CN114019222B - Half-wave detection method for high-precision measurement of residual current - Google Patents
Half-wave detection method for high-precision measurement of residual current Download PDFInfo
- Publication number
- CN114019222B CN114019222B CN202111305968.1A CN202111305968A CN114019222B CN 114019222 B CN114019222 B CN 114019222B CN 202111305968 A CN202111305968 A CN 202111305968A CN 114019222 B CN114019222 B CN 114019222B
- Authority
- CN
- China
- Prior art keywords
- residual current
- resistor
- amplifier
- effective value
- current signal
- 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.)
- Active
Links
- 238000001514 detection method Methods 0.000 title claims abstract description 34
- 238000005259 measurement Methods 0.000 title claims abstract description 24
- 238000005070 sampling Methods 0.000 claims abstract description 34
- 238000000034 method Methods 0.000 claims abstract description 13
- 238000013507 mapping Methods 0.000 claims abstract description 10
- 238000006243 chemical reaction Methods 0.000 claims description 24
- 239000003990 capacitor Substances 0.000 claims description 15
- 230000003321 amplification Effects 0.000 claims description 3
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 3
- 238000004364 calculation method Methods 0.000 claims description 2
- 238000011161 development Methods 0.000 abstract description 3
- 238000010586 diagram Methods 0.000 description 4
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000012544 monitoring process Methods 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
- G01R19/145—Indicating the presence of current or voltage
- G01R19/15—Indicating the presence of current
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Current Or Voltage (AREA)
Abstract
The application relates to a half-wave detection method and a half-wave detection circuit for high-precision measurement of residual current, wherein the method comprises the following steps: sampling ADC values of a plurality of points at equal intervals in a positive half period of an alternating current signal through a residual current sampling circuit; calculating effective values of ADC values of a plurality of sampled points through an effective value algorithm; calculating the current value of the residual current signal according to the mapping relation between the real residual current signal and the effective value; by applying the method, the ADC values of a plurality of points are sampled at equal intervals in the positive half period of the alternating current signal through the residual current sampling circuit, then the effective value of the sampled ADC values of the plurality of points is calculated by using an effective value algorithm, and finally the current value of the residual current signal is calculated according to the mapping relation between the real residual current signal and the effective value; the main work is completed by software calculation, the detection speed is high, the detection accuracy is high, and the development cost and time can be effectively saved.
Description
Technical Field
The invention relates to the technical field of monitoring of fire-fighting equipment, in particular to a half-wave detection method for high-precision measurement of residual current.
Background
The residual current detection has wide application in the aspect of monitoring fire-fighting equipment, and can accurately and rapidly detect the residual current, thereby having great significance for electric equipment. The current residual current detection is usually carried out by adopting a direct current offset detection means, and a method capable of rapidly and simply detecting alternating current signals is not available.
Disclosure of Invention
The invention aims to solve the technical problems of the prior art, and provides a half-wave detection method for high-precision measurement of residual current and a half-wave detection circuit for detecting the high-precision measurement of residual current.
The technical scheme adopted for solving the technical problems is as follows:
a half-wave detection method for high-precision measurement of residual current is constructed, which comprises the following steps:
The first step: sampling ADC values of a plurality of points at equal intervals in a positive half period of an alternating current signal through a residual current sampling circuit;
and a second step of: calculating effective values of ADC values of a plurality of sampled points through an effective value algorithm;
And a third step of: and calculating the current value of the residual current signal according to the mapping relation between the real residual current signal and the effective value.
The invention relates to a half-wave detection method for high-precision measurement of residual current, wherein a residual current sampling circuit adopted in the first step comprises the following steps: the two output signal ends of the residual current transformer are respectively and correspondingly connected with a first access end and a second access end, a first conversion resistor for converting an accessed current signal into a voltage signal, and a first amplifier for amplifying the converted voltage signal;
the first sampling method is that an ADC analog sampling port of the singlechip is connected with the output end of the first amplifier to sample signals.
The invention relates to a half-wave detection method for high-precision measurement of residual current, wherein the first access end and the second access end are respectively connected with two ends of a first conversion resistor, one end of the first conversion resistor is connected with a non-inverting input end of a first amplifier, and the other end of the first conversion resistor is grounded; the output end of the first amplifier is connected with a first resistor, and the inverting input end of the first amplifier is connected with a second resistor and a third resistor in parallel; one end of the second resistor, which is away from the inverting input end of the first amplifier, is connected with one end of the first resistor, which is connected with the first amplifier; the negative power supply end of the first amplifier is connected with one end, far away from the first amplifier, of the first resistor through a first capacitor.
According to the half-wave detection method for the high-precision measurement of the residual current, the first access end is connected with the first TVS tube and the second capacitor in parallel; one end, far away from the first access end, of the first TVS tube is connected with the second access end; one end of the second capacitor, which is far away from the first access end, is connected with the second access end; and one end, far away from the first switching resistor, of the fourth resistor is connected with the non-inverting input end of the first amplifier in series.
The invention relates to a half-wave detection method for high-precision measurement of residual current, wherein in the third step, the current value of a residual current signal is calculated according to the mapping relation between a real residual current signal and an effective value by using the formula:
Xrms＝IS/Nb*R5*(R2+R3)/R3/3.3*4096；
Wherein Xrms is the effective value obtained in the second step; IS the current value of the residual current; nb is the amplification factor of the current transformer; r5 is the resistance value of the first conversion resistor; r2 is the resistance value of the second resistor; r3 is the third resistance.
The invention relates to a half-wave detection method for high-precision measurement of residual current, wherein the method adopted in the first step is as follows:
And equidistant sampling is carried out in a complete alternating current signal period to obtain a plurality of sampling data, the residual current sampling circuit is used for amplifying the signal in the positive half period, and the signal in the negative half period is filtered to obtain the ADC value of a plurality of points which are sampled at equal intervals in the positive half period of the alternating current signal.
The invention relates to a half-wave detection method for high-precision measurement of residual current, wherein in the second step, the effective value of ADC values of a plurality of sampled points is calculated by an effective value algorithm, and the method comprises the following steps:
and (3) obtaining an effective value through a root mean square algorithm by using a plurality of point ADC values acquired in the positive half period of the alternating current signal obtained in the first step, and then multiplying the effective value by the coefficient proportion of a hardware circuit to obtain an actual effective value.
The half-wave detection circuit for high-precision measurement of the residual current comprises a third access end and a fourth access end which are respectively and correspondingly connected with two output signal ends of a residual current transformer, a second conversion resistor for converting an accessed current signal into a voltage signal, and a second amplifier for amplifying the converted voltage signal; the third access end and the fourth access end are respectively connected with two ends of the second switching resistor, one end of the second switching resistor is connected with the non-inverting input end of the second amplifier, and the other end of the second switching resistor is grounded;
The output end of the second amplifier is connected with a fifth resistor, and the inverting input end of the second amplifier is connected with a sixth resistor and a seventh resistor in parallel; one end of the seventh resistor, which is away from the inverting input end of the second amplifier, is grounded, and one end of the sixth resistor, which is away from the inverting input end of the second amplifier, is connected with one end of the fifth resistor, which is connected with the second amplifier; and the negative power supply end of the second amplifier is connected with one end, far away from the second amplifier, of the fifth resistor through a third capacitor.
The invention relates to a half-wave detection circuit for high-precision measurement of residual current, wherein a second TVS tube and a fourth capacitor are connected in parallel with a third access end; one end, far away from the third access end, of the second TVS tube is connected with the fourth access end; one end of the fourth capacitor, which is far away from the third access end, is connected with the fourth access end; and one end, far away from the second switching resistor, of the second switching resistor is connected with the non-inverting input end of the second amplifier in series.
The application has the beneficial effects that: by applying the method of the application, the ADC values of a plurality of points are sampled at equal intervals in the positive half period of the alternating current signal through the residual current sampling circuit, then the effective value of the sampled ADC values of the plurality of points is calculated by using the effective value algorithm, and finally the current value of the residual current signal is calculated according to the mapping relation between the real residual current signal and the effective value, without DC offset, the main work is finished by software calculation, the detection speed is high, the detection accuracy is high, and the development cost and time can be effectively saved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the present invention will be further described with reference to the accompanying drawings and embodiments, in which the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained by those skilled in the art without inventive effort:
FIG. 1 is a flow chart of a half-wave detection method for high-precision measurement of residual current in a preferred embodiment of the invention;
FIG. 2 is a half-wave detection method residual current sampling circuit diagram for high-precision measurement of residual current in a preferred embodiment of the present invention;
FIG. 3 is a schematic diagram of the application of a half-wave detection method for high-precision measurement of residual current in a three-phase distribution system residual current transformer according to a preferred embodiment of the present invention;
fig. 4 is a schematic diagram of an application of a half-wave detection method for high-precision measurement of residual current in a residual current transformer of a single-phase distribution system according to a preferred embodiment of the present invention;
fig. 5 is a half-wave detection method AINO end output waveform diagram of the residual current high-precision measurement according to the preferred embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the following description will be made in detail with reference to the technical solutions in the embodiments of the present invention, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by a person skilled in the art without any inventive effort, are intended to be within the scope of the present invention, based on the embodiments of the present invention.
The half-wave detection method for high-precision measurement of residual current in the preferred embodiment of the invention is shown in fig. 1, and referring to fig. 2-5, the method comprises the following steps:
S01: sampling ADC values of a plurality of points at equal intervals in a positive half period of an alternating current signal through a residual current sampling circuit;
s02: calculating effective values of ADC values of a plurality of sampled points through an effective value algorithm;
S03: and calculating the current value of the residual current signal according to the mapping relation between the real residual current signal and the effective value.
By applying the method, the ADC values of a plurality of points are sampled at equal intervals in the positive half period of the alternating current signal through the residual current sampling circuit, then the effective value of the sampled ADC values of the plurality of points is calculated by using an effective value algorithm, and finally the current value of the residual current signal is calculated according to the mapping relation between the real residual current signal and the effective value; the main work is completed by software calculation, the detection speed is high, the detection accuracy is high, and the development cost and time can be effectively saved.
It should be noted that, as shown in fig. 3, the three-phase distribution system has A, B, C, N four wires passing through the residual current transformer at the same time, and as shown in fig. 4, the single-phase distribution system has L, N two wires passing through the residual current transformer at the same time;
preferably, the residual current sampling circuit used in the first step includes: the two output signal ends of the residual current transformer are respectively and correspondingly connected with a first access end and a second access end, a first conversion resistor for converting an accessed current signal into a voltage signal, and a first amplifier for amplifying the converted voltage signal;
As shown in fig. 2, two output signals of the residual current transformer are respectively connected to two ct_input ends (a first connection end and a second connection end), current is converted into a voltage signal through a first conversion resistor R5 and then amplified through a first amplifier U1, then transmitted to an analog sampling port of an ADC of the singlechip through AIN0 for signal sampling, current is connected to an INPUT end of an operational amplifier through the residual current transformer, voltage lifting of a central point is not performed, error introduction is reduced, signal positive period signal is directly amplified and output, and an actual value is obtained through CPU operation.
The first step of sampling method is that the ADC analog sampling port of the singlechip is connected with the output end of the first amplifier to sample signals.
Preferably, the first access terminal (the upper ct_input port in fig. 2) and the second access terminal (the lower ct_input port in fig. 2) are respectively connected to two ends of the first switching resistor R5, one end of the first switching resistor R5 is connected to the non-inverting INPUT terminal of the first amplifier U1, and the other end of the first switching resistor R5 is grounded; the output end of the first amplifier U1 is connected with a first resistor R1, and the inverting input end of the first amplifier U1 is connected with a second resistor R2 and a third resistor R3 in parallel; one end, deviating from the inverting input end of the first amplifier U1, of the second resistor R2 is connected with one end, connected with the first amplifier U1, of the first resistor R1; the negative power supply end of the first amplifier U1 is grounded, and the negative power supply end of the first amplifier U1 is connected with one end, far away from the first amplifier U1, of the first resistor R1 through a first capacitor C1. Preferably, the first access terminal is connected in parallel with a first TVS tube TVS1 and a second capacitor C2; one end of the first TVS tube TVS1, which is far away from the first access end, is connected with the second access end; one end of the second capacitor C2, which is far away from the first access end, is connected with the second access end; one end of the first conversion resistor R5 far away from the first access end is connected with a fourth resistor R4 in series, and one end of the fourth resistor R4 far away from the first conversion resistor R5 is connected with the non-inverting input end of the first amplifier U1.
