CN104330762B - Line fault detection circuit for current transformer - Google Patents
Line fault detection circuit for current transformer Download PDFInfo
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- CN104330762B CN104330762B CN201410676933.2A CN201410676933A CN104330762B CN 104330762 B CN104330762 B CN 104330762B CN 201410676933 A CN201410676933 A CN 201410676933A CN 104330762 B CN104330762 B CN 104330762B
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Abstract
The invention provides a line fault detection circuit for a current transformer. The line fault detection circuit for the current transformer comprises a current parameter collecting unit, a current transformer line monitoring unit, a signal amplifying unit and a central processing unit; the current parameter collection unit and the signal amplification unit achieve collection and amplification of current signals of a power distribution loop and current transformer line monitoring signals at different times and transmits to the central processing unit; the central processing unit obtains the current size of the power distribution loop and a connecting line state of the current transformer through analysis and processing and displays a current parameter of the current loop through a display screen; the line fault detection circuit for the current transformer instantly gives out fault alarm when detects that a connecting line of the current transformer is in an abnormal state. The line fault detection circuit for the current transformer has the advantages of avoiding influences to measurement of normal current parameters from line monitoring through a controllable and time division monitoring method and enabling line detection and current parameter measurement to be achieved at different times.
Description
Technical field
The present invention relates to a kind of path monitoring circuit, the line fault observation circuit of specifically a kind of current transformer.
Background technology
In general path monitoring circuit（Such as：Relay, blower fan etc.）, all can using one it is fixed, far below quilt
The low-voltage of measurement equipment operation voltage so can both monitor equipment under test, and be unlikely to again to cause equipment carrying out path monitoring
Action.
And current transformer is just not suitable for using this detection method carrying out path monitoring, reason is as follows：
1）Current transformer is measurement size of current in itself, and the faradic current of transformer is very little：General mutual inductance
Device no-load voltage ratio is 2000:1,2A electric current can only also produce the faradic current of 1mA, and as residual current（That is leakage current）It is just more micro-
Weak, normal residual current only has tens to hundreds of milliampere, and the faradic current which obtains just only tens arrives hundreds of microampere, if folded
Plus a foreign current（Call bias current in the following text）Extreme influence will be caused to measuring electric current, or even be flooded by bias current；
2）The coil impedance of bias current size and transformer has a direct relation, and the concordance of the coil impedance of transformer
Poor, the size of current for so resulting in superposition is inconsistent, and the error amount caused by its consistency may cover measured value,
Also allowing for the major function of transformer --- current measurement is extremely inaccurate, so all kinds of electric instruments on market are showed no
Path monitoring is carried out to current transformer.
The controller of existing current instruments and all kinds of relevant powered flow measurements is aligned because of unresolved path monitoring
The often impact caused by parameter measurement so that row line prison is not entered in this kind of field of employment to the connection line of current sensor
Survey.
In the case where path monitoring is not made, if field connection terminal loosens or rodent bites connection line broken,
Current transformer will be caused to open a way, and current transformer forbids open circuit --- Current Transformer Secondary side open circuit is just quite
In a booster transformer, magnitude of voltage can be at a relatively high, it will so that site operation personnel has serious potential safety hazard.
The content of the invention
The purpose of the present invention is to overcome the deficiencies in the prior art, there is provided a kind of line fault prison of current transformer
Survey method, in the case where fixed bias current is not added with, can either complete the monitoring of current transducer signal output cord, and not
Affect the measurement of normal current parameter, effective guarantee Electrical Safety.
According to the technical scheme that the present invention is provided, the line fault observation circuit of described current transformer includes：Electric current
Parameter acquisition unit, current transformer path monitoring unit, signal amplification unit and CPU, the current parameters are adopted
Collection unit, current transformer path monitoring unit connection current transformer, current transformer path monitoring unit connection electric current ginseng
Counting collection unit and CPU, the output of current parameters collecting unit process single through signal amplification unit connection central authorities
Unit；Current parameters collecting unit and signal amplification unit timesharing complete the current signal of distribution loop and current transformer circuit prison
Survey the collection of signal, amplify, and pass to CPU, by analyzing and processing, CPU show that distribution is returned respectively
The connection line state of the size of current and current transformer on road, and show the electric current ginseng of current loop by display screen in real time
Number；When the connection line for detecting current transformer is in abnormality（Including short circuit and the state of open circuit）When, send at once
Fault alarm sound equipment.
Current parameters and line fault information can also be uploaded to prison by 485 communication modules by the CPU
Control backstage.
