CN109459617B - Method for measuring resistance of grounding loop of intelligent grounding early warning device in power test - Google Patents
Method for measuring resistance of grounding loop of intelligent grounding early warning device in power test Download PDFInfo
- Publication number
- CN109459617B CN109459617B CN201810012016.2A CN201810012016A CN109459617B CN 109459617 B CN109459617 B CN 109459617B CN 201810012016 A CN201810012016 A CN 201810012016A CN 109459617 B CN109459617 B CN 109459617B
- Authority
- CN
- China
- Prior art keywords
- resistance
- grounding
- measuring
- voltage
- analog
- 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
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/16—Measuring impedance of element or network through which a current is passing from another source, e.g. cable, power line
- G01R27/18—Measuring resistance to earth, i.e. line to ground
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/20—Measuring earth resistance; Measuring contact resistance, e.g. of earth connections, e.g. plates
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Measurement Of Resistance Or Impedance (AREA)
Abstract
The invention discloses a method for measuring the resistance of a grounding loop of an intelligent grounding early warning device in a power test, wherein a grounding resistance measuring module comprises a constant current source measuring unit and a constant voltage source measuring unit, the constant current source measuring unit comprises a constant current source, a voltage measuring quantum unit and an analog-digital converter, and the analog-digital converter respectively amplifies voltage signals in a differentiated mode through five internal channels and then performs AD conversion; the constant voltage source detection unit is used for capacity measurement and comprises a constant voltage source and a Hall sensor, and the constant voltage source detection unit and the constant current source measurement unit work alternately. The substantial effects of the invention are as follows: the gain channel of the digital-to-analog converter is arranged, so that the resistance measurement of the ground loop around the threshold is more accurate, the resistance measurement precision of the ground resistance far away from the threshold is reduced, the integral measurement efficiency of the converter is improved, a constant voltage source measurement unit is added, and the reliability of ground protection in the power test is improved.
Description
Technical Field
The invention relates to the technical field of electric power, in particular to a method for measuring resistance of a grounding loop of an intelligent grounding early-warning device in an electric power test.
Background
In the electric power overhaul test process, reliable test grounding is the necessary guarantee of accurate experimental data and life equipment safety. The transformer substation is required to perform voltage-withstanding or partial-discharge high-voltage tests on power equipment such as transformers, transformers and cables regularly, and all tested instruments and equipment must be reliably grounded so as to guarantee personal safety. The existing grounding early warning device for the power test judges whether grounding is qualified or not by measuring whether grounding loop resistance exceeds threshold setting or not, so that the accuracy and the measuring speed of measuring the grounding loop resistance become core problems of the early warning device.
Chinese patent is granted No. CN 103207342B, granted No. 2016, 09.07, a day, discloses an intelligent early warning device for overhaul test grounding, which mainly comprises: the device comprises a CPU controller, a grounding resistance measuring circuit, a control circuit, a voice alarm system, an LCD display and a keypad, wherein the CPU controller is connected with a direct current voltammetry grounding resistance measuring circuit which is formed by a direct current constant current output, grounding and auxiliary grounding point differential voltage measuring circuit, and the CPU controller is triggered to perform resistance timing measurement by timing interruption; the CPU controller is connected with a control loop output, an I/O port of the CPU controller is adopted, and a relay and a contactor for controlling the on-off of a test power supply are connected; the CPU controller is provided with a keyboard which is connected with an interface of the CPU controller and realizes related operation and resistance constant value setting; it can realize the setting of fixed value, the real-time measurement and display of ground resistance, the real-time control of test power supply, etc. However, in the above patent, a dc voltammetry resistance measurement module, which is mainly a differential voltage measurement circuit between a 0.5A dc constant current output, a ground and an auxiliary ground point, is designed on a ground resistance measurement circuit to measure the ground resistance, and the ground resistance measurement method makes the analog-to-digital converter AD7705 not fully utilized, so that the ground circuit resistance measurement accuracy is reduced, and the measurement efficiency is reduced.
Disclosure of Invention
The invention aims to solve the technical problem of how to design a method for improving the measurement accuracy and the measurement efficiency of measuring loop resistance.
The technical scheme adopted by the invention for solving the problems is as follows: a method for measuring the resistance of grounding loop of intelligent early-warning device for electric power test grounding is characterized in that the grounding resistance measuring module comprises a constant current source measuring unit and a constant voltage source measuring unit, the constant current source measuring unit comprises a constant current source, a voltage measuring quantum unit and an analog-to-digital converter AD7705, the constant current source is connected to the grounding loop, the voltage measuring quantum unit is used for measuring the voltages at two ends of the grounding loop and transmitting voltage signals to the digital-to-analog converter AD7705, and the digital-to-analog converter AD7705 amplifies the voltage signals through an internal programmable gain amplifier and then performs AD conversion; the constant voltage source detection unit comprises a constant voltage source and a Hall sensor, the constant voltage source is connected to a grounding loop, and the Hall sensor is located in the grounding loop and transmits acquired current signals to the processor module.
Preferably, the hall sensor is a magnetic balance type current sensor, and the response time of the hall sensor is less than 10 mus.
Preferably, the threshold resistance B of the ground resistance is set to 0.2 Ω, and the setting method of the digital-to-analog converter AD7705 is as follows:
s1: the digital-to-analog converter AD7705 is divided into 5 gain amplification channels, a first gain channel is used for amplifying voltage signals within a resistance range of 0-0.15 omega, a second gain channel is used for amplifying voltage signals within a resistance range of 0.15-0.25 omega, a third gain channel is used for amplifying voltage signals within a resistance range of 0.25-2 omega, a fourth gain channel is used for amplifying voltage signals within a resistance range of 2-5 omega, and a fifth gain channel is used for amplifying voltage signals with a resistance value of more than 5 omega;
s2: the resistance range served by the second gain channel is (0.5B, 1.5B), and when the gain multiple is set by the gain channel, the voltage signal is amplified to be close to the full-scale voltage of the analog-to-digital converter, so that the resistance measurement of the resistance range is most accurate;
s3: amplifying voltage signals of a first gain channel and a third gain channel which are adjacent to a second gain channel to 80% of the full-scale voltage of the digital-to-analog converter;
s4: amplifying the voltage signal of the fourth gain channel to the magnitude of 60% of the full-scale voltage of the digital-to-analog converter;
s5: the voltage signal of the fifth gain channel is amplified to the magnitude of 50% of the full-scale voltage of the digital-to-analog converter.
Preferably, the constant current source measuring unit and the constant voltage source measuring unit alternately operate in each period of measuring the ground resistance.
Preferably, the work cycle of the ground resistance measurement module is set to 80ms, wherein the constant current source measurement unit works for 60ms, the constant voltage source measurement unit works for 20ms, and the constant voltage source is used as a supplementary measurement mode to increase the stability of the ground resistance measurement.
The substantial effects of the invention are as follows: the gain channel of the digital-to-analog converter AD7705 is set, so that the resistance measurement of a ground circuit around a threshold value is more accurate, the resistance measurement precision of the ground resistance far away from the threshold value is reduced, the overall measurement efficiency of the converter is improved, a constant voltage source measurement unit is added, and the reliability of ground protection in an electric power test is improved.
Drawings
Fig. 1 is a schematic diagram of the structural principle of the intelligent grounding early warning device for the power test.
In the figure: 1. the device comprises a processor module, a grounding resistance measuring module, a relay output module, a voice prompt module, a display module, a control key, a debugging interface, an output power switch, an auxiliary power transformer, a leakage protection circuit breaker, a power output port, a power input port and a power output port, wherein the processor module is 2, the grounding resistance measuring module, 3, the relay output module, 4, the voice prompt module, 5, the display module, 6, the control key, 7, the debugging interface, 8, the output power switch.
Detailed Description
The following provides a more detailed description of the present invention, with reference to the accompanying drawings.
FIG. 1 is a schematic diagram of a structural principle of an intelligent grounding early warning device for an electric power test, an input power supply of the intelligent grounding early warning device for the electric power test is connected to a power output port 11 through a power input port 12, an output power switch 8 and an earth leakage protection circuit breaker 10 in sequence to supply power to relevant devices for the electric power test, the input power supply supplies power to a processor module 1 through the power input port 12 and an auxiliary power transformer 9 in sequence, a grounding resistance measurement module 2, a relay output module 3, a voice prompt module 4, a display module 5, a control key 6 and a debugging interface 7 are all connected with the processor module 1, when a grounding resistance value measured by the grounding resistance detection module is greater than a set threshold value, the processor module 1 controls the relay output module 3 to disconnect the power output of the earth leakage protection circuit breaker 10, and the grounding resistance measurement module 2 comprises, the constant current source measuring unit comprises a constant current source, a voltage measuring quantum unit and an analog-to-digital converter AD7705, the constant current source is connected to the grounding loop, the voltage measuring quantum unit is used for measuring voltages at two ends of the grounding loop and transmitting voltage signals to the digital-to-analog converter AD7705, and the digital-to-analog converter AD7705 amplifies the voltage signals through an internal programmable gain amplifier and then performs AD conversion; the constant voltage source detection unit comprises a constant voltage source and a Hall sensor, the constant voltage source is connected to the grounding loop, and the Hall sensor is located in the grounding loop and transmits the acquired current signals to the processor module 1. The constant current source measuring unit and the constant voltage source measuring unit work alternately in each period of measuring the ground resistance, wherein the constant voltage source measuring unit is used for measuring the residual capacitance resistance, the resistance measuring result is transmitted to the processor module 1 when the constant current source measuring unit measures the error, and the power output is cut off through the leakage protection circuit breaker 10 when the ground resistance exceeds the threshold value, so that the safety of electric power experimenters is ensured. The working period of the grounding resistance measuring module 2 is set to 80ms, the constant current source measuring unit works for 60ms, the constant voltage source measuring unit works for 20ms, and the stability of measuring the grounding resistance is improved by taking the constant voltage source as a supplementary measuring mode.
The setting of the grounding resistance threshold is generally less than 0.5 omega, and the grounding resistance threshold is adjusted according to the temperature and the humidity of the power test area. In general, the threshold resistance B of the ground resistance is set to 0.2 Ω, and the digital-to-analog converter AD7705 is set as follows:
s1: the digital-to-analog converter AD7705 is divided into 5 gain amplification channels, a first gain channel is used for amplifying voltage signals within a resistance range of 0-0.15 omega, a second gain channel is used for amplifying voltage signals within a resistance range of 0.15-0.25 omega, a third gain channel is used for amplifying voltage signals within a resistance range of 0.25-2 omega, a fourth gain channel is used for amplifying voltage signals within a resistance range of 2-5 omega, and a fifth gain channel is used for amplifying voltage signals with a resistance value of more than 5 omega;
s2: the resistance range served by the second gain channel is (0.5B, 1.5B), and when the gain multiple is set by the gain channel, the voltage signal is amplified to be close to the full-scale voltage of the analog-to-digital converter, so that the resistance measurement of the resistance range is most accurate;
s3: amplifying voltage signals of a first gain channel and a third gain channel which are adjacent to a second gain channel to 80% of the full-scale voltage of the digital-to-analog converter;
s4: amplifying the voltage signal of the fourth gain channel to the magnitude of 60% of the full-scale voltage of the digital-to-analog converter;
s5: the voltage signal of the fifth gain channel is amplified to the magnitude of 50% of the full-scale voltage of the digital-to-analog converter.
The voltage signal of the second gain channel is amplified to be close to the full-scale voltage of the analog-digital converter, so that the resistance value within the resistance value range is measured most accurately, meanwhile, the measurement accuracy of other gain channels is correspondingly reduced, the measurement efficiency of the digital-analog converter AD7705 is improved, a power supply can be cut off more rapidly when the grounding is poor, and the safety of the intelligent grounding early warning device for the power test is improved.
The above-described embodiments are only preferred embodiments of the present invention, and are not intended to limit the present invention in any way, and other variations and modifications may be made without departing from the spirit of the invention as set forth in the claims.
