CN115219970A - Ammeter testing device and testing method - Google Patents
Ammeter testing device and testing method Download PDFInfo
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Abstract
The application discloses an ammeter testing device and method, and belongs to the technical field of testing. The method comprises the steps of obtaining terminal voltages at two ends of a sampling resistor and a current value of the sampling resistor, and calculating to obtain a resistance value of the sampling resistor; comparing the resistance value of the sampling resistor with a preset parameter value, if the resistance value of the sampling resistor is not in the range of the parameter value, indicating that the ammeter test does not pass, and updating or recording the number of times of failing to pass and the total number of times of the ammeter; when the total times reach a preset time threshold, dividing the number of times of failing of the ammeter by the total times to obtain the failure rate of the ammeter; and if the failure rate of the ammeter is greater than a preset qualified threshold value, judging that the ammeter is not qualified. That is to say, the proportion of the qualified group number of the sampling resistors in the multi-group test is determined based on the terminal voltage and the current value of the plurality of groups of sampling resistors, so that whether the ammeter is qualified or not can be judged, the screening difficulty of the ammeter is reduced, and the screening efficiency of the ammeter is improved.
Description
Technical Field
The application relates to the technical field of testing, in particular to an ammeter testing device and method.
Background
The sampling resistor in the current ammeter is generally installed in the ammeter by adopting a welding process. In the mass production process of the ammeter, based on machining errors caused by a welding process, the resistance value of the sampling resistor of the ammeter obtained through production is deviated from the designed standard resistance value, and when the deviation is overlarge, the measuring error of the ammeter is increased, and then the larger electric energy metering error is caused. Therefore, the ammeter is corrected before being put into practical application, and the ammeter with the measurement error still larger than the allowable error range after correction is removed. The process of rejecting unqualified ammeters according to the corrected measurement errors of the ammeters is too complicated, and the screening efficiency of the unqualified ammeters is low.
Disclosure of Invention
The application mainly aims to provide an ammeter testing device and method, and aims to solve the technical problem that screening efficiency of existing unqualified ammeters is low.
In order to achieve the above object, the present application provides an ammeter testing method, comprising the steps of:
acquiring terminal voltages at two ends of a sampling resistor and a current value of the sampling resistor;
calculating to obtain the resistance value of the sampling resistor according to the terminal voltages at the two ends of the sampling resistor and the current value of the sampling resistor;
comparing the resistance value of the sampling resistor with a preset parameter value, if the resistance value of the sampling resistor is not in the range of the parameter value, indicating that the ammeter test does not pass, and updating or recording the number of times of failing to pass and the total number of times of the ammeter;
when the total times reach a preset time threshold, dividing the number of times of non-passing of the ammeter by the total times to obtain the failure rate of the ammeter;
and if the failure rate of the ammeter is greater than a preset qualified threshold value, determining that the ammeter is not qualified.
Optionally, the ammeter testing method further comprises the following steps:
acquiring a temperature value of the sampling resistor;
correcting the current value of the sampling resistor based on the temperature value of the sampling resistor to obtain a corrected current value of the sampling resistor;
the step of calculating the resistance value of the sampling resistor according to the terminal voltages at the two ends of the sampling resistor and the corrected current value of the sampling resistor comprises the following steps:
and calculating to obtain the resistance value of the sampling resistor according to the terminal voltages at the two ends of the sampling resistor and the corrected current value of the sampling resistor.
Optionally, the step of obtaining the temperature value of the sampling resistor includes:
acquiring a thermal imaging graph of the sampling resistor in a power-on state;
analyzing and calculating a thermal imaging graph of the sampling resistor in the power-on state to obtain a calculated temperature value of the sampling resistor;
obtaining an expansion value of the sampling resistor as a temperature correction coefficient of the sampling resistor according to the image of the sampling resistor in the electrified state and the image of the sampling resistor in the non-electrified state;
and correcting the calculated temperature value of the sampling resistor based on the temperature correction coefficient to obtain the temperature value of the sampling resistor.
Optionally, the step of analyzing and calculating the thermal imaging diagram of the sampling resistor in the power-on state to obtain a calculated temperature value of the sampling resistor includes:
dividing a thermal imaging graph in the electrified state of the sampling resistor into a plurality of sub-graphs;
extracting a color value of each pixel point in the subgraph to obtain an RGB color value of each pixel point;
carrying out mean value clustering on the RGB color values of each pixel point to obtain a plurality of clustering centers corresponding to the R color value, the G color value and the B color value respectively;
calculating to obtain mean values corresponding to the R color value, the G color value and the B color value according to a plurality of clustering centers corresponding to the R color value, the G color value and the B color value respectively, and using the mean values as the RGB color values of the subgraph;
determining the temperature value of the subgraph according to the mapping relation between the preset RGB color value and the temperature value;
and calculating the average value of the temperature values of the plurality of sub-graphs to serve as the calculated temperature value of the sampling resistor.
