CN111812411B - Atmospheric electric field sensor driven to simulate rotation through electronic switch - Google Patents
Atmospheric electric field sensor driven to simulate rotation through electronic switch Download PDFInfo
- Publication number
- CN111812411B CN111812411B CN202010607894.6A CN202010607894A CN111812411B CN 111812411 B CN111812411 B CN 111812411B CN 202010607894 A CN202010607894 A CN 202010607894A CN 111812411 B CN111812411 B CN 111812411B
- Authority
- CN
- China
- Prior art keywords
- electronic switch
- shielding
- semicircular
- electric field
- fan
- 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
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
- G01R29/08—Measuring electromagnetic field characteristics
- G01R29/0864—Measuring electromagnetic field characteristics characterised by constructional or functional features
- G01R29/0878—Sensors; antennas; probes; detectors
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R29/00—Arrangements for measuring or indicating electric quantities not covered by groups G01R19/00 - G01R27/00
- G01R29/12—Measuring electrostatic fields or voltage-potential
- G01R29/14—Measuring field distribution
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation
Abstract
The invention relates to an atmospheric electric field sensor driven to rotate in a simulation way through an electronic switch, which comprises an insulated installation shaft, wherein a circular shielding sheet, a first semicircular static sheet and a second semicircular static sheet are sequentially and concentrically arranged on the installation shaft, the circular shielding sheet is uniformly divided into 2n mutually insulated fan-shaped shielding surfaces, each fan-shaped shielding surface is a metal conductive surface, the first semicircular static sheet and the second semicircular static sheet are not shielded by each other and respectively correspond to the n fan-shaped shielding surfaces, each fan-shaped shielding surface is connected with the ground through the electronic switch, the electronic switch is connected with a driving circuit, and the driving circuit controls the electronic switch to realize grounding shielding and hanging leakage of the fan-shaped shielding surfaces. Compared with the prior art, the electronic switch controls the sector shielding and the de-shielding to simulate the rotation of the millstone according to a certain time sequence, and overcomes the defects of large volume, high power consumption and low reliability of the traditional millstone mechanical rotary sensor.
Description
Technical Field
The invention relates to the field of lightning early warning and detection, in particular to an atmospheric electric field sensor which is driven to simulate rotation by an electronic switch.
Background
Lightning activity can cause significant changes in the ground electric field, which can greatly affect human activity, especially in buildings, transmission lines, etc., and can cause serious losses. According to incomplete statistics of national power departments, the tripping times of the power system caused by lightning attack of the high-voltage transmission line in China account for 40% -70% of the total tripping times of the power system, and the tripping rate of the overhead transmission line caused by lightning attack can be higher in places with higher probability of occurrence of lightning in western China and other areas. Therefore, the development of the lightning monitoring and early warning system has great significance for the safe and stable operation of the power grid in China.
The most critical component in lightning monitoring systems is the atmospheric electric field sensor. At present, the ground electric field instrument adopts a millstone type mechanical rotary sensor, the sensor consists of a movable sheet and a static sheet, the movable sheet is driven by a motor to rotate, and the rotating movable sheet alternately shields and leaks the static sheet, so that an electric signal proportional to the atmospheric field intensity is induced. In order to improve the sensitivity of measurement, the current method is mainly realized by increasing the area of a blade and the rotating speed of a motor. Increasing the area of the blade of the millstone is not beneficial to the miniaturization of the measuring device, improves the power loss of a rotating speed increasing system, and the service life and reliability of the measuring device are affected by the high-speed rotation of the blade.
Disclosure of Invention
The invention aims to overcome the defects of large volume, high power consumption and low reliability of a rotating structure of the traditional millstone type mechanical rotating atmospheric electric field sensor in the prior art, and provides an atmospheric electric field sensor which is driven to simulate rotation through an electronic switch.
