CN203277078U - Electronic current transformer - Google Patents
Electronic current transformer Download PDFInfo
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- CN203277078U CN203277078U CN 201320250786 CN201320250786U CN203277078U CN 203277078 U CN203277078 U CN 203277078U CN 201320250786 CN201320250786 CN 201320250786 CN 201320250786 U CN201320250786 U CN 201320250786U CN 203277078 U CN203277078 U CN 203277078U
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- winding
- iron core
- electronic current
- mutual inductor
- current transformer
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Abstract
The utility model discloses an electronic current transformer which comprises an iron core and a winding, wherein the iron core is wound with the winding; the sectional area of the iron core is 4.5-100 cm <2>, the number of turns of the winding is 1,000-40,000, and the sectional area of a winding wire is 0.00007-5 mm <2>; and an output rear end of the winding is in parallel connection with a first resistor or a secondary current transformer. The electronic current transformer has the benefits that the structure is simple, and the output waveform is unsaturated and is not distorted when the electronic current transformer encounters a failure current within 70 times of a rated current or the largest direct component; and the electronic current transformer is not prone to be interfered by an outside magnetic, has good stability, high accuracy, a wide frequency band and a large measurement range, doesn't require a rear-end integral circuit, and can really reflect the attenuation state of the largest aperiodic component and eliminate a secondary trailing phenomenon after fault removal according to the optimized selection of parameters.
Description
Technical field
The utility model relates to a kind of current transformer, relates in particular to a kind of electronic current mutual inductor that the response of good transition process is arranged of measuring short circuit current and aperiodic component for electric power system.
Background technology
In the monitoring of circuit on power system, the primary current instrument transformer plays vital effect to the measurement of system power with to the judgement of line fault always.Tradition primary current instrument transformer can be that the line current of 600A or 1200A changes the electric current of 5A or 1A into usually with rated current, then converts small voltage or little electric current to by the secondary current transformer in secondary protector, and then the progress of disease is to microcomputer protecting device.Usually when being short-circuited fault; circuit can occur with respect to and decide doubly even higher fault current of electric current 20-30; and contain decaying DC component; and traditional primary current instrument transformer is under so large fault current; iron core has almost entered magnetically saturated working point, if meet larger DC component, just seriously saturated again; cause that protection is not moving, produce serious consequence.
development along with national intelligent grid, intelligent substation has begun to come into the system of State Grid, electronic current mutual inductor is the important component part of intelligent grid, with respect to traditional primary current instrument transformer, Luo-coil is as the primary sensing element that detects electric current, have without magnetic saturation, the characteristics such as measuring range is wide, can replace traditional primary current instrument transformer, but in actual applications, extraneous magnetic field and ambient temperature all have very large interference to Luo-coil, exist poor stability, low precision, frequency band is narrow and mate the insoluble technical bottlenecks such as not good with the rear end integrating circuit.
Summary of the invention
the technical problems to be solved in the utility model is, easily reach magnetic saturation when meeting with large fault current or larger DC component for the iron core of current transformer in prior art, easily distortion, poor stability, low precision, the defects that frequency band is narrow and not good etc. with rear end integrating circuit coupling, provide a kind of simple in structure, do not distort meeting with 70 times output waveform is unsaturated during with the fault current of interior rated current or maximum DC component, not being subject to external magnetic field disturbs, good stability, precision is high, bandwidth, measuring range is large, need not the rear end integrating circuit, and the electronic current mutual inductor of secondary conditions of streaking after choosing the attenuation state that can truly reflect maximum aperiodic component and eliminate failure removal according to the optimization of parameter.
The technical scheme that its technical problem that solves the utility model adopts is: a kind of electronic current mutual inductor comprises iron core and the winding on the iron core; The sectional area of iron core is 4.5-100cm
2, the number of turn of winding is the 1000-40000 circle, and the sectional area of winding conducting wire is 0.00007-5mm
2The output rear end of winding is parallel with the first resistance or secondary current transformer.
