CN102760568A - Current transformer - Google Patents
Current transformer Download PDFInfo
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- CN102760568A CN102760568A CN2011101112265A CN201110111226A CN102760568A CN 102760568 A CN102760568 A CN 102760568A CN 2011101112265 A CN2011101112265 A CN 2011101112265A CN 201110111226 A CN201110111226 A CN 201110111226A CN 102760568 A CN102760568 A CN 102760568A
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Abstract
The invention discloses a current transformer, which comprises an iron core, a primary winding and a second winding, wherein the cross section of the iron core is 1-4cm<2>; the iron core is provided with at least one air gap along a direction of cutting magnetic lines; the number of turns of the primary winding is 1-25 turns, and the number of turns of the secondary winding is 2000-10000 turns; and the diameter of a coil of the secondary winding is 0.06-0.21mm. When meeting a maximum direct-current component under 20-60 times of rated current, the current transformer can output saturated and distorted waveforms and can really reflect the attenuation state of the maximum direct-current component and eliminate the trailing phenomenon of secondary stage of waveforms according to optimized selection of parameters after faults are removed.
Description
Technical field
The present invention designs a kind of current transformer, relates in particular to a kind of current transformer that the response of good transition process is arranged that the electric power system microcomputer protective relay is measured short circuit current and aperiodic component that is used for.
Background technology
When short trouble appears in the electric power system primary equipment, the short circuit current of running current more than 20 times will appear in the system.Owing to have inductance in the loop, short circuit current can not increase immediately simultaneously.Therefore a direct current with periodic component opposite current and decay also occurs in the moment (during t=0) that just begins short circuit, promptly aperiodic component is superimposed with short circuit current.When the voltage initial angle was 0 ° or 180 °, the maximum instantaneous value of short circuit current half cycle after short circuit occurred, and is generally 1.8Im.And traditional instrument transformer rises to 20 times of rated value at electric current after; Magnetic flux unshakable in one's determination is near the zone of saturation; Thereby when primary system contained aperiodic component, instrument transformer as easy as rolling off a log further increasing because of magnetic flux unshakable in one's determination produced saturated, thereby cause the output waveform distortion; The aperiodic component of the secondary progress of disease is decayed in advance, and secondary output has a series of phenomenons such as hangover behind the failure removal.In recent years, along with the upgrading of system, also required instrument transformer can accurately measure 30 times even 40 times short circuit current of running current, and can accurately reflect the waveform of aperiodic component truly.This also is difficult to realize in the current transformer technology of present stage.Especially in system short trouble appears, when the instrument transformer primary current rises to 20 times of-60 times of rated current; Existing current transformer is the DC component of progress of disease 20-160ms accurately; There is not good transient process response; The attenuation state that can not truly reflect aperiodic component, secondary waveform had conditions of streaking when primary current was zero behind easy saturated distortion of output waveform and the failure removal.
Summary of the invention
Technical problem to be solved by this invention is that the deficiency to above-mentioned prior art provides when meeting maximum DC component under a kind of 20 times of-60 times of rated current the unsaturated undistorted current transformer of output waveform.This current transformer is chosen based on Parameter Optimization and then the attenuation state that can truly reflect maximum aperiodic component and the phenomenon of eliminating secondary hangover after the excision fault
For solving the problems of the technologies described above, the technical scheme that the present invention adopts is: a kind of current transformer, comprise iron core, winding and secondary winding, and the cross section of said iron core is 1cm
2-4cm
2Said iron core upper edge cutting magnetic line direction is provided with at least one air gap; The number of turn of a said winding is 1 circle-25 circle, and the number of turn of said secondary winding is 2000 circles-10000 circles; The coil footpath diameter of said secondary winding is 0.06mm-0.21mm.
As the further improved technical scheme of the present invention, the number of turn of a said winding is 1 circle-15 circle, and the number of turn of said secondary winding is 2500 circles-6000 circles.
As the further improved technical scheme of the present invention, said iron core is formed or is formed or formed or be made up of at least one pair of rectangular slits iron core by at least one pair of annular incision iron core by at least one pair of ED iron core by a folded EI iron core stack.
As the further improved technical scheme of the present invention, said iron core is by at least one pair of annular incision iron core and one pair of annular iron core-closed superimposed form or by at least one pair of rectangular slits iron core and one pair of rectangle iron core-closed superimposed composition.
