Method and test device for generating a physical test quantity by capturing a freehand drawn signal waveform

Abstract

Method for generating a physical test quantity (R(t), I(t)) by capturing a freehand drawn signal waveform (S1) for functional testing of an electrical protection and monitoring device (20), comprising the method steps: Freehand drawing of a signal waveform (S1) in an x / y coordinate system (7) on a touch-sensitive screen (6) and mapping of the drawn signal waveform (S1) using a computing unit (8) on the touch-sensitive screen (6), Validating the depicted signal curve (S2) using the computing unit (8) to determine whether the depicted signal curve (S2) represents a unique function curve y=f(x) in the coordinate system (7), Post-processing of the validated signal waveform (S3) by digital signal processing methods using the computing unit (8), Scaling a value range and a time axis of the post-processed signal waveform (S4) using the processing unit (8), Generating a time course of the physical test quantity (R(t), I(t)) according to the scaled signal course (S R (t), S I (t)) by means of an electronic test quantity generator (10), displaying the instantaneous value of the physical test quantity (R(t), I(t)) on the touch-sensitive screen (6) when playing back the scaled signal waveform ((S R (t), S r (t)), wherein the instantaneous value of the physical test quantity (R(t), I(t)) displayed in real time is synchronously shown on the scaled signal waveform ((S R (t), S I (t)) travels with it.

Description

[0001] The invention relates to a method and a test device for generating a physical test parameter by capturing a freehand drawn signal waveform for functional testing of an electrical protection and monitoring device.

[0002] According to applicable standards and regulations, particularly the DIN VDE 0100 / IEC 60364 series, protective and monitoring devices, as safety-relevant components of an earthed or unearthed power supply system, must undergo cyclical testing to verify their proper functioning. For standardized, compliant protective devices such as overcurrent protection devices and residual current devices (RCDs), as described in DIN VDE 0100-410 / IEC 60364-4-41, the testing procedure and the test parameters to be set are clearly defined in DIN VDE 0100-600 / IEC 60364-6 and DIN VDE 0105-100.

[0003] Particularly in industrial settings, the response characteristics of various protective and monitoring devices are selected on an application-specific basis, as this is the only way to achieve an optimal balance between protection against electric shock and fire, as well as maximum operational reliability for an industrial plant. Even in specialized and novel applications that are not (yet) subject to any standard, application-specific protection concepts must be developed and implemented. As a result, these systems incorporate, among other things, modular residual current devices (MRCDs), residual current monitoring devices (RCMs), and insulation monitoring devices (IMDs) with freely configurable response parameters and measurement profiles.

[0004] If the protection regarding response level and trigger time is regulated application-specifically, then the testing also leaves the standardized terrain and requires possibilities to carry out the tests adapted to the set parameters and profiles of the respective protection or monitoring device.

[0005] A test in this context encompasses more than simply ramping up to a response value and observing at which test values ​​the protective device triggers, or simply inserting a constant fault resistance or fault current as the test variable. Rather, testing in such cases involves the temporal signal waveform of a physical test variable, which can assume any (signal) shape. Elementary signals include, among others, sinusoidal, rectangular, and pulsed waveforms, as well as exponential waveforms of test variables such as the time course of current or the time change of a resistance value.

[0006] The question here is not only whether a protective device responds as required, but also whether various test parameter profiles can lead to misinterpretations by the protective or monitoring device and thus to false triggers, which should be avoided in the interest of smooth plant operation.

[0007] Installation test equipment is known from the state of the art that has the capability of performing ramp tests, meaning the test parameter (current, resistance value) is increased until the response values ​​of IMDs, RCDs, etc., are reached and trigger them. As an example, a device from Gossen Metrawatt GmbH can be mentioned, which automatically (linearly) increases the resistance value as the test parameter within a predefined range to test an IMD (see operating instructions: https: / / www.gmc-instruments.de / media / doku / ix / profitest-master-iq / profitest-master-seculifeip-iq-ba_d.pdf, page 59ff).