Preferably, in the third step, the current value of the residual current signal is calculated according to the mapping relation between the actual residual current signal and the effective value by using the formula:
Xrms＝IS/Nb*R5*(R2+R3)/R3/3.3*4096；
wherein Xrms is the effective value obtained in the second step; IS the current value of the residual current; nb is the amplification factor of the current transformer; r5 is the resistance value of the first conversion resistor; r2 is the resistance value of the second resistor; r3 is the third resistance value; by the mode, the current value of the residual current can be detected very conveniently, quickly and accurately.
Preferably, the method adopted in the first step is as follows:
And equidistant sampling is carried out in a complete alternating current signal period to obtain a plurality of sampling data, the residual current sampling circuit is used for amplifying the signal in the positive half period, and the signal in the negative half period is filtered to obtain the ADC value of a plurality of points which are sampled at equal intervals in the positive half period of the alternating current signal.
Preferably, the alternating current signal period is 20MS, 512 equidistant samples are carried out for 512 times in 20MS to obtain 512 sampled data, the residual current sampling circuit is used for amplifying the signals of the positive half period, and the signals of the negative half period are filtered, so that the 512 points are ordered, and 256 points in the positive sequence (large value) direction are adopted for carrying out a root mean square effective value algorithm;
preferably, in the second step, the effective value of the ADC values of the sampled multiple points is calculated by an effective value algorithm, which includes:
obtaining an effective value through a root mean square algorithm by a plurality of point ADC values acquired in the positive half period of the alternating current signal obtained in the first step, and then multiplying the effective value by the coefficient proportion of a hardware circuit to obtain an actual effective value;
The formula adopted in the calculation is as follows:
Preferably, during sampling, an analog signal is connected to an ADC interface of the processing unit to obtain 256 point ADC values acquired in the positive half period of an alternating current signal, an effective value is obtained through a root mean square algorithm, and then the effective value is multiplied by the coefficient proportion of a hardware circuit to obtain an actual effective value.
Referring to fig. 2, the half-wave detection circuit for high-precision measurement of residual current comprises a third access terminal and a fourth access terminal which are respectively and correspondingly connected with two output signal terminals of a residual current transformer, a second conversion resistor for converting an accessed current signal into a voltage signal, and a second amplifier for amplifying the converted voltage signal; the third access end and the fourth access end are respectively connected with two ends of a second conversion resistor, one end of the second conversion resistor is connected with the non-inverting input end of the second amplifier, and the other end of the second conversion resistor is grounded; the output end of the second amplifier is connected with a fifth resistor, and the inverting input end of the second amplifier is connected with a sixth resistor and a seventh resistor in parallel; one end of the seventh resistor, which is far away from the inverting input end of the second amplifier, is grounded, and one end of the sixth resistor, which is far away from the inverting input end of the second amplifier, is connected with one end of the fifth resistor, which is connected with the second amplifier; the negative power supply end of the second amplifier is grounded, and the negative power supply end of the second amplifier is connected with one end, far away from the second amplifier, of the fifth resistor through a third capacitor. The third access end is connected with a second TVS tube and a fourth capacitor in parallel; one end of the second TVS tube, which is far away from the third access end, is connected with the fourth access end; one end of the fourth capacitor, which is far away from the third access end, is connected with the fourth access end; one end of the second conversion resistor, which is far away from the third access end, is connected with an eighth resistor in series, and one end of the eighth resistor, which is far away from the second conversion resistor, is connected with the non-inverting input end of the second amplifier.
The circuit is consistent with the circuit above, and the principle and functions are not repeated;
It will be understood that modifications and variations will be apparent to those skilled in the art from the foregoing description, and it is intended that all such modifications and variations be included within the scope of the following claims.