The aim of the invention can be achieved by the following technical scheme:
the utility model provides an atmospheric electric field sensor through electronic switch drive simulation rotation, includes insulating installation axle, the epaxial circular shielding piece that sets gradually with one heart of installation, first semicircle quiet piece and second semicircle quiet piece, circular shielding piece evenly falls into 2n fan-shaped shielding surfaces that insulate each other, and each fan-shaped shielding surface is the metal conduction face, first semicircle quiet piece and second semicircle quiet piece are each other not sheltered from and are corresponding to n respectively fan-shaped shielding surface, link to each other through electronic switch between each fan-shaped shielding surface and the ground, electronic switch is connected with drive circuit, drive circuit control electronic switch realizes the ground shielding and the unsettled exposure of fan-shaped shielding surface.
Preferably, the electronic switches connected with n fan-shaped shielding surfaces corresponding to the first semicircular static plate are a group, and the electronic switches connected with the other n fan-shaped shielding surfaces are a group;
under the action of a driving circuit, the two groups of n electronic switches realize the gradual shielding of the first semicircular static piece and the second semicircular static piece to the gradual shielding removal according to a certain switching sequence, and the sensing function of the atmospheric electric field is realized in a periodic cycle.
Preferably, the circular shielding sheet is made of a double-sided printed circuit board, the sector shielding surfaces with odd numbers are arranged on the top layer and coated with copper, the sector shielding surfaces with even numbers are arranged on the bottom layer and coated with copper, and projections of adjacent radii of adjacent sector shielding surfaces in the vertical direction are overlapped.
Preferably, the first semicircular static plate and the second semicircular static plate are both metal conductive plates.
Preferably, the radius of the first semicircular static piece is equal to that of the second semicircular static piece.
Preferably, the radius of the first semicircular static piece and the radius of the second semicircular static piece are slightly smaller than the radius of the circular shielding piece.
Preferably, the first semicircular static piece and the second semicircular static piece are arranged in parallel.
Preferably, the electronic switch is an ultra-low leakage current electronic switch.
Preferably, the ultra-low leakage current electronic switch is a MOS switch.
Preferably, the driving circuit adopts a programmable logic device.
Compared with the prior art, the invention has the following beneficial effects:
1. the electronic switch is adopted to simulate the rotation of the shielding sheet, the rapid switching characteristic of the electronic switch can be utilized, dA (t)/dt is increased, a mechanical rotating structure is avoided, the sensitivity of the sensor can be improved by adjusting the frequency of a driving signal, and the electronic switch has the advantages of low power consumption, high reliability, easiness in realization of a circuit structure and high practical value.
2. The circular shielding sheet is manufactured by adopting the double-sided printed circuit board, in order to ensure that no gap is reserved between two adjacent fan-shaped shielding surfaces, the fan-shaped shielding surfaces with odd numbers are arranged on the top layer to cover copper, the fan-shaped shielding surfaces with even numbers are arranged on the bottom layer to cover copper, projections of adjacent radiuses of the adjacent fan-shaped shielding surfaces in the vertical direction are overlapped, no gap is reserved during shielding, and shielding quality is ensured.
Drawings
FIG. 1 is a schematic diagram of a sensor according to the present invention;
FIG. 2 is a schematic view of a circular shield sheet;
FIG. 3 is a diagram of the connection of an electronic switch to 1 to n sector shields;
FIG. 4 is a diagram of the connection of an electronic switch to n+1 to 2n sector shields;
FIG. 5 is a schematic diagram of a driving circuit;
FIG. 6 is a schematic diagram of the operation of the internal registers of the drive circuit, wherein (a) is a schematic diagram of the input from SDI to the internal registers when/CS is low; (b) (c) a schematic of the rising edge of each clock achieving a cyclic left shift and the falling edge of each pulse latching the output G1-Gn signals when/CS is high, respectively;
the drawing is marked: 01. the device comprises a circular shielding sheet 02, a mounting shaft 03, a first semicircular static sheet 04, a second semicircular static sheet 05, an electronic switch group 06 and a driving circuit.