As the further improved technical scheme of the present invention, said iron core is by at least two pairs of annular incision iron cores perhaps superimposed side by side composition mutually.
As the further improved technical scheme of the present invention, said iron core is by at least two pairs of ED iron cores perhaps superimposed side by side composition mutually.
As the further improved technical scheme of the present invention, said iron core is by at least two pairs of rectangular slits iron cores perhaps superimposed side by side composition mutually.
Operation principle of the present invention is:
Produce the moment of aperiodic component in system, and when meeting maximum short circuit angle, the spoke value of first ripple can increase to 1.8 times of steady short, then by decay successively such as 1.47 times, 1.29 times, until stable state.Therefore during several ripple, iron core is operated in the quite high state of B to instrument transformer before the progress of disease, is prone to cause waveform saturated and exciting current is excessive.The influence of remanent magnetism also can strengthen saturation condition unshakable in one's determination in addition.Therefore will be in limited volume when designing from 1, reduce the magnetic flux Φ under maximum operating currenbt unshakable in one's determination, 2, improve the magnetizing inductance of instrument transformer, 3, choose or design the iron core that hangs down remanent magnetism, set about three aspects.
At first, drop to the magnetic flux under the maximum operating currenbt below the zone of saturation at limited volume.Therefore the line footpath is thick as far as possible, and core section is big as far as possible, and the secondary number of turn is many as far as possible.Line of the present invention footpath is thick, the secondary number of turn is many, therefore can the magnetic flux under the maximum operating currenbt be dropped to and reduce to 70%-80%BT.
The second, when the primary current progress of disease when secondary because magnetic flux is 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 the secondary current is slackened greatly.Thereby influence the true reflection of secondary output for aperiodic component; Simultaneously because the existence of exciting current makes primary current and secondary current have certain phase angle difference, therefore after the protection action; Primary current has been 0, and secondary current produces conditions of streaking because of the existence of angular difference.Increase the excitation impedance of instrument transformer, it is enough big that core section is wanted, and the secondary number of turn is abundant.Core section of the present invention is big, the secondary number of turn is many, so its excitation impedance is greater than 13K, and above phenomenon can be eliminated basically.
The 3rd, during system short-circuit, several magnetic fluxs that decuple the nominal operation state will appear in the current transformer iron core, behind the failure removal, will produce very big remanent magnetism in the iron core.And when remanence direction when the aperiodic component direction of magnetization is identical during with next short circuit; Degree of saturation unshakable in one's determination will be increased; Thereby the transient process response characteristic of current transformer is worsened, and when short circuit coincides with faulty line, also possibly influence relaying protection and excise fault once more.Therefore to select the iron core of band air gap for use, or on the iron core of closed magnetic circuit, air gap is set.Available iron core has: EI silicon steel sheet, ED iron core, CD iron core, and the upper shed of EI silicon steel sheet, annular core upper shed or rectangle iron core upper shed also can mix stack with iron core-closed with the band air-gap iron core.Yet exist air gap that magnetizing inductance is reduced in the magnetic circuit, cause a part of aperiodic component from field excitation branch line, to be shunted, thereby reduce the mutual inductor measuring accuracy of measurement, and will realize enough big volume being arranged above some combination.But the excessive device that also can cause of volume is excessive and too heavy, so the present invention has realized Parameter Optimization in the volume of certain limit.
Core section of the present invention is big, the line footpath is thick, the secondary number of turn is many; Select the iron core of band air gap for use; Therefore can the magnetic flux under the maximum operating currenbt be dropped to and reduce to 70%-80%BT and its excitation impedance greater than 13K; Thereby can under 20 times of-60 times of rated current, meet maximum DC component the time, output waveform is unsaturated not to distort, and can choose the attenuation state that further can truly reflect maximum DC component and eliminate after the excision fault time and the phenomenon of hangover according to Parameter Optimization.
Description of drawings
Fig. 1 is a structural representation of the present invention.
Fig. 2 is an EI core structure sketch map of the present invention.
Fig. 3 for of the present invention not with the EI core structure sketch map of air gap.
Fig. 4, Fig. 5 and Fig. 6 have the EI core structure sketch map of the air gap of diverse location after the cutting of the direction of cutting magnetic line for the present invention.
Fig. 7 is the one-sided air gap annular core structural representation that is provided with of the present invention.
