CN111190134A - Electric energy meter dynamic response time characteristic test method and calibration device - Google Patents
Electric energy meter dynamic response time characteristic test method and calibration device Download PDFInfo
- Publication number
- CN111190134A CN111190134A CN201911365898.1A CN201911365898A CN111190134A CN 111190134 A CN111190134 A CN 111190134A CN 201911365898 A CN201911365898 A CN 201911365898A CN 111190134 A CN111190134 A CN 111190134A
- Authority
- CN
- China
- Prior art keywords
- dynamic
- electric energy
- response time
- energy meter
- meter
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000010998 test method Methods 0.000 title claims abstract description 8
- 238000012360 testing method Methods 0.000 claims abstract description 38
- 238000000034 method Methods 0.000 claims abstract description 17
- 230000003750 conditioning effect Effects 0.000 claims abstract description 13
- 238000005259 measurement Methods 0.000 claims description 7
- 238000012797 qualification Methods 0.000 claims 1
- 238000001514 detection method Methods 0.000 abstract description 5
- 238000012795 verification Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000003908 quality control method Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R35/00—Testing or calibrating of apparatus covered by the other groups of this subclass
- G01R35/04—Testing or calibrating of apparatus covered by the other groups of this subclass of instruments for measuring time integral of power or current
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Testing Electric Properties And Detecting Electric Faults (AREA)
Abstract
A test method and a calibration device for the dynamic response time characteristic of an electric energy meter are provided, wherein the method provides a calculation formula for the dynamic response time of the electric energy meter; measuring the metering error of the tested meter for multiple times by taking the calculated dynamic response time as reference time; and comparing the dynamic error and the standard deviation thereof measured by the test with a specified limit value, and indicating that the dynamic response time characteristic of the electric energy meter is qualified only if the dynamic error and the standard deviation thereof simultaneously meet the requirements. The checking device comprises a master controller, a dynamic signal generator, a signal conditioning circuit, a standard table, an error display unit and an error calculation unit. The invention can carry out quantitative detection on the dynamic response time characteristic of the electric energy meter and promote the dynamic metering performance of the electric energy meter to be improved.
Description
Technical Field
The invention relates to a method for testing dynamic response time characteristics of an electric energy meter and a calibration device, belonging to the technical field of electric energy meter measurement.
Background
The electric energy meter is an important metering instrument for electric energy trade settlement, and the metering accuracy and the operation reliability of the electric energy meter directly influence the economic benefits of both electric energy supply parties. With the development of power electronic technology and the increase of nonlinear loads, a large amount of dynamic electric energy signals exist in a power grid. In order to ensure that the electric energy meter can accurately measure the dynamic electric energy signal, the dynamic performance of the electric energy meter needs to be detected.
Although the existing electric energy meter dynamic performance detection method has requirements on basic errors of the electric energy meter under dynamic signals, the time for detecting the dynamic basic errors of the electric energy meter is not specified. If the electric energy meter needs to meet the requirement of a dynamic basic error under a long detection time, the electric energy meter still does not meet the actual use requirement. Because the dynamic signal is rapidly changed under the actual operation condition, the dynamic signal cannot be kept unchanged for a long time; the dynamic electric energy metered by the electric energy meter in a short time possibly has larger error; in addition, the detection efficiency is affected by overlong detection time, and the popularization and application of the dynamic electric energy meter are not facilitated.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, further improve the accuracy of the electric energy meter in dynamic electric energy metering, promote the improvement of the dynamic metering performance of the electric energy meter, and enable the electric energy meter to meet the actual application requirements.
