JP4450457B2 - Lightning surge cutoff transformer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lightning surge cutoff transformer that cuts off a lightning surge that penetrates and conducts an electric wire and damages precision electronic devices, information devices, automatic control devices, and the like, and protects these electric and electronic devices.
[0002]
[Prior art]
FIG. 6 is a circuit diagram for explaining how a lightning surge current flows in a circuit that supplies electric power from the commercial power supply 5 to the electrical device 6 via a transformer. The transformer is an insulating transformer composed of a primary coil 1, a secondary coil 2, an iron core 3 and an electrostatic shielding plate 4. In addition, Lu and Cu are an inductance component and a capacitance component of the ground impedance of the U-phase line, and Lv and Cv are an inductance component and a capacitance component of the ground impedance of the V-phase line. Further, Cs is a capacitance distributed between the primary coil 1 and the electrostatic shielding plate 4 and between the secondary coil 2 and the electrostatic shielding plate 4.
[0003]
From the viewpoint of electrical equipment installed on the ground, lightning surge is a common mode noise that draws a huge loop around the earth from the sky. After this lightning surge has entered the electrical line, it is not 100% common mode noise but noise that is a combination of common mode noise component and normal mode noise component. As can be seen from FIG. 6, there is always a significant difference in the ground impedance of the electric line between the two round-trip lines, and there is a considerable difference in the impedance and its distribution in the transformer. Some lightning surge currents have a significant shift in level and phase between the two wires.
[0004]
As a result, most of the lightning surge current Iu traveling from the U terminal to the V terminal of the primary coil 1 of the transformer and the lightning surge current Iv traveling in the opposite direction cancel each other in the primary coil 1. The lightning surge current difference component flows through the primary coil 1 as a large amount of normal mode noise lightning surge current. The lightning surge current of the normal mode noise component shifts from the primary side to the secondary side due to the electromagnetic induction effect inherent in the transformer. The transition of the lightning surge current of the normal mode noise component due to the electromagnetic induction to the secondary side cannot be prevented by the electrostatic shielding plate 4 disposed between the primary coil 1 and the secondary coil 2. This is because the electrostatic shielding plate is not involved in principle in electromagnetic induction.
[0005]
By the way, Japanese Patent Laid-Open No. 6-77063 discloses a first insulating layer, an input-side winding, a second insulating layer, a first insulating layer that is in direct contact with the iron core from the input side to the output side of the iron core to be wound. 1 shielding plate, 3rd insulating layer, 2nd shielding plate, 4th insulating layer, 3rd shielding plate, 5th insulating layer, output side coil | winding, 6th insulating layer, 4th shielding A lightning protection transformer comprising a plate and a seventh insulating layer is disclosed. In short, in the coaxial concentric insulation transformer, the input side coil is arranged on the inner side, the output side coil is arranged on the outer side, and three shielding plates are sandwiched between the input side coil and the output side coil, and the iron core is sandwiched between them. And a lightning protection transformer constructed by arranging one shielding plate coaxially with the iron core on the outer peripheral side of the output side coil.
This lightning protection transformer is configured to prevent the lightning surge of the common mode noise component from affecting the electrical equipment connected to the output side coil. Therefore, when the lightning surge current of the normal mode noise component flows through the input side coil, the lightning surge current of the normal mode noise component shifts to the secondary side due to the inherent electromagnetic induction action of the transformer. In the transformer having the input side coil and the output side coil arranged coaxially, the three shielding plates arranged between the input side coil and the output side coil, and the outer peripheral side of the output side coil The single shield plate disposed cannot prevent the normal mode noise component containing a large amount of high frequency components from shifting to the secondary side of the lightning surge current. As described above, the conventional lightning surge cutoff transformer cannot prevent the normal mode noise component from shifting to the secondary side of the lightning surge.
[0006]
[Problems to be solved by the invention]
The problem to be solved by the present invention is to provide a highly reliable lightning surge cutoff transformer that can surely cut off not only common mode noise components of lightning surge current but also normal mode noise components containing a large amount of high frequency components. It is.
