the time domain, so that the polarity can be distinguished, as described later. The fundamental frequency of the test signal can be selected to produce a time-varying signal that can be transmitted via a current or voltage converter of the device 600 (e.g., via a transformer and / or a capacitor). Details of this aspect are described above in conjunction with Figures 1 to 5 discussed and applied in the same way to Figure 6 , where, for example, phase 1 corresponds to circuit 601 and phase 2 corresponds to circuit 602.

[0105] In step 204, as described above, the generated test signal is injected into the circuit 601, 602. The test signal can be injected simultaneously. The test signal injected in this way passes through an electrical component, which includes, for example, one or more transformers or capacitors or other power engineering equipment (e.g., a circuit breaker or a test switch). Based on the injected test signal, an output signal is generated at the above-mentioned measurement point. When the electrical component is correctly connected, for example, it is expected that the test signal injected into the circuit 601 will be substantially output at the test plug 618, 619 of the test switch 611, and in the case of injection at the test plug 614, 615, the voltage will change. However, the expected waveform will be substantially unchanged. Similarly, when the electrical component is correctly connected, for example, it is expected that the signal injected into the circuit 602 will be substantially output at the test plug 638, 639 of the test switch 631.

[0106] In the case of improper wiring, in which, for example, the lines of the first circuit 601 and the lines of the second circuit 602 are connected in an incorrect manner, conversely, a signal injected into the first circuit 601 will exist in the second circuit 601, and / or a signal injected into the second circuit 604 will exist in the first circuit 601.

[0107] In step 206, a plurality of measurement signals are acquired at the test switches 611 and 631, for example as described above. The plurality of measurement signals may be acquired simultaneously or sequentially. In the acquisition devices 651, 653, the acquired measurement signals may optionally be pre-processed (for example by filtering).

[0108] In step 208, the assignment between the test signal and the measurement signal is determined. In other words, the test signal is identified in the measurement signal in step 208. The individual test signals can be identified in the measurement signal by means of a narrowband filter or a discrete Fourier transform of the fourth and fifth harmonics.

[0109] By comparing the amplitude of the fundamental wave of the corresponding measurement signal with the amplitude of the higher harmonics (e.g. with the amplitude of the fourth harmonic and the fifth harmonic), the waveforms P1(t) and P2(t) can be distinguished. Since the relevant harmonics of the test signal do not appear in the power engineering device 600 during normal operation, a relatively low threshold value (e.g. 1% or 4% of the fundamental wave) can be used for the comparison. Thus, even weak signals can be clearly assigned.

[0110] Based on the assignment between the test signal and the measurement signal determined in step 208, it can be easily determined whether the expected test signal is acquired at the corresponding test plugs 618, 619, 638 and 639. If the assignment is not as expected, incorrect wiring can be determined.

[0111] In step 210, the polarity of the measurement signals acquired at the test plugs 618, 619, 638 and 639 is determined. As described above with reference to the electrical device 150, the polarity is detected based on a waveform that is asymmetrical in the time domain.

[0112] In step 212 , the circuit assignment and polarity determined in this way can be output, for example, on a display device of the user.

[0113] Alternatively or additionally, the detected circuit allocation can be compared with a target allocation and / or the detected polarity can be compared with a target polarity in step 214. If a deviation between the detected state and the target state has been determined, a warning can be automatically output.

[0114] In summary, the different test signals described above, which have different combinations of asymmetrical waveforms and higher harmonics in the time domain, enable a quick and reliable check of the wiring of an electrical device. Since the test signal has no direct current, no saturation effects occur, for example, in transformers or capacitors, and the test signal can be transmitted through the converter without any problems. In addition, the test signal allows polarity errors to be detected and the individual phases to be clearly distinguished. The threshold for identifying higher harmonics here can be selected to be relative to the fundamental wave and therefore independent of the absolute amplitude of the signal. Therefore, the method is also applicable to partial signals that may occur, for example, due to current distribution or in the case of an undesirable ground connection. A larger threshold value, for example 4% instead of 1%, can also be used. Therefore, the method can also tolerate frequency-dependent amplitude changes, such as the frequency response in the case of a converter.

[0115] For the individual test signals and harmonics of the test signals, the phase position does not need to be evaluated. Therefore, the method tolerates relatively small phase shifts, such as the frequency-dependent phase response in the case of a converter. Furthermore, no synchronization is required between the test signal generating device and the acquisition device.

[0116] The different test signals and their linear combinations have the same asymmetry properties in the time domain and can therefore be reliably assigned to a polarity.

[0117] Using additional harmonics and / or additional different amplitudes can distinguish more than three phases. This can, for example, distinguish additional phases simultaneously, such as in a 2x 3 phase system, or use a coding with a Hamming distance greater than 1 to increase the robustness against amplitude errors.

Claims

1. A method for testing the wiring of an electrical device having a plurality of circuits, comprising: - generating (202) a plurality of test signals (160-162), wherein each of the plurality of test signals (160-162) has a waveform that is asymmetric in the time domain and a combination of harmonics from a predefined group of higher harmonics, wherein the combination of harmonics of the plurality of test signals (160-162) is different, - injecting (204) the plurality of test signals (160-162) into a plurality of first connections (142-144) assigned to the plurality of circuits at a first point (141) of the electrical device (100), wherein a different test signal of the plurality of test signals (160-162) is injected into each first connection of the plurality of first connections (142-144), - acquiring (206) a plurality of measurement signals at a second point (145) of the electrical device (100), at a plurality of second connections (146-148) assigned to the plurality of electrical circuits, and - determining (208) an allocation between first connections of the plurality of first connections (142-144) and second connections of the plurality of second connections (146-148), respectively, based on the injected test signals (160-162) and the acquired measurement signals.