The technical scheme of the invention is that the method for testing the dynamic response time characteristic of the electric energy meter is used for testing the dynamic response time characteristic of the electric energy meter; a calculation formula of the dynamic response time of the electric energy meter is provided; when the dynamic error of the electric energy meter is checked, the checking device is required to give out the dynamic metering error of the electric energy meter within the specified response time; checking for many times to obtain a group of error data, and calculating the standard deviation of the measurement results for many times; and comparing the error and the standard deviation thereof measured by multiple times of verification with the limit value specified in the technical standard of the electric energy meter, and indicating that the dynamic response time characteristic of the electric energy meter is qualified only if the error and the standard deviation thereof simultaneously meet the requirements. The method judges whether the electric energy meter can accurately measure the dynamic signal stably in real time or not through the test of the dynamic response time characteristic of the electric energy meter, and the test method comprises the following steps:
(1) selecting an electric energy meter with the accuracy grade of A grade as a tested meter;
(2) selecting a standard device with the accuracy grade of B grade (two accuracy grades higher than A grade) under a dynamic test signal as a checking device;
(3) dynamic basic error limit of the agreed tested table is EbThe standard deviation limit value of the error obtained by M times (the value range of M is more than or equal to 5 and less than or equal to 10) of measurement is S0；
(4) Calculating the dynamic response time of the electric energy meter according to the meter constant of the standard meter, the dynamic basic error limit value of the tested meter and the meter constant of the tested meter in the checking device, and expressing the dynamic response time by using the number N of the checking pulses;
(5) using a checking device to carry out M times of error checking on the checked table, and setting the number of checking pulses as N; the checking device gives out the basic error value of the detected table after receiving N pulses sent by the detected table, and records the error value gamma at the moment.
(6) Carrying out M times of error check according to the conditions in the step (5) to obtain a group of dynamic errors gammaiI takes 1,2,3, …, 8; calculating to obtain standard deviation S according to the measured error value1。
(7) Judging the dynamic response time characteristic of the electric energy meter, and judging gammai|≤EbAnd S1≤S0Whether the two are true at the same time; if the two conditions are met, the dynamic response time characteristic of the detected electric energy meter is qualified;if not, the dynamic response time characteristic of the table to be detected is not qualified.
The requirement of the step (2) of the method for the checking device with the accuracy grade of B grade is as follows: the device can continuously generate dynamic test signals, the accuracy grade of a standard meter in the device is not lower than grade C (two accuracy grades higher than grade B), and the electric energy under the dynamic signals can be accurately measured.
The mathematical expression of the calculation of the dynamic response time is as follows:
in the above formula, C0(pulse) meter constants, imp/kWh, which are standard meters in the plant; cLThe (pulse) meter constant for the meter under test, imp/kWh; ebIs the basic error limit of the table to be detected; round () is a floor function.
In step (5), the requirements for performing dynamic error check on the table to be checked by using the checking device are as follows: the calibration device generates continuous dynamic test signals, and a standard meter and a tested meter in the device perform electric energy metering on the same dynamic test signal; the pulse output of the checked table is connected to an error calculation unit of the checking device; the number of the checking pulses is set to be N on the checking device, and when the device receives N pulses sent by the checked meter, an error value is displayed.
The method comprises the following steps of (7) judging that the electric energy meter dynamic response time characteristic is qualified: dynamic error gammaiAnd standard deviation S1Are not greater than the specified limits.
The invention relates to a device for checking the dynamic response time characteristic of an electric energy meter, which comprises a master controller, a dynamic signal generator, a signal conditioning circuit, a standard meter, an error display unit and an error calculation unit, wherein the master controller is connected with the dynamic signal generator through a communication line; the output end of the dynamic signal generator is connected with the input end of the signal conditioning circuit; the output end of the signal conditioning circuit is respectively connected with the input ends of the standard table and the detected table; the output ends of the standard table and the detected table are respectively connected with the corresponding input ports of the error calculation unit; the output end of the error calculation unit is connected with the error calculation unit; and the master controller is connected with and controls the dynamic signal generator.
The signal conditioning circuit conditions and sends the dynamic test signal sent by the dynamic signal generator to the standard table and the detected table; and the standard table and the detected table respectively output respective dynamic response pulses to the error calculation unit for dynamic response error calculation.