[0007]
[Problems to be solved by the invention]
A lightning surge cutoff transformer that solves the above-described problem is provided between a primary coil wrapped with a first electromagnetic shielding plate, a secondary coil wrapped with a second electromagnetic shielding plate, and between the primary coil and the secondary coil. It comprised from the 3rd electromagnetic shielding board arrange | positioned, the core of the shape arrange | positioned so that the said primary coil and the said secondary coil may not be coaxial concentric, and the case of the electroconductive material which accommodates these. The case is provided with a primary side ground terminal, a secondary side ground terminal and an intermediate ground terminal which are physically and electrically separated from each other, and the primary side ground terminal and the secondary side ground terminal are respectively provided. The first electromagnetic shielding plate and the second electromagnetic shielding plate were connected via corresponding lead plates, respectively, and the intermediate ground terminal was connected to the third electromagnetic shielding plate via a frame of conductive material. Further, the primary side grounding terminal, the secondary side grounding terminal, and the intermediate grounding terminal are terminals having a pressing plate structure to which a strip-shaped grounding connection conductor can be connected.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a plan view showing a simplified case and terminal portion according to an embodiment of the present invention, FIG. 4 is a perspective view of a state assembled to a frame, and FIG. 5 is a side view of the state assembled to a frame. is there. As shown in these drawings, a lightning surge cutoff transformer according to an embodiment of the present invention includes a primary coil 10 wrapped with a first electromagnetic shielding plate, a secondary coil 20 wrapped with a second electromagnetic shielding plate, and these. A case 50 made of a conductive material is used as a conductive material case 50. The coaxial eccentric core transformer 30 includes an iron core 30 serving as a magnetic path of the coil and an intermediate electromagnetic shielding plate 40 disposed between the primary coil 10 and the secondary coil 20. It is housed and configured. The intermediate electromagnetic shielding plate 40 is fixed to the frame 51.
[0010]
As shown in an enlarged cross-sectional view in FIG. 2, the primary coil 10 is formed by coating an outer peripheral surface of a coil formed by winding a copper wire 11 in multiple layers and a number of turns with an inner insulating layer 12, and an aluminum foil 13 thereon. The coil is configured to be wrapped around the entire circumference and further covered with the outer insulating layer 14. The aluminum foil 13 is the first electromagnetic shielding plate in the present invention. Further, the secondary coil 20 is also formed by coating the outer peripheral surface of a coil formed by winding a copper wire in multiple layers and multiple turns with an inner insulating layer, wrapping it all over with aluminum foil, and further over it. The coil is configured to be covered with an outer insulating layer, and the aluminum foil functions as the second electromagnetic shielding plate in the present invention.
[0011]
The primary coil 10 and the secondary coil 20 are substantially donut-shaped coils as shown in a perspective view in FIG. One end of the strip grounding lead wire 15 is connected to the first electromagnetic shielding plate 13 enclosing the primary coil 10. Similarly, one end of the grounding lead wire 25 of the strip is connected to the second electromagnetic shielding plate of the secondary coil 20. One end of each of the pair of primary side lead wires 18 is connected to the beginning and end of winding of the copper wire 11 of the primary coil 10, and the other end of each of the pair of primary side lead wires 18 is connected to the pair of primary side terminals 19. Similarly, one end of each of the pair of secondary lead wires 28 is connected to the beginning and end of winding of the copper wire of the secondary coil 20, and the other end of each pair is connected to the pair of secondary terminals 29. Has been.
[0012]
An iron core 30 that forms a magnetic path between the primary coil 10 and the secondary coil 20 includes an E-type core piece and an I-type core piece having predetermined dimensions manufactured by punching a non-oriented silicon steel sheet having a thickness of 0.5 mm, for example. Are generally laminated to a predetermined thickness. FIG. 3 is a perspective view showing the E-type core pieces 30a and 30b in a state before being laminated and assembling the iron core and being stacked separately on the left and right.
[0013]
The pair of primary side terminals 19 and the pair of secondary side terminals 29 are respectively attached to the left and right side plates of the case 50.
