CN204190711U - Transformer grounding line current induction amplifier - Google Patents
Transformer grounding line current induction amplifier Download PDFInfo
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- CN204190711U CN204190711U CN201420746276.XU CN201420746276U CN204190711U CN 204190711 U CN204190711 U CN 204190711U CN 201420746276 U CN201420746276 U CN 201420746276U CN 204190711 U CN204190711 U CN 204190711U
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- transformer
- feedback resistor
- operational amplifier
- positive feedback
- integrated operational
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- 238000002955 isolation Methods 0.000 abstract description 2
- 238000012544 monitoring process Methods 0.000 abstract description 2
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- 230000005684 electric field Effects 0.000 description 2
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- 238000009413 insulation Methods 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
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- 229910000976 Electrical steel Inorganic materials 0.000 description 1
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- HSFWRNGVRCDJHI-UHFFFAOYSA-N alpha-acetylene Natural products C#C HSFWRNGVRCDJHI-UHFFFAOYSA-N 0.000 description 1
- 230000008859 change Effects 0.000 description 1
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- 230000007704 transition Effects 0.000 description 1
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- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
Abstract
Transformer grounding line current induction amplifier, comprise current transformer, described current transformer inside is second siding ring, described current transformer has centre bore, transformer grounding line, through centre bore, also comprises rectifier diode, filter capacitor, integrated operational amplifier, reference voltage generator; Described rectifier diode positive and negative electrode is connecting secondary lateral coil starting point and integrated operational amplifier in-phase input end respectively, described filter capacitor is connected between rectifier diode negative pole and ground, and described reference voltage generator output connects integrated operational amplifier inverting input; Also comprise quiescent potential initialization circuit, described quiescent potential initialization circuit is the divider resistance string between DC power supply terminal and ground.The utility model carries out the isolation amplifier of mutual inductance type to transformer grounding line current, significantly improves test speed and testing reliability, and monitoring means warning is timely and safe and reliable.
Description
Technical field
The utility model belongs to field of power electronics, relates to a kind of transformer grounding line current induction amplifier.
Background technology
In transformer device structure, coil and iron core, between iron core and casing, there is certain parasitic capacitance, power transformer is when normally running, non-uniform electric field is produced around electrified coil, under electric field action, be coupled by parasitic capacitance, floating potential over the ground will be produced, cause iron core and coil to reach and puncture insulation, produce partial discharge etc.Therefore, need the electromotive force of normal induction to discharge, make them all be in zero potential, therefore need the reliability ground connection of designing and completing a bit.
But because iron core magnetic flux density is uneven, short near iron core inside casing magnetic circuit, magnetic resistance is little, long near iron core housing magnetic circuit, and magnetic resistance is large, so when appearance more than 2 ground connection, just can cause potential difference, 2 and multiple spot potential difference will form loop, generation circulation each other.Circulation may from milliampere level to tens of ampere, and cause iron core vortex to generate heat, and causes silicon steel sheet insulating layer to damage, even involves coil insulation, make oil temperature increase, occur methane, excessive acetylene etc., cause Accident of Transformer to occur.
By upper conclusion: the necessary one point earth of iron core, but never allow and multipoint earthing at 2.For realizing aforementioned grounding requirement, transformer is installed and has usually been installed earth connection, realizes the protective effect of one point earth.
Existing transformer iron core grounding current relies on manual testing, the not only original backwardness of method, detection mode is dangerous, the more important thing is can not Timeliness coverage problem, especially, when current unattended substation is extensively universal, patrol and detection chance greatly reduces, more difficult discovery fault promptly and accurately, accident treatment opportunity will be incured loss through delay, even cause the state of affairs to expand.
Utility model content
For overcome existing transformer core grounding line current detection method exist need Attended mode manual testing, detection mode is dangerous and can not the technological deficiency of Timeliness coverage current anomaly, the utility model discloses a kind of transformer grounding line current induction amplifier.
Transformer grounding line current induction amplifier described in the utility model, for measuring transformer earth connection electric current, comprise current transformer, described current transformer inside is second siding ring, described current transformer has centre bore, transformer grounding line, through centre bore, also comprises rectifier diode, filter capacitor, integrated operational amplifier, reference voltage generator; Described rectifier diode positive and negative electrode is connecting secondary lateral coil starting point and integrated operational amplifier in-phase input end respectively, described filter capacitor is connected between rectifier diode negative pole and ground, and described reference voltage generator output connects integrated operational amplifier inverting input;
Also comprise quiescent potential initialization circuit, described quiescent potential initialization circuit is the first divider resistance string be connected between the DC power supply terminal of induced current amplifier and ground; The divider node of described first divider resistance string connects rectifier diode negative pole.
Preferably, described reference voltage generator is the second divider resistance string be connected between the DC power supply terminal of electric current induction amplifier and ground, the output of divider node reference voltage generator.