Claims (4)
1. A method for measuring the resistance of grounding loop of intelligent early-warning device for electric power test grounding is characterized in that the grounding resistance measuring module comprises a constant current source measuring unit and a constant voltage source measuring unit,
the constant current source measuring unit comprises a constant current source, a voltage measuring quantum unit and an analog-to-digital converter AD7705, the constant current source is connected to the grounding loop, the voltage measuring quantum unit is used for measuring the voltages at two ends of the grounding loop and transmitting voltage signals to the analog-to-digital converter AD7705, and the analog-to-digital converter AD7705 amplifies the voltage signals through an internal programmable gain amplifier and then performs AD conversion;
the constant voltage source measuring unit comprises a constant voltage source and a Hall sensor, the constant voltage source is connected to a grounding loop, and the Hall sensor is positioned in the grounding loop and transmits the acquired current signal to the processor module;
setting the threshold resistance B of the grounding resistance to be 0.2 omega, and setting the setting method of the analog-to-digital converter AD7705 as follows:
s1: the method comprises the following steps that an analog-to-digital converter AD7705 is divided into 5 gain amplification channels, a first gain channel is used for amplifying voltage signals within a resistance range of 0-0.15 omega, a second gain channel is used for amplifying voltage signals within a resistance range of 0.15-0.25 omega, a third gain channel is used for amplifying voltage signals within a resistance range of 0.25-2 omega, a fourth gain channel is used for amplifying voltage signals within a resistance range of 2-5 omega, and a fifth gain channel is used for amplifying voltage signals with resistance values more than 5 omega;
s2: the resistance range served by the second gain channel is (0.5B, 1.5B), and when the gain multiple is set by the gain channel, the voltage signal is amplified to be close to the full-scale voltage of the analog-to-digital converter, so that the resistance measurement of the resistance range is most accurate;
s3: amplifying voltage signals of a first gain channel and a third gain channel which are adjacent to a second gain channel to 80% of the full-scale voltage of the analog-to-digital converter;
s4: amplifying the voltage signal of the fourth gain channel to the magnitude of 60% of the full-scale voltage of the analog-to-digital converter;
s5: the voltage signal of the fifth gain channel is amplified to 50% of the full-scale voltage of the analog-to-digital converter.
2. The method for measuring the resistance of the grounding loop of the intelligent early warning device for the grounding in the power test according to claim 1, wherein the Hall sensor is a magnetic balance type current sensor, and the response time of the Hall sensor is less than 10 μ s.
3. The method for measuring the resistance of the grounding loop of the intelligent early warning device for the grounding in the power test according to claim 1, wherein the constant current source measuring unit and the constant voltage source measuring unit work alternately in each period of measuring the grounding resistance.
4. The method for measuring the resistance of the grounding loop of the intelligent early warning device for the grounding in the power test according to claim 3, wherein the working period of the grounding resistance measuring module is set to 80ms, wherein the constant current source measuring unit works for 60ms, the constant voltage source measuring unit works for 20ms, and the constant voltage source is used as a supplementary measuring mode to increase the stability of the grounding resistance measurement.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810012016.2A CN109459617B (en) | 2018-01-05 | 2018-01-05 | Method for measuring resistance of grounding loop of intelligent grounding early warning device in power test |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810012016.2A CN109459617B (en) | 2018-01-05 | 2018-01-05 | Method for measuring resistance of grounding loop of intelligent grounding early warning device in power test |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109459617A CN109459617A (en) | 2019-03-12 |
| CN109459617B true CN109459617B (en) | 2020-12-22 |
Family
ID=65606220