The dynamic test signal generated by the checking device is mainly formed by a power frequency signal through sinusoidal amplitude modulation, frequency modulation and phase modulation.
The working principle of the invention is as follows, the invention provides a method for testing the dynamic response time characteristic of an electric energy meter, which is mainly realized on the basis of a dynamic performance checking device of the electric energy meter. The electric energy meter dynamic performance checking device is different from a common electric energy meter checking device in that the electric energy meter dynamic performance checking device can generate a dynamic test signal, and a standard meter used in the device has good dynamic performance. The dynamic test signal generated by the device is mainly formed by a power frequency signal through sinusoidal amplitude modulation, frequency modulation and phase modulation.
The method has the advantages that the dynamic response time characteristic test method for the electric energy meter requires the electric energy meter to obtain dynamic basic errors under the specified number of check pulses, and the basic errors also accord with corresponding error limit values; it is also required that the standard deviation calculated from the dynamic basic errors measured a number of times does not exceed a specified limit. The test method defines the dynamic response time index of the electric energy meter and meets the requirement of practical application. The test can quantitatively detect the dynamic response time characteristic of the electric energy meter, and is beneficial to standardizing and improving the dynamic performance index of the electric energy meter; the dynamic performance of the electric energy meter can be further distinguished, quality control of the dynamic performance of the electric energy meter can be enhanced, the dynamic performance index of the electric energy meter can be promoted, and popularization and application of the dynamic performance of the electric energy meter are facilitated.
Drawings
FIG. 1 is a test flow chart of a method for testing dynamic response time characteristics of an electric energy meter according to the present invention;
fig. 2 is a structural schematic block diagram of the electric energy meter dynamic response time characteristic verification device of the present invention.
Detailed Description
Fig. 1 shows a flow of a method for testing dynamic response time characteristics of an electric energy meter according to an embodiment of the present invention.
The accuracy grade of the tested meter is known to be 0.5 grade, the basic error limit value is 0.5 percent, the standard deviation limit value is 0.1 percent, and the meter constant is 1200 imp/kWh; the accuracy grade of the checking device is 0.1 grade, and the instrument constant of the standard table is 2 multiplied by 106imp/kWh; the measurement times M are 8.
The specific test steps are as follows:
step 1: selecting an electric energy meter with the accuracy grade of 0.5 grade as a tested meter;
step 2: selecting a standard device with the accuracy grade of 0.1 grade under a dynamic test signal as a checking device;
and step 3: the limit value of the basic error of the tested table is 0.5%, and the limit value of the standard deviation of 8 measurement results is 0.1%;
and 4, step 4: calculating the dynamic response time (the number of check pulses is expressed as 2) of the electric energy meter according to the meter constant of the standard meter, the dynamic basic error limit of the tested meter and the meter constant of the tested meter;
and 5: using a checking device to check the dynamic error of the checked table, and setting the number of checking pulses to be 2; when the checking device receives 2 pulses sent by the detected table, the basic error value of the detected table is given, and the error value gamma at the moment is recorded.
Step 6: carrying out error checking for 8 times according to the conditions in the step (5) to obtain a group of error values gammai(i takes 1,2,3, …, 8); according to the measured error value, calculating to obtain the standard deviation S1。
And 7: determine | γiLess than or equal to 0.5 percent and S1Whether the content is less than or equal to 0.1 percent or not is true simultaneously; if the two conditions are met, the dynamic response time characteristic of the detected electric energy meter is qualified; if the dynamic response time characteristic of the table to be detected is not qualified, improvement is needed.
In step (2) of this embodiment, the requirement for the verification apparatus with accuracy class of 0.1 is: the device can continuously generate dynamic test signals, the accuracy grade of a standard meter in the device is not lower than 0.03 grade, and the electric energy under the dynamic signals can be accurately measured.