Fig. 8 is provided with air gap annular core structural representation for bilateral of the present invention
Fig. 9 is an ED core structure sketch map of the present invention.
Figure 10 is the one-sided air gap rectangle iron core structural representation that is provided with of the present invention.
Figure 11 is provided with air gap rectangle iron core structural representation for bilateral of the present invention.
Embodiment
As shown in Figure 1, a kind of current transformer comprises iron core, winding and secondary winding, and the cross section of said iron core is 1cm
2-4cm
2Said iron core upper edge cutting magnetic line direction is provided with at least one air gap; The number of turn of a said winding is 1 circle-25 circle, and the number of turn of said secondary winding is 2000 circles-10000 circles; The coil footpath diameter of said secondary winding is Φ 0.06mm-Φ 0.21mm.The number of turn of a said winding is preferably 1 circle-15 circle, and present embodiment adopts 8 circles, and the number of turn of said secondary winding is preferably 2500 circles-6000 circle, and present embodiment adopts 2500 circles.Said core section is meant the cross section of that part of iron core that passes a side winding and secondary winding, and this area of section is 3.5cm
2The coil footpath diameter of secondary winding is 0.10mm.
Said iron core can be formed or formed or formed or formed or be made up of at least one pair of rectangular slits iron core by at least one pair of annular incision iron core by at least one pair of ED iron core by the EI iron core stack after the folded cutting by a folded EI iron core stack.As shown in Figure 2, folded the EI iron core is superimposed forms by one for the iron core of present embodiment.Be air gap 3 in E sheet 1 and I sheet 2 contacted parts.The length A of every EI iron core is 28mm-40mm, and height B is 25mm-40mm, and length and width all are preferably 30mm in the present embodiment; Thickness after the stack is 10mm-45mm, is that 40mm. is certain in the present embodiment, also can adopt the EI iron core stack after the as shown in Figure 3 one folded cutting to form; This shape iron core can cut into the EI iron core in other words; Also can cut into the non-standard style of various various combinations along the direction of cutting magnetic line, for example Fig. 4, Fig. 5 and shown in Figure 6 cut out the air gap 4 different with EI sheet position, air gap 5 or air gap 6 along the cutting magnetic line direction; Other no longer detail all with aforementioned identical.
Like Fig. 7 and shown in Figure 8, present embodiment and embodiment 1 are basic identical, and difference is that the iron core of present embodiment adopts annular incision iron core, the long-pending 2cm of being of core section
2, the number of turn of a winding is 5 circles, and the number of turn of secondary winding is 4000 circles, and the coil footpath diameter of secondary winding is 0.08mm.Said iron core can be made up of one pair of annular incision iron core, also can be by at least two pairs of annular incision iron core superimposed compositions.Present embodiment as shown in Figure 3 only adopts one pair of annular core of establishing air gap 8.The outer diameter A of annular core is 18mm-40mm, and internal diameter B is 12mm-30mm, and thickness C is 6mm-18mm, and preferred external diameter B is 36mm in the present embodiment, and internal diameter A is 20mm, and thickness C is 16mm.The superimposed use of annular core that can certainly adopt the annular core that is provided with air gap and not establish air gap.Perhaps can also adopt like Fig. 9, Figure 10 or a pair of ED iron core or at least two pairs of ED iron cores or a pair of rectangular slits iron core or at least two pairs of perhaps superimposed side by side compositions of rectangular slits iron core phase shown in Figure 11.
Claims (7)
1. current transformer comprises iron core, winding and secondary winding, it is characterized in that:
The cross section of said iron core is 1cm
2-4cm
2Said iron core upper edge cutting magnetic line direction is provided with at least one air gap; The number of turn of a said winding is 1 circle-25 circle, and the number of turn of said secondary winding is 2000 circles-10000 circles; The coil diameter of said secondary winding is 0.06mm-0.21mm.
2. current transformer according to claim 1 is characterized in that: the number of turn of a said winding is 1 circle-15 circle, and the number of turn of said secondary winding is 2500 circles-6000 circles.
3. current transformer according to claim 1 and 2 is characterized in that: said iron core is formed or is formed or formed or be made up of at least one pair of rectangular slits iron core by at least one pair of annular incision iron core by at least one pair of ED by a folded EI iron core stack.