Optionally, the step of performing mean value clustering on the RGB color values of each pixel point to obtain a plurality of clustering centers corresponding to the R color value, the G color value, and the B color value includes:
initializing K clustering centers;
distributing the R color value or the G color value or the B color value of each pixel point to a cluster set where a cluster center corresponding to the minimum distance is located according to the principle of the minimum distance, wherein the distance is calculated by adopting the Euclidean distance;
taking the mean value of all R color values or G color values or B color values in each cluster set as a new cluster center;
and repeating the step of distributing the R color value or the G color value or the B color value of each pixel point to a cluster set where a cluster center corresponding to the minimum distance is located according to the principle of the minimum distance, wherein the distance adopts the Euclidean distance to calculate, and the step of taking the mean value of all the R color values or the G color values or the B color values in each cluster set as a new cluster center until the cluster center is not changed any more, so that a plurality of cluster centers corresponding to the R color values or the G color values or the B color values are obtained.
Optionally, the step of obtaining an expansion value of the sampling resistor as a temperature correction coefficient of the sampling resistor according to the image of the sampling resistor in the energized state and the image of the sampling resistor in the non-energized state includes:
calculating the area value of the image in the electrified state of the sampling resistor and the area value of the image in the unpowered state of the sampling resistor;
and calculating the difference value between the area value of the image in the electrified state of the sampling resistor and the area value of the image in the non-electrified state of the sampling resistor, and dividing the difference value by the area value of the image in the non-electrified state of the sampling resistor to obtain the expansion value of the sampling resistor as the temperature correction coefficient of the sampling resistor.
Optionally, the step of obtaining an expansion value of the sampling resistor as a temperature correction coefficient of the sampling resistor according to the image of the sampling resistor in the energized state and the image of the sampling resistor in the unenergized state includes:
constructing a two-dimensional coordinate system by taking the central point of the image in the electrified state of the sampling resistor and the image in the unpowered state of the sampling resistor as original points;
calculating the distance between the characteristic point in the image of the sampling resistor in the electrified state and the corresponding characteristic point in the image of the sampling resistor in the non-electrified state to obtain a plurality of distance values corresponding to the characteristic points;
and calculating a sum value of distance values corresponding to a plurality of feature points, and dividing the sum value with the contour perimeter value of the image in the non-electrified state of the sampling resistor to obtain an expansion value of the sampling resistor as a temperature correction coefficient of the sampling resistor.
In addition, to achieve the above object, the present application further provides an ammeter testing device adapted to any one of the above methods, the ammeter testing device comprising:
the power supply access interface is used for accessing a working power supply to provide electric energy for the sampling resistor;
the voltage detection module is used for detecting the terminal voltages at two ends of the sampling resistor;
the current detection module is used for detecting the current value of the sampling resistor;
the micro-control module is connected with the voltage detection module and the current detection module and used for calculating the resistance value of the sampling resistor according to the terminal voltages at the two ends of the sampling resistor and the current value of the sampling resistor; the ammeter is used for testing the current of the ammeter and is used for comparing the resistance value of the sampling resistor with a preset parameter value, if the resistance value of the sampling resistor is not in the range of the parameter value, the ammeter does not pass the test, and the number of times of failing to pass and the total number of times of failing to pass of the ammeter are updated or recorded; and when the total times reaches a preset time threshold value, dividing the number of times of failing of the ammeter by the total times to obtain the rejection rate of the ammeter, and if the rejection rate of the ammeter is greater than the preset pass threshold value, judging that the ammeter is not qualified.
Optionally, the ammeter testing device further comprises:
the temperature detection module is connected with the micro control module and is used for acquiring the temperature value of the sampling resistor;
the micro-control module is further configured to: and correcting the current value of the sampling resistor based on the temperature value of the sampling resistor to obtain the corrected current value of the sampling resistor, and calculating to obtain the resistance value of the sampling resistor according to the terminal voltages at the two ends of the sampling resistor and the corrected current value of the sampling resistor.