[0008] Furthermore, patent application DE 10 2009 022 227 A1 describes a method and a system for defining the signal or spectral profile of a signal to be generated in a signal generator on a touch-sensitive screen. The signal or spectral profile is entered by touching the touch-sensitive screen, followed by processing steps for verification and scaling.

[0009] Patent application US 2018 / 0328991A1 discloses a battery-powered relay tester for testing a protective relay, the tester being designed to offer greater mobility and flexibility due to its battery operation. A pulse train P with variable amplitude and variable pause times is generated as the test signal S.

[0010] The patent application DE 10 2014 203 355 A1 describes a measuring method and a measuring device with fingertip zoom, whereby a section-by-section magnified display of a measurement signal can be achieved by touching a touch-sensitive screen.

[0011] A disadvantage of the test devices available on the market is that, beyond the known sinusoidal, rectangular, pulsed, or exponential time profiles of the test quantity, more sophisticated, especially freely definable, arbitrary test quantity profiles cannot be generated or can only be generated with considerable effort.

[0012] The present invention is therefore based on the objective of providing the operator of the electrical system with a possibility to implement any application-specific time profiles of the test variables on site in an uncomplicated and user-friendly manner during a functional test of the electrical protection and monitoring device.

[0013] This task is solved using a method that comprises the following steps: Freehand drawing of a signal waveform in an x / y coordinate system on a touchscreen and mapping of the drawn signal waveform on the touchscreen using a processing unit; validation of the mapped signal waveform using the processing unit to determine whether the mapped signal waveform represents a unique function y=f(x) in the coordinate system; post-processing of the validated signal waveform using digital signal processing methods with the processing unit; scaling of the value range and time axis of the post-processed signal waveform using the processing unit; and generation of a time series of the physical test quantity corresponding to the scaled signal waveform using an electronic test quantity generator.and displaying the current value of the test quantity on the touch-sensitive screen while playing back the scaled signal waveform, whereby the instantaneous value of the physical test quantity displayed in real time moves synchronously along the scaled signal waveform.

[0014] The basic idea of ​​the present invention is to offer the user of an electrical protection and monitoring device a possibility to specify any application-specific time course of the physical test quantity (time function of a current or resistance) by drawing a time signal curve freehand in conjunction with a digital signal processing according to the invention, to actually generate this physical test quantity in an electronic test quantity generator and to apply it to the electrical protection and monitoring device for functional testing.

[0015] First, the user draws any desired signal waveform freehand on a touch-sensitive screen (touch display) using a stylus or finger. The drawn signal waveform is then immediately mapped as a line in the x / y coordinate system by a processing unit that recognizes the pressed display pixels, with the x-axis representing the elapsed time and the y-axis representing the value (magnitude) of the measured quantity.

[0016] In the next step, the displayed signal waveform is validated. This involves using an algorithm to check whether the signal waveform represents a unique function y=f(x) and is therefore a valid signal waveform. Invalid function waveforms, such as those that migrate backwards along the time axis, are detected by the processing unit and corrected to a valid function if possible. If no correction is possible, the input signal waveform is discarded.

[0017] The validated signal waveform is then further processed using digital signal processing techniques. In particular, filter algorithms are applied to reduce noise and eliminate outliers.

[0018] The value range and the time axis of the post-processed signal curve are then scaled in order to generate a physical test parameter curve adapted to the protection and monitoring device to be checked and corresponding to the desired measurement task.

[0019] Finally, the physical test parameter is generated in an electronic test parameter generator according to the scaled signal curve and applied to the protection and monitoring device to be tested.

[0020] Simultaneously, the current value of the physical test quantity is displayed in real time on the touch-sensitive screen.

[0021] In a further advantageous embodiment, a standard signal waveform is generated during validation.

[0022] The validity check can be extended by an algorithm which develops a standard signal waveform (sine, square, trapezoid, ...) from a freely drawn signal waveform using approximation methods.

[0023] The problem underlying the invention is further solved by a test device comprising a touch-sensitive screen for capturing and displaying a freehand-drawn signal waveform in an x / y coordinate system, a computing unit configured to display the drawn signal waveform on the touch-sensitive screen, to validate the displayed signal waveform to determine whether it represents a unique function y=f(x) in the coordinate system, to post-process the validated signal waveform, to scale the value range and time axis of the post-processed signal waveform, and to display the instantaneous value of the physical test quantity on the touch-sensitive screen when the scaled signal waveform is played back, wherein the instantaneous value of the physical test quantity displayed in real time moves synchronously along the scaled signal waveform.and with an electronic test parameter generator to generate a time-dependent profile of the physical test parameter corresponding to the scaled signal profile.

[0024] The claimed structural features of the test device according to the invention carry out the corresponding process steps of the method according to the invention. Thus, the technical effects achieved with the method and the resulting advantages also apply equally to the test device.

[0025] The task of realizing more sophisticated time signal profiles of a test parameter is solved by the fact that the test device according to the invention comprises, in addition to the electronic test parameter generator for generating the desired test parameter profile, an electronic operating unit consisting of the computing unit and the touch-sensitive screen (touch display).

[0026] The electronic control unit with touch display has a processing unit, preferably a microcontroller, for executing an algorithm that evaluates and, if necessary, corrects (validity check) the signal waveforms drawn on the touch display in the x / y coordinate system, digitally processes them using filter algorithms, and scales them. The electronic test parameter generator then generates the desired time waveform of the test parameter based on the hand-drawn time signal waveform.

[0027] The interaction of an electronic operating unit consisting of the touch-sensitive screen and the computing unit for capturing and processing the drawn signal curve with the electronic test parameter generator for generating a time course of a physical test parameter allows for user-friendly and application-specific provision of test parameter time courses for functional testing of protection and monitoring devices.

[0028] In particular, the direct conversion of a freely drawn, arbitrary signal curve into a test parameter time curve makes it possible to optimize the measurement and trigger profiles of the protection and monitoring device to be tested in an existing plant with its specific physical properties in an iterative process and to quickly run through different test profiles.

[0029] Further advantageous design features will become apparent from the following description and the drawings, which illustrate a preferred embodiment of the invention by means of examples. They show: Fig. 1: freehand drawing and mapping of a signal waveform on a touch-sensitive screen, Fig. 2: a validated and post-processed signal waveform, Fig. 3: an invalid signal waveform that must be discarded, Fig. 4: another invalid signal waveform to be discarded, Fig. 5: a non-valid but correctable signal pattern, Fig. 6: one from Fig. 5 corrected signal waveform, Fig. 7: a functional block diagram of a test device according to the invention and Fig. 8: a process sequence according to the invention.

[0030] Fig. Figure 1 shows a freehand drawing of a signal waveform S1 of an ohmic resistor with the resistance value on the y-axis over a time axis as the x-axis in an x / y coordinate system 7 on a touch display 6 with a graphical user interface. If the drawn (S1) signal waveform S2, represented in the x / y coordinate system 7, is considered valid (S3) by an evaluation algorithm and digitally post-processed, the post-processed signal waveform S4, with reduced noise and free of outliers, is obtained as shown in Fig. 2 shown. Preferably, the post-processed signal waveform S4 is shown in Fig. 2 shown in a different color. The signal waveforms shown are from Fig. 1 (S1, S2) and Fig. 2 (S3, S4) are each independent representations in this example and are not causally related.

[0031] The algorithm generates either a valid signal curve - corresponding to a function f(x) - from the pixel points drawn on the touch display 6, which are displayed directly to the user as feedback on the touch display 6, or prompts the user to re-enter the data in case of incorrect input.

[0032] The algorithm is able to detect invalid function curves, such as signal curves that migrate backwards in time, and correct them if possible.

[0033] Fig. 3 and Fig. 4 show invalid signal curves S5, which are discarded by the algorithm because multiple signal points exist at the same time or the drawn / mapped signal curve S1 / S2 is able to return in time.