Specifically, the current transformer path monitoring unit includes audion Q2, and the base stage of audion Q2 is through resistance
R4 connects the I/O port of CPU, and audion Q2 emitter stages connect reference voltage, audion Q2 colelctor electrodes through resistance R3
It is connected to the ungrounded end of current transformer T1；The current parameters collecting unit includes being connected to current transformer T1 two ends
's：Resistance R25, TVS diode D6 and electric capacity C4；The signal amplification unit includes operational amplifier U5B, current transformer T1
Ungrounded end through resistance R14 concatenation operation amplifier U5B inverting input, the inverting input of operational amplifier U5B
Also connect itself outfan through resistance R17, the in-phase input end of operational amplifier U5B is grounded through resistance R15, operation amplifier
The outfan of device U5B is connected to the AD acquisition ports of CPU again through RC filter circuits；When current signal is measured, in
Central Processing Unit exports high level by I/O port so that audion Q2 is in cut-off state, and test circuit is not turned on, now electric current
The faradic current that transformer is produced changes into voltage signal U1 by resistance R25, and obtains after operational amplifier U5B amplifies
U2, U2 are input into CPU AD acquisition port, carry out data processing by CPU and obtain tested current value, now
Measured value is only related to tested electric current；When monitoring current transformer circuit, CPU exports low electricity by I/O port
It is flat so that audion Q2 is in the conduction state, test circuit conducting.
It is an advantage of the invention that：The present invention adopts the method that " controllable ", " timesharing " are monitored to evade path monitoring to normal
The impact of current parameters measurement：1st, increase the audion controlled by the I/O port of CPU and carry out control circuit observation circuit；
2nd, path monitoring and current parameters measurement timesharing are carried out, parameter measurement is not carried out when circuit is monitored, it is equally normal in measurement
By the I/O port shut-down circuit observation circuit of CPU during current parameters.
Description of the drawings
Fig. 1 is the circuit structure block diagram of the present invention.
Fig. 2 is the workflow diagram of the present invention.
Fig. 3 is the circuit theory diagrams of the present invention.
Specific embodiment
The invention will be further described with reference to the accompanying drawings and examples.
As shown in figure 1, the present invention includes：Current parameters collecting unit, current transformer path monitoring unit, signal amplify
The auxiliary unit such as unit, CPU and human computer conversation, communication.The current parameters collecting unit, current transformer line
Road monitoring means connection current transformer, current transformer path monitoring unit connection current parameters collecting unit and central authorities' process
Unit, the output of current parameters collecting unit connect CPU through signal amplification unit.The CPU
Keystroke handling unit, RS485 communication modules, display lamp, alarm sound and display unit etc. can also be connected with.
Current parameters collecting unit and signal amplification unit timesharing complete the current signal and transformer circuit of distribution loop
The collection of monitoring signals, amplification, and CPU is passed to, CPU draws distribution respectively by analyzing and processing
The connection line state of the size of current and current transformer in loop, and the current parameters of current loop are shown in real time, and ought detect
The connection line for measuring current transformer is in abnormality（Short circuit or open circuit）When, fault alarm sound equipment is sent at once, is reminded
Operator arouse attention.Current parameters and line fault information can be also uploaded to prison by RS485 communication modules by the present invention
Control backstage, to ensure Electrical Safety.
It is illustrated in figure 2 the handling process of circuit of the present invention：Systematic parameter initialization is carried out after electricity in present device, so
Current transformer path monitoring circuit is closed afterwards, is carried out leakage current parameter acquisition, and calculation process is carried out to parameter and is shown in real time
Show.It is firing current transformer path monitoring circuit after the completion of normal current parameter acquisition, and to opening after path monitoring
Current signal carries out parameter processing, analysis, discriminates whether to exist the circuit exception shape such as short-circuit, breaking of current transformer connecting line
State, if there is exception, then sends line fault warning signal.Then will move in circles into next handling process.Electric current
Transformer path monitoring unit primarily to prevent the outlet line of current transformer from opening a way, and because outlet line open circuit causes
High pressure, brings potential safety hazard to operator.
Fig. 3 lower rights inframe circuit is current parameters collecting unit, and upper right side inframe circuit is that current transformer circuit is supervised
Unit is surveyed, left side is electric current and path monitoring parameter amplifier section.Current transformer path monitoring unit includes audion Q2, three
The base stage of pole pipe Q2 connects CPU through resistance R4（By taking single-chip microcomputer as an example）I/O port Line_Test, audion Q2
Emitter stage connects reference voltage VCC through resistance R3, and audion Q2 colelctor electrodes are connected to the ungrounded end of current transformer T1；Electricity
Stream parameter acquisition unit includes being connected to current transformer T1 two ends：Resistance R25, TVS diode D6（Two-way transient state suppresses two
Pole pipe P6KE5.0CA）With electric capacity C4；Signal amplification unit includes operational amplifier U5B, the ungrounded end Jing of current transformer T1
The inverting input of resistance R14 concatenation operation amplifier U5B is crossed, the inverting input of operational amplifier U5B is also through resistance R17
Connect itself outfan, the in-phase input end of operational amplifier U5B is grounded through resistance R15, the outfan of operational amplifier U5B
It is connected to AD acquisition ports AN_IL of single-chip microcomputer again through RC filter circuits.
Concrete principle is：When current signal is measured, single-chip microcomputer exports high level by I/O port Line_Test so that three
Pole pipe Q2 is in cut-off state, and test circuit is not turned on, and the faradic current that now current transformer is produced changes into electricity by R25
Pressure signal U1, and U2 is obtained after amplifier U5B is amplified, U2 input Chip Microcomputer A/D acquisition ports AN_IL carry out data by single-chip microcomputer
Process obtains tested current value, and measured value now is only related to tested electric current, has no bearing on path monitoring element circuit.
When monitoring current transformer circuit, single-chip microcomputer exports low level by I/O port Line_Test so that audion
Q2 is in the conduction state, test circuit conducting, is now divided into following 3 kinds of situations：
1）Under normal circumstances：The electric current I1 that test circuit is produced is divided into two-way：Flow through the I2 of R25 and flow through current transformer
The I3 of itself, without outside faradic current（Alternating current）When voltage U1 be after R25 in parallel with R0 with R3 composition bleeder circuits
Partial pressure value, this value are exactly a fixed value:U1=((R25//R0)/((R25//R0)+R3)) * VCC, if measuring such one
The magnitude of voltage of individual fixation, we are it may determine that current transformer circuit is normal；When there is outside faradic current, U1 is exactly one
The integrated value of the induced voltage that partial pressure value and faradic current are produced on R25, faradic current are AC signals, so U1 now
Voltage is an alternating current-direct current integrated signal, is the signal being continually changing：10ms is higher（Positive half cycle）, 10ms it is low（Negative half period）,
According to the character that this changes, we can also judge that present current transformer is in normal condition.
2）When current transformer line short, U1=0 V can very easily be judged.
3）When current transformer open lines, the voltage of U1 is exactly fixed, R25 and R3 compositions a bleeder circuit
Partial pressure value：U1=(R25/ (R25+R3)) * VCC, and never change（Except the change of AD Acquisition Errors）.
This invention removes the monitoring of current sensor line fault（Broken string and short circuit monitoring）Normal current parameters are measured
Caused impact.Also the normality of current transformer circuit can be differentiated using the alternation performance of exchange measured signal.
The present invention needs to consider following factor when implementing：
1st, because path monitoring electric current is superimposed upon in normal current parameter, conducting transmission line need to determine when monitoring that normal current is joined
Influence degree of the number in the case of maximum current and minimum current to path monitoring, it is impossible to because of the normal presence for measuring electric current
Cause the erroneous judgement of path monitoring；
2nd, consider that the turn-off speed of audion affects, after path monitoring loop is closed, how long start normal current
It is to need to take into full account the characteristic of audion and actual measurement that parameter measurement is most suitable.
Claims (4)
1. the line fault observation circuit of current transformer, is characterized in that, including：Current parameters collecting unit, current transformer
Path monitoring unit, signal amplification unit and CPU, the current parameters collecting unit, current transformer circuit prison
Unit connection current transformer is surveyed, current transformer path monitoring unit connection current parameters collecting unit and central authorities process single
Unit, the output of current parameters collecting unit connect CPU through signal amplification unit；Current parameters collecting unit and
Signal amplification unit timesharing completes collection, the amplification of the current signal of distribution loop and current transformer path monitoring signal, and
CPU is passed to, by analyzing and processing, CPU show that the size of current and electric current of distribution loop are mutual respectively
The connection line state of sensor, and show the current parameters of current loop by display screen in real time；When detecting current transformer
Connection line be in abnormality when, send at once fault alarm sound equipment.
2. the line fault observation circuit of current transformer as claimed in claim 1, is characterized in that, the CPU is also
RS485 communication modules are connected with, current parameters and line fault information are uploaded to by monitoring backstage by RS485 communication modules.
3. the line fault observation circuit of current transformer as claimed in claim 1, is characterized in that, the company of the current transformer
Link includes the state of short circuit and open circuit in abnormality.