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201810012016.2A Active CN109459617B (en) | 2018-01-05 | 2018-01-05 | Method for measuring resistance of grounding loop of intelligent grounding early warning device in power test |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN109459617B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111458579A (en) * | 2020-03-23 | 2020-07-28 | 朔黄铁路发展有限责任公司 | Electrical test apparatus, electrical test method, electrical test device, electrical test apparatus, and storage medium |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1808285A (en) * | 2006-01-26 | 2006-07-26 | 上海微电子装备有限公司 | High-precision analog-to-digital converter based on PGA and control method thereof |
| CN200953038Y (en) * | 2006-05-15 | 2007-09-26 | 西安四方机电有限责任公司 | Counterpoise comprehensive parameter testing device |
| CN201887460U (en) * | 2010-12-24 | 2011-06-29 | 大连新安越电力设备有限公司 | Iron core two-point grounding protection device of inductive transformer |
| CN202649455U (en) * | 2012-06-29 | 2013-01-02 | 珠海派诺科技股份有限公司 | Embedded accuracy tester for current transformer |
| CN103207342A (en) * | 2013-01-10 | 2013-07-17 | 嘉兴电力局 | Ground intelligent pre-warning device for overhauling test |
| CN103813595A (en) * | 2014-02-24 | 2014-05-21 | 南京创维平面显示科技有限公司 | Efficient power source capable of supplying electricity in constant voltage and constant current alternation mode |
-
2018
- 2018-01-05 CN CN201810012016.2A patent/CN109459617B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1808285A (en) * | 2006-01-26 | 2006-07-26 | 上海微电子装备有限公司 | High-precision analog-to-digital converter based on PGA and control method thereof |
| CN200953038Y (en) * | 2006-05-15 | 2007-09-26 | 西安四方机电有限责任公司 | Counterpoise comprehensive parameter testing device |
| CN201887460U (en) * | 2010-12-24 | 2011-06-29 | 大连新安越电力设备有限公司 | Iron core two-point grounding protection device of inductive transformer |
| CN202649455U (en) * | 2012-06-29 | 2013-01-02 | 珠海派诺科技股份有限公司 | Embedded accuracy tester for current transformer |
| CN103207342A (en) * | 2013-01-10 | 2013-07-17 | 嘉兴电力局 | Ground intelligent pre-warning device for overhauling test |
| CN103813595A (en) * | 2014-02-24 | 2014-05-21 | 南京创维平面显示科技有限公司 | Efficient power source capable of supplying electricity in constant voltage and constant current alternation mode |
Also Published As
| Publication number | Publication date |
|---|---|
| CN109459617A (en) | 2019-03-12 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN103344913B (en) | A kind of electromagnetic relay checkout equipment and method | |
| CN201569703U (en) | Dynamic resistance measuring device of high-voltage circuit breaker | |
| CN102033195A (en) | Device and method for measuring dynamic resistance of high-voltage circuit breaker | |
| US8964926B2 (en) | Ex-core nuclear instrumentation system | |
| CN101403777A (en) | Resistive current tester for great current zinc oxide lightning arrester | |
| CN203133146U (en) | Transformer neutral point current measuring device | |
| CN202018479U (en) | High-precision testing device for portable-type loop resistor | |
| CN201096849Y (en) | A high level voltage measuring system for high-voltage DC transmission conversion valve | |
| CN212458609U (en) | Data acquisition device | |
| CN111707341A (en) | Data acquisition device and data acquisition method for rail weighbridge and rail weighbridge | |
| CN103968987A (en) | Contact finger pressure on-line detection device of high-voltage isolating switch | |
| CN109459617B (en) | Method for measuring resistance of grounding loop of intelligent grounding early warning device in power test | |
| CN201382997Y (en) | DC power detecting device | |
| CN102098368A (en) | Mobile phone | |
| CN201311463Y (en) | Resistive current tester of high-current zinc oxide arrester | |
| CN116908588A (en) | High-reliability testing device for initiating explosive device electromagnetic valve | |
| CN111257645A (en) | Device and method for testing direct current resistance of auxiliary contact of high-voltage and low-voltage circuit breakers | |
| CN216285463U (en) | Power flow analyzer for power system | |
| CN101477143A (en) | Electronic current mutual inductor data processing method based on multi-sensor data amalgamation technology | |
| CN210005595U (en) | thermal resistance four-wire system real-time measuring circuit | |
| CN106814294A (en) | Based on bilateral bridge direct-current charging post insulation detecting circuit and detection method | |
| CN2399735Y (en) | Computer controlled insulation monitor | |
| CN214150964U (en) | High-voltage switch dynamic characteristic tester with stable measurement data | |
| CN205090930U (en) | Half -bridge wheatstone bridge that eliminates wire resistance influence measurement system that meets an emergency | |
| CN220289806U (en) | Multisection zinc oxide arrester leakage current measures auxiliary 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 |