CN202917323U - Current transformer - Google Patents
Current transformer Download PDFInfo
- Publication number
- CN202917323U CN202917323U CN 201220620818 CN201220620818U CN202917323U CN 202917323 U CN202917323 U CN 202917323U CN 201220620818 CN201220620818 CN 201220620818 CN 201220620818 U CN201220620818 U CN 201220620818U CN 202917323 U CN202917323 U CN 202917323U
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- current transformer
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- winding
- shunt
- secondary winding
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Abstract
The utility model relates to a current transformer which comprises a magnetic ring, a primary coil, a secondary coil and a shunt which is arranged on a to-be-tested circuit in series, wherein the primary coil and a second coil are wound on the magnetic ring, the primary coil is connected with the shunt in parallel, and the secondary coil outputs signals for test and analysis. The current transformer is simple in structure, and not easy to interfere by outer magnetic field, and can really reflect the damping state of maximum non-periodic components and eliminate the phenomenon of trailing after fault elimination according to optimal selection of parameters. The current transformer can be used for waveform follow and unit combination after fault wave record and multiple reclosure, a traditional relay protection and a once current mutual inductor.
Description
Technical field
The utility model designs a kind of current transformer; relate in particular to and a kind ofly measure the current transformer that the response of good transition process is arranged of short circuit current and aperiodic component for the electric power system microcomputer protective relay, and can be used in that waveform behind failure wave-recording, the multiple shot reclosing is followed, on merge cells and traditional protection and the primary current instrument transformer.
Background technology
When the electric power system primary equipment broke down, the electric current of running current more than 20 times can appear in the system.In addition, owing in the circuit inductance is arranged, short circuit current can not increase suddenly.So a direct current with periodic component opposite current and decay also can occur in incipient moment (during t=0), namely 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 traditional instrument transformer electric current be raised to rated value 20 after, magnetic flux unshakable in one's determination is near the zone of saturation, thereby causes the output waveform distortion, the aperiodic component of the secondary progress of disease is decayed in advance, secondary output is with a series of phenomenons such as hangovers behind the failure removal.In recent years, along with the upgrading of system, also required instrument transformer can accurately measure 30 times or even 40 times short circuit current of running current, and can accurately reflect truly the waveform of aperiodic component.This is to be difficult to realize, especially in system short trouble appears, when the instrument transformer primary current is raised 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, output waveform when easily primary current is zero behind saturated and distortion and the failure removal secondary waveform conditions of streaking is arranged, damping time constant error, peak error are large.Existing small product size is large, and complex process and unstable can not satisfy the upgrading requirement of system.
Proposition 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 ammeter, instrument transformer, Luo-coil is as the primary sensing element that detects electric current, it is good to have the linearity, without magnetic saturation; Measuring range is wide, can be from several A to hundreds of kA.But there is very large interference in extraneous magnetic field to Luo-coil.
The utility model content
The utility model is for above-mentioned deficiency of the prior art, be to provide under a kind of 20 times of-60 times of rated current when meeting maximum DC component, output waveform is unsaturated not to distort and accurate progress of disease performance, simple in structure, the current transformer that not disturbed by external magnetic field is arranged.
Concrete technical scheme of the present utility model is as follows:
A kind of current transformer comprises magnet ring, winding, a secondary winding, is serially connected in the shunt on the circuit under test;
A described winding and secondary winding are on magnet ring, and one time winding is in parallel with shunt, and the output signal of secondary winding is used for measuring and analyzing.
The output of described secondary winding is connected with the input of amplifier.
The number of turn of a winding is 5 circles-3000 circles, and the number of turn of secondary winding is 5 circles-50000 circles; The number of turn of a preferred winding is 10 circles-2000 circles, and the number of turn of secondary winding is 10 circles-20000 circles.During concrete the use, all be to get the number of turn of secondary winding greater than the number of turn of a winding generally.
The wire diameter of described secondary winding is Φ 0.02mm-Φ 1.5mm.
The sectional area of described magnet ring is 0.2 c ㎡-100 c ㎡.
Described shunt is resistance, and its resistance is 0.01m Ω-10 Ω; The multiplication factor of amplifier is at 1 times-300 times; Preferred shunt resistance is 0.1m Ω-1 Ω.
Operation principle of the present utility model is:
Produce the moment of aperiodic component in system, and when running into maximum short circuit angle, the amplitude of first ripple can increase to 1.8 times of steady short, then by the successively decay such as 1.47 times, 1.29 times, until stable state.Therefore during several ripple, magnet ring is operated in the quite high state of B to instrument transformer before the progress of disease, causes easily waveform saturated and exciting current is excessive.The impact of remanent magnetism also can strengthen the saturated of magnet ring in addition.To in limited volume, satisfy unsaturated the reaching of waveform when therefore designing and hangover can not occur, can transfer current mode to voltage-type, pass through again an amplifier with voltage amplification.
At the i.e. shunt of a little resistance of high accuracy in parallel on winding of the primary side of instrument transformer, can transfer maximum operating currenbt to small voltage, instrument transformer to secondary, is secondary winding on an in parallel amplifier at the secondary side of magnet ring with the primary voltage progress of disease, by no-load voltage ratio voltage or electric current is amplified.Therefore can meet maximum DC component under 20 times of-60 times of rated current, output waveform is unsaturated not to distort, and the phenomenon of secondary hangover after choosing the attenuation state that further truly reflects maximum DC component and eliminate fault according to the optimization of parameter.
