JP2005049311A - Current sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small sized current sensor with high sensitivity with respect to a current sensor that is suitable to use the zero phase current transformer of a ground leakage breaker. <P>SOLUTION: The current sensor is constituted of an annular core 1 of a high magnetic permeability material, a core case 2 containing the annular core, an output voltage detecting a winding wire 3 wound on the core case, a shield plate 4 or a shield case 5, an exterior case 6, a lead wire 3a connected to the winding wire, and an insulative resin 7 filled into the gap of the exterior case; and therein a plate 4a of a material with a high-saturated magnetic flux density is used for the cover, or internal surface, or external surface of the core case. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a current sensor, and more particularly to a current sensor suitable for use in a zero-phase current transformer of an earth leakage breaker.

  The structure of a conventional current sensor will be described. FIG. 3 is a sectional view of a conventional current sensor. A winding 33 for detecting an output voltage wound around a core case 32 in which the annular core 31 is housed, and a shield plate 34, a shield case 35, and an outer case 36 are sequentially provided on the outer side thereof. It is composed of a functional resin 37. The annular core 31 is a laminate of high magnetic permeability material, for example, permalloy or ferrite plate, and a material having a higher saturation magnetic flux density, for example, a plate 34a of silicon steel or pure iron, is provided on the upper portion of the laminate 31. Are stacked.

  When a current sensor having a conventional structure passes through a power line through the hole in the center of the current sensor and a current leaks or a short circuit occurs at the tip of the power line, the inside of the power line indicated by Iin and Iout in FIG. Since the input / output current balance is lost, a voltage is generated in the output voltage detection winding 33 wound around the core case 32 by the principle of electromagnetic induction.

  In the current sensor having the conventional structure, if the current value flowing through the power line is increased, the magnetic characteristics of the core are saturated, and the error of the output voltage becomes large. In addition, a material having a higher saturation magnetic flux density, for example, a plate 34a made of silicon steel or pure iron, must be laminated to prevent saturation of magnetic characteristics and prevent an error in output voltage from becoming large.

  With recent miniaturization of electronic devices, there is a strong demand for downsizing of the earth leakage breaker, and there is also a demand for high sensitivity capable of obtaining an output voltage with respect to a minute leakage current. Along with this, miniaturization and high sensitivity have been demanded for current sensors.

  Patent Document 1 is an example of a prior art document relating to downsizing of a current sensor. This relates to miniaturization of only the test coil of the zero-phase current transformer, and there is no description of miniaturization or high sensitivity of the current sensor.

Utility Model Registration No. 252222255

  Although miniaturization and high sensitivity of current sensors are requirements for mutually conflicting characteristics, the present invention considers various constituent materials and structures of current sensors, and provides a small and highly sensitive current sensor. Objective.

  According to the present invention, an annular core made of a high magnetic permeability material, a core case that houses the annular core, a winding for detecting an output voltage wound around the core case, a shield plate or a shield case, and an exterior case And a lead plate connected to the winding and an insulating resin filled in a gap between the outer case, and a plate made of a material having a high saturation magnetic flux density on the lid or inner peripheral surface or outer peripheral surface of the core case A current sensor characterized by using can be obtained.

  According to the present invention, the material having a high saturation magnetic flux density is a plate of silicon steel or pure iron, and the annular core of the high magnetic permeability material is a laminate of permalloy or ferrite plates, or permalloy. A current sensor characterized in that the shield plate or shield case is made of silicon steel or pure iron having a high saturation magnetic flux density. can get.

  As described above, by using a plate made of a material having a high saturation magnetic flux density at the top of the core laminated body, which has been used for preventing saturation of the magnetic properties of the annular core, as a lid or inner peripheral surface or outer peripheral surface of the core case. The core itself can be downsized. Further, by replacing the saturation-preventing core material with a high permeability material, the sensitivity of the current sensor can be increased.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2.

  FIG. 1 is a cross-sectional view of the current sensor of the present invention. An annular core 1 made of a high magnetic permeability material is housed in a core case 2, and a shield plate 4 or a shield case 5 is attached to the core case 2 around which a winding 3 for detecting an output voltage is wound. The current sensor has a configuration in which the gap between the outer case 6 is filled with an insulating resin 7, and a plate 4a made of a material having a high saturation magnetic flux density is used as the lid of the core case.