In step (4) of this embodiment, the application requirement of the dynamic response time calculation formula is: the instrument constant of the known standard meter, the instrument constant of the known checked meter and the basic error limit; it should be noted that the dynamic response time is indirectly represented by the number of the verification pulses, and when the load current is not changed, the number of the verification pulses reflects the length of the verification time. The dynamic response time can be indirectly represented by the number N of the check pulses, and the mathematical expression is as follows:
in the formula: c0(pulse) meter constants, imp/kWh, which are standard meters in the plant; cLThe (pulse) meter constant for the meter under test, imp/kWh; ebIs the basic error limit of the table to be detected; round () is a floor function.
Substituting numerical values, then there are:
in step (5) of this embodiment, the requirements for performing dynamic error check on the table to be checked by the checking device are as follows: the calibration device generates continuous dynamic test signals, and a standard meter and a tested meter in the device perform electric energy metering on the same dynamic test signal; the pulse output of the checked table is connected to an error calculation unit of the checking device; the number of the check pulses is set to be 2 on the checking device, and when the device receives 2 pulses sent by the checked meter, an error numerical value is displayed.
Wherein, the step (6) is to repeat the measurement for 8 times under the condition of the step (5) to obtain 8 error values, and finally calculate the standard deviation S according to a group of error data measured1。
And (7) judging whether the dynamic response time characteristic of the tested table meets the requirement or not according to the data obtained by the test. And when the errors and the standard deviations measured in the dynamic response time meet the requirements of corresponding accuracy levels, judging that the dynamic response time characteristics of the electric energy meter are qualified.
Fig. 2 is a schematic block diagram of a structure of the device for verifying dynamic response time characteristics of an electric energy meter according to the embodiment.
The device for verifying the dynamic response time characteristic of the electric energy meter comprises a master controller, a dynamic signal generator, a signal conditioning circuit, a standard meter, an error display unit and an error calculation unit, wherein the master controller is used for controlling the dynamic signal generator to generate a dynamic signal; the output end of the dynamic signal generator is connected with the input end of the signal conditioning circuit; the output end of the signal conditioning circuit is respectively connected with the input ends of the standard table and the detected table; the output ends of the standard table and the detected table are respectively connected with the corresponding input ports of the error calculation unit; the output end of the error calculation unit is connected with the error calculation unit; and the master controller is connected with and controls the dynamic signal generator.
The master controller in the electric energy meter dynamic response time characteristic checking device controls the dynamic signal generator to generate a required dynamic signal; the dynamic signal is output to the standard table and the detected table through the conditioning circuit; the standard meter and the detected meter simultaneously measure the electric energy of the dynamic signal, the generated pulse is output and connected to the error calculation unit, and finally the error value is displayed through the error display unit. According to the embodiment given above, it can be seen that the number of the check pulses is 2, that is, when the error calculation unit receives the second pulse generated by the meter under test, the error calculation unit immediately performs the error calculation on the electric energy value measured by the meter under test and the electric energy value measured by the standard meter, and displays the error on the error display unit.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art; the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (8)
1. A test method for dynamic response time characteristics of an electric energy meter is characterized in that whether the electric energy meter can accurately measure dynamic signals stably in real time or not is judged through a test of the dynamic response time characteristics of the electric energy meter, and the test method comprises the following steps:
(1) selecting an electric energy meter with the accuracy grade of A grade as a tested meter;
(2) selecting a standard device with the accuracy grade of B grade under the dynamic test signal as a checking device;
(3) dynamic basic error limit of the agreed tested table is EbThe standard deviation limit of the error obtained by M times of measurement is S0；
(4) Calculating the dynamic response time of the electric energy meter according to the meter constant of the standard meter, the dynamic basic error limit value of the tested meter and the meter constant of the tested meter in the checking device, and expressing the dynamic response time by using the number N of the checking pulses;
(5) using a checking device to carry out M times of error checking on the checked table, and setting the number of checking pulses as N; the checking device gives out the basic error value of the detected table after receiving N pulses sent by the detected table, and records the error value gamma at the moment.
