CN205176099U - Leakage detection protection circuit - Google Patents
Leakage detection protection circuit Download PDFInfo
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- CN205176099U CN205176099U CN201520149497.3U CN201520149497U CN205176099U CN 205176099 U CN205176099 U CN 205176099U CN 201520149497 U CN201520149497 U CN 201520149497U CN 205176099 U CN205176099 U CN 205176099U
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- 230000003321 amplification Effects 0.000 claims abstract description 9
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 9
- 239000003990 capacitor Substances 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 abstract 1
- 238000012360 testing method Methods 0.000 description 7
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- 229920006395 saturated elastomer Polymers 0.000 description 3
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- 230000006698 induction Effects 0.000 description 1
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- Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)
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Abstract
The utility model provides an electric leakage detection protection circuit, include: the low-frequency amplifying circuit is connected with the secondary side of the current transformer; and the pulse conversion circuit is connected with the output end of the low-frequency amplification circuit and generates a pulse signal of which the width is in direct proportion to the output current of the low-frequency amplification circuit. The utility model discloses a set up low frequency amplifier circuit, can effectively the filtering high frequency interference ripple, improve detection circuitry's interference killing feature. The high-gain amplification of low-frequency leakage signals is guaranteed, meanwhile, high-frequency interference is effectively inhibited, the requirement on the mutual inductor is low, and the mutual inductor with a magnetic core framework is not needed. Therefore, the problem that the current transformer is easy to saturate can be solved, the current transformer can be miniaturized, and complexity and cost are reduced.
Description
Technical field
The utility model relates to detection of electrical leakage field, in particular to a kind of leakage current detection protection circuit.
Background technology
The ultimate principle of electric-leakage detection circuit is all based on Hough current law: the algebraic sum flowing into the electric current of any node in circuit is zero, and it adopts zero-sequence transformer as sampling element.In the normal situation of electrical equipment, the vector of each phase current equals zero, therefore the secondary side winding no signal of zero-sequence transformer exports, when there is leak current fault, the vector of each phase current is non-vanishing, fault current makes the annular core of zero-sequence transformer produce magnetic flux, and the secondary side of current transformer has induction current.Present leakage current detection protection circuit, the process for front end signal is generally as follows:
The secondary side of current transformer has sensor current signal, and (patent: 200880106718.1), if voltage signal is less, then by amplifier by voltage amplification (patent: 201210425853.0) to be directly converted to voltage signal use.
If existing circuit shortcoming is that leakage current test accuracy requirement is high, and sensing range wide (such as 0 ~ 100mA), magnetic saturation is there is for avoiding zero-sequence transformer, the magnetic core of mutual inductor needs to have larger area, namely mutual inductor size is larger, be unfavorable for testing circuit miniaturization, and good output linearity degree will be kept in wider range of current, the complexity of mutual inductor realization can be increased and realize cost.
Utility model content
The utility model aims to provide a kind of leakage current detection protection circuit that can solve current transformer magnetic saturation problem.
The utility model provides a kind of leakage current detection protection circuit, comprising: low-frequency amplifier circuit, is connected with the secondary side of current transformer; Pulse switching circuit, is connected with the output terminal of low-frequency amplifier circuit, and the pulse signal that the output current producing width and low-frequency amplifier circuit is proportional.
Further, leakage current detection protection circuit also comprises: pulse signal filtering circuit, is connected with the output terminal of pulse switching circuit, to remove the interference ripple in pulse signal.
Further, low-frequency amplifier circuit comprises: operational amplifier, and the backward end of operational amplifier is connected with the secondary side of current transformer, is arranged in series amplification resistance parallel with one another and the first filter capacitor between the output terminal of operational amplifier and backward end; The forward end of operational amplifier is connected with direct supply.
Further, the second filter capacitor has been arranged in series between the forward end of operational amplifier and ground.