  2 is an enlarged cross-sectional view of the annular core 1 and the core case 2. FIG. 2 (a) is a diagram in which the lid is a plate 4a made of a material having a high saturation magnetic flux density, and FIG. 2 (b) is an outer peripheral surface of the core case. FIG. 2C is a diagram in which the lid is a plate 4a made of a material having a high saturation magnetic flux density, and FIG. 2C is a diagram in which the inner peripheral surface lid of the core case is a plate 4a made of a material having a high saturation magnetic flux density.

(Example 1)
As an annular core, a laminate of 20 plates of 78% Ni permalloy having an outer diameter of 10 mm, an inner diameter of 6 mm, and a thickness of 0.3 mm, and a plastic core having an inner diameter dimension that can accommodate the laminated body and a thickness of 0.3 mm The case was housed in a 6% Si silicon steel case, and an insulation-coated electric wire having an outer diameter of 0.1 mm was wound around the core case 1000 times, and the beginning and end of this electric wire were connected to the lead-out electric wire. Further, the wound core case is sandwiched between pure iron shield plates and stored in a pure iron shield case. The shield case is stored in a plastic outer case having an outer diameter of 15 mm, an inner diameter of 4 mm, and a height of 10 mm. An epoxy resin was filled in the gap inside the outer case and cured to obtain a current sensor.

(Example 2)
As an annular core, 20 plates of Mn—Zn ferrite outer diameter 10 mm—inner diameter 6 mm—thickness 0.3 mm are laminated, and the inner diameter of the laminate can be accommodated and the thickness is 0.3 mm. In the core case, the lid was housed in a pure iron, and an insulating coated electric wire having an outer diameter of 0.1 mm was wound around the core case 1000 times, and the leading end and the terminal end of the electric wire were connected to the lead wire. Further, the core case with winding up is sandwiched between 6% Si silicon steel shield plates and stored in a pure iron shield case. This shield case is an outer case made of plastic with an outer diameter of 15 mm, an inner diameter of 4 mm, and a height of 12 mm. And filled with epoxy resin in the gap inside the exterior case and cured to obtain a current sensor.

  According to the first embodiment and the second embodiment described above, the height of the annular core can be reduced by 1 mm. Therefore, the height can be reduced by 10% compared to the conventional current sensor. Also, by replacing the material with high saturation magnetic flux density at the top of the annular core laminate with a high permeability material, the volume of the high permeability material can be increased by 17%, and the sensitivity of the current sensor is about 15%. Can be improved.

Sectional drawing of the current sensor of this invention. The expanded sectional view of an annular core and a core case. FIG. 2A shows a plate made of a material having a high saturation magnetic flux density for the lid. FIG.2 (b) is a figure which shows the board of a material with a high saturation magnetic flux density for the outer peripheral surface cover of a core case. FIG.2 (c) is a figure which shows the board of a material with a high saturation magnetic flux density for the inner peripheral surface cover of a core case. The cross-section figure of the conventional current sensor.

Explanation of symbols

1 annular core
2 Core Case 3 Winding 3a for Output Voltage Detection Leader Wire 4 Shield Plate 4a Case Cover 5 Shield Case 6 Exterior Case 7 Insulating Resin 31 Annular Core 32 Core Case 33 Winding 33a for Output Voltage Detection Leader Wire 34 Shield Plate 34a Plate 35 of material with high saturation magnetic flux density Shield case 36 Exterior case 37 Insulating resin

Claims (5)

  An annular core of a high magnetic permeability material, a core case that houses the annular core, a winding for output voltage detection wound around the core case, a shield plate or shield case, an exterior case, and the winding In the current sensor composed of an insulating resin filled in the gap between the lead wire to be connected and the outer case, a plate made of a material having a high saturation magnetic flux density is used for the lid or inner peripheral surface or outer peripheral surface of the core case. And current sensor.   2. The current sensor according to claim 1, wherein the material having a high saturation magnetic flux density is a plate of silicon steel or pure iron.   2. The current sensor according to claim 1, wherein the annular core of the high-permeability material is a laminate of permalloy plates or a permalloy plate formed by winding a circular or square shape. .   2. The current sensor according to claim 1, wherein the annular core of the high magnetic permeability material is a laminate of ferrite plates.   2. The current sensor according to claim 1, wherein the shield plate or the shield case uses a material such as silicon steel or pure iron having a high saturation magnetic flux density.

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