[0034] Fig. Figure 5 also shows an invalid signal waveform S5, since the function reverses in time in the vicinity of t = T / 4. In contrast to the invalid signal waveforms S5 in Fig. 3 and Fig. However, this is not intentionally caused here, but is to be expected as a drawing inaccuracy with vertical lines when drawing freehand. Here, the algorithm is able to correct the signal waveform to a valid function, as can be seen from the corrected signal waveform S6 in Fig. 6 is evident.

[0035] Fig. Figure 7 shows a functional block diagram of a test device 2 according to the invention. The test device 2 functionally comprises an electronic operating unit 4 consisting of a touch display 6 and a computing unit 8 as well as an electronic test parameter generator 10.

[0036] The processing unit 8 is a microcontroller, which must be able to display the six pixels drawn on the touch display to the user as feedback without any time delay. Only in this way can the requirement of fluid drawing, as with a pen on paper, be met.

[0037] Structurally, the test device 2 is preferably designed as a self-contained structural unit with the main components electronic control unit 4 and electronic test parameter generator 10, wherein the electronic control unit 4 in turn comprises as its main components the touch-sensitive screen 6 and the computing unit 8.

[0038] In another configuration, commercially available smartphones or tablet computers can also be used as electronic control units 4 with corresponding interfaces to a background system with a test parameter generator 10.

[0039] The test parameter generator 10 can be configured as a signal generator to produce a current or voltage waveform. A transistor-based (resistor) circuit can be used to generate a time-dependent change in resistance as the test parameter. Alternatively, controllable relay cards with corresponding discrete resistors are conceivable at this point, which set the test parameter in a power supply system with the protection or monitoring device 20 under test.

[0040] As the respective interface between the individual components, Fig. Of the components 6, 8, and 10 shown in Figure 7, the first component to be mentioned is the pixel information between the touch display 6 and the microcontroller 8. The touch display 6 transmits the pixel information in x / y coordinates via pressed display points to the microcontroller 8, while the microcontroller adjusts the brightness and color of the pixels of the touch display 6 in real time. From the pixel information of the touch input, the microcontroller 8 processes and then scales a signal waveform S. R (t), S I The test parameter (resistance or current) is calculated (t) and transmitted to the electronic test parameter generator 10 via any data connection. Here, the physical test parameter R(t), I(t) is then actually generated with effect on the protection or monitoring device 20 installed in the power supply system.

[0041] Fig. Section 8 describes, by way of example, a possible algorithm for implementing a process flow according to the invention.

[0042] The listed procedure steps show in detailed instructions the mapping of the drawn signal waveform S1, the validation of the mapped signal waveform S2, the post-processing of the validated signal waveform S3 and the final scaling of the post-processed signal waveform S4.

[0043] The following agreements apply: T: End time; N: Line width in pixels, e.g. 5 pixels; FC: Color code, e.g.: 0x0FF; M: Maximum permissible number of defects, e.g. 15.

[0044] The individual procedural steps are as follows: - Clearing or white-coding a 2D field that contains the pixel information for the touch display. - Capturing the display points pressed with a finger or stylus, storing them in a display buffer field, and immediately plotting a strip (Y-column) at position X with a width of 1 pixel and a height of N pixels with the color FC, e.g., black, where N represents the line width. - If pixels were pushed to the right outside the labelable area of ​​the coordinate system, then start processing. - Set the position pointer to zero and incrementally traverse the Y columns in the X direction of the display buffer. - If a Y-column contains more pixels of the drawing color FC than 1.5 times the line width, then increment the error counter. - Calculate the average of the Y positions where the color FC is located, across the entire Y column at position X. - Write the mean value to a separate 1D function buffer at position X. Repeat this routine until all columns have been processed; if the error counter reaches the set limit M beforehand, abort the routine and report the procedure error. An invalid function is present. - Next, calculate the moving average over, for example, 5 values ​​from the function buffer. This serves to eliminate gaps, such as where no drawing occurred due to insufficient pressure on the display, and to smooth out any abrupt changes in the function's output. If more than 5 values ​​are missing, the last valid value is used until a new value is found. Alternatively, gaps in the function can be filled by linear interpolation between the last and next value. Finally, the pixel-position-based function with discrete time points is scaled to the set time frame in the X-direction and the unit, e.g., ohms or amperes, of the test quantity in the Y-direction and can be "played back" on the electronic test quantity generator.