Further, pulse switching circuit comprises the first comparer and bleeder circuit; The first end of bleeder circuit is connected with the output terminal of low-frequency amplifier circuit, the second end ground connection of bleeder circuit; Bleeder circuit comprises the first divider resistance and second divider resistance of series connection mutually, has output node between the first divider resistance and the second divider resistance; The forward end of the first comparer is connected with output node, and the backward end of the first comparer is connected with the output terminal of low-frequency amplifier circuit.
Further, bleeder circuit also comprises three filter capacitor in parallel with the second divider resistance.
Further, pulse signal filtering circuit comprises the second comparer and reference value arranges circuit; Reference value arranges circuit and comprises first reference value and arrange circuit and the second reference value arranges circuit; First reference value is arranged on circuit has the first reference point, and the first reference point is connected with the output terminal of pulse switching circuit and the forward end of the second comparer; Second reference value is arranged on circuit has the second reference point, and the second reference point is connected with the backward end of the second comparer, and the reference voltage of the first reference point is greater than the reference voltage of the second reference point.
Further, the first end that first reference value arranges circuit is connected with direct supply, and first reference value arranges the second end ground connection of circuit, and first reference value arranges on circuit and has been arranged in series at least two divider resistances; The first end that second reference value arranges circuit is connected with direct supply, and the second reference value arranges the second end ground connection of circuit, and the second reference value arranges on circuit and has been arranged in series at least two divider resistances.
According to leakage current detection protection circuit of the present utility model, by arranging low-frequency amplifier circuit, can effectively filtering high frequency interference ripple, improve the antijamming capability of testing circuit.Effectively high frequency interference is inhibit while the plus and blowup ensureing low frequency electric leakage signal, low to transformer request, do not need the mutual inductor using band magnetic core framework.Thus the easily saturated problem of current transformer can be solved, make current transformer can more miniaturization, reduce complexity and cost.
Accompanying drawing explanation
The accompanying drawing forming a application's part is used to provide further understanding of the present utility model, and schematic description and description of the present utility model, for explaining the utility model, is not formed improper restriction of the present utility model.In the accompanying drawings:
Fig. 1 is the principle schematic according to leakage current detection protection circuit of the present utility model;
Embodiment
Below with reference to the accompanying drawings and describe the utility model in detail in conjunction with the embodiments.
As shown in Figure 1, according to leakage current detection protection circuit of the present utility model, comprising: low-frequency amplifier circuit, be connected with the secondary side of current transformer; Pulse switching circuit, is connected with the output terminal of low-frequency amplifier circuit, and the pulse signal that the output current producing width and low-frequency amplifier circuit is proportional.The utility model is by arranging low-frequency amplifier circuit, directly leakage current signal is converted to the higher voltage signal of amplitude, adopt compared to existing technology and current signal is changed to voltage signal, again by the working method of voltage signal amplification, low-frequency amplifier circuit of the present utility model, to High frequency filter, effectively inhibits high frequency interference while the plus and blowup ensureing low frequency electric leakage signal, low to transformer request, do not need the mutual inductor using band magnetic core framework.Thus the easily saturated problem of current transformer can be solved, make current transformer can more miniaturization, reduce complexity and cost.
Particularly, shown in composition graphs 1, low-frequency amplifier circuit comprises operational amplifier U6-B, the backward end of operational amplifier U6-B is connected with the secondary side of current transformer, is arranged in series amplification resistance R225 parallel with one another and the first filter capacitor C232 between the output terminal of operational amplifier U6-B and backward end; The forward end of operational amplifier U6-B is connected with direct supply, usually, has been arranged in series the second filter capacitor C272 between the forward end of operational amplifier and ground, thus prevents the direct supply be connected with forward end from disturbing.
In the utility model, low frequency part in leakage current signal can effectively be amplified by low-frequency amplifier circuit, and the undesired signal of filtering high frequency, namely the electric capacity C232 of circuit Small And Medium Capacity can by the high-frequency interferencing signal short circuit in current signal, and high-frequency signal gain myopia is β
h=1/2 π fc<<1, realizes the decay of high-frequency interferencing signal, and then low frequency signal amplifies through amplifying resistance R225, and low frequency signal gain myopia is β
l=R=3300 realizes the amplification of low frequency signal.
