Current transformer

A technology for current transformers and iron cores, applied in the direction of inductors, transformer/inductor cores, transformer/inductor coils/windings/connections, etc., which can solve the problem of easy saturation of output waveforms and distortion of secondary currents that will cause tailing , can not truly reflect the attenuation state of non-periodic components, and the current transformer cannot accurately transmit and change DC components, etc., to achieve the effect of eliminating tailing

Active Publication Date: 2013-07-24
NANJING JIANGBEI AUTOMATION TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The technical problem to be solved by the present invention is that in the prior art, when a short-circuit fault occurs in the system and its primary current rises to 20-60 times the rated current, the current transformer cannot accurately transmit the DC component with a decay time constant of 20-200ms , can not truly reflect the attenuation state of the non-periodic component, its output waveform is easy to saturate and distort, and the secondary current will tail when the primary current is zero after the fault is removed. 20-60 times, it can accurately transmit the DC component with an attenuation time constant of 20-200ms, can truly reflect the attenuation state of the non-periodic component, the output waveform is not saturated and distorted, and can eliminate the tailing phenomenon of the secondary waveform after fault removal Current Transformer

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Embodiment 1

[0029] Such as figure 1 As shown, a current transformer includes an iron core, a primary winding and a secondary winding, wherein the cross-sectional area of ​​the iron core is 0.5-3.5cm2, and at least one air gap 1 is provided on the iron core along the direction of the cutting magnetic force line; The number of turns of the winding is 1-25 turns, preferably 1-15 turns; the number of turns of the secondary winding is 10001-30000 turns, preferably 10001-20000 turns; in addition, the coil cross-sectional area of ​​the primary winding is 0.5- 4mm 2 , preferably 1mm 2 , the coil diameter of the secondary winding is in the range of 0.05-0.3 mm, preferably 0.1 mm.

[0030] In this embodiment, a resistor is connected in parallel at both ends of the secondary winding, and the resistance of the resistor ranges from 1 ohm to 5000 ohm. In addition, the iron core can be composed of one or more of a stack of EI iron cores with air gaps, at least one pair of ED iron cores, at least one ...

Embodiment 2

[0032] Such as Figure 7 and Figure 8 As shown, this embodiment is basically the same as Embodiment 1, except that the iron core used in this embodiment is an annular iron core, and the cross-sectional area of ​​this annular iron core is 2cm 2 , the number of turns of the primary winding is 5 turns, the number of turns of the secondary winding is 15000 turns, and the coil cross-sectional area of ​​the primary winding is 1.5mm 2 , the coil cross-sectional area of ​​the secondary winding is 0.1mm 2 .

[0033] In the second embodiment, a resistor may be connected in parallel at both ends of the secondary winding, and the resistance value of the resistor ranges from 1 ohm to 5000 ohm. The iron core may consist of at least one pair of annular notched iron cores. Such as Figure 8 As shown, the present embodiment only adopts an annular iron core with an air gap 1, the outer diameter of the annular iron core is 18-40mm, the inner diameter is 12-30mm, and the thickness is 6-18mm...

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Abstract

The invention discloses a current transformer which comprises an iron core, primary winding and secondary winding. At least one air gap arranged along a magnetic field line cutting direction is arranged on the iron core, and the sectional area of the iron core is 0.5cm<2> to 3.5cm<2>. The number of turns of the primary winding is 1 turn to 25 turns, and the sectional area of coils of the primary winding is 0.5mm<2> to 4mm<2>. The number of turns of the secondary winding is 10001 turns to 30000 turns, and the diameter range of the coils of the secondary winding is 0.05mm to 0.3mm. The current transformer has the advantages that when a primary current rises to 20 times to 6o times of a rated current, the current transformer can accurately transform direct current components with decay time constant of 20ms to 200ms, and can truly reflect a nonperiodic decay state, output waveforms of the current transformer are difficult to be saturate and are not distorted, and the trailing phenomenon generated by secondary waveforms after fault removal can be further eliminated.

Description

technical field [0001] The invention relates to a current transformer, in particular to a current transformer used for measuring short-circuit current and aperiodic component in microcomputer relay protection of electric power system. Background technique [0002] When a short-circuit fault occurs in the primary equipment of the power system, a short-circuit current of more than 20 times the normal operating current will appear in the system, but due to the inductance in the circuit, the circuit current in the system will not increase immediately, so at the beginning of the moment, That is, when t=0, there will also be a direct current that is opposite to the periodic component current and attenuates, that is, the non-periodic component, which is superimposed on the short-circuit current. When the initial angle of the voltage is 0°-180°, the maximum instantaneous value of the short-circuit current appears within half a cycle wave after the short-circuit, usually 1.8Im. In t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01F38/28H01F27/26H01F3/14H01F27/28
Inventor 赵晶晶
Owner NANJING JIANGBEI AUTOMATION TECH
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