Optionally, the temperature detection module includes:
the thermal imaging unit is used for acquiring a thermal imaging graph in the electrified state of the sampling resistor;
the image unit is used for acquiring an image of the sampling resistor in an electrified state and an image of the sampling resistor in a non-electrified state;
the micro-processing unit is connected with the thermal imaging unit and the image unit and is used for analyzing and calculating a thermal imaging graph in the electrified state of the sampling resistor to obtain a calculated temperature value of the sampling resistor; the sampling resistor is also used for obtaining an expansion value of the sampling resistor according to the image of the sampling resistor in the electrified state and the image of the sampling resistor in the non-electrified state as a temperature correction coefficient of the sampling resistor; and the temperature correction module is also used for correcting the calculated temperature value of the sampling resistor based on the temperature correction coefficient to obtain the temperature value of the sampling resistor.
Compared with the prior art that the screening efficiency of unqualified ammeter is low, the testing device and the testing method of the ammeter obtain the terminal voltages at two ends of a sampling resistor and the current value of the sampling resistor; calculating to obtain the resistance value of the sampling resistor according to the terminal voltages at the two ends of the sampling resistor and the current value of the sampling resistor; comparing the resistance value of the sampling resistor with a preset parameter value, if the resistance value of the sampling resistor is not in the range of the parameter value, indicating that the ammeter test does not pass, and updating or recording the number of times of failing to pass and the total number of times of the ammeter; when the total times reach a preset time threshold value, dividing the number of times of failing of the ammeter by the total times to obtain the failure rate of the ammeter; if the rejection rate of the ammeter is greater than the preset qualified threshold value, the ammeter is judged to be unqualified, the proportion of the qualified group of the sampling resistors in the test is determined based on the terminal voltage and the current value of the multiple groups of sampling resistors, whether the ammeter is qualified or not can be judged, the screening difficulty of the ammeter is reduced, and the screening efficiency of the ammeter is improved.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and together with the description, serve to explain the principles of the application.
In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a schematic flow chart diagram of a first embodiment of an ammeter testing method of the present application;
FIG. 2 is a schematic flow chart of a second embodiment of the current meter testing method of the present application;
fig. 3 is a schematic structural diagram of a first embodiment of an ammeter testing device of the present application.
The implementation, functional features and advantages of the object of the present application will be further explained with reference to the embodiments, and with reference to the accompanying drawings.
Detailed Description
It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.
An embodiment of the present application provides an ammeter testing method, and referring to fig. 1, fig. 1 is a schematic flow diagram of a first embodiment of the ammeter testing method of the present application.
In this embodiment, the ammeter testing method includes:
s10, acquiring terminal voltages at two ends of a sampling resistor and a current value of the sampling resistor;
step S20, calculating to obtain the resistance value of the sampling resistor according to the terminal voltages at the two ends of the sampling resistor and the current value of the sampling resistor;
step S30, comparing the resistance value of the sampling resistor with a preset parameter value, if the resistance value of the sampling resistor is not in the range of the parameter value, indicating that the ammeter test does not pass, and updating or recording the number of times of failing and the total number of times of the ammeter, otherwise, indicating that the ammeter test passes, and updating or recording the total number of times;
s40, when the total times reach a preset times threshold, dividing the number of times of non-passing of the ammeter by the total times to obtain the fraction defective of the ammeter;
and S50, if the rejection rate of the ammeter is greater than a preset qualified threshold value, judging that the ammeter is unqualified, otherwise, judging that the ammeter is qualified.
It should be noted that, in this embodiment, the preset parameter value may be set according to the material of the sampling resistor, which is not limited in this embodiment; the preset number threshold and the preset qualified threshold may be set according to the accuracy of the voltage detection module for detecting the terminal voltages at the two ends of the sampling resistor and the accuracy of the current detection module for detecting the current value of the sampling resistor, which is not limited in this embodiment. The voltage detection module can be a voltmeter or a voltage detection circuit; the current detection module can be an ammeter or a current detection circuit.
In this embodiment, compared with the prior art in which the screening efficiency of an unqualified ammeter is low, the present embodiment determines the proportion of the qualified sets of sampling resistors in a plurality of sets of tests based on the terminal voltages and the current values of a plurality of sets of sampling resistors, and can determine whether the ammeter is qualified, thereby reducing the screening difficulty of the ammeter and further improving the screening efficiency of the ammeter.
An ammeter testing method is further provided in the embodiments of the present application, and referring to fig. 2, fig. 2 is a schematic flow diagram of a second embodiment of the ammeter testing method of the present application.
It should be noted that, in the first embodiment of the ammeter testing method, it is not considered that the sampling resistor consumes a part of the current due to heat generated by energization, so that a deviation occurs between the current value detected by the current detection module and the current value actually flowing through the sampling resistor. Therefore, in the second embodiment of the ammeter testing method, the current value of the sampling resistor needs to be corrected according to the temperature value of the sampling resistor.
