JP4507988B2 - Current transformer - Google Patents

Description

  The present invention relates to a current transformer, and is used, for example, to operate a measuring instrument or a protective relay.

  In general, a current transformer is used to transform a large current in a high-voltage circuit or a low-voltage circuit into a small current proportional to the large current and operate a measuring instrument or a protective relay. Such a current transformer includes an iron core that derives a magnetic flux from a primary conductor, a secondary coil that converts the derived magnetic flux into a secondary current, an insulating layer that covers the secondary coil and the iron core, and And a secondary terminal provided in a part of the insulating layer and drawn out from the secondary coil. The current transformer configured as described above is used by connecting a measuring instrument or a protective relay to the secondary terminal (for example, Patent Document 1).

The secondary current of the current transformer is proportional to the primary current regardless of the secondary impedance. Since the secondary terminal voltage is proportional to the secondary side load impedance, for example, when the secondary side impedance is infinite, the secondary terminal voltage becomes infinitely high. For this reason, when the secondary side of the current transformer is opened, an extremely high voltage of several thousand volts is generated on the secondary side, which causes dielectric breakdown of the secondary coil, relay, and the like and an electric shock accident.
JP-A-60-2003.

  As a countermeasure against the breakdown or electric shock accident, a means for absorbing a high voltage by connecting an arrester to the secondary terminal side is generally employed. There was a fear of becoming.

  The current transformer is determined so that the primary current flows from the power source side (K direction side in FIG. 1 described later) to the load side (L direction side in FIG. 1 described later). It is necessary to set the mounting direction of the current transformer in accordance with the current flow direction. The secondary terminal of a general current transformer has a structure provided only at one location. When changing the mounting direction, for example, attaching a wiring for connecting a measuring instrument or a protective relay to the secondary terminal It becomes difficult. For this reason, there was a fear that the apparatus would be enlarged in consideration of the above-described mounting property.

  This invention is made | formed based on the said subject, and it is providing the current transformer for operating a measuring device and a protection relay, for example, without enlarging.

In order to solve the above-mentioned problems, the present invention provides an iron core that derives a magnetic flux from a primary conductor, a secondary coil that converts the magnetic flux into a secondary current, and An insulating main body (details will be described later) covering the iron core and the secondary coil, a secondary terminal penetrating a part of the insulating main body and connected to the secondary coil, and an end of the secondary terminal , Dimensions of the secondary terminal insulating portion having a secondary terminal exposed portion (details will be described later) exposed from the insulating main body (both sides of the front and back surfaces of the insulating main body), through which the secondary terminal penetrates. The thickness dimension in the same direction as the penetration direction is the dimension of the secondary terminal peripheral insulating portion to which the grounding metal fitting is attached in the insulation main body, and is made thinner than the thickness dimension in the same direction as the penetration direction. Between the grounding bracket for attaching the insulating body and the exposed portion of the secondary terminal. Characterized in that it has secured a gap.

The invention according to claim 2 is the dimension of the secondary terminal insulating portion through which the secondary terminal in the insulating body penetrates in the invention according to claim 1 , wherein the thickness dimension in the same direction as the penetration direction is It is characterized in that it is a dimension other than the secondary terminal insulating part in the insulating main body and is thinner than the thickness dimension in the same direction as the penetration direction.

The invention according to claim 3 is used in the invention according to claim 1 or 2 , wherein the dimension between the grounding fitting attached to the insulating body and the exposed portion of the secondary terminal is 1.5 to 2.5 mm. The battery is discharged at a voltage of 2500V to 5000V.

According to the configuration as in the first aspect of the invention , the high voltage can be absorbed by the gap between the secondary terminal exposed portion and the grounding fitting without using a high voltage absorbing means such as an arrester. Furthermore, the gap can be formed by utilizing the difference between the thickness dimension of the secondary terminal insulating part and the thickness dimension of the secondary terminal surrounding insulating part to which the grounding metal fitting is attached adjacent to the secondary terminal insulating part .

According to the configuration of the second aspect of the present invention, the gap can be formed by utilizing the difference between the thickness dimension of the secondary terminal insulating part and the thickness dimension of the insulating body other than the secondary terminal insulating part.

According to the configuration of the third aspect of the present invention, it is possible to form a gap corresponding to discharge at a working voltage of 2500 V to 5000 V.

  As described above, according to the present invention, for example, a measuring instrument and a protective relay can be operated without increasing the size.

In particular , the configuration having a gap between the secondary terminal exposed portion and the grounding metal can absorb a high voltage generated on the secondary side of the current transformer with a simple structure.