4. current transformer according to claim 1 and 2 is characterized in that: said iron core is by at least one pair of annular incision iron core and one pair of annular iron core-closed superimposed form or by at least one pair of rectangular slits iron core and one pair of rectangle iron core-closed superimposed composition.
5. current transformer according to claim 3 is characterized in that: said iron core is by at least two pairs of annular incision iron cores perhaps superimposed side by side composition mutually.
6. current transformer according to claim 3 is characterized in that: said iron core is by at least two pairs of ED iron cores perhaps superimposed side by side composition mutually.
7. current transformer according to claim 3 is characterized in that: said iron core is by at least two pairs of rectangular slits iron cores perhaps superimposed side by side composition mutually.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011101112265A CN102760568A (en) | 2011-04-28 | 2011-04-28 | Current transformer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011101112265A CN102760568A (en) | 2011-04-28 | 2011-04-28 | Current transformer |
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| Publication Number | Publication Date |
|---|---|
| CN102760568A true CN102760568A (en) | 2012-10-31 |
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| CN2011101112265A Pending CN102760568A (en) | 2011-04-28 | 2011-04-28 | Current transformer |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103219140A (en) * | 2013-04-24 | 2013-07-24 | 南京江北自动化技术有限公司 | Current transformer |
| CN103227045A (en) * | 2013-05-09 | 2013-07-31 | 南京江北自动化技术有限公司 | Electronic current transformer |
| US10018647B2 (en) * | 2014-05-16 | 2018-07-10 | Defence Research Development Organisation | Velocity interferometer for any reflector with variable sensitivity range and time resolution |
Citations (6)
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| JP2000235051A (en) * | 1999-02-17 | 2000-08-29 | Fuji Electric Co Ltd | Detector for detecting direct current component contained in alternating current |
| CN1397963A (en) * | 2002-08-16 | 2003-02-19 | 余湘权 | Current measuring device and method using current mutual inductor with high transforming ratio |
| US6563411B1 (en) * | 1998-09-17 | 2003-05-13 | Vacuumschmelze Gmbh | Current transformer with direct current tolerance |
| CN1484884A (en) * | 2002-03-12 | 2004-03-24 | 松下电器产业株式会社 | Communication radar system |
| CN1688003A (en) * | 2005-06-23 | 2005-10-26 | 安泰科技股份有限公司 | Anti-DC component current transformer core and mfg. method and use thereof |
| CN202196657U (en) * | 2011-04-28 | 2012-04-18 | 南京江北自动化技术有限公司 | Current transformer |
-
2011
- 2011-04-28 CN CN2011101112265A patent/CN102760568A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6563411B1 (en) * | 1998-09-17 | 2003-05-13 | Vacuumschmelze Gmbh | Current transformer with direct current tolerance |
| JP2000235051A (en) * | 1999-02-17 | 2000-08-29 | Fuji Electric Co Ltd | Detector for detecting direct current component contained in alternating current |
| CN1484884A (en) * | 2002-03-12 | 2004-03-24 | 松下电器产业株式会社 | Communication radar system |
| CN1397963A (en) * | 2002-08-16 | 2003-02-19 | 余湘权 | Current measuring device and method using current mutual inductor with high transforming ratio |
| CN1688003A (en) * | 2005-06-23 | 2005-10-26 | 安泰科技股份有限公司 | Anti-DC component current transformer core and mfg. method and use thereof |
| CN202196657U (en) * | 2011-04-28 | 2012-04-18 | 南京江北自动化技术有限公司 | Current transformer |
Non-Patent Citations (1)
| Title |
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| 林辉，王辉: "《电力电子》", 31 March 2002, 武汉理工大学出版社, article "磁性元件设计", pages: 176 * |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103219140A (en) * | 2013-04-24 | 2013-07-24 | 南京江北自动化技术有限公司 | Current transformer |
| CN103219140B (en) * | 2013-04-24 | 2016-08-10 | 南京江北自动化技术有限公司 | A kind of current transformer |
| CN103227045A (en) * | 2013-05-09 | 2013-07-31 | 南京江北自动化技术有限公司 | Electronic current transformer |
| US10018647B2 (en) * | 2014-05-16 | 2018-07-10 | Defence Research Development Organisation | Velocity interferometer for any reflector with variable sensitivity range and time resolution |
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Application publication date: 20121031 |