In technical scheme described in the utility model, described electronic current mutual inductor comprises iron core and winding, wherein winding is on iron core, and the output rear end at winding also is parallel with the first resistance or secondary current transformer, therefore described electronic current mutual inductor is not only simple in structure, and compare Luo-coil, because cored existence in described electronic current mutual inductor, make it have advantages of bandwidth on the one hand, make it can realize measuring accurately fully in the 23 subharmonic scopes that protection requires; Also make on the other hand its coil leakage inductance greatly reduce, so just guaranteed that described electronic current mutual inductor is not vulnerable to external magnetic field and disturbs, good stability.in addition, because Luo-coil is operated near open-circuit condition, be actually the differential to primary current, this just causes increasing in its back-end integrating circuit so that its differential signal is reduced, could truly reflect the waveform of primary current, and the electric capacity original paper in integrating circuit etc. very easily are subject to the impact of ambient temperature and strengthen measure error, what is more important is because the existence of coil D.C. resistance, Luo-coil is not a pure differential device, integrating circuit is difficult to realize measuring accurately by good coupling with Luo-coil, therefore compare with Luo-coil of the prior art, electronic current mutual inductor described in the utility model need not the rear end integrating circuit just can truly reflect the waveform of primary current, and can also avoid because the measure error that the electric capacity original paper in integrating circuit causes because very easily be subject to ambient temperature effect, further improved the certainty of measurement of described electronic current mutual inductor.
In technical scheme described in the utility model, described electronic current mutual inductor is generally directly to offer electronic circuit, its secondary load is smaller, and generally adopts high magnetic conductive material as iron core, and the iron core that sectional area is less just can satisfy the requirement of certainty of measurement.Described electronic current mutual inductor can also be the little electric current below 1A with the 5A of the secondary output of traditional instrument transformer or 1A current reduction, can make like this internal power consumption of described electronic current mutual inductor close to zero; And secondary current is as the signal of measuring primary current, technical scheme described in the utility model changes current signal into voltage signal by output parallel connection the first resistance or the secondary current transformer at winding, and its amplitude is proportional to primary current and phase difference is minimum.Because in described electronic current mutual inductor, the number of turn of winding reaches the 1000-40000 circle, make its internal power consumption almost nil, so just guaranteed that described electronic current mutual inductor has higher certainty of measurement, and also significantly enlarged its measuring range.
in technical scheme described in the utility model, produce the moment of aperiodic component in system, and when meeting maximum short circuit angle, the amplitude of first ripple can increase to 1.8 times of steady short, then by 1.47 times, 1.29 doubly wait decay successively, until stable state, therefore current transformer is before the progress of disease during several ripple, iron core easily causes saturated under the very high state of magnetic field intensity and exciting current is excessive, and the impact of remanent magnetism also can strengthen the degree of saturation of iron core, therefore to reduce the magnetic flux of iron core under maximum operating currenbt in limited volume when design, improve the magnetizing inductance of current transformer, choose or design the iron core of low remanent magnetism, therefore in technical scheme described in the utility model, the sectional area of iron core is 4.5-100cm ﹠lt, sup TranNum="79" ﹠gt, 2 ﹠lt, /sup ﹠gt, the number of turn of winding is the 1000-40000 circle, so just can guarantee in limited volume, the magnetic flux under maximum operating currenbt to be dropped to below the zone of saturation, make its meet with 70 times of output waveforms during with the fault current of interior rated current or maximum DC component be difficult for saturated, can distorted yet.
in addition, when the primary current progress of disease when secondary, due to magnetic flux near the zone of saturation, magnetizing inductance is less, quite a few aperiodic component flows back to from field excitation branch line, and the aperiodic component in secondary current is weakened greatly, thereby affect secondary output for the true reflection of aperiodic component, simultaneously because the existence of exciting current, make primary current and secondary current have certain phase angle difference, therefore after the protection action, primary current has been zero, and secondary current produces conditions of streaking because of the existence of phase angle difference, therefore have the iron core of enough large sectional area and the attenuation state that the abundant winding of the number of turn can truly reflect aperiodic component in technical scheme described in the utility model, can also eliminate the phenomenon of secondary waveform hangover after failure removal.
As a kind of improvement to technical scheme described in the utility model, the number of turn of winding is the 2000-20000 circle.
As a kind of improvement to technical scheme described in the utility model, the resistance of the first resistance is 0.01m Ω-500 Ω.The first resistance in parallel can be voltage form output with current conversion in the output rear end of winding.In addition, if the first resistance greater than 500 Ω, can affect the response characteristic of described electronic current mutual inductor, such as can make degradation under the DC component respond of described current transformer.
As a kind of improvement to technical scheme described in the utility model, iron core is being provided with at least one air gap along the cutting magnetic line direction, and the length of air gap or arc length are 0-5cm.Usually current transformer is when running into DC component, the impact of direct current makes transformer iron core enter fast the zone of saturation, make current transformer cause the output waveform distortion because saturated or induction reactance descends or follow poor, can make significantly fast reducing of the remanent magnetism that causes because of direct current therefore offer the air gap of right quantity on iron core, thereby make the magnetic density of iron core be controlled at all the time unsaturated state.Due to offering of air gap, iron core can be in the accumulation that meets with fast quick-recovery remanent magnetism under the severeest DC component, especially longer in fault time, or in the larger situation of damping time constant, the following air gap of 5cm can make the remanent magnetism of iron core accumulation recover rapidly and control iron core and be in unsaturated state, by the control of gas length or arc length, guarantee that iron core has enough large magnetic permeability to come the waveform of true progress of disease primary current simultaneously.During greater than 5cm, will cause iron core because of the too low shunting that again strengthens exciting current of magnetic permeability when gas length or arc length, and also can affect the true progress of disease ability of primary fault electric current.