  Hereinafter, a current transformer according to an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is an explanatory diagram of an equivalent circuit of an example of a current transformer (reference numeral 1 in FIG. 1) in the present embodiment, and FIG. 2 is a structural cross-sectional view for explaining a configuration example of the current transformer of FIG. . 3 is a front view of the current transformer of FIG. 2, FIG. 4 is a bottom view of the current transformer of FIG. 3 viewed from below, and FIG. 5 is a cross-sectional view taken along line AA of the current transformer of FIG. It is.

  First, an example of the current transformer of this embodiment will be described with reference to the equivalent circuit shown in FIG. In FIG. 1, reference numeral 2 denotes a primary conductor. The primary conductor 2 is connected to a power supply side primary terminal K and a load side primary terminal L, and a primary current flows. The magnetic flux generated by the primary current passes through the iron core (for example, the annular core) 3 and circulates in the iron core 3. Reference numeral 4 denotes a secondary coil, and a secondary current flows by the magnetic flux circulating in the iron core 3 as described above. Both ends of the secondary coil 4 are respectively connected to the power supply side secondary terminal k2 and the load side secondary terminal l2, and the secondary current is supplied from the power supply side secondary terminal k2 to the load side secondary terminal l2. Flowing. Symbol E indicates grounding, and a gap G is provided between the grounding E and the power supply side secondary terminal k2.

  Next, a configuration example of the current transformer shown in the equivalent circuit of FIG. 1 will be described with reference to FIGS. 2-5, the secondary coil 4 is formed by winding a conductor (for example, linear conductor) around the cyclic | annular iron core (henceforth a cyclic | annular iron core) 3 as shown in figure. . The annular core 3 and the secondary coil 4 are covered with, for example, an insulating resin member to form an insulating molded body (hereinafter referred to as an insulating main body) 5.

  The insulating body 5 is coated with the annular core 3 and the secondary coil 4 (covered with an insulating resin member) on one end side of the insulating body 5 (upper side of the insulating body 5 in the figure), and has a hollow portion 6 inside. An annular insulating molded body (hereinafter referred to as a primary terminal side insulator) 7 and an other end side of the insulating main body 5 (in the drawing, from a part of the primary terminal side insulator 7 to the lower side). And a rectangular insulating molded body (hereinafter referred to as a secondary terminal-side insulator) 8. The primary terminal side insulator 7 and the secondary terminal side insulator 8 are integrally formed of, for example, the insulating resin member. The primary conductor 2 passes through the hollow portion 6.

  A part of the end portion of the secondary terminal side insulator 8 (in the drawing, the end portion of the insulating body 5 opposite to the primary terminal side insulator 7) has a thickness direction (that is, secondary terminals k2, l2). The dimension in the through direction of the secondary terminals k2 and 12 and the primary conductor 2 in the figure is a part of the primary terminal side insulator 7 and the secondary terminal side insulator 8 (in the figure, the secondary terminal A portion (hereinafter referred to as a secondary terminal insulating portion) 9 thinner than the dimension in the thickness direction in the substantially central portion of the side insulator 8 and the secondary terminal surrounding insulating portion described later is formed. Further, at the end of the secondary terminal side insulator 8, the portion adjacent to the secondary terminal insulator 9 has a thickness direction (that is, secondary terminals k2, l2 (secondary terminals in the figure). k2 and 12 and the dimension of the primary conductor 2) in the penetrating direction) is thicker than the dimension in the thickness direction of the secondary terminal insulating portion 9 (in FIG. 3, the substantially central portion of the secondary terminal side insulator 8 and The same dimensions; hereinafter referred to as secondary terminal peripheral insulating portions) 16a and 16b are formed.

  In the secondary terminal side insulator 8, orthogonal to the through direction of the primary conductor 2 (that is, through direction of the secondary terminals k 2, 12 (secondary terminals k 2, 12, and primary conductor 2 in the figure)). For example, as shown in FIGS. 3 and 5, a fixing screw 17 is attached to the side surface (surface on which the secondary terminal insulating portion 9 is not formed) on the direction side.

  As described above, the primary current of the primary conductor 2 penetrating the hollow portion 6 causes the magnetic flux to circulate in the annular core 3, and the secondary current flows to the secondary coil 4 by the circulating magnetic flux. The secondary coil 4 is led out from the primary terminal side insulator 7 to the secondary terminal side insulator 8, and its end (for example, in the case of a secondary coil made of a linear conductor, both ends of the conductor Part) is arranged in the secondary terminal insulating part 9 (for example, arranged at a position where the end part can be connected to the power supply side secondary terminal k2 and the load side secondary terminal l2).