[0014]
The primary side ground terminal 17 and the secondary side ground terminal 27 are respectively attached to the left and right side plates of the case 50 via insulators, and the frame ground terminal 41 is attached to the frame 51. Thus, the primary side ground terminal 17, the secondary side ground terminal 27, and the frame ground terminal 41 are attached to the case 50 so as to be physically and electrically separated from each other. Each of these three ground terminals is independently connected to a counterpart ground (a ground electrode or a chassis). For example, the primary side ground terminal 17 is a power source ground electrode, and the secondary side ground terminal 27 is a chassis of an electric device. Further, the frame ground terminal 41 is connected to the other ground electrode of the electrical equipment.
[0015]
The primary side ground terminal 17 is connected to the first electromagnetic shielding plate 13 enclosing the primary coil 10 via the first primary coil shielding lead plate 15 and the second primary coil shielding lead plate 16. . The secondary-side ground terminal 27 is a second electromagnetic shielding plate that encloses the secondary coil 20 via the first secondary coil shield lead plate 25 and the second secondary coil shield lead plate 26. It is connected to the. The frame ground terminal 41 is connected to the intermediate electromagnetic shielding plate 40 via a frame 51 made of a conductive material.
[0016]
As specifically shown in FIG. 5, the primary side ground terminal 17 is composed of a detachable wide pressing plate 17a and an attaching / detaching tool 17b. The bolts constituting the attachment / detachment tool 17b are erected on the side plate 52 at a position in contact with the end of the second primary coil shield lead plate 16 fixed to the side plate 52. When connecting a belt-like ground wire (not shown), that is, a conductive belt, to the primary ground terminal 17, the detachable wide pressing plate 17a is removed from the bolt of the detachable tool 17b. After the end of the conductive band is disposed at a predetermined position of the primary side ground terminal 17, the conductive band is pressed by a detachable wide pressing plate 17a, and further fixed by tightening the bolt and nut of the detachable tool 17b. Is done. Further, the structure of the secondary side ground terminal 27 attached to the side plate opposite to the side plate 52 is composed of a detachable wide holding plate and a detachable tool, similar to the structure of the primary side ground terminal 17 described above. It is a thing. Furthermore, the structure of the frame ground terminal 41 attached to the frame 51 is also composed of a detachable wide pressing plate and an attaching / detaching tool.
[0017]
As described above, in the lightning surge cutoff transformer of the embodiment of the present invention described in detail, the lightning surge current of the common mode noise component is the first electromagnetic shielding plate, the first electromagnetic shielding plate, which is independently grounded via the ground terminal, It is shielded by the two electromagnetic shielding plates and the intermediate electromagnetic shielding plate, and no transition to the secondary side occurs.
[0018]
On the other hand, a lightning surge current of a normal mode noise component containing a large amount of high-frequency components flows in the primary coil 10, and most of the high-frequency components of the magnetic flux due to this current is in the iron core 30, which is a low-frequency material for power. Rather, it passes through the air core formed of a gap or an insulator in the primary coil 10 and the surrounding space. However, since the primary coil 10 and the secondary coil 20 are arranged coaxially differently in the magnetic flux passing through the air core formed of a gap or an insulator in the primary coil 10 and the surrounding space, the secondary coil 20 and Are difficult to link, and electromagnetic induction from the primary side to the secondary side hardly occurs. Therefore, the lightning surge current of the normal mode noise component containing a large amount of high frequency components hardly transfers from the primary coil 10 to the secondary coil 20 due to the electromagnetic induction action. Thus, in the lightning surge cutoff transformer according to the present invention, the lightning surge current of the common mode noise component and the lightning surge of the normal mode component are reliably prevented from shifting from the primary side to the secondary side.
[0019]
As described above, the lightning surge cutoff transformer according to the present invention employs a ground terminal structure that uses a conductive band as the ground conductor. High-frequency impedance can be reduced by grounding using a ground conductor of a conductive band instead of a normal ground wire. By reducing the high-frequency impedance, the lightning surge current of the common mode noise component can easily flow to the ground, and at the same time, the generation of a high voltage due to the conductor resistance and the resulting lightning surge emission can be reduced.