Detailed Description
The invention will now be described in detail with reference to the drawings and specific examples. The present embodiment is implemented on the premise of the technical scheme of the present invention, and a detailed implementation manner and a specific operation process are given, but the protection scope of the present invention is not limited to the following examples.
Examples
As shown in fig. 1, the application provides an atmospheric electric field sensor which is driven to simulate rotation through an electronic switch, and the electronic switch controls the rotation of a sector shielding and shielding simulation millstone according to a certain time sequence, so that the defects of large size, high power consumption and low reliability of the traditional millstone type mechanical rotary sensor are overcome, and the sensor has the advantages of micro power consumption, small size and high reliability. The sensor comprises an insulated mounting shaft 02, wherein a circular shielding plate 01, a first semicircular static plate 03 and a second semicircular static plate 04 are concentrically arranged on the mounting shaft 02 from top to bottom in sequence. The shielding plate and the static plate are insulated from each other.
As shown in fig. 2, the circular shielding sheet 01 is uniformly divided into 2n sector shielding surfaces insulated from each other, namely, sectors, each sector shielding surface is a metal conductive surface, and n consecutive sector shielding surfaces are divided into two groups. The first semicircular static piece 03 and the second semicircular static piece 04 are placed in parallel, are not shielded from each other, and correspond to n fan-shaped shielding surfaces respectively. In this embodiment, the circular shielding plate 01 has a group of semicircles from sector 1 to sector n, and a group of semicircles from sector n+1 to sector 2n, the first semicircular static plate 03 is mounted directly under the semicircles from sector 1 to sector n, and the second semicircular static plate 04 is mounted directly under the semicircles from sector n+1 to sector 2 n.
Each sector shielding surface is connected with the ground through an electronic switch, the electronic switch is connected with a driving circuit 06, and the driving circuit 06 controls the electronic switch to realize the grounding shielding and the suspension leakage of the sector shielding surfaces. The electronic switch is conducted to ground the sector shielding surface, shielding of the corresponding static plate is achieved, the electronic switch is cut off, the sector shielding surface is in a high-resistance state, and signals are induced by the corresponding static plate under the action of an electric field. The n electronic switches connected with the corresponding n fan-shaped shielding surfaces of the first semicircular static piece 03 are a group, the other n electronic switches connected with the fan-shaped shielding surfaces are a group, and the two groups of n electronic switches form an electronic switch group 05. Under the drive of the electronic switch group 05, the two groups of n fan-shaped shielding surfaces realize the gradual shielding and gradual exposure of the static plates according to a certain switching sequence, the two groups of driving signals are 180 degrees different, and the difference is induced on the first semicircular static plate 03 and the second semicircular static plate 04, so that the sensing function of an atmospheric electric field is realized.
The first semicircular static piece 03 and the second semicircular static piece 04 are metal conductive pieces, have the same radius and are slightly smaller than the radius of the circular shielding piece 01.
In this embodiment, the electronic switch specifically adopts an MOS switch with ultra-low leakage current. The two groups of n driving circuits 06 respectively correspond to the two groups of n electronic switches, and the two groups of n electronic switches realize the cycle from gradual shielding to gradual de-shielding of the first semicircular static piece 03 and the second semicircular static piece 04 according to a certain switching sequence under the action of the driving circuits 06.
The principle of the sensor is as follows:
the radius of the metal induction sheet (static sheet) of the electric field sensor is R, the static sheet is in an electric field E, the induction charge Q (t) on the static sheet changes along with time, the charge size is in direct proportion to the external electric field intensity, and the relation is shown in the formula (1):
Q(t)＝-ε 0 EA(t) (1)
epsilon in formula (1) 0 ＝8.854×10 -12 F/m is the free space dielectric constant, A (t) represents the surface area of the blade where the stator is in the electric field E, which is positive when the direction of the electric field is directed from the rotor to the stator. When the electronic switch is turned on gradually, the shielding sheet is grounded gradually, so that the static sheet (induction sheet) is shielded gradually, the switch is turned off gradually until the static sheet is completely shielded, the shielding sheet is suspended, the static sheet (induction sheet) is shielded until the shielding is completely removed, the circulation is repeated all the time, and the induction current on the static sheet (induction sheet) can be calculated by differentiating induction charges with respect to time, as shown in the formula (2):
as can be seen from equation (2), when dA (t)/dt is increased, the sensitivity of the sensor can be improved, and the conventional mechanical millstone sensor can obtain higher sensitivity only by increasing the rotation speed of the motor and increasing the area of the sensor sensing piece. However, increasing the rotation speed of the motor and increasing the area of the sensor chip causes problems of high power consumption and poor reliability. The electronic switch simulation shielding plate is adopted to rotate, the rapid switching characteristic of the electronic switch can be utilized, dA (t)/dt is increased, and a mechanical rotating structure is avoided. Therefore, the circuit has the advantages of low power consumption, high reliability, easy realization of circuit structure and high practical value.
The specific implementation mode of the atmospheric electric field sensor is as follows:
1) The shield of the sensor is uniformly divided into 2n sectors and each sector is insulated from the other as shown in fig. 2. The circular shielding piece 01 is manufactured by the double-sided printed circuit board, in order to ensure that no gap is reserved between two adjacent fan-shaped shielding surfaces, the fan-shaped shielding surfaces with odd numbers are arranged on the top layer to cover copper, the fan-shaped shielding surfaces with even numbers are arranged on the bottom layer to cover copper, projection of adjacent radiuses of the adjacent fan-shaped shielding surfaces in the vertical direction is overlapped, no gap is reserved during shielding, and shielding quality is ensured.
2) Each sector-shaped shielding surface is connected with an ultralow leakage current electronic switch, taking a semicircle formed by the sector-shaped shielding surfaces 1 to n as an example, and the connection mode is shown in fig. 3. One end of the electronic switch Q1 is connected to the fan-shaped shielding surface, the other end of the electronic switch Q1 is grounded, when the electronic switch is turned on when a high-level driving signal is applied to the control electrode G1, the fan-shaped shielding surface is grounded, and the fan-shaped shielding surface shields the induction piece with a corresponding area right below; when a low-level driving signal is applied to the control electrode G1, the switch is turned off, the fan-shaped shielding surface is suspended, and the induction sheet right below is exposed in an atmospheric electric field to generate an induction signal; q1 to Qn are respectively connected with the fan-shaped shielding surfaces 1 to n, and G1 to Gn are switch control ends. Similarly, the other semicircle is similar thereto as shown in fig. 4.
3) The driving circuit 06 of the electronic switch is constituted by a piece of programmable logic device (FPGA), as shown in fig. 5. The control terminals G1 to Gn of the electronic switch are led out from the I/O port of the programmable logic device FPGA and used as control signals of the electronic switch, the CLK terminal is a clock input terminal, the SDI is an external data input terminal, and the/CS is the control terminal of the chip. when/CS is at low level, external data is serially input into an internal register of the FPGA under the cooperation of a clock CLK; when/CS is high, the external data input is disabled, and the logic circuits within the FPGA are activated, and the output signals G1-Gn are started at clock beats. A 2 n-bit register is designed inside the programmable logic device as shown in fig. 6. The control signal is outputted from the high n bits of the register, and inputted from the SDI to the internal register in cooperation with the clock CLK when/CS is low, as shown in (a) of fig. 6; when/CS is at high level, the 2n register carries out cyclic left shift operation, the rising edge of each clock realizes cyclic left shift, the falling edge of each pulse latches and outputs G1 to Gn signals, as shown in (b) and (c) of fig. 6, and the like, so that the gradual shielding to complete shielding of the sensing piece can be realized, and then the same function of the mechanical rotation millstone sensor can be realized from gradual shielding to complete shielding. The sensitivity of the sensor can be changed by adjusting the frequency of CLK.
Claims (9)
1. The atmospheric electric field sensor is characterized by comprising an insulated mounting shaft (02), wherein a circular shielding sheet (01), a first semicircular static sheet (03) and a second semicircular static sheet (04) are sequentially and concentrically arranged on the mounting shaft (02), the circular shielding sheet (01) is uniformly divided into 2n mutually insulated sector shielding surfaces, each sector shielding surface is a metal conductive surface, the first semicircular static sheet (03) and the second semicircular static sheet (04) are mutually non-shielded and respectively correspond to the n sector shielding surfaces, each sector shielding surface is connected with the ground through an electronic switch, and the electronic switch is connected with a driving circuit (06), and the driving circuit (06) controls the electronic switch to realize the grounding shielding and suspension leakage of the sector shielding surfaces;
the electronic switches connected with n fan-shaped shielding surfaces corresponding to the first semicircular static piece (03) are a group, and the electronic switches connected with the other n fan-shaped shielding surfaces are a group;
under the action of a driving circuit (06), the two groups of n electronic switches realize the gradual shielding of the first semicircular static piece (03) and the second semicircular static piece (04) to the gradual shielding removal according to a certain switching sequence, and the sensing function of an atmospheric electric field is realized periodically and circularly; wherein, the two groups of driving signals are 180 degrees different, and difference is induced on the first semicircular static piece (03) and the second semicircular static piece (04).
2. An atmospheric electric field sensor driven by an electronic switch to rotate in a simulated manner according to claim 1, wherein the circular shielding plate (01) is made of a double-sided printed circuit board, the odd-numbered fan-shaped shielding surfaces are arranged on the top layer and coated with copper, the even-numbered fan-shaped shielding surfaces are arranged on the bottom layer and coated with copper, and projections of adjacent radii of adjacent fan-shaped shielding surfaces in the vertical direction are overlapped.
3. An atmospheric electric field sensor driven by an electronic switch to simulate rotation according to claim 1, wherein said first semicircular static plate (03) and said second semicircular static plate (04) are both metal conductive plates.
4. An atmospheric electric field sensor driven by an electronic switch to simulate rotation according to claim 1, wherein the radius of the first semicircular static plate (03) and the radius of the second semicircular static plate (04) are equal.
5. An atmospheric electric field sensor driven by an electronic switch to simulate rotation according to claim 4, wherein the radius of said first semicircular static plate (03) and said second semicircular static plate (04) is slightly smaller than the radius of the circular shielding plate (01).
6. An atmospheric electric field sensor driven by an electronic switch to simulate rotation according to claim 1, wherein said first semicircular static plate (03) and said second semicircular static plate (04) are disposed in parallel.
7. An atmospheric electric field sensor driven by an electronic switch to simulate rotation according to claim 1, wherein said electronic switch is an ultra low leakage current electronic switch.
8. An atmospheric electric field sensor driven by an electronic switch to simulate rotation according to claim 7, wherein said ultra low leakage current electronic switch is a MOS switch.