  In the secondary terminal insulating portion 9, one surface (hereinafter referred to as an insulator surface) 13 side to the other surface (hereinafter referred to as an insulator back surface) 14 of the side surfaces of the primary conductor 2 on the penetrating direction side. As shown in FIG. 5, the ends of the plurality of power supply side secondary terminals k2 and the load side secondary terminal l2 penetrate through each side (in the figure, one power supply side secondary terminal k2 respectively. , The load-side secondary terminal l2 passes through), and protrudes from both sides of the secondary terminal insulating portion 9.

  At each end of the power supply side secondary terminal k2 and the load side secondary terminal l2, a portion of the secondary terminal insulating portion 9 exposed from the surface on the insulator surface 13 side to the outer peripheral side (hereinafter, secondary terminal exposed) A mounting screw 15 is attached to the mounting screw 15, and a terminal 20 such as a measuring instrument, a protective relay, or a circuit is connected to the mounting screw 15. In the secondary terminal exposed portion exposed from the surface on the insulator back surface 14 side of the secondary terminal insulating portion 9 to the outer peripheral side, the mounting screw 15 can be mounted in the same manner as the insulator surface 13 side, and the measuring instrument and protection Terminals 20 such as relays and circuits can be attached.

  Fixing screws 17 are provided from the insulator surface 13 to the insulator back surface 14 in the secondary terminal peripheral insulating portions 16a and 16b protruding outward from the secondary terminal insulating portion 9. That is, the fixing screw 17 is arranged to penetrate in the same direction as the penetration direction of the primary conductor 2. In the fixing screw 17, a grounding metal 18 is attached to a portion penetrating to the insulator back surface 14, and the grounding metal 18 is fixed to the secondary terminal surrounding insulating parts 16 a and 16 b. A gap G is formed between the grounding metal fitting 18 and each secondary terminal exposed portion of the power supply side secondary terminal k2 and the load side secondary terminal l2.

  According to the current transformer 1 configured as described above, an extremely high voltage of, for example, several thousand volts generated when the secondary side of the current transformer 1 is opened is separated from the power source side secondary terminal k2. G is discharged. Therefore, the gap G is provided in the current transformer 1 itself, and it is not necessary to provide an additional arrester or the like as in the prior art, and the current transformer 1 can be reduced in size. In addition, the operator of the current transformer 1 (the installation operator) does not need installation work of the above-described arrester, etc., and it is not necessary to consider forgetting installation that may occur when the arrester is applied. Etc.) does not require labor (for example, using nerves), and handling is good.

  Further, in order to reduce the size of the current transformer 1, a secondary terminal insulating portion 9 having a thickness dimension smaller than the thickness dimension of a part of the primary terminal side insulator 7 and the secondary terminal side insulator 8 is formed. The power source side secondary terminal k2 and the load side secondary terminal l2 are passed through the secondary terminal insulating portion 9, and between the power source side secondary terminal k2 and the load side secondary terminal l2 and the grounding fitting 18. By configuring so that the gap G is formed, the protrusion on the outer peripheral side of the grounding metal fitting 18 is prevented from exceeding the thickness dimension of the grounding metal fitting 18 (that is, it projects by the thickness dimension of the grounding metal fitting 18). The size of the flow device 1 can be reduced.

  Furthermore, in order to improve the handleability, the ends of the power supply side secondary terminal k2 and the load side secondary terminal l2 provided in the secondary terminal insulating part 9 are exposed from the surface of the secondary terminal insulating part 9. The terminal 20 such as a measuring instrument, a protective relay, or a circuit can be connected from any one of the insulator surface 13 and the insulator back surface 14, so that connection work by a handler (connection worker or the like) is facilitated. In this case, the ground metal fitting 18 may be provided on the insulator front surface 13 or the insulator back surface 14 to be used, and the gap G may be formed.

  As a result, the terminal 20 of the measuring instrument, the protective relay, the circuit, etc. can be attached from at least one of the insulator front surface 13 and the insulator back surface 14, so that it is ensured only for the attachment of the terminal 20, for example. Space (extra installation space) is not required. In addition, even when the mounting location of the power supply side secondary terminal k2 and the load side secondary terminal l2 is changed, it can be easily changed with respect to either the insulator surface 13 or the insulator back surface 14. In the gap G, for example, when discharging at a working voltage of 2500 V to 5000 V, the gap dimension is set to 1.5 to 2.5 mm. The circuit applied in the current transformer 1 needs to be discharged at 2000 V or higher because the soundness of the circuit is confirmed at 2000 V, for example, and when 5000 V or higher, dielectric breakdown may occur at various locations. There is. For this reason, in the said current transformer 1, it is desirable to discharge by 2500V-5000V, and when discharging by this voltage, it is more appropriate by setting a gap dimension to 1.5-2.5 mm as mentioned above. Can be used.

  As described above, according to the current transformer of the present embodiment, the ends of the plurality of secondary terminals penetrating the insulating body are drawn to the outer peripheral side of the insulating body (that is, terminal exposed portions are formed). In addition, measuring instruments, protective relays, circuits, etc. can be easily attached selectively to these ends (eg, from either the insulator surface side or the insulator back surface side in the secondary terminal insulator). (Good handling), for example, when the end of the secondary terminal is replaced or when the mounting location is changed, the work is selectively performed (for example, the insulator surface side of the secondary terminal insulating portion is attached) If it is, the mounting can be changed to the back side of the insulator), so that the mounting space provided in the conventional current transformer is unnecessary (the current transformer can be miniaturized).

  Further, the annular core and the secondary coil are covered with an insulating molded body, and a secondary terminal (for example, a conductor drawn from the secondary coil) connected to the secondary coil with respect to a part of the insulating molded body The end of the secondary terminal penetrates the insulating molded body, the end of the secondary terminal is disposed opposite the gap, and the high voltage at the end of the secondary terminal is discharged through the gap. Can be configured. In this current transformer, a gap is formed simply by attaching it to a grounding fixture or the like (that is, since the current transformer itself is provided with a gap, the work for attaching the gap is unnecessary), and a separate high voltage absorbing means (arrester) Etc.) (that is, there is no need to consider forgetting the installation that may occur when applying the arrester, etc.), and there is no need to install a high voltage absorbing means. (E.g., the operator does not need to use nerves), the handleability is good, and the size can be reduced.

  Although the present invention has been described in detail only for the specific examples described above, it is obvious to those skilled in the art that various changes and modifications are possible within the scope of the technical idea of the present invention. Such variations and modifications are naturally within the scope of the claims.

Explanatory drawing of the equivalent circuit of an example of the current transformer concerning embodiment of this invention. FIG. 2 is a structural cross-sectional view illustrating a configuration example of a current transformer in FIG. 1. The front view of the current transformer of FIG. The bottom view which looked at the current transformer of Drawing 3 from the lower part side. Sectional drawing from the AA line of the current transformer of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Current transformer, 2 ... Primary conductor, 3 ... Ring core, 4 ... Secondary coil, 5 ... Insulation body, 6 ... Hollow part, 7 ... Primary terminal side insulation part, 8 ... Secondary terminal Side insulation part, 9 ... secondary terminal insulation part, 13 ... insulator surface, 14 ... insulator back surface, 15 ... mounting screw, 16a, 16b ... secondary terminal peripheral insulation part, 17 ... fixing screw, 18 ... grounding metal fitting, 20 ... terminal, E ... ground, K ... power source side primary terminal, L ... load side primary terminal, k2 ... power source side secondary terminal, l2 ... load side secondary terminal.

Claims (3)

An iron core for deriving the magnetic flux from the primary conductor, a secondary coil for converting the magnetic flux into a secondary current, an insulating body covering the iron core and the secondary coil,
A secondary terminal that penetrates a portion of the insulating body and connects to the secondary coil;
A secondary terminal exposed portion that is an end of the secondary terminal and is exposed from the insulating body;
The dimension of the secondary terminal insulation part through which the secondary terminal penetrates among the insulation bodies, and the thickness dimension in the same direction as the penetration direction is the secondary terminal surrounding insulation part to which the grounding metal fitting is attached. The gap is secured between the grounding metal fitting for attaching the insulating body and the exposed portion of the secondary terminal by making the thickness smaller than the thickness dimension in the same direction as the penetration direction. Flutes. The dimension of the secondary terminal insulating part through which the secondary terminal penetrates in the insulating main body, and the thickness dimension in the same direction as the penetrating direction is a dimension other than the secondary terminal insulating part in the insulating main body. The current transformer according to claim 1, wherein the current transformer is thinner than a thickness dimension in the same direction as the direction. 2. The battery according to claim 1 , wherein a dimension between the grounding fitting attached to the insulating main body and the exposed portion of the secondary terminal is 1.5 to 2.5 mm and discharged at a working voltage of 2500 V to 5000 V. Item 3. A current transformer according to item 2 .

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