Claims (2)
1. The half-wave detection method for high-precision measurement of residual current is characterized by comprising the following steps of:
The first step: sampling ADC values of a plurality of points at equal intervals in a positive half period of an alternating current signal through a residual current sampling circuit;
and a second step of: calculating effective values of ADC values of a plurality of sampled points through an effective value algorithm;
And a third step of: calculating the current value of the residual current signal according to the mapping relation between the real residual current signal and the effective value;
the method adopted in the first step is as follows:
Equidistant sampling is carried out in a complete alternating current signal period to obtain a plurality of sampling data, a residual current sampling circuit is used for amplifying signals of a positive half period, and signals of a negative half period are filtered to obtain ADC values of a plurality of points which are sampled at equal intervals in the positive half period of the alternating current signal;
The residual current sampling circuit used in the first step includes: the two output signal ends of the residual current transformer are respectively and correspondingly connected with a first access end and a second access end, a first conversion resistor for converting an accessed current signal into a voltage signal, and a first amplifier for amplifying the converted voltage signal;
the first sampling method is that an ADC analog sampling port of a singlechip is connected with the output end of a first amplifier to sample signals;
The first access end and the second access end are respectively connected with two ends of the first conversion resistor, one end of the first conversion resistor is connected with the non-inverting input end of the first amplifier, and the other end of the first conversion resistor is grounded; the output end of the first amplifier is connected with a first resistor, and the inverting input end of the first amplifier is connected with a second resistor and a third resistor in parallel; one end of the second resistor, which is away from the inverting input end of the first amplifier, is connected with one end of the first resistor, which is connected with the first amplifier; the negative power supply end of the first amplifier is connected with one end, far away from the first amplifier, of the first resistor through a first capacitor;
the first access end is connected with a first TVS tube and a second capacitor in parallel; one end, far away from the first access end, of the first TVS tube is connected with the second access end; one end of the second capacitor, which is far away from the first access end, is connected with the second access end; a fourth resistor is connected in series with one end of the first conversion resistor, which is far away from the first access end, and one end of the fourth resistor, which is far away from the first conversion resistor, is connected with the non-inverting input end of the first amplifier;
in the third step, the current value of the residual current signal is calculated according to the mapping relation between the actual residual current signal and the effective value by using the formula:
Xrms＝IS/Nb*R5*(R2+R3)/R3/3.3*4096；
Wherein Xrms is the effective value obtained in the second step; IS the current value of the residual current; nb is the amplification factor of the current transformer; r5 is the resistance value of the first conversion resistor; r2 is the resistance value of the second resistor; r3 is the third resistance.
2. The half-wave detection method for high-precision measurement of residual current according to claim 1, wherein the effective value calculation method for calculating the effective values of the ADC values of the plurality of sampled points by the effective value algorithm in the second step comprises the steps of:
and (3) obtaining an effective value through a root mean square algorithm by using a plurality of point ADC values acquired in the positive half period of the alternating current signal obtained in the first step, and then multiplying the effective value by the coefficient proportion of a hardware circuit to obtain an actual effective value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111305968.1A CN114019222B (en) | 2021-11-05 | 2021-11-05 | Half-wave detection method for high-precision measurement of residual current |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111305968.1A CN114019222B (en) | 2021-11-05 | 2021-11-05 | Half-wave detection method for high-precision measurement of residual current |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114019222A CN114019222A (en) | 2022-02-08 |
| CN114019222B true CN114019222B (en) | 2024-05-14 |
Family
ID=80061542