In this embodiment, the ammeter testing method includes:
and S01, acquiring terminal voltages at two ends of a sampling resistor, a current value of the sampling resistor and a temperature value of the sampling resistor.
Further, the step of obtaining the temperature value of the sampling resistor includes:
and step S011, acquiring a thermal imaging graph in the electrified state of the sampling resistor.
And step S012, analyzing and calculating the thermal imaging graph of the sampling resistor in the power-on state to obtain the calculated temperature value of the sampling resistor.
Specifically, the step of analyzing and calculating the thermal imaging graph of the sampling resistor in the power-on state to obtain the calculated temperature value of the sampling resistor includes:
dividing a thermal imaging graph in the electrified state of the sampling resistor into a plurality of sub-graphs;
extracting color values of each pixel point in the subgraph to obtain RGB color values of each pixel point;
carrying out mean value clustering on the RGB color values of each pixel point to obtain a plurality of clustering centers corresponding to the R color value, the G color value and the B color value respectively;
calculating to obtain mean values corresponding to the R color value, the G color value and the B color value according to a plurality of clustering centers corresponding to the R color value, the G color value and the B color value respectively, and using the mean values as the RGB color values of the subgraph;
determining a temperature value of the sub-graph according to a mapping relation between a preset RGB color value and the temperature value;
and calculating the average value of the temperature values of the plurality of sub-graphs to serve as the calculated temperature value of the sampling resistor.
The step of performing mean value clustering on the RGB color values of each pixel point to obtain a plurality of clustering centers corresponding to the R color value, the G color value and the B color value respectively comprises the following steps of:
initializing K clustering centers;
distributing the R color value or the G color value or the B color value of each pixel point to a cluster set where a cluster center corresponding to the minimum distance is located according to the principle of the minimum distance, wherein the distance is calculated by adopting the Euclidean distance;
taking the mean value of all R color values or G color values or B color values in each cluster set as a new cluster center;
and repeating the step of distributing the R color value or the G color value or the B color value of each pixel point to a cluster set where a cluster center corresponding to the minimum distance is located according to the principle of the minimum distance, wherein the distance adopts the Euclidean distance to calculate, and the step of taking the mean value of all the R color values or the G color values or the B color values in each cluster set as a new cluster center until the cluster center is not changed any more, so that a plurality of cluster centers corresponding to the R color values or the G color values or the B color values are obtained.
It should be noted that when a plurality of clustering centers corresponding to the R color values are determined, K color values can be randomly selected from the R color values of each pixel point as initialized K clustering centers; when a plurality of clustering centers corresponding to the G color values are determined, K color values can be randomly selected from the G color values of each pixel point to serve as K initialized clustering centers; when a plurality of clustering centers corresponding to the B color values are determined, K color values can be randomly selected from the B color values of each pixel point to serve as K initialized clustering centers.
And S013, obtaining an expansion value of the sampling resistor as a temperature correction coefficient of the sampling resistor according to the image of the sampling resistor in the electrified state and the image of the sampling resistor in the non-electrified state.
When the sampling resistor is energized to generate heat, the sampling resistor conducts heat with air in the surrounding environment due to a temperature difference with the air temperature in the surrounding environment, and thus the temperature value of the sampling resistor obtained through the thermal imaging graph is deviated. Therefore, the temperature value of the sampling resistor obtained through the imaging graph needs to be corrected by using the expansion value of the sampling resistor as the temperature correction coefficient of the sampling resistor.
It should be noted that the image in the sampling resistor energized state and the image in the sampling resistor unenergized state are acquired by the image unit, the image unit may be a camera in this embodiment, and the shooting position, shooting angle, and the like of the camera when acquiring the image in the sampling resistor energized state are the same as the shooting position, shooting angle, and the like of the camera when acquiring the image in the sampling resistor unenergized state.
Furthermore, there are two ways to obtain the expansion value of the sampling resistor as the temperature correction coefficient of the sampling resistor according to the image of the sampling resistor in the electrified state and the image of the sampling resistor in the non-electrified state.
The first method is as follows: calculating the area value of the image in the electrified state of the sampling resistor and the area value of the image in the unpowered state of the sampling resistor;
and calculating a difference value between the area value of the image of the sampling resistor in the electrified state and the area value of the image of the sampling resistor in the non-electrified state, and dividing the difference value by the area value of the image of the sampling resistor in the non-electrified state to obtain an expansion value of the sampling resistor as the temperature correction coefficient of the sampling resistor.
The second method comprises the following steps: the sampling resistor is provided with a plurality of characteristic points, and a two-dimensional coordinate system is constructed by taking the central point of the image of the sampling resistor in the electrified state and the image of the sampling resistor in the non-electrified state as original points;
calculating the distance between the characteristic point in the image of the sampling resistor in the electrified state and the corresponding characteristic point in the image of the sampling resistor in the non-electrified state to obtain a plurality of distance values corresponding to the characteristic points;
and calculating a sum of distance values corresponding to a plurality of feature points, and dividing the sum by the contour perimeter value of the image in the unpowered state of the sampling resistor to obtain an expansion value of the sampling resistor as a temperature correction coefficient of the sampling resistor.
Since the sampling resistor is provided with a plurality of feature points, the plurality of feature points are present in the image in the sampling resistor energized state and the image in the sampling resistor non-energized state, and when calculating the feature points in the image in the sampling resistor energized state and the feature points in the image in the sampling resistor non-energized state, it is necessary to associate the feature points. For example, the a feature point in the image in the sampling resistor energized state corresponds to the a feature point in the image in the sampling resistor unenergized state, and both the a feature point in the image in the sampling resistor energized state and the a feature point in the image in the sampling resistor unenergized state are the a feature points on the sampling resistor.
It should be noted that the contour perimeter value of the image in the non-energized state of the sampling resistor is the length value of the outer edge in the image in the non-energized state of the sampling resistor.
Step S014, correcting the calculated temperature value of the sampling resistor based on the temperature correction coefficient to obtain the temperature value of the sampling resistor.
In this embodiment, the temperature value of the sampling resistor may be calculated according to the formula K '= K × (1 + p), where K' represents the temperature value of the sampling resistor, K represents the calculated temperature value of the sampling resistor, and p represents the temperature correction coefficient (expansion value).
And S02, correcting the current value of the sampling resistor based on the temperature value of the sampling resistor to obtain a corrected current value of the sampling resistor.
In this embodiment, a current correction coefficient corresponding to the temperature value of the sampling resistor is obtained by looking up a preset correspondence table between the temperature of the sampling resistor and the current correction coefficient according to the temperature value of the sampling resistor, so as to correct the current value of the sampling resistor, thereby obtaining a corrected current value of the sampling resistor. Wherein, the temperature of different sampling resistors corresponds to different current correction coefficients.
And S03, calculating to obtain the resistance value of the sampling resistor according to the terminal voltages at the two ends of the sampling resistor and the corrected current value of the sampling resistor.
And S30, comparing the resistance value of the sampling resistor with a preset parameter value, if the resistance value of the sampling resistor is not in the range of the parameter value, indicating that the ammeter test does not pass, and updating or recording the number of times of failing to pass and the total number of times of the ammeter.
And S40, when the total times reach a preset times threshold, dividing the number of times of non-passing of the ammeter by the total times to obtain the failure rate of the ammeter.
And S50, if the rejection rate of the ammeter is greater than a preset qualified threshold, judging that the ammeter is unqualified.
An ammeter testing device is further provided in the embodiments of the present application, and referring to fig. 3, fig. 3 is a schematic structural diagram of the ammeter testing device in the first embodiment of the present application.
In this embodiment, the ammeter testing device comprises:
the power supply access interface 10 is used for accessing a working power supply to provide electric energy for the sampling resistor;
the voltage detection module 20 is used for detecting terminal voltages at two ends of the sampling resistor;
a current detection module 30, configured to detect a current value of the sampling resistor;
the micro-control module 40 is connected with the voltage detection module and the current detection module, and is used for calculating a resistance value of the sampling resistor according to the terminal voltages at the two ends of the sampling resistor and the current value of the sampling resistor; the ammeter is used for testing the current of the ammeter and is used for comparing the resistance value of the sampling resistor with a preset parameter value, if the resistance value of the sampling resistor is not in the range of the parameter value, the ammeter does not pass the test, and the number of times of failing to pass and the total number of times of failing to pass of the ammeter are updated or recorded; and when the total times reaches a preset time threshold value, dividing the number of times of failing of the ammeter by the total times to obtain the rejection rate of the ammeter, and if the rejection rate of the ammeter is greater than the preset pass threshold value, judging that the ammeter is not qualified.
It should be noted that, since the sampling resistor in this embodiment is a sampling resistor in an ammeter, the working power supply is preferably commercial power.
In this embodiment, the voltage detection module may be a voltmeter or a voltage detection circuit; the current detection module can be an ammeter or a current detection circuit.
Optionally, the ammeter testing device further comprises:
the temperature detection module 50 is connected with the micro control module and is used for acquiring the temperature value of the sampling resistor;
the micro-control module is further configured to: and correcting the current value of the sampling resistor based on the temperature value of the sampling resistor to obtain the corrected current value of the sampling resistor, and calculating to obtain the resistance value of the sampling resistor according to the terminal voltages at the two ends of the sampling resistor and the corrected current value of the sampling resistor.
Optionally, the temperature detection module includes:
the thermal imaging unit is used for acquiring a thermal imaging graph in the electrified state of the sampling resistor;
the image unit is used for acquiring an image of the sampling resistor in an electrified state and an image of the sampling resistor in a non-electrified state;
the micro-processing unit is connected with the thermal imaging unit and the image unit and is used for analyzing and calculating a thermal imaging graph in the electrified state of the sampling resistor to obtain a calculated temperature value of the sampling resistor; the sampling resistor is also used for obtaining an expansion value of the sampling resistor according to the image of the sampling resistor in the electrified state and the image of the sampling resistor in the non-electrified state as a temperature correction coefficient of the sampling resistor; and the temperature correction module is also used for correcting the calculated temperature value of the sampling resistor based on the temperature correction coefficient to obtain the temperature value of the sampling resistor.
Optionally, analyzing and calculating the thermal imaging graph of the sampling resistor in the power-on state to obtain a calculated temperature value of the sampling resistor includes:
dividing the thermal imaging graph in the electrified state of the sampling resistor into a plurality of subgraphs;
extracting a color value of each pixel point in the subgraph to obtain an RGB color value of each pixel point;
carrying out mean value clustering on the RGB color values of each pixel point to obtain a plurality of clustering centers corresponding to the R color value, the G color value and the B color value respectively;
calculating to obtain mean values corresponding to the R color value, the G color value and the B color value according to a plurality of clustering centers corresponding to the R color value, the G color value and the B color value respectively, and using the mean values as the RGB color values of the subgraph;
determining the temperature value of the subgraph according to the mapping relation between the preset RGB color value and the temperature value;
and calculating the average value of the temperature values of the plurality of subgraphs to serve as the calculated temperature value of the sampling resistor.
Optionally, the performing mean value clustering on the RGB color values of each pixel point to obtain a plurality of clustering centers corresponding to the R color value, the G color value, and the B color value respectively includes:
initializing K clustering centers;
distributing the R color value or the G color value or the B color value of each pixel point to a cluster set where a cluster center corresponding to the minimum distance is located according to the principle of the minimum distance, wherein the distance is calculated by adopting the Euclidean distance;
taking the mean value of all R color values or G color values or B color values in each cluster set as a new cluster center;
and repeating the step of distributing the R color value or the G color value or the B color value of each pixel point to a cluster set where a cluster center corresponding to the minimum distance is located according to the principle of the minimum distance, wherein the distance adopts the Euclidean distance to calculate, and the step of taking the mean value of all the R color values or the G color values or the B color values in each cluster set as a new cluster center until the cluster centers do not change any more, so as to obtain a plurality of cluster centers corresponding to the R color values or the G color values or the B color values.
Optionally, the obtaining an expansion value of the sampling resistor according to the image of the sampling resistor in the energized state and the image of the sampling resistor in the non-energized state as a temperature correction coefficient of the sampling resistor includes:
calculating the area value of the image of the sampling resistor in the electrified state and the area value of the image of the sampling resistor in the non-electrified state;
and calculating a difference value between the area value of the image of the sampling resistor in the electrified state and the area value of the image of the sampling resistor in the non-electrified state, and dividing the difference value by the area value of the image of the sampling resistor in the non-electrified state to obtain an expansion value of the sampling resistor as the temperature correction coefficient of the sampling resistor.
Optionally, a plurality of feature points are arranged on the sampling resistor, and obtaining an expansion value of the sampling resistor as a temperature correction coefficient of the sampling resistor according to the image of the sampling resistor in the powered state and the image of the sampling resistor in the unpowered state includes:
constructing a two-dimensional coordinate system by taking the central point of the image of the sampling resistor in the electrified state and the image of the sampling resistor in the non-electrified state as original points;
calculating the distance between the characteristic point in the image of the sampling resistor in the electrified state and the corresponding characteristic point in the image of the sampling resistor in the non-electrified state to obtain a plurality of distance values corresponding to the characteristic points;
and calculating a sum of distance values corresponding to a plurality of feature points, and dividing the sum by the contour perimeter value of the image in the unpowered state of the sampling resistor to obtain an expansion value of the sampling resistor as a temperature correction coefficient of the sampling resistor.
The specific implementation of the ammeter testing device of the present application is substantially the same as the embodiments of the ammeter testing method described above, and is not described herein again.
The embodiment of the present application further provides a storage medium, where an ammeter test program is stored on the storage medium, and the ammeter test program implements the steps of the ammeter test method when executed by a processor.
The specific implementation of the storage medium of the present application is substantially the same as that of each embodiment of the above-mentioned ammeter testing method, and is not described herein again.
It should be noted that, in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or system that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or system. Without further limitation, an element defined by the phrases "comprising one of 8230; \8230;" 8230; "does not exclude the presence of additional like elements in a process, method, article, or system that comprises the element.
The above-mentioned serial numbers of the embodiments of the present application are merely for description and do not represent the merits of the embodiments.
Through the description of the foregoing embodiments, it is clear to those skilled in the art that the method of the foregoing embodiments may be implemented by software plus a necessary general hardware platform, and certainly may also be implemented by hardware, but in many cases, the former is a better implementation. Based on such understanding, the technical solutions of the present application or portions thereof contributing to the prior art may be embodied in the form of a software product, which is stored in a storage medium (such as ROM/RAM, magnetic disk, optical disk) as described above and includes several instructions for enabling a terminal device (which may be a mobile phone, a computer, a server, or a network device) to execute the method described in the embodiments of the present application.
The above description is only a preferred embodiment of the present application, and not intended to limit the scope of the present application, and all modifications of equivalent structures and equivalent processes, which are made by the contents of the specification and the drawings of the present application, or which are directly or indirectly applied to other related technical fields, are included in the scope of the present application.
Claims (10)
1. An ammeter testing method is characterized by comprising the following steps:
acquiring terminal voltages at two ends of a sampling resistor and a current value of the sampling resistor;
calculating to obtain the resistance value of the sampling resistor according to the terminal voltages at the two ends of the sampling resistor and the current value of the sampling resistor;
comparing the resistance value of the sampling resistor with a preset parameter value, if the resistance value of the sampling resistor is not in the range of the parameter value, indicating that the ammeter does not pass the test, and updating or recording the number of times of failing to pass and the total number of times of failing to pass of the ammeter;
when the total times reach a preset time threshold value, dividing the number of times of failing of the ammeter by the total times to obtain the failure rate of the ammeter;
and if the failure rate of the ammeter is greater than a preset qualified threshold value, determining that the ammeter is not qualified.
2. The ammeter testing method of claim 1 further comprising the steps of:
acquiring a temperature value of the sampling resistor;
correcting the current value of the sampling resistor based on the temperature value of the sampling resistor to obtain a corrected current value of the sampling resistor;
the step of calculating the resistance value of the sampling resistor according to the terminal voltages at the two ends of the sampling resistor and the corrected current value of the sampling resistor comprises the following steps:
and calculating to obtain the resistance value of the sampling resistor according to the terminal voltages at the two ends of the sampling resistor and the corrected current value of the sampling resistor.
3. The ammeter testing method of claim 2, wherein the step of obtaining the temperature value of the sampling resistor comprises:
acquiring a thermal imaging graph of the sampling resistor in a power-on state;
analyzing and calculating a thermal imaging graph of the sampling resistor in the power-on state to obtain a calculated temperature value of the sampling resistor;
obtaining an expansion value of the sampling resistor as a temperature correction coefficient of the sampling resistor according to the image of the sampling resistor in the electrified state and the image of the sampling resistor in the non-electrified state;
and correcting the calculated temperature value of the sampling resistor based on the temperature correction coefficient to obtain the temperature value of the sampling resistor.
4. The ammeter testing method of claim 3 wherein said step of analyzing and calculating the thermal imaging profile of said sampled resistor during the energized state to obtain the calculated temperature value of said sampled resistor comprises:
dividing a thermal imaging graph in the electrified state of the sampling resistor into a plurality of sub-graphs;
extracting a color value of each pixel point in the subgraph to obtain an RGB color value of each pixel point;
carrying out mean value clustering on the RGB color values of each pixel point to obtain a plurality of clustering centers corresponding to the R color value, the G color value and the B color value respectively;
calculating to obtain mean values corresponding to the R color value, the G color value and the B color value according to a plurality of clustering centers corresponding to the R color value, the G color value and the B color value respectively, and using the mean values as the RGB color values of the subgraph;
determining a temperature value of the sub-graph according to a mapping relation between a preset RGB color value and the temperature value;
and calculating the average value of the temperature values of the plurality of subgraphs to serve as the calculated temperature value of the sampling resistor.