(6) Carrying out M times of error check according to the conditions in the step (5) to obtain a group of dynamic errors gammaiI takes 1,2,3, …, 8; calculating to obtain standard deviation S according to the measured error value1。
(7) Judging the dynamic response time characteristic of the electric energy meter, and judging gammai|≤EbAnd S1≤S0Whether the two are true at the same time; if the two conditions are met, the dynamic response time characteristic of the detected electric energy meter is qualified; if not, the dynamic response time characteristic of the table to be detected is not qualified.
2. The method for testing the dynamic response time characteristic of the electric energy meter according to claim 1, wherein the mathematical expression of the calculation of the dynamic response time is as follows:
in the above formula, C0Is the instrument constant of a standard meter in the device, imp/kWh; cLimp/kWh, the meter constant for the meter under test; ebIs the basic error limit value of the detected table; round () is a floor function.
3. The method of claim 1, wherein the class B level is two levels of accuracy higher than the class a level.
4. The method for testing the dynamic response time characteristic of the electric energy meter according to claim 1, wherein the value range of M is as follows: m is more than or equal to 5 and less than or equal to 10.
5. The method for testing the dynamic response time characteristic of the electric energy meter according to claim 1, wherein the standard for judging the qualification of the dynamic response time characteristic of the electric energy meter is as follows: dynamic error gammaiAnd standard deviation S1Are not greater than the specified limits.
6. The method for testing the dynamic response time characteristic of the electric energy meter according to claim 1, wherein the calibration device comprises a master controller, a dynamic signal generator, a signal conditioning circuit, a standard meter, an error display unit and an error calculation unit; the output end of the dynamic signal generator is connected with the input end of the signal conditioning circuit; the output end of the signal conditioning circuit is respectively connected with the input ends of the standard table and the detected table; the output ends of the standard table and the detected table are respectively connected with the corresponding input ports of the error calculation unit; the output end of the error calculation unit is connected with the error calculation unit; and the master controller is connected with and controls the dynamic signal generator.
7. The method for testing the dynamic response time characteristics of the electric energy meter according to claim 6, wherein the signal conditioning circuit conditions and sends the dynamic test signal sent by the dynamic signal generator to the standard meter and the tested meter; and the standard table and the detected table respectively output respective dynamic response pulses to the error calculation unit for dynamic response error calculation.
8. The method as claimed in claim 7, wherein the dynamic test signal generated by the device is formed by subjecting a power frequency signal to sine amplitude modulation, frequency modulation and phase modulation.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911365898.1A CN111190134B (en) | 2019-12-26 | 2019-12-26 | Dynamic response time characteristic test method and verification device for electric energy meter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911365898.1A CN111190134B (en) | 2019-12-26 | 2019-12-26 | Dynamic response time characteristic test method and verification device for electric energy meter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111190134A true CN111190134A (en) | 2020-05-22 |
| CN111190134B CN111190134B (en) | 2024-05-14 |
Family
ID=70708004
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911365898.1A Active CN111190134B (en) | 2019-12-26 | 2019-12-26 | Dynamic response time characteristic test method and verification device for electric energy meter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111190134B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114047472A (en) * | 2021-12-22 | 2022-02-15 | 安徽南瑞中天电力电子有限公司 | Metering error monitoring system of intelligent electric meter and monitoring method and device thereof |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61126484A (en) * | 1984-11-22 | 1986-06-13 | Toshiba Corp | Standard instrument with arithmetic function |