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111305968.1A Active CN114019222B (en) | 2021-11-05 | 2021-11-05 | Half-wave detection method for high-precision measurement of residual current |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114019222B (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103645396A (en) * | 2013-11-25 | 2014-03-19 | 泉州市嘉凯机电科技有限公司 | Method and device for low-voltage arc fault detection |
| CN108711822A (en) * | 2018-05-23 | 2018-10-26 | 浙江中凯科技股份有限公司 | A kind of guard method of residual current, device and residual current operated protective device |
| CN111090001A (en) * | 2019-10-21 | 2020-05-01 | 浙江恒业电子有限公司 | Residual current testing system and method |
| CN211402532U (en) * | 2019-10-21 | 2020-09-01 | 浙江恒业电子有限公司 | Residual current testing device |
| DE102019204272A1 (en) * | 2019-03-27 | 2020-10-01 | Siemens Aktiengesellschaft | Residual current device and procedure |
-
2021
- 2021-11-05 CN CN202111305968.1A patent/CN114019222B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103645396A (en) * | 2013-11-25 | 2014-03-19 | 泉州市嘉凯机电科技有限公司 | Method and device for low-voltage arc fault detection |
| CN108711822A (en) * | 2018-05-23 | 2018-10-26 | 浙江中凯科技股份有限公司 | A kind of guard method of residual current, device and residual current operated protective device |
| DE102019204272A1 (en) * | 2019-03-27 | 2020-10-01 | Siemens Aktiengesellschaft | Residual current device and procedure |
| CN111090001A (en) * | 2019-10-21 | 2020-05-01 | 浙江恒业电子有限公司 | Residual current testing system and method |
| CN211402532U (en) * | 2019-10-21 | 2020-09-01 | 浙江恒业电子有限公司 | Residual current testing device |
Non-Patent Citations (1)
| Title |
|---|
| 基于半波真有效值的触/漏电故障电流检测;左金威 等;《四川电力技术》;20170630;第40卷(第3期);66-72 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114019222A (en) | 2022-02-08 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN109541283B (en) | Non-contact voltage measurement system and method | |
| CN109782054B (en) | Alternating voltage commutation differential measurement device and method based on quantum voltage | |
| CN112098916A (en) | System and method for superposing ripples on direct current loop in direct current electric energy detection device | |
| Tung et al. | An Arduino-Based System for Monitoring and Protecting Overvoltage and Undervoltage. | |
| CN102445608B (en) | Monitoring device and calibration method for electric energy quality | |
| JPS61292067A (en) | Method for measuring electric energy | |
| CN114019222B (en) | Half-wave detection method for high-precision measurement of residual current | |
| CN112881865A (en) | High-precision zero sequence voltage detection circuit and method for power distribution network | |
| CN115656864B (en) | Radio frequency power supply signal acquisition circuit and semiconductor process equipment | |
| JPH10232250A (en) | Rms converter, and method and apparatus for measuring rms value | |
| CN114019404A (en) | Three-phase alternating current power supply sequence detection method and system | |
| CN113155159B (en) | Bridge detector | |
| JP4054652B2 (en) | Storage battery internal impedance measurement method and storage battery internal impedance measurement device | |
| CN211718374U (en) | Current detection circuit and current detection equipment | |
| CN110554290B (en) | Cable insulation state monitoring device and monitoring method based on state sensing | |
| CN110138083B (en) | Measurement and control circuit of power distribution unit and calibration method thereof | |
| CN208060600U (en) | A kind of integrator circuit applying to Rogowski coil signal processing | |
| CN105548666A (en) | Electric automobile charging current calculation method free from sampling resistor | |
| JPH1010163A (en) | Effective voltage value measuring apparatus | |
| JPH0251075A (en) | Arrester monitoring apparatus | |
| CN212540524U (en) | Current measurement circuit and equipment applying same | |
| CN217639287U (en) | Resistance measuring circuit | |
| CN217278623U (en) | Line load network detection and fault positioning device | |
| CN214503794U (en) | High-precision zero-sequence voltage detection circuit for power distribution network | |
| CN216117782U (en) | Small voltage signal sampling circuit |
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 | ||
| CB02 | Change of applicant information | ||
| CB02 | Change of applicant information |
Address after: 518000 the three floor of the new world apartment, Nanshan Avenue, Nanshan District, Shenzhen, Guangdong (for office only). Applicant after: Shenzhen hi tech investment Sanjiang Electronics Co.,Ltd. Address before: 518000 the three floor of the new world apartment, Nanshan Avenue, Nanshan District, Shenzhen, Guangdong (for office only). Applicant before: SHENZHEN FANHAI SANJIANG ELECTRONICS Co.,Ltd. |
|
| GR01 | Patent grant | ||
| GR01 | Patent grant |