When system short-circuit, 20-30 times of rated current can appear in primary side, obtains less voltage behind the shunt by the little resistance of high accuracy, again by the magnet ring isolation, realizes the output voltage of user's needs by the amplifier of magnet ring primary side.Avoided like this occurring Flux saturation, thereby made wave distortion.Simultaneously also with the conditions of streaking elimination, and can reach the accurately aperiodic component progress of disease of height.
The utility model is simple in structure and be not subject to external magnetic field and disturb, current transformer choose according to the optimization of parameter so that can truly reflect the attenuation state of maximum aperiodic component and eliminate failure removal after secondary conditions of streaking.The utility model can be used in that waveform behind failure wave-recording, the multiple shot reclosing is followed, on merge cells and the traditional protection.
Description of drawings
Fig. 1 is the structural representation of the utility model specific embodiment voltage amplification;
Fig. 2 is the structural representation that the utility model specific embodiment electric current amplifies;
Wherein: 1-shunt, winding of 2-, 3-secondary winding, 4-amplifier, 5-magnet ring.
Embodiment
Further specify the utility model below in conjunction with accompanying drawing.
Referring to Fig. 1, the current transformer that the utility model provides comprises magnet ring 5, winding 2, a secondary winding 3, is serially connected in 1, winding 2 of a shunt on the cable and secondary winding 3 on magnet ring 5, and one time winding 2 is in parallel with shunt 1; When the voltage of the output of secondary winding 3 during less than 100 millivolts, the output of secondary winding 3 is connected with the input of amplifier 4; Described shunt adopts the resistance of the little resistance of high accuracy.
Wherein, the sectional area of magnet ring is 0.2 c ㎡-100 c ㎡.The number of turn of a winding is 5 circles-3000 circles, is preferably 10 circles-2000 circle.The number of turn of secondary winding is 5 circles-50000 circles, is preferably 10 circles-20000 circle; The wire diameter of secondary winding is Φ 0.02mm-Φ 1.5mm.The shunt resistance is 0.01m Ω-10 Ω, is preferably 0.1m Ω-1 Ω.The multiplication factor of amplifier is at 1 times-300 times.
The number of turn of a winding adopts 300 circles in the present embodiment, and the number of turn of secondary winding adopts 500 circles, and the sectional area of magnet ring is 12.72c ㎡, and the shunt resistance adopts 5m Ω, and the multiplication factor of amplifier is 20 times.
At the i.e. shunt of a little resistance of high accuracy in parallel on winding of the primary side of instrument transformer, can transfer maximum operating currenbt to small voltage, instrument transformer to secondary, is secondary winding on an in parallel amplifier at the secondary side of magnet ring with the primary voltage progress of disease,
By no-load voltage ratio voltage or electric current are amplifiedTherefore can meet maximum DC component under 20 times of-60 times of rated current, output waveform is unsaturated not to distort, and the phenomenon of secondary hangover after choosing the attenuation state that further truly reflects maximum DC component and eliminate fault according to the optimization of parameter.
When system short-circuit, 20-30 times of rated current can appear in primary side, obtains less voltage behind the shunt by the little resistance of high accuracy, again by the magnet ring isolation, realizes the output voltage of user's needs by the amplifier of magnet ring primary side.Avoided like this occurring Flux saturation, thereby made wave distortion.Simultaneously also with the conditions of streaking elimination, and can reach the accurately aperiodic component progress of disease of height.
Claims (8)
1. current transformer is characterized in that comprising magnet ring, winding, a secondary winding, is serially connected in the shunt on the circuit under test;
A described winding and secondary winding are on magnet ring, and one time winding is in parallel with shunt, and the output signal of secondary winding is used for measuring and analyzing.
2. current transformer according to claim 1 is characterized in that the output of described secondary winding is connected with the input of amplifier.
3. current transformer according to claim 1 and 2, the number of turn that it is characterized in that a winding is 5 circles-3000 circles, the number of turn of secondary winding is 5 circles-50000 circles.
4. current transformer according to claim 3, the number of turn that it is characterized in that a winding is 10 circles-2000 circles, the number of turn of secondary winding is 10 circles-20000 circles.
5. current transformer according to claim 4, the wire diameter that it is characterized in that described secondary winding is Φ 0.02mm-Φ 1.5mm.
6. current transformer according to claim 5, the sectional area that it is characterized in that described magnet ring is 0.2 c ㎡-100 c ㎡.
7. current transformer according to claim 6 is characterized in that described shunt is resistance, and its resistance is 0.01m Ω-10 Ω; The multiplication factor of amplifier is at 1 times-300 times.
8. current transformer according to claim 7 is characterized in that described shunt resistance is 0.1m Ω-1 Ω.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220620818 CN202917323U (en) | 2012-11-22 | 2012-11-22 | Current transformer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220620818 CN202917323U (en) | 2012-11-22 | 2012-11-22 | Current transformer |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN202917323U true CN202917323U (en) | 2013-05-01 |
Family
ID=48165611
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN 201220620818 Expired - Lifetime CN202917323U (en) | 2012-11-22 | 2012-11-22 | Current transformer |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN202917323U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103000361A (en) * | 2012-11-22 | 2013-03-27 | 南京江北自动化技术有限公司 | Current transformer |
-
2012
- 2012-11-22 CN CN 201220620818 patent/CN202917323U/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103000361A (en) * | 2012-11-22 | 2013-03-27 | 南京江北自动化技术有限公司 | Current transformer |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CX01 | Expiry of patent term | ||
| CX01 | Expiry of patent term |
Granted publication date: 20130501 |