9. An atmospheric electric field sensor driven by an electronic switch to simulate rotation according to claim 1, wherein said driving circuit (06) employs a programmable logic device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010607894.6A CN111812411B (en) | 2020-06-30 | 2020-06-30 | Atmospheric electric field sensor driven to simulate rotation through electronic switch |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202010607894.6A CN111812411B (en) | 2020-06-30 | 2020-06-30 | Atmospheric electric field sensor driven to simulate rotation through electronic switch |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111812411A CN111812411A (en) | 2020-10-23 |
| CN111812411B true CN111812411B (en) | 2023-05-30 |
Family
ID=72856349
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202010607894.6A Active CN111812411B (en) | 2020-06-30 | 2020-06-30 | Atmospheric electric field sensor driven to simulate rotation through electronic switch |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111812411B (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5315232A (en) * | 1991-01-03 | 1994-05-24 | Stewart Michael F | Electric field measuring system |
| RU2196339C1 (en) * | 2001-07-27 | 2003-01-10 | Башкирский государственный университет | Set measuring charge of static electricity |
| JP2018173347A (en) * | 2017-03-31 | 2018-11-08 | 京セラドキュメントソリューションズ株式会社 | Surface potential sensor, surface potential measuring method, and image forming apparatus |
| CN108896839A (en) * | 2018-09-27 | 2018-11-27 | 云南电网有限责任公司电力科学研究院 | A kind of measurement method of the DC electric field based on high-speed analog switch |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201255750Y (en) * | 2008-10-23 | 2009-06-10 | 国家林业局哈尔滨林业机械研究所 | Differential atmospheric electric field sensor |
| CN103235195B (en) * | 2013-04-28 | 2015-07-29 | 北京理工大学 | A kind of Non-contact static detection device |
| CN208805546U (en) * | 2018-09-27 | 2019-04-30 | 云南电网有限责任公司电力科学研究院 | A kind of measuring device of the DC electric field based on high-speed analog switch |
-
2020
- 2020-06-30 CN CN202010607894.6A patent/CN111812411B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5315232A (en) * | 1991-01-03 | 1994-05-24 | Stewart Michael F | Electric field measuring system |
| RU2196339C1 (en) * | 2001-07-27 | 2003-01-10 | Башкирский государственный университет | Set measuring charge of static electricity |
| JP2018173347A (en) * | 2017-03-31 | 2018-11-08 | 京セラドキュメントソリューションズ株式会社 | Surface potential sensor, surface potential measuring method, and image forming apparatus |
| CN108896839A (en) * | 2018-09-27 | 2018-11-27 | 云南电网有限责任公司电力科学研究院 | A kind of measurement method of the DC electric field based on high-speed analog switch |
Non-Patent Citations (1)
| Title |
|---|
| 基于地面电场仪的雷电监测装置设计;朱武等;高电压技术;第45卷(第5期);第1490-1495页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111812411A (en) | 2020-10-23 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| WO2020113940A1 (en) | Anti-magnetic metering and detection device | |
| CN203658526U (en) | Live-line detection device used for partial discharging of distribution cable | |
| CN111812411B (en) | Atmospheric electric field sensor driven to simulate rotation through electronic switch | |
| CN110501619B (en) | High-frequency response partial pressure measuring device | |
| CN101893650B (en) | Voltage measurement device for high-voltage direct-current power transmission valve assembly | |
| CN1130958C (en) | Vacuum plasma lightning arresting method and device | |
| CN204028179U (en) | Anti-static electric energy meter housing | |
| CN204405728U (en) | A kind of arrester discharge counter | |
| CN101793926A (en) | Aging test bench | |
| Ji et al. | Influence of voltage waveforms on partial discharge characteristics of protrusion defect in GIS | |
| CN115356534A (en) | Method for reducing frequency spectrum leakage during power grid current FFT harmonic extraction | |
| CN212410745U (en) | Excitation source of transformer substation grounding grid positioning device | |
| CN203444096U (en) | Verifying device of ultrahigh frequency partial discharge detector of high-voltage switch device | |
| RU104729U1 (en) | ELECTROSTATIC FLUXMETER | |
| CN104635025A (en) | Discharge counter and discharge counting method for arrester | |
| CN208904881U (en) | A kind of DC power supply for electromagnetic compatibility test | |
| CN218381153U (en) | Non-magnetic metering device of intelligent water meter | |
| CN109540178B (en) | Counting structure for judging position of character wheel based on capacitance | |
| CN209264839U (en) | A kind of atmospheric electric field detector stator structure | |
| CN204841936U (en) | Old and useless circuit board iron element recovery system | |
| CN211652941U (en) | Novel protective pressing plate rapid measuring instrument | |
| US3814908A (en) | Illuminated figure indicating, counter | |
| CN214228146U (en) | Circuit structure for simultaneously driving multiple motors to operate | |
| CN217931881U (en) | Switch cabinet discharge detection system based on ultrasonic ranging | |
| CN110569955A (en) | character wheel position judging and counting device based on capacitance and metering instrument |
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 |