5. The ammeter testing method of claim 4, wherein the step of performing mean value clustering on the RGB color values of each pixel point to obtain a plurality of clustering centers corresponding to each of the R color value, the G color value and the B color value comprises:
initializing K clustering centers;
distributing the R color value, the G color value or the B color value of each pixel point to a cluster set where a cluster center corresponding to the minimum distance is located according to the principle of the minimum distance, wherein the distance is calculated by adopting an Euclidean distance;
taking the mean value of all R color values or G color values or B color values in each cluster set as a new cluster center;
and repeating the step of distributing the R color value or the G color value or the B color value of each pixel point to a cluster set where a cluster center corresponding to the minimum distance is located according to the principle of the minimum distance, wherein the distance adopts the Euclidean distance to calculate, and the step of taking the mean value of all the R color values or the G color values or the B color values in each cluster set as a new cluster center until the cluster center is not changed any more, so that a plurality of cluster centers corresponding to the R color values or the G color values or the B color values are obtained.
6. The ammeter testing method as set forth in claim 3, wherein the step of obtaining the expansion value of the sampling resistor as the temperature correction coefficient of the sampling resistor from the image of the sampling resistor in the energized state and the image of the sampling resistor in the unenergized state comprises:
calculating the area value of the image of the sampling resistor in the electrified state and the area value of the image of the sampling resistor in the non-electrified state;
and calculating the difference value between the area value of the image in the electrified state of the sampling resistor and the area value of the image in the non-electrified state of the sampling resistor, and dividing the difference value by the area value of the image in the non-electrified state of the sampling resistor to obtain the expansion value of the sampling resistor as the temperature correction coefficient of the sampling resistor.
7. The ammeter testing method as claimed in claim 3, wherein a plurality of characteristic points are provided on the sampling resistor, and the step of obtaining the expansion value of the sampling resistor as the temperature correction coefficient of the sampling resistor from the image of the sampling resistor in the energized state and the image of the sampling resistor in the non-energized state comprises:
constructing a two-dimensional coordinate system by taking the central point of the image in the electrified state of the sampling resistor and the image in the unpowered state of the sampling resistor as original points;
calculating the distance between the characteristic point in the image in the electrified state of the sampling resistor and the corresponding characteristic point in the image in the unpowered state of the sampling resistor to obtain a plurality of distance values corresponding to the characteristic points;
and calculating a sum value of distance values corresponding to a plurality of feature points, and dividing the sum value with the contour perimeter value of the image in the non-electrified state of the sampling resistor to obtain an expansion value of the sampling resistor as a temperature correction coefficient of the sampling resistor.
8. An ammeter testing device adapted for use in the ammeter testing method as set forth in any one of claims 1 to 7, wherein the ammeter testing device comprises:
the power supply access interface is used for accessing a working power supply to provide electric energy for the sampling resistor;
the voltage detection module is used for detecting the terminal voltages at two ends of the sampling resistor;
the current detection module is used for detecting the current value of the sampling resistor;
the micro-control module is connected with the voltage detection module and the current detection module and used for calculating the resistance value of the sampling resistor according to the terminal voltages at the two ends of the sampling resistor and the current value of the sampling resistor; the resistance value of the sampling resistor is compared with a preset parameter value, if the resistance value of the sampling resistor is not in the range of the parameter value, the ammeter is indicated to fail in test, and the number of times of failing to pass and the total number of times of failing to pass of the ammeter are updated or recorded; and when the total times reaches a preset time threshold, the number of times of failing of the ammeter is divided by the total times to obtain the failure rate of the ammeter, and if the failure rate of the ammeter is greater than the preset pass threshold, the ammeter is judged to be failed.
9. The ammeter testing device of claim 8, further comprising:
the temperature detection module is connected with the micro control module and is used for acquiring a temperature value of the sampling resistor;
the micro-control module is further configured to: and correcting the current value of the sampling resistor based on the temperature value of the sampling resistor to obtain the corrected current value of the sampling resistor, and calculating to obtain the resistance value of the sampling resistor according to the terminal voltages at the two ends of the sampling resistor and the corrected current value of the sampling resistor.
10. The ammeter testing device of claim 9, the temperature detection module comprising:
the thermal imaging unit is used for acquiring a thermal imaging graph in the electrified state of the sampling resistor;
the image unit is used for acquiring an image of the sampling resistor in an electrified state and an image of the sampling resistor in a non-electrified state;
the micro-processing unit is connected with the thermal imaging unit and the image unit and is used for analyzing and calculating a thermal imaging graph in the electrified state of the sampling resistor to obtain a calculated temperature value of the sampling resistor; the sampling resistor is also used for obtaining an expansion value of the sampling resistor as a temperature correction coefficient of the sampling resistor according to the image of the sampling resistor in the electrified state and the image of the sampling resistor in the non-electrified state; and the temperature correction module is also used for correcting the calculated temperature value of the sampling resistor based on the temperature correction coefficient to obtain the temperature value of the sampling resistor.
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