In addition, low-frequency amplifier circuit of the present utility model does not adopt testing circuit conventional at present like that the current signal that mutual inductor produces to be converted to voltage signal, again by working method that voltage signal is amplified by amplifier, but directly leakage current signal is input to backward end, by amplifying, faint current signal is converted to the higher voltage signal of amplitude.The testing circuit that contrast is at present conventional, will disturb ripple also as effective dose integration, the utility model employing filtering circuit, can effective filtering interfering ripple, the antijamming capability of raising testing circuit.Simultaneously because manner of comparison is faster than integral way speed, the detection protection speed of circuit can be improved.
Shown in composition graphs 1, in the utility model, pulse switching circuit comprises the first comparer U14-A and bleeder circuit, and the first end of bleeder circuit is connected with the output terminal of low-frequency amplifier circuit, the second end ground connection of bleeder circuit; Bleeder circuit comprises the first divider resistance R230 and the second divider resistance R5 of series connection mutually, has output node between the first divider resistance R230 and the second divider resistance R5; The forward end of the first comparer U14-A is connected with output node, and the backward end of the first comparer U14-A is connected with the output terminal of low-frequency amplifier circuit.Namely in the output signal of low-frequency amplifier circuit, on the forward end being connected to the first comparer U14-A by bleeder circuit and backward end, in theory, when the operational amplifier U6-B output signal in low-frequency amplifier circuit is greater than zero, the first comparer U14-A output low level.
In the utility model, pulse switching circuit is by bleeder circuit and the first comparer, produce the pulse signal that width is directly proportional to current signal, the reference voltage amplifying the direct supply that resistance R225 is connected with operational amplifier U6-B forward end in low-frequency amplifier circuit determines the proportionate relationship of pulse width and current signal.Amplify resistance R225 and reference voltage in debugging low-frequency amplifier circuit, can make to start to produce pulse signal when leakage current is 20mA, and pulse signal reaches desired width when 25mA.Now due to the ripple interference of completely filtering in low-frequency amplifier circuit amplifying signal, the forward position of pulse signal and rear edge are with the interference ripple of low amplitude value.Usually, requiring in relatively low leakage circuit, the output signal of the first comparer directly can export the control signal as IC.
Preferably, leakage current detection protection circuit of the present utility model is in order to eliminate ripple interference, and be also provided with pulse signal filtering circuit, pulse signal filtering circuit comprises the second comparer and reference value arranges circuit; Reference value arranges circuit and comprises first reference value and arrange circuit and the second reference value arranges circuit; First reference value is arranged on circuit has the first reference point, and the first reference point is connected with the output terminal of pulse switching circuit and the forward end of the second comparer; Second reference value is arranged on circuit has the second reference point, and the second reference point is connected with the backward end of the second comparer, and the reference voltage of the first reference point is greater than the reference voltage of the second reference point.Namely by arranging the second comparer and corresponding reference voltage, compared with setting reference value by the pulse signal with low amplitude value interference ripple, filtering amplitude is less than the interference ripple of reference value, makes pulse signal more clean, for IC provides desirable detection signal.
Shown in composition graphs 1, the first end that first reference value arranges circuit is connected with direct supply, and first reference value arranges the second end ground connection of circuit, and first reference value arranges on circuit and has been arranged in series at least two divider resistances; The first end that second reference value arranges circuit is connected with direct supply, second reference value arranges the second end ground connection of circuit, second reference value arranges on circuit and has been arranged in series at least two divider resistances, selects suitable divider resistance, can regulate corresponding reference value.
As can be seen from the above description, the utility model the above embodiments achieve following technique effect:
According to leakage current detection protection circuit of the present utility model, by arranging low-frequency amplifier circuit, can effectively filtering high frequency interference ripple, improve the antijamming capability of testing circuit.Effectively high frequency interference is inhibit while the plus and blowup ensureing low frequency electric leakage signal, low to transformer request, do not need the mutual inductor using band magnetic core framework.Thus the easily saturated problem of current transformer can be solved, make current transformer can more miniaturization, reduce complexity and cost.