As a kind of improvement to technical scheme described in the utility model, iron core is comprised of at least one pair of closed magnetic core.
As a kind of improvement to technical scheme described in the utility model, iron core is comprised of at least one pair of band air gap magnetic core and one pair of closed magnetic core.
As a kind of improvement to technical scheme described in the utility model, the secondary current transformer comprises secondary iron core, winding of secondary and secondary secondary winding; The sectional area of secondary iron core is 0.5-4.5cm
2The number of turn of a winding of secondary is the 1-1000 circle, and its coil section is long-pending is 0.00007-5mm
2The number of turn of secondary secondary winding is the 2500-35000 circle, and the diameter range of its coil is 0.03-1mm.Because system nominal current is generally 600A or 1200A, and the 20-30 that system power can reach rated current when breaking down doubly, when the first resistance of the output rear end parallel connection of winding when larger, the first resistance will cause heating even to damage because bearing larger in short-term power, therefore can be at the output rear end of a winding secondary current transformer in parallel replacing the first resistance, the primary current of system is converted to small voltage to reach the effect same with secondary winding output rear end the first resistance in parallel.In addition, identical with described electronic current mutual inductor, the fault current that is equivalent to tens times of rated current for guaranteeing true reflection, secondary iron core in the secondary current transformer also must have enough large sectional area, the number of turn of secondary secondary winding is also abundant, so just can make the secondary iron core be operated in lower zone; Because the input current of secondary current transformer is converted to little electric current lower than 1A by described electronic current mutual inductor, therefore in the secondary current transformer, the sectional area of secondary iron core is long-pending much smaller more than core section, usually choose 0.5-4.5cm
2Get final product, meanwhile, the number of turn of a winding of secondary is chosen the 1-1000 circle, the number of turn of secondary secondary winding is chosen for the 2500-35000 circle, these have guaranteed further that all the secondary iron core can be in lower regional work, also can guarantee larger excitation induction reactance reducing the shunting of exciting current, thereby guarantee the true progress of disease.
As a kind of improvement to technical scheme described in the utility model, the output of secondary secondary winding is parallel with the second resistance, and the resistance of the second resistance is 1-5000 Ω.Can be voltage form output with current conversion at the output of secondary secondary winding the second resistance in parallel.In addition, this second resistance is 1-5000 Ω, if the second resistance greater than 5000 Ω, can affect the response characteristic of described electronic current mutual inductor, such as can make degradation under the DC component respond of described electronic current mutual inductor.
As a kind of improvement to technical scheme described in the utility model, the secondary iron core is being provided with air gap along the cutting magnetic line direction.Offer air gap and can make significantly fast reducing of the remanent magnetism that causes because of direct current on the secondary iron core, thereby the magnetic density of secondary iron core can be controlled at unsaturated state, with the output waveform distortion of avoiding described electronic current mutual inductor to cause because saturated or induction reactance descend.
In addition, in technical scheme described in the utility model, all being not specifically noted is prior art in the art.
Therefore, the beneficial effects of the utility model have been to provide a kind of electronic current mutual inductor, this electronic current mutual inductor is simple in structure, do not distort meeting with 70 times output waveform is unsaturated during with the fault current of interior rated current or maximum DC component, not being subject to external magnetic field disturbs, good stability, precision is high, bandwidth, measuring range is large, need not the rear end integrating circuit, and secondary conditions of streaking after choosing the attenuation state that can truly reflect maximum aperiodic component and eliminate failure removal according to the optimization of parameter.
Description of drawings
The utility model is described in further detail below in conjunction with drawings and Examples, in accompanying drawing:
Fig. 1 is the structural representation that the output rear end of the utility model winding is parallel with the electronic current mutual inductor of the first resistance;
Fig. 2 is the structural representation that the output rear end of the utility model winding is parallel with the electronic current mutual inductor of secondary current transformer;
Fig. 3 is the iron core of double-side band air gap or the structural representation of secondary iron core;
Fig. 4 is the iron core of single-side belt air gap or the structural representation of secondary iron core;
Now that the label declaration in accompanying drawing is as follows: 1 is the first resistance, and 2 is the secondary current transformer, and 3 is air gap.
Embodiment
In order to make the purpose of this utility model, technical scheme and advantage clearer, below in conjunction with drawings and Examples, the utility model is further elaborated.Should be appreciated that specific embodiment described herein only in order to explaining the utility model, and be not used in restriction the utility model.
Embodiment one:
As shown in Figure 1, a kind of electronic current mutual inductor comprises iron core and winding, and winding is on iron core, and wherein, the sectional area of iron core is 4.5-100cm
2, be preferably 30cm
2The number of turn of winding is the 1000-40000 circle, is preferably the 2000-20000 circle, and the sectional area of winding conducting wire is 0.00007-5mm
2As shown in Figure 3 and Figure 4, iron core is being provided with at least one air gap 3 along the cutting magnetic line direction, and the length of this air gap 3 or arc length are 0-5cm, and iron core is comprised of one pair of closed magnetic core.In addition, the output rear end of winding is parallel with the first resistance 1, and the resistance of this first resistance 1 is 0.01m Ω-500 Ω, preferred 1 Ω.
Embodiment two:
As shown in Figure 2, the present embodiment and embodiment one are basic identical, and difference is that the output rear end of winding is parallel with secondary current transformer 2, and this secondary current transformer 2 comprises secondary iron core, winding of secondary and secondary secondary winding, wherein, the sectional area of secondary iron core is 0.5-4.5cm
2, as shown in Figure 3 and Figure 4, the secondary iron core also is being provided with air gap 3 along the cutting magnetic line direction; The number of turn of a winding of secondary is the 1-1000 circle, and its coil section is long-pending is 0.00007-5mm
2, the number of turn of secondary secondary winding is the 2500-35000 circle, and the diameter range of its coil is 0.03-1mm.In addition, also be parallel with the second resistance at the output of secondary secondary winding, the resistance of this second resistance is 1-5000 Ω.
Should be understood that, for those of ordinary skills, can be improved according to the above description or conversion, and all these improve and conversion all should belong to the protection range of the utility model claims.
Claims (9)
1. an electronic current mutual inductor, is characterized in that, comprises iron core and the winding on the iron core; The sectional area of described iron core is 4.5-100cm
2, the number of turn of winding is the 1000-40000 circle, and the sectional area of winding conducting wire is 0.00007-5mm
2The output rear end of described winding is parallel with the first resistance (1) or secondary current transformer (2).
2. electronic current mutual inductor according to claim 1, is characterized in that, the number of turn of described winding is the 2000-20000 circle.
3. electronic current mutual inductor according to claim 1, is characterized in that, the resistance of described the first resistance (1) is 0.01m Ω-500 Ω.
4. electronic current mutual inductor according to claim 1, is characterized in that, described iron core is being provided with at least one air gap (3) along the cutting magnetic line direction, and the length of described air gap (3) or arc length are 0-5cm.
5. electronic current mutual inductor according to claim 1, is characterized in that, described iron core is comprised of at least one pair of closed magnetic core.
6. electronic current mutual inductor according to claim 1, is characterized in that, described iron core is comprised of at least one pair of band air gap magnetic core and one pair of closed magnetic core.
7. electronic current mutual inductor according to claim 1, is characterized in that, described secondary current transformer (2) comprises secondary iron core, winding of secondary and secondary secondary winding; The sectional area of described secondary iron core is 0.5-4.5cm
2The number of turn of a winding of described secondary is the 1-1000 circle, and its coil section is long-pending is 0.00007-5mm
2The number of turn of described secondary secondary winding is the 2500-35000 circle, and the diameter range of its coil is 0.03-1mm.
8. electronic current mutual inductor according to claim 7, is characterized in that, the output of described secondary secondary winding is parallel with the second resistance, and the resistance of described the second resistance is 1-5000 Ω.
9. electronic current mutual inductor according to claim 7, is characterized in that, described secondary iron core is being provided with air gap (3) along the cutting magnetic line direction.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320250786 CN203277078U (en) | 2013-05-09 | 2013-05-09 | Electronic current transformer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201320250786 CN203277078U (en) | 2013-05-09 | 2013-05-09 | Electronic current transformer |
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| Publication Number | Publication Date |
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| CN203277078U true CN203277078U (en) | 2013-11-06 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 201320250786 Expired - Lifetime CN203277078U (en) | 2013-05-09 | 2013-05-09 | Electronic current transformer |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103227045A (en) * | 2013-05-09 | 2013-07-31 | 南京江北自动化技术有限公司 | Electronic current transformer |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103227045A (en) * | 2013-05-09 | 2013-07-31 | 南京江北自动化技术有限公司 | Electronic current transformer |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term | ||
| CX01 | Expiry of patent term |
Granted publication date: 20131106 |