Preferably, positive feedback resistor string is connected with between the output of described integrated operational amplifier and the negative pole of rectifier diode, described positive feedback resistor string is composed in series by the first positive feedback resistor and the second positive feedback resistor, wherein the first positive feedback resistor connects integrated operational amplifier output, and the second positive feedback resistor connects rectifier diode negative pole;
First positive feedback resistor resistance is greater than the second positive feedback resistor, and the first positive feedback resistor is connected integrated operational amplifier in-phase input end with the intermediate node of the second positive feedback resistor.
Further, described first positive feedback resistor resistance is greater than 10:1 with the ratio of the second positive feedback resistor resistance.
Preferably, described integrated operational amplifier is sluggish integrated operational amplifier.
Preferably, the output of described integrated operational amplifier is also connected with warning device.
Adopt transformer grounding line current induction amplifier described in the utility model, transformer grounding line current is carried out to the isolation amplifier of mutual inductance type, significantly improve test speed and testing reliability, monitoring means warning is timely and safe and reliable.
Accompanying drawing explanation
Fig. 1 is a kind of embodiment circuit theory diagrams of the utility model.
Embodiment
Below in conjunction with accompanying drawing, embodiment of the present utility model is described in further detail.
Transformer grounding line current induction amplifier described in the utility model, for measuring transformer earth connection electric current, comprise current transformer, described current transformer inside is second siding ring, described current transformer has centre bore, transformer grounding line, through centre bore, also comprises rectifier diode, filter capacitor, integrated operational amplifier, reference voltage generator; Described rectifier diode positive and negative electrode is connecting secondary lateral coil starting point and integrated operational amplifier in-phase input end respectively, described filter capacitor is connected between rectifier diode negative pole and ground, and described reference voltage generator output connects integrated operational amplifier inverting input;
Also comprise quiescent potential initialization circuit, described quiescent potential initialization circuit is the first divider resistance string be connected between the DC power supply terminal of induced current amplifier and ground; The divider node of described first divider resistance string connects rectifier diode negative pole.
As shown in Figure 1, described second siding ring terminal ground connection, described induced current amplifier comprises rectifier diode D3, filter capacitor C3, integrated operational amplifier IC1, reference voltage generator; Described rectifier diode positive and negative electrode is connecting secondary lateral coil starting point and integrated operational amplifier in-phase input end respectively, described filter capacitor is connected between rectifier diode negative pole and ground, and described reference voltage generator output connects integrated operational amplifier inverting input; Also comprise quiescent potential initialization circuit, described quiescent potential initialization circuit is the first divider resistance string be connected between the DC power supply terminal of induced current amplifier and ground; The divider node of described first divider resistance string connects rectifier diode negative pole.
Visible in Fig. 1, two end points S1, S2 of current transformer core earth connection, through second siding ring, export the earth current signal collected, through rectifier diode D3 halfwave rectifier at second siding ring end points S3, S4 end, filter capacitor C3 filtering, coordinates the work of subsequent conditioning circuit with DC form.
Be current signal due to what collect from second siding ring end, for this reason, be converted to voltage signal over the ground through resistance R3, to meet integrated transporting discharging with the structural principle of voltage for main work.Two divider resistances R2, R3 of first divider resistance string also have and produce DC point by source voltage, to adapt to the object of the input voltage working range of integrated operational amplifier, such as supply voltage 12V, the input voltage working range of integrated operational amplifier IC1 is within the scope of 2-8V, then the ratio that can arrange R2 and R3 makes the DC voltage value of divider node at about 4V.
As shown in Figure 1
,reference voltage generator for being connected on the second divider resistance string between the DC power supply terminal of induced current amplifier and ground, can be composed in series by divider resistance R5 and R6, and the common port of divider node and R5 and R6 is as the output of reference voltage generator.
A kind of preferred implementation is be connected with positive feedback resistor string between the output and the negative pole of rectifier diode of integrated operational amplifier, described positive feedback resistor string is composed in series by the first positive feedback resistor R7 and the second positive feedback resistor R4, wherein the first positive feedback resistor connects integrated operational amplifier output, and the second positive feedback resistor connects rectifier diode; First positive feedback resistor resistance is greater than the second positive feedback resistor, and the first positive feedback resistor is connected integrated operational amplifier in-phase input end with the intermediate node of the second positive feedback resistor.
The effect of above-mentioned positive feedback resistor string is the multiplication factor increasing voltage signal.Such as arrange:
R4=10k Ω, R7=100k Ω, then gain amplifier:
Integrated operational amplifier voltage amplification factor A=1+R7/R4=1+100/10=11 doubly.
To adopt BH-0.66 type current transformer, first and second ER effect is 1:15 than pass, for less grounding small current---as 1A, after the 1:15 no-load voltage ratio of current transformer, secondary have electric current:
1÷15＝0.067A
Do in voltage transitions through resistor current again, even if 1:1 carries out, also can only have 0.067V, be difficult to accordingly promote subsequent conditioning circuit.But after adding gain amplifier, then have:
0.067 × 11=0.74V, namely integrated operational amplifier output OUT produces the changing value of 0.74V, may produce logic effect completely, promotes subsequent conditioning circuit or carries out further A/D sampling.Integrated operational amplifier output can directly or a distant place connect warning circuit, also can further after drive amplification connection signal treatment facility carry out follow-up signal and judge to process.
The warning that produces for avoiding current fluctuation switches frequent, and integrated operational amplifier can select sluggish integrated operational amplifier, arranges sluggish scope and to fluctuate the wrong report brought with filtering high-frequency current.
The utility model can adopt dc-battery to power, but frequently changes battery for avoiding, and reduces costs, and also the civil power that transformer connects can be converted into direct current and use as induced current amplifier power supply.
Previously described is each preferred embodiment of the present utility model, preferred implementation in each preferred embodiment is if not obviously contradictory or premised on a certain preferred implementation, each preferred implementation can stack combinations use arbitrarily, design parameter in described embodiment and embodiment is only the utility model proof procedure in order to clear statement utility model people, and be not used to limit scope of patent protection of the present utility model, scope of patent protection of the present utility model is still as the criterion with its claims, the equivalent structure change that every utilization specification of the present utility model and accompanying drawing content are done, in like manner all should be included in protection range of the present utility model.
Claims (6)
1. transformer grounding line current induction amplifier, for measuring transformer earth connection electric current, it is characterized in that, comprise current transformer, described current transformer inside is second siding ring, described current transformer has centre bore, and transformer grounding line, through centre bore, also comprises rectifier diode, filter capacitor, integrated operational amplifier, reference voltage generator; Described rectifier diode positive and negative electrode is connecting secondary lateral coil starting point and integrated operational amplifier in-phase input end respectively, described filter capacitor is connected between rectifier diode negative pole and ground, and described reference voltage generator output connects integrated operational amplifier inverting input;
Also comprise quiescent potential initialization circuit, described quiescent potential initialization circuit is the first divider resistance string be connected between the DC power supply terminal of induced current amplifier and ground; The divider node of described first divider resistance string connects rectifier diode negative pole.
2. transformer grounding line current induction amplifier as claimed in claim 1, it is characterized in that, described reference voltage generator is the second divider resistance string be connected between the DC power supply terminal of electric current induction amplifier and ground, the output of divider node reference voltage generator.
3. transformer grounding line current induction amplifier as claimed in claim 1, it is characterized in that, positive feedback resistor string is connected with between the output of described integrated operational amplifier and the negative pole of rectifier diode, described positive feedback resistor string is composed in series by the first positive feedback resistor and the second positive feedback resistor, wherein the first positive feedback resistor connects integrated operational amplifier output, and the second positive feedback resistor connects rectifier diode negative pole;
First positive feedback resistor resistance is greater than the second positive feedback resistor, and the first positive feedback resistor is connected integrated operational amplifier in-phase input end with the intermediate node of the second positive feedback resistor.
4. transformer grounding line current induction amplifier as claimed in claim 3, it is characterized in that, described first positive feedback resistor resistance is greater than 10:1 with the ratio of the second positive feedback resistor resistance.
5. transformer grounding line current induction amplifier as claimed in claim 1, it is characterized in that, described integrated operational amplifier is sluggish integrated operational amplifier.
6. transformer grounding line current induction amplifier as claimed in claim 1, it is characterized in that, the output of described integrated operational amplifier is also connected with warning device.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420746276.XU CN204190711U (en) | 2014-12-03 | 2014-12-03 | Transformer grounding line current induction amplifier |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420746276.XU CN204190711U (en) | 2014-12-03 | 2014-12-03 | Transformer grounding line current induction amplifier |
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| Publication Number | Publication Date |
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| CN204190711U true CN204190711U (en) | 2015-03-04 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201420746276.XU Expired - Fee Related CN204190711U (en) | 2014-12-03 | 2014-12-03 | Transformer grounding line current induction amplifier |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105092940A (en) * | 2015-07-07 | 2015-11-25 | 国网上海市电力公司 | Alarming device for the electrification of a current transformer secondary circuit |
-
2014
- 2014-12-03 CN CN201420746276.XU patent/CN204190711U/en not_active Expired - Fee Related
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN105092940A (en) * | 2015-07-07 | 2015-11-25 | 国网上海市电力公司 | Alarming device for the electrification of a current transformer secondary circuit |
| CN105092940B (en) * | 2015-07-07 | 2018-09-28 | 国网上海市电力公司 | A kind of secondary loop of mutual inductor electrification alarming device |
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| Date | Code | Title | Description |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20150304 Termination date: 20191203 |