The foregoing is only preferred embodiment of the present utility model, be not limited to the utility model, for a person skilled in the art, the utility model can have various modifications and variations.All within spirit of the present utility model and principle, any amendment done, equivalent replacement, improvement etc., all should be included within protection domain of the present utility model.
Claims (8)
1. a leakage current detection protection circuit, is characterized in that, comprising:
Low-frequency amplifier circuit, is connected with the secondary side of current transformer;
Pulse switching circuit, is connected with the output terminal of described low-frequency amplifier circuit, and the pulse signal that the output current producing width and described low-frequency amplifier circuit is proportional.
2. leakage current detection protection circuit according to claim 1, is characterized in that, described leakage current detection protection circuit also comprises:
Pulse signal filtering circuit, is connected with the output terminal of described pulse switching circuit, to remove the interference ripple in pulse signal.
3. leakage current detection protection circuit according to claim 1 and 2, is characterized in that, described low-frequency amplifier circuit comprises:
Operational amplifier, the backward end of described operational amplifier is connected with the secondary side of described current transformer, is arranged in series amplification resistance parallel with one another and the first filter capacitor between the output terminal of described operational amplifier and backward end;
The forward end of described operational amplifier is connected with direct supply.
4. leakage current detection protection circuit according to claim 3, is characterized in that,
The second filter capacitor has been arranged in series between the forward end of described operational amplifier and ground.
5. leakage current detection protection circuit according to claim 1 and 2, is characterized in that,
Described pulse switching circuit comprises the first comparer and bleeder circuit;
The first end of described bleeder circuit is connected with the output terminal of described low-frequency amplifier circuit, the second end ground connection of described bleeder circuit;
Described bleeder circuit comprises the first divider resistance and second divider resistance of series connection mutually, has output node between described first divider resistance and described second divider resistance;
The forward end of described first comparer is connected with described output node, and the backward end of described first comparer is connected with the output terminal of described low-frequency amplifier circuit.
6. leakage current detection protection circuit according to claim 5, is characterized in that,
Described bleeder circuit also comprises three filter capacitor in parallel with described second divider resistance.
7. leakage current detection protection circuit according to claim 2, is characterized in that,
Described pulse signal filtering circuit comprises the second comparer and reference value arranges circuit;
Described reference value arranges circuit and comprises first reference value and arrange circuit and the second reference value arranges circuit;
Described first reference value is arranged on circuit has the first reference point, and described first reference point is connected with the output terminal of described pulse switching circuit and the forward end of described second comparer;
Described second reference value is arranged on circuit has the second reference point, and described second reference point is connected with the backward end of described second comparer, and the reference voltage of described first reference point is greater than the reference voltage of described second reference point.
8. leakage current detection protection circuit according to claim 7, is characterized in that,
The first end that described first reference value arranges circuit is connected with direct supply, and described first reference value arranges the second end ground connection of circuit, and described first reference value arranges on circuit and has been arranged in series at least two divider resistances;
The first end that described second reference value arranges circuit is connected with direct supply, and described second reference value arranges the second end ground connection of circuit, and described second reference value arranges on circuit and has been arranged in series at least two divider resistances.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520149497.3U CN205176099U (en) | 2015-03-16 | 2015-03-16 | Leakage detection protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201520149497.3U CN205176099U (en) | 2015-03-16 | 2015-03-16 | Leakage detection protection circuit |
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| CN205176099U true CN205176099U (en) | 2016-04-20 |
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| CN201520149497.3U Expired - Fee Related CN205176099U (en) | 2015-03-16 | 2015-03-16 | Leakage detection protection circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104749416A (en) * | 2015-03-16 | 2015-07-01 | 珠海格力电器股份有限公司 | Leakage detection protection circuit |
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2015
- 2015-03-16 CN CN201520149497.3U patent/CN205176099U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104749416A (en) * | 2015-03-16 | 2015-07-01 | 珠海格力电器股份有限公司 | Leakage detection protection circuit |
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| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20160420 |
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| CF01 | Termination of patent right due to non-payment of annual fee |