4. the line fault observation circuit of current transformer as claimed in claim 1, is characterized in that, the current transformer circuit
Monitoring means include audion Q2, and the base stage of audion Q2 connects the I/O port of CPU, audion Q2 through resistance R4
Emitter stage connects reference voltage through resistance R3, and audion Q2 colelctor electrodes are connected to the ungrounded end of current transformer T1；It is described
Current parameters collecting unit includes being connected to current transformer T1 two ends：Resistance R25, TVS diode D6 and electric capacity C4；It is described
Signal amplification unit includes operational amplifier U5B, and the ungrounded end of current transformer T1 is through resistance R14 concatenation operation amplifiers
The inverting input of U5B, the inverting input of operational amplifier U5B also connect itself outfan, operation amplifier through resistance R17
The in-phase input end of device U5B is grounded through resistance R15, and the outfan of operational amplifier U5B is connected to through RC filter circuits again
The AD acquisition ports of CPU；When current signal is measured, CPU exports high level by I/O port so that three
Pole pipe Q2 is in cut-off state, and test circuit is not turned on, and the faradic current that now current transformer is produced is converted by resistance R25
Into voltage signal U1, and U2 is obtained after operational amplifier U5B amplifies, U2 input CPU AD acquisition ports, by
Central Processing Unit carries out data processing and obtains tested current value, and measured value now is only related to tested electric current；When monitoring electricity
During current transformer circuit, CPU exports low level by I/O port so that audion Q2 is in the conduction state, test electricity
Road turns on.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410676933.2A CN104330762B (en) | 2014-11-21 | 2014-11-21 | Line fault detection circuit for current transformer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410676933.2A CN104330762B (en) | 2014-11-21 | 2014-11-21 | Line fault detection circuit for current transformer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN104330762A CN104330762A (en) | 2015-02-04 |
| CN104330762B true CN104330762B (en) | 2017-05-10 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410676933.2A Active CN104330762B (en) | 2014-11-21 | 2014-11-21 | Line fault detection circuit for current transformer |
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Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105700425A (en) * | 2015-12-31 | 2016-06-22 | 天津派塔尔节能技术有限公司 | Heat tracing system transmitting data through GPRS |
| CN107979071A (en) * | 2017-12-06 | 2018-05-01 | 国家电网公司 | Remote monitoring of power transmission line system |
| CN113917219A (en) * | 2021-10-08 | 2022-01-11 | 广东电网有限责任公司东莞供电局 | Automatic detection alarm device |
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|---|---|---|---|---|
| CN1272676A (en) * | 1999-05-02 | 2000-11-08 | 罗毅 | Electric current mutual-inductor |
| CN2872376Y (en) * | 2006-02-15 | 2007-02-21 | 邓加慧 | Off-circuit or short-circuit monitor |
| CN201293818Y (en) * | 2008-11-10 | 2009-08-19 | 德清伊特电子有限公司 | Circuit for detecting current transformer abnormity |
| CN101666846A (en) * | 2009-09-25 | 2010-03-10 | 深圳市科陆电子科技股份有限公司 | System and method for detecting anomaly of secondary wiring of current mutual inductor |
| CN102590591A (en) * | 2012-03-05 | 2012-07-18 | 常熟开关制造有限公司(原常熟开关厂） | Detection circuit for monitoring state of current transformer |
| CN204228942U (en) * | 2014-11-21 | 2015-03-25 | 无锡韩光电器股份有限公司 | The line fault observation circuit of current transformer |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH02273027A (en) * | 1989-04-14 | 1990-11-07 | Mitsubishi Electric Corp | Device for protecting open circuit of secondary circuit of current transformer |
-
2014
- 2014-11-21 CN CN201410676933.2A patent/CN104330762B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1272676A (en) * | 1999-05-02 | 2000-11-08 | 罗毅 | Electric current mutual-inductor |
| CN2872376Y (en) * | 2006-02-15 | 2007-02-21 | 邓加慧 | Off-circuit or short-circuit monitor |
| CN201293818Y (en) * | 2008-11-10 | 2009-08-19 | 德清伊特电子有限公司 | Circuit for detecting current transformer abnormity |
| CN101666846A (en) * | 2009-09-25 | 2010-03-10 | 深圳市科陆电子科技股份有限公司 | System and method for detecting anomaly of secondary wiring of current mutual inductor |
| CN102590591A (en) * | 2012-03-05 | 2012-07-18 | 常熟开关制造有限公司(原常熟开关厂） | Detection circuit for monitoring state of current transformer |
| CN204228942U (en) * | 2014-11-21 | 2015-03-25 | 无锡韩光电器股份有限公司 | The line fault observation circuit of current transformer |
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| CN104330762A (en) | 2015-02-04 |
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