2. The method of claim 1, wherein: The plurality of test signals (160-162) are simultaneously injected into the plurality of first connection portions (142-144).

3. The method according to claim 1 or 2, wherein: The predefined group of higher harmonics includes the fourth harmonic and the fifth harmonic.

4. The method according to any one of the preceding claims, wherein: The waveform which is asymmetric in the time domain includes at least a second harmonic and / or a third harmonic in addition to the fundamental wave.

5. The method according to any one of the preceding claims, wherein: The fundamental wave of the waveform which is asymmetrical in the time domain has a frequency which is not equal to the power supply frequency of the electrical device.

6. The method according to any one of the preceding claims, wherein: The fundamental wave of the waveform which is asymmetrical in the time domain has a frequency of 50 to 60 Hz, optionally a frequency of 51 to 55 Hz, and again optionally a frequency of 52.63 Hz.

7. The method according to any one of the preceding claims, wherein: The amplitude of the nth harmonic of the group of higher harmonics has a 1 / nth amplitude relative to the amplitude of the fundamental wave of the asymmetric waveform in the time domain. 2 The amplitude factor.

8. The method according to any one of the preceding claims, wherein: Determining (208) the allocation includes: - filtering the measurement signal using a bandpass filter, the center frequency of which corresponds to the frequency of a harmonic from a predefined group of higher harmonics, and - Compare the filtered measurement signal to a threshold value.

9. The method according to any one of the preceding claims, wherein: Determining (208) the allocation includes: - determining the amplitude of a frequency in the measurement signal, the frequency in the measurement signal corresponding to a frequency of a harmonic from a predefined group of higher harmonics, and - The determined amplitude is compared to a threshold value.

10. The method according to claim 8 or 9, wherein: The threshold is set based on the amplitude of the fundamental wave of the waveform that is asymmetrical in the time domain.

11. The method according to any one of the preceding claims, wherein: A first one of the different combinations has a fourth harmonic and no fifth harmonic, a second one of the different combinations has a fifth harmonic and no fourth harmonic, and a third one of the different combinations has neither a fourth harmonic nor a fifth harmonic.

12. The method according to any one of the preceding claims, wherein: A first combination among the different combinations has a fourth harmonic, no fifth harmonic, and no sixth harmonic, a second combination among the different combinations has a fifth harmonic, no fourth harmonic, and no sixth harmonic, and a third combination among the different combinations has a sixth harmonic, no fourth harmonic, and no fifth harmonic.

13. The method according to any one of the preceding claims, in, a first one of the different combinations has only certain higher harmonics with a first amplitude factor, a second one of the different combinations has only certain higher harmonics with a second amplitude factor, and a third one of the different combinations has only certain higher harmonics with a third amplitude factor, The first amplitude factor, the second amplitude factor and the third amplitude factor are different.

14. The method of any one of the preceding claims, further comprising: - outputting to a user an allocation between a first connection of the plurality of first connections and a second connection of the plurality of second connections, respectively, and / or - comparing the assignments between first connections of the first plurality of connections and second connections of the second plurality of connections, respectively, with predefined assignments between first connections of the first plurality of connections and second connections of the second plurality of connections, respectively.

15. The method of any preceding claim, further comprising: - determining (210) the polarity of the acquired measurement signal in order to test the wiring of the electrical device according to the determined polarity.

16. The method of claim 15, wherein: Determining (210) the polarity of a corresponding one of the acquired measurement signals comprises: - determining the derivative of the corresponding measurement signal, - generating a comparison signal by comparing said derivative with a threshold value, - determining a mean value of said comparison signal, and - determining the polarity of the corresponding measurement signal based on the average value of the comparison signal.

17. The method of claim 15, wherein: Determining (210) the polarity of a corresponding one of the acquired measurement signals comprises: - determining a correlation factor based on the corresponding measurement signal and the asymmetric waveform in the time domain, and - determining the polarity of the corresponding measurement signal based on the correlation factor.

18. A test device for testing the wiring of an electrical device having a plurality of circuits, comprising: - a test signal generating device (152) configured to generate a plurality of test signals (160-162), wherein each of the plurality of test signals (160-162) has a waveform that is asymmetric in the time domain and a combination of harmonics from a predefined group of higher harmonics, wherein the combinations of the harmonics of the plurality of test signals (160-162) are different, - an injection device (154) configured to inject the plurality of test signals (160-162) into a plurality of first connections (142-144) assigned to the plurality of circuits at a first point (141) of the electrical device (100), wherein a different test signal of the plurality of test signals (160-162) is injected into each first connection of the plurality of first connections (142-144), - an acquisition device (156) configured to acquire a plurality of measurement signals at a second point (145) of the electrical device (100), at a plurality of second connections (146-148) assigned to the plurality of circuits, and A processing device (158) configured to determine an allocation between first connections of the plurality of first connections (142-144) and second connections of the plurality of second connections (146-148), respectively, based on the injected test signals (160-162) and the acquired measurement signals.

19. The testing device of claim 18, wherein: The testing device (150) is configured to perform the method according to any one of claims 1-17.

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