[0020]
By the way, it has been explained that the transition from the primary side to the secondary side is surely prevented, but in the lightning surge cutoff transformer according to the present invention, the transition of the lightning surge current from the secondary side to the primary side is also reliably prevented. Of course.
[0021]
In the embodiment, aluminum foil is used for the first electromagnetic shielding plate and the second electromagnetic shielding plate that wrap the primary coil 10 and the secondary coil 20, respectively, but the electromagnetic shielding plate is formed by vacuum deposition. Also good. Of course, a conductive material other than aluminum can be used as the material of the electromagnetic shielding plate.
[0022]
Furthermore, although the Example which used the iron core of the shape which comprises a coaxial eccentric core transformer for the iron core 30 was demonstrated, the iron core of the shape which comprises a transaxial eccentric core transformer, or a different-axis eccentric twist transformer is comprised. It is also possible to use an iron core having a shape.
[0023]
【The invention's effect】
In the present invention, the first electromagnetic shielding plate enclosing the primary coil, the second electromagnetic shielding plate enclosing the secondary coil, and the third electromagnetic shielding plate disposed between the primary coil and the secondary coil. Prevents the transition of lightning surge current of common mode noise components to the secondary side, and at the same time, the primary coil, secondary coil, and iron core constitute a coaxial eccentric, eccentrically eccentric, or eccentrically eccentric twist transformer As a result, the transition of the lightning surge current of the normal mode noise component to the secondary side could be prevented. Therefore, the common mode noise component of lightning surge current as well as the normal mode noise component including a large amount of high frequency components are ensured without complicating the configuration and hardly considering the cost increase. It is now possible to provide a reliable lightning surge cut-off transformer that cuts off the light.
[Brief description of the drawings]
FIG. 1 is a plan view of a lightning surge cutoff transformer according to an embodiment of the present invention, in which a case and a terminal are simplified.
FIG. 2 is an enlarged cross-sectional view of a primary coil.
FIG. 3 is a perspective view of a primary coil, a secondary coil, and an iron core.
FIG. 4 is a perspective view of an embodiment of the present invention in a state assembled to a frame.
FIG. 5 is a side view of an embodiment of the present invention assembled to a frame.
FIG. 6 is a circuit diagram for explaining a situation where a lightning surge current flows in a transformer.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Primary coil 2 Secondary coil 3 Iron core 4 Electrostatic shielding board 5 Commercial power supply 6 Electric equipment 10 Primary coil 11 Copper wire 12 Insulator 13 Primary coil shielding aluminum foil 14 Insulator 15 Primary coil shielding lead board 15, 16 Primary Coil shield lead plate 17 Primary side ground terminal 18 Primary coil lead wire 19 Primary side terminal 20 Secondary coil 25, 26 Secondary coil shield lead plate 27 Secondary side ground terminal 28 Secondary coil lead wire 29 Secondary Side terminal 30 Iron core 30a, 30b Iron core piece 40, 40a, 40b Intermediate electromagnetic shielding plate 41 Frame ground terminal as intermediate ground terminal 50 Case 51 Frame

Claims (1)

A primary coil wrapped with a first electromagnetic shielding plate, a secondary coil wrapped with a second electromagnetic shielding plate, a third electromagnetic shielding plate disposed between the primary coil and the secondary coil, and In a lightning surge cutoff transformer composed of an iron core having a shape in which a primary coil and the secondary coil are not coaxially concentric with each other and a case made of a conductive material that houses them, the case is physically connected to each other. A primary side ground terminal, a secondary side ground terminal, and an intermediate ground terminal that are electrically separated from each other are provided, and the primary side ground terminal and the secondary side ground terminal are connected to the first side through corresponding lead plates, respectively. A first electromagnetic shielding plate and a second electromagnetic shielding plate, respectively, the intermediate grounding terminal being connected to the third electromagnetic shielding plate via a frame of a conductive material ; Secondary ground terminal and middle indirect Terminals, lightning surge blocking transformer, wherein the belt-like ground connection conductor is a terminal pressing plate like structure can be connected.

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