JP2012134073A - Auxiliary electrode for measuring grounding resistance - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an auxiliary electrode for measuring grounding resistance capable of satisfactorily grounding while having high conductivity, even for a hard foundation to which a metal bar conventionally being used as the auxiliary electrode is unusable to drive in.SOLUTION: On a periphery of the auxiliary electrode main body for measuring grounding resistance composed of a soft net knitted with silver-plated chemical fiber as material, borders are prepared with high conductance tape, and connection clips are fixed on the proper place for connecting lead wires and also connection terminals consisting of conductive thin metal plate are fixed on other parts of the periphery. The net which is combined and knitted with silver-plated chemical fiber and not silver-plated chemical fiber is acceptable for the main body. Raschel knit is preferable for a net knitting method.

Description

  The present invention relates to an auxiliary electrode suitable for use in measuring the ground resistance of a ground electrode attached to a steel tower, a utility pole, or the like to which a transformer, a lightning arrester, a high-voltage device or the like is attached.

  Grounding work is required by law to prevent accidents caused by electric leakage in power poles equipped with transformers, lightning arresters, and high-voltage equipment. This grounding work is performed by embedding a grounding member at a predetermined depth around the pole position to form a grounding electrode and connecting a grounding wire to the grounding electrode.

  Conventionally, this grounding member embedding work is driven by placing a grounding member such as a metal rod into the ground with a hammer and measuring the grounding resistance of the embedded grounding member, and the resistance value is below a specified value. .

  The measurement of the ground resistance is generally performed by a method as shown in FIG. That is, the ground electrode to be measured 101 and the auxiliary electrodes (ground rods) 102 and 103 are connected to the measuring device M by the lead wire 105, and a current (generally alternating current) is used between the ground electrode to be measured 101 and the auxiliary electrode 103. To measure resistance. In this case, the distance L between the measured ground electrode 101 and the auxiliary electrodes 102 and 103 is about 5 to 10 m.

    FIG. 4 shows this measurement principle. When the ground electrode 101 to be measured and the auxiliary electrode 103 are connected to the power source 107 as shown in FIG. 4A, the potential drop between the electrodes 101 and 103 is shown in FIG. ) As shown. In this case, if the distance between the two is sufficiently long, the potential at the center portion becomes flat. Therefore, the potential drop E1 due to the resistance R1 of the ground electrode 101 to be measured and the potential drop E2 due to the resistance R2 of the auxiliary electrode 103 are clearly at the center portion. Will be separated. Therefore, if another auxiliary electrode 102 is provided in the central portion and the potential difference E1 between the ground electrode 101 to be measured and the auxiliary electrode 102 in the central portion is measured, R1 = E1 / I from the relationship of E1 = IR1. The ground resistance R1 of the measured ground electrode 101 is obtained.

  As an auxiliary electrode for measuring the ground resistance, a metal rod rich in conductivity is used, and this is driven into the soil for measurement.In the case of dry gravel, concrete, bedrock, etc. There was a problem that measurement could not be performed well because a grounding electrode (grounding rod) made of a metal rod could not be driven. For this reason, a method has been adopted in which a metal net is placed on the ground surface, a grounding rod is placed, and water is applied from above to measure the ground.

  However, the metal mesh has a large area and is hard and difficult to deform, so it is inconvenient for handling such as transportation and storage, and it is difficult to adhere to the ground, and the grounding resistance of the auxiliary electrode becomes too large and accurate. There was a problem that measured values could not be obtained.

  In order to solve this problem, the present inventors have developed an auxiliary electrode composed of a flexible net knitted from silver-plated chemical fiber as a material and has already filed a patent application (see Patent Document 1 below). ). This auxiliary electrode is actually widely used in the field and has been well received.

JP-A-11-97087

  However, the newly developed auxiliary electrode has a problem in that it is difficult to connect the lead wire, which takes time. An object of the present invention is to further improve the newly developed auxiliary electrode, to make the connection with the lead wire simple and reliable, and to be extremely convenient practically.

  In order to solve the above problems, the present invention employs the following configuration. That is, the auxiliary electrode for grounding resistance measurement according to the present invention has a flexible net knitted from silver-plated chemical fiