CN2143784Y - Device for measuring loop resistance by using pulse constant current source - Google Patents
Device for measuring loop resistance by using pulse constant current source Download PDFInfo
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- CN2143784Y CN2143784Y CN 92234486 CN92234486U CN2143784Y CN 2143784 Y CN2143784 Y CN 2143784Y CN 92234486 CN92234486 CN 92234486 CN 92234486 U CN92234486 U CN 92234486U CN 2143784 Y CN2143784 Y CN 2143784Y
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Abstract
The utility model discloses a loop resistance measuring device which is composed of a pulse constant current source, a standard resistance, a signal amplification circuit, an A/D converting circuit, a current identification circuit, a micro-process computer data processing system and a panel operation display system. A measuring current of the utility model is larger than 100A. The utility model is suitable for measuring loop resistance of high voltage switches, loop resistance of high voltage switches requiring or capable of using a high current to measure, and devices or loops requiring or capable of using a high current to measure. Resistance of the devices and loops is under 10000 Omega/mu.
Description
The utility model relates to pulsed constant current supply and computer technology combines, the application in microresistivity survey and the device of realization thereof, the particularly application in the high voltage electric switch loop resistance measurement.
The loop resistance of high-voltage switch gear is the production of high-voltage switch gear and an important indicator in the working service.After in 1980, relevant ministries and commissions of country have formulated series of standards (GB in succession with reference to international electrical engineering standard (IEC), JB) and file, these standards and file have all been done clear and definite regulation to the measuring method and the measuring condition of high-voltage switch gear loop resistance, summarize and get up to have three: (1) measures electric current is direct current, (2) measure electric current greater than 100A, the standard of (3) loop resistance tens of between hundreds of micro-ohms.The measuring method of loop resistance roughly has three kinds: 1. direct current bridge, and 2. common microresistivity survey instrument, 3. Dyn. cooperates voltage table and reometer.The measurement electric current of preceding two kinds of methods is generally less than 5A, does not meet standard, just progressively eliminates at present.The measurement electric current conformance with standard of a kind of method in back, but owing to equipment heaviness, the easy to operate fixed-site that only limits to use.
Present more employing be homemade current source, the 220VAC power supply is passed through transformation, inserts measured piece after lotus root pressure regulation, rectification, produce the above Rectified alternating current of 100A, on voltage table and reometer, read the terminal voltage value of the current value and the measured piece of the measured piece of flowing through respectively, calculate resistance value according to Ohm law then.The complete conformance with standard of this method regulation, but still dislike that its equipment volume is big, operation inconvenience, direct weakness such as reading.Shanghai Hu Xi ammeter factory improves based on the above method, makes " circuit resistance tester ", is characterized in transformer, is assembled together from lotus root pressure regulator, rectification circuit and voltage table, reometer, constitutes independently instrument.By regulating the output voltage from the lotus root pressure regulator, make the reometer displayed value be stabilized in the 100A place during measurement, the terminal voltage of measured piece shows on digital millivoltmeter after amplifying circuit amplifies.When the enlargement factor of adjusting in advance made electric current be 100A, the demonstration number of digital millivoltmeter just in time was the resistance value of measured piece, thereby had realized direct reading indirectly.The main performance index of this tester is as follows,
Measure electric current: manual adjustments 100A ripple factor 0.67
Measurement range: digital millivoltmeter ± 0.5% ± 2 word
1.5 grades in reometer ± 1.5% complete machine precision
Resolving power: 1 μ Ω three and half shows
Size: 200 * 300 * 420mm
Weight: 15KG
The purpose of this utility model is to utilize pulsed constant current supply and a kind of light circuit resistance tester of little process computer technological development.
Principle of the present utility model is that large value capacitor and measuring resistance, large power triode and measured piece are unified into the pulse constant current loop.After capacitor was charged to setting voltage, the conducting of control large power triode was discharged to the loop.Terminal voltage signal on measuring resistance and the measured piece is sampled on the pulse section of current value by the data acquisition system (DAS) that CPU and A/D converter constitute, calculate measured resistance according to Ohm law greater than 100A.
Adopt pulse high current power supply can reduce the volume and weight of device effectively.But, the pulse heavy current can produce very big induced electromotive force in the voltage detecting loop of measured piece, seriously disturb tested voltage signal, therefore must realize constant current on the effective measurement section in pulse current, thereby suppress the interference of induced electromotive force effectively.Figure one .(a) be the principle of the pulsed constant current supply that adopts of the utility model, it is the discharge loop that is composed in series by energy-storage capacitor C, large power triode T and tested loop, and triode is operated in the amplification region.If capacitor C is dashed electricity to the Uo volt before the discharge, the t that then discharges flows through the loop electric charge and is in second
Iot＝UoC－UcC
Wherein, Uc is the t voltage at electric capacity two ends constantly, and Io is the discharge current in the loop, and when the drive current steady of importing from the base stage of triode T was constant, Io also was a steady.Along with the increase of t discharge time, the voltage U c at electric capacity two ends reduces gradually, when
Uc＝IoR
The time, triode is cut off.The discharge characteristic time of this circuit is
τ＝（Uo－IoR）C／Io （1）
As seen, sufficiently high charging voltage Uo and enough big storage capacitor C can guarantee the long discharge characteristic time, need only the drive current steady, and hold time and be no more than τ, just can obtain comparatively ideal high power pulse square wave.Figure one .(b) express the input-output characteristic curve of pulsed constant current supply, wherein, I
iBe the strength of current of drive signal, h
FEIt is the direct current enlargement factor of triode.
Storage capacitor can be replaced by the energy-storage units that several electric capacity are formed through connection in series-parallel, and high-power three pipes can be the Darlington modules, also can change the current amplification unit of being made up of several triodes into.
Figure two is structural representations of the present utility model.Pulsed constant current supply is emitted pulse current more than the 100A to the series loop of measured piece and measuring resistance under the control of discharge signal, voltage drop signal on the measured piece is input to the A/D change-over circuit after signal amplification circuit amplifies, the voltage drop signal on the measuring resistance also inputs to the A/D change-over circuit simultaneously.The electric current discriminator circuit provides high level on the time section of pulse current greater than 100A, in order to the control data collection.A/D change-over circuit by little process computer control carries out the A/D conversion to the voltage signal on measured piece and the measuring resistance.Little process computer multi-group data that transfer swaps out to pulsatile once is gathered, is stored, and calculates the loop resistance value of measured piece according to ohm ratemeter, and carries out digital filtering, statistical average and error correction, send panel to show at last.The voltage amplification multiplying power that changes amplifying circuit just can realize that range switches, and it is to be finished by the control of little process computer by panel operation.
Figure three-Tu six describes is loop resistance measurement device according to above-mentioned principle and structural design, as an embodiment of the present utility model.Below in conjunction with three-six figure the concrete structure and the function of the each several part circuit among the figure one are elaborated.
Figure three is pulsed constant current supply and driving circuit thereof.The secondary output 20VAC of transformer B2 and the alternating voltage of 80VAC.Wherein, 20VAC is after the rectification of D1-D4 pipe, and by the mu balanced circuit voltage stabilizing that T1, T2, DW1 form, output 20VDC is as the power supply of driving circuit.Discharge control signal is by 4. holding input after the U1 photoelectric coupling is defeated by the driving circuit of being made up of W1, T3, T4.Drive current is delivered to the collector of high power valve T7 by the output of T4 emitter-base bandgap grading through R8.Thereby regulate W1 and can change the power that drive current is adjusted impulse discharge current.80VAC after the D11-D14 rectification by T5, T6, DW2 voltage stabilizing, in order to storage capacitor C4 is dashed.Measured piece by 1., 2. two ends place in circuit.Capacitor C 4, triode T7 and measuring resistance R19 and measured piece have constituted figure one .(a) shown in the pulse constant current circuit.The storage capacitor C4=10000 μ F that present embodiment is selected for use, the T7 pipe is selected 2SD548(or 3DG14I-T for use), measuring resistance R19=0.01 Ω adjusts W1 and makes discharge current I=120A, then by (1) formula as can be known the characteristic width of pulse be τ ≈ 6.6mS.
Discharge loop has been incorporated the negative-feedback circuit that R18, D17, D18 form triode T7 into; when measured piece does not insert the loop well; 1. 2. two ends present bigger resistance; clump and form great negative feedback T7 is operated near the state that ends; amplifying circuit is protected; voltage on the measuring resistance is 0 at this moment, for little process computer provides failure message.
Among the figure four, form enlargement factor by operational amplifier U14 and resistance R 40-R47 and be respectively the terminal voltage that 5,50 and 200 voltage signal amplifying circuit is used to amplify measured piece, its input end is 1. 2. in parallel with measured piece.Voltage signal after the amplification is exported to the A/D change-over circuit by 5. holding.Three kinds of enlargement factors correspond respectively to 10000 μ Ω, 1000 μ Ω and three ranges of 100 μ Ω of this device.
The electric current discriminator circuit is made up of voltage comparator U13 among the figure five and resistance R 33-R36, is provided+reference voltage of 1VDC for U13 by+12VDC power supply and potentiometer W3.Voltage signal on the measuring resistance R19 is by 3. holding input U13.The ohmically voltage drop of standard is greater than 1V during greater than 100A when discharge pulse, and comparer U13 exports high level, and this high level makes little process computer control A/D change-over circuit begin sampling.
The A/D change-over circuit is by A/D converter U16, U17(AD0809 among the figure five) form, power supply+12VDC and R50, R51, W4, DW8 form bleeder circuit provides 5.1VDC for U16, U17 reference voltage.3. voltage signal on the measuring resistance by holding 26 pin that are input to U16 by R35, and U16 is used for the ohmically voltage signal of transfer standard.5. 26 pin of U17 link to each other with the output terminal of signal amplification circuit, in order to the terminal voltage signal on the conversion measured piece.The A/D transfer process of U16, U17 is by address wire A10, A11, A12 and RD, the WR signal controlling of central processing unit U10.The data line D0-D7 of U16, U17 links to each other with the P0 mouth of U10, and the CLK signal of U16, U17 is provided by the ale signal of U10.After central processing unit U10 has finished data acquisition last time, high level of P1.6 pin (7 pin) output holds for the INO of U10 with the high level of electric current discriminator circuit output with non-generation look-at-me, U10 carries out interrupt routine, and the starting A/D converter is sampled once more.The P1.6 pin (7 pin) of U10 was exported a high level again after sampling was finished, like this, and the CPU second mining sample process of just can conducting oneself with dignity.When the deficiency of the pulse current in discharge loop 100A, the LM311 output low level in the discriminator circuit, the U25 door is by locking, and look-at-me has just no longer produced, thereby has guaranteed that CPU can only sample on the pulse section of pulse current greater than 100A.
I/O interface chip U18 among central processing unit U10 among the figure five, address latch U11, program storage U12 and the figure four has formed a complete little process computer, is used for whole device course of work control and data analysis are handled.Clock signal is provided by C37, C39 and crystal oscillator C38.Discharge control signal is exported to discharge driving circuit among the figure three by 1 pin (P1.0) of U10 by U19, in order to the work of gating pulse constant current source.The C0 of U18, C1 pin link to each other with 10,9 pin of analog switch U15 in the amplifying circuit respectively, are used to select the enlargement ratio of amplifying circuit.The B1 of U18, B2, B3 pin provide the range indicator signal to display system.Data after central processing unit U10 handles are exported to display system by the PA mouth of U18.The required charactron chip selection signal of display system is exported by the B4-B7 pin of U18.The P1 mouth of U10 is connected with the panel operation system, then applies for signal and measures operational orders such as applying for signal in order to receive the range choosing.
The panel operation system by among the figure five touch key AN1-AN5 and stabilivolt DW3-DW6, Sheffer stroke gate U25 form.Wherein, AN5, C35, C36, R31, R32 and U25 form reset circuit, powering on or producing 24 times of high level pulses more than the clock period during pressing AN5, for the U10 in little process computer, U18 provide reset signal.Touch key AN1-AN4, stabilivolt DW3-DW6 and be connected with the P1 mouth of U10, be used separately as the selection application of three ranges and measure application with the operational order circuit that resistance R 23-R26 constitutes.Each concrete function of pressing key is stipulated in the watchdog routine of little process computer among the AN1-AN4.
Panel display partly is made up of numeral demonstration, range demonstration pulsed constant current supply charging indication etc.The latter is made up of luminotron LED1 among the figure three and driving element thereof etc.The rising of storage capacitor C4 both end voltage during along with charging, LED1 is finished towards electric process when reaching the brightest to bright by dark gradually, and device just has been in state to be measured.The range indicator signal is shown by luminotron LED2, LED3, LED4 respectively after U19 promotes by B1, B2, the B3 output of the U18 in the microprocessor.The represented range of each luminotron is stipulated by the watchdog routine of little process computer.Digital display portion is by four charactron LED7-LED10 among the figure four, and pusher U22, U23 constitute.Data after little process computer is handled offer four charactrons by the output of PA mouth simultaneously after driving gate U22, U23 promote.The chip selection signal of charactron is by the output of the B4-B7 mouth of U18, by driver U20, U21 select current numeral should charactron.Four charactrons show that in turn each charactron is lighted 2.5mS at every turn.
In figure six, the voltage of two groups of 12VAC of the secondary output of transformer B1 and one group of 5VAC, after bridge rectifier, filtering, voltage stabilizing, for whole device provide+12VDC ,-12VDC and+working power of 5VDC.Because pulsed constant current supply and driving circuit thereof among the figure three are worked under the pulse high current situation, are the interference of avoiding causing thus, this partial circuit provides power supply by separated transformer B2.
Following form has been listed the model and the specification of all components and parts of present embodiment employing.
The structure that figure three～figure six describes provides a complete hardware supported for embodiment of the present utility model, the working routine of the operating process explanation complete machine when using below in conjunction with reality and the function of software.
After the ★ energized, power light LED5 lights; Power supply charges to the C4 electric capacity in the discharge loop; Reset circuit produces reset enable signal CPU and the I/O interface chip resets.
★ presses measurement range selection key AN1, and AN2 or AN3, the P1 mouth of CPU receive the application signal of selected range, and the forward position of this application signal starts CPU and selects and the corresponding data processor of this range.C0 by the I/O interface chip, C1 human hair combing waste go out instruction makes amplifying circuit select corresponding enlargement ratio; B1 by the I/O sheet or B2 or B3 pin are lighted corresponding range pilot lamp LED2 or LED3 or LED4; CPU accesses the measurement current value when measuring the last time that is stored among the RAM, and shows (this moment, displayed value was 0 if never measure) by I/O sheet U18 on charactron.The back edge of gear application signal makes the CPU program get back to the resistance show state.
When ★ is charged to assigned voltage 70～80V when capacitor C 4, charging indicator light LED1 reach the brightest degree represent the charging finish, can measure.
★ presses and measures key AN4, and the P1 mouth of CPU goes out to trigger the discharge instruction by the P1.0 human hair combing waste after receiving and measuring the application signal, if this moment, measured piece did not have good connection, and the then digital failure message " Err " that shows.
When ★ reaches 100A when pulse current, electric current discriminator circuit output high level.Start the interrupt routine of CPU, two A/D converter U16, U17 synchronously carry out quick repeated sampling to the voltage signal on measuring resistance R19 and the measured piece.When pulse current drops to 100A, electric current discriminator circuit output low level, the notice A/D converter stops sampling.
★ CPU log-on data handling procedure calculates the current value of discharge pulse, stores among the RAM for future reference.With adopt data carry out digital filtering, statistical average, and carry out the systematic error correction of this range, the resistance value that obtains after the processing shows on charactron through the I/O interface chip from the output of P0 mouth.
The ★ one-shot measurement finishes.
After 4 discharges of ★ capacitor C, measure and wait for that pilot lamp extinguishes, capacitor C 4 beginnings charging again, pilot lamp brightens gradually, can measure when reaching the brightest next time.
★ pins any range options button and can show the current value of this time measuring on the data presentation pipe if need.
According to the loop resistance measurement device that schematic diagram three～figure six makes, its main performance index is as follows,
Measure electric current: 100A～130A
Measurement range: 1～10000 μ Ω
Precision: numeral shows ± 1.5% ± 2 words
1.5 grades of complete machine precision
Resolving power: 0.5 μ Ω
Power supply: 220VAC ± 10% 50HZ
Size: 126 * 320 * 360mm(height * wide * length)
Weight: 5KG
The utility model has adopted pulsed constant current supply that the measurement electric current is provided, and has improved measurement strength of current, has reduced the volume and weight of power unit, utilizes CPU microcomputer quick sampling and data processing function, has guaranteed measuring accuracy.Only need press the measurement range selection key during actual the use and measure key, can finish measurement.
Claims (3)
1, utilize pulsed constant current supply to measure the device of loop resistance, it is characterized in that this device by pulsed constant current supply, measuring resistance, the little process computer of A/D change-over circuit and CPU is formed.
2, according to the device of claim 1 regulation, it is characterized in that pulsed constant current supply is made of the series loop of high withstand voltage, a jumbo electric capacity reserves unit, a current amplification unit and a measuring resistance.
3, according to the device of claim 2 regulation, it is characterized in that: the capacitance energy storage unit is made of an electric capacity, or is made up of behind series and parallel electric capacity; Current amplification unit is made up of a large power triode, or is made up of through series and parallel triode; Or form by the Darlington transistor module.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 92234486 CN2143784Y (en) | 1992-10-14 | 1992-10-14 | Device for measuring loop resistance by using pulse constant current source |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 92234486 CN2143784Y (en) | 1992-10-14 | 1992-10-14 | Device for measuring loop resistance by using pulse constant current source |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN2143784Y true CN2143784Y (en) | 1993-10-13 |
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ID=33776539
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 92234486 Expired - Fee Related CN2143784Y (en) | 1992-10-14 | 1992-10-14 | Device for measuring loop resistance by using pulse constant current source |
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| Country | Link |
|---|---|
| CN (1) | CN2143784Y (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102353841A (en) * | 2011-09-29 | 2012-02-15 | 沈玉良 | Resistance measuring device for laser trimmer |
| CN102455386A (en) * | 2010-10-27 | 2012-05-16 | 华东电力试验研究院有限公司 | Method for testing resistance of conductive loop of generator circuit breaker |
| CN105158581A (en) * | 2015-09-28 | 2015-12-16 | 国网甘肃省电力公司 | High-capacity capacitor capacity measurement circuit |
| CN106771635A (en) * | 2017-02-15 | 2017-05-31 | 武汉市欧睿科技有限公司 | A kind of circuit resistance tester |
| CN114384459A (en) * | 2021-12-09 | 2022-04-22 | 国电南瑞三能电力仪表(南京)有限公司 | Method, system and device for detecting reliability of hard connection |
-
1992
- 1992-10-14 CN CN 92234486 patent/CN2143784Y/en not_active Expired - Fee Related
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102455386A (en) * | 2010-10-27 | 2012-05-16 | 华东电力试验研究院有限公司 | Method for testing resistance of conductive loop of generator circuit breaker |
| CN102353841A (en) * | 2011-09-29 | 2012-02-15 | 沈玉良 | Resistance measuring device for laser trimmer |
| CN105158581A (en) * | 2015-09-28 | 2015-12-16 | 国网甘肃省电力公司 | High-capacity capacitor capacity measurement circuit |
| CN105158581B (en) * | 2015-09-28 | 2018-01-16 | 国网甘肃省电力公司 | Large bulk capacitance cubic content measurement circuit |
| CN106771635A (en) * | 2017-02-15 | 2017-05-31 | 武汉市欧睿科技有限公司 | A kind of circuit resistance tester |
| CN114384459A (en) * | 2021-12-09 | 2022-04-22 | 国电南瑞三能电力仪表(南京)有限公司 | Method, system and device for detecting reliability of hard connection |
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Free format text: CORRECT: PATENTEE ADDRESS; FROM: ROOM 1B-501, JINLONG HOUSING ESTATE, NANHANG ROAD, HAIKOU CITY, HAINAN PROVINCE TO: ROOM 204, NO. 35, RONG LANE HOUSING ESTATE, WUXI CITY, JIANGSU PROVINCE, 214603 |
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| CP02 | Change in the address of a patent holder |
Address after: 214603 room 35, Lane 204, Rong Lane Village, Jiangsu, Wuxi Patentee after: Hainan Haitian science and technology development industry Co., Ltd. Address before: Room 1B-501, Jinlong Village, South China Road, Haikou, Hainan Patentee before: Hainan Haitian science and technology development industry Co., Ltd. |
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| C19 | Lapse of patent right due to non-payment of the annual fee | ||
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