[0045] In summary, a time- and value-discrete function is generated from a freehand drawn "image" with signal shape characteristics, the mathematical classification of which is not further identified.

[0046] The validity check is ultimately based on assessing whether there are so many pixels in a column at a given point X that more than one line must be present. Since this can occur due to clumsy drawing, a certain number of errors is permitted and is not critical due to the averaging process for each column. Averaging for each column always generates a valid function. Nevertheless, the validity of the freely drawn function is still checked, as invalidly drawn functions, in conjunction with the averaging, would lead to signal patterns that would be unexpected for the user.

[0047] The signal waveform S4, calculated in processing unit 8 and cleaned of outliers, jumps, and gaps using digital signal processing algorithms, is then plotted on the touch display 6 in a different color than the drawing color, e.g., red, and replaces the freehand drawing (drawn signal waveform S1). This differently colored waveform does not interfere with subsequent input and evaluation and can simply be drawn over.

[0048] Is the scaled signal waveform S R (t), S I (t) “played out”, a point with the current value of the physical test quantity R(t), I(t) moves along the scaled signal curve S R (t), S I (t) synchronously with the set physical test quantity R(t), I(t), whereby the already traversed part of the signal waveform receives a different color (not equal to the character color).

Claims

[1] Method for generating a physical test variable (R(t), I(t)) by detecting a freehand drawn signal curve (S1) for functional testing of an electrical protection and monitoring device (20), comprising the method steps: Freehand drawing of a signal curve (S1) in an x / y coordinate system (7) on a touch-sensitive screen (6) and displaying the drawn signal curve (S1) on the touch-sensitive screen (6) by means of a computing unit (8), Validating the displayed signal curve (S2) by means of the computing unit (8) to determine whether the displayed signal curve (S2) represents a unique function curve y=f(x) in the coordinate system (7), Post-processing of the validated signal curve (S3) by digital signal processing methods using the computing unit (8), Scaling a value range and a time axis of the post-processed signal curve (S4) by means of the computing unit (8), Generating a time course of the physical test quantity (R(t), I(t)) according to the scaled signal course (S R (t), S I (t)) by means of an electronic test variable generator (10), displaying the instantaneous value of the physical test variable (R(t), I(t)) on the touch-sensitive screen (6) when playing back the scaled signal curve ((S R (t), S r (t)), whereby the instantaneous value of the physical test quantity (R(t), I(t)) displayed in real time is synchronized on the scaled signal curve ((S R (t), S I (t)) migrates along. [2] Method according to claim 1, characterized by that a standard signal curve is generated during validation. [3] Test device (2) for generating a physical test value (R(t), I(t)) by recording a freehand drawn signal curve (S1) for functional testing of an electrical protection and monitoring device (20), with a touch-sensitive screen (6) for capturing and displaying a freehand drawn signal curve (S1) in an x / y coordinate system (7), a computing unit (8) which is configured for displaying the drawn signal curve (S1) on the touch-sensitive screen (6), to validate the displayed signal curve (S2) as to whether the displayed signal curve (S2) represents a unique function curve y=f(x) in the coordinate system (7), for post-processing the validated signal curve (S3), for scaling a value range and a time axis of the post-processed signal curve (S4), for displaying the instantaneous value of the physical test quantity (R(t), I (t)) on the touch-sensitive screen (6) when playing back the scaled signal curve ((S R (t), S r (t)), whereby the instantaneous value of the physical test quantity (R(t), I(t)) displayed in real time is synchronized on the scaled signal curve ((S R (t), S I (t)) migrates along, and with an electronic test variable generator (10) for generating a time profile of the physical test variable (R(t), I (t)) corresponding to the scaled signal profile (S R (t), S r (t)).

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