| JP2007327764A (en) * | 2006-06-06 | 2007-12-20 | Tokyo Keiki Kogyo Kk | System for measuring instrumental error of watt-hour meter |
| WO2015085830A1 (en) * | 2013-12-09 | 2015-06-18 | 国家电网公司 | Apparatus for testing dynamic characteristics of electronic energy meter |
| CN107861091A (en) * | 2017-10-23 | 2018-03-30 | 国网江西省电力公司电力科学研究院 | A kind of dynamic property source tracing method based on dynamic electric energy calibrator |
| CN212646969U (en) * | 2019-12-26 | 2021-03-02 | 国网江西省电力有限公司电力科学研究院 | Calibration device for dynamic response time characteristic of electric energy meter |
-
2019
- 2019-12-26 CN CN201911365898.1A patent/CN111190134B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61126484A (en) * | 1984-11-22 | 1986-06-13 | Toshiba Corp | Standard instrument with arithmetic function |
| JP2007327764A (en) * | 2006-06-06 | 2007-12-20 | Tokyo Keiki Kogyo Kk | System for measuring instrumental error of watt-hour meter |
| WO2015085830A1 (en) * | 2013-12-09 | 2015-06-18 | 国家电网公司 | Apparatus for testing dynamic characteristics of electronic energy meter |
| CN107861091A (en) * | 2017-10-23 | 2018-03-30 | 国网江西省电力公司电力科学研究院 | A kind of dynamic property source tracing method based on dynamic electric energy calibrator |
| CN212646969U (en) * | 2019-12-26 | 2021-03-02 | 国网江西省电力有限公司电力科学研究院 | Calibration device for dynamic response time characteristic of electric energy meter |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN114047472A (en) * | 2021-12-22 | 2022-02-15 | 安徽南瑞中天电力电子有限公司 | Metering error monitoring system of intelligent electric meter and monitoring method and device thereof |
| CN114047472B (en) * | 2021-12-22 | 2024-02-23 | 安徽南瑞中天电力电子有限公司 | Metering error monitoring system of intelligent ammeter and monitoring method and device thereof |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111190134B (en) | 2024-05-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN101694518B (en) | Direct current energy meter test device, energy error test method and creeping calibration method | |
| CN201378204Y (en) | Automatic detecting and metrological characteristic analyzing device for energy meter standard devices | |
| CN101281243B (en) | Device and method for testing equipotential closed loop electrical energy meter | |
| CN107478382B (en) | Automatic detection device and detection method for pressure instrument | |
| CN104459588A (en) | System and method for current sensor test | |
| CN212646969U (en) | Calibration device for dynamic response time characteristic of electric energy meter | |
| CN105629052B (en) | Chip power-consumption real-time detection method | |
| CN103969614A (en) | Calibration method for digital multimeter | |
| CN105301546A (en) | Ultrasonic partial discharge tester verification method and system | |
| CN106018505A (en) | Calibration method for concrete chlorine ion content meter | |
| CN114200381B (en) | Intelligent ammeter reliability detection system and method | |
| CN111190134B (en) | Dynamic response time characteristic test method and verification device for electric energy meter | |
| CN207502618U (en) | Nonlinear-load power output device | |
| CN206695822U (en) | A kind of vibrating string type sensor work condition online testing device | |
| CN107861091A (en) | A kind of dynamic property source tracing method based on dynamic electric energy calibrator | |
| CN209656238U (en) | A kind of electric and electronic product vibration test proficiency testing device | |
| CN107589396B (en) | dynamic performance tracing method based on conventional electric energy calibrator | |
| CN101871971A (en) | Method for measuring frequency-phase characteristic of electrical network | |
| CN107677894A (en) | Nonlinear-load power output device | |
| CN113156273B (en) | Electrical strength test capability verification method and device | |
| CN114859281A (en) | Calibration device and method for function generator | |
| CN107861033A (en) | The calibration method and system of oscillation wave partial discharge detection system position error | |
| CN210005590U (en) | forward and reverse microwave power measuring circuits | |
| CN106840246A (en) | A kind of vibrating string type sensor work condition on-line testing method and device | |
| CN106707220A (en) | Typical non-linear load single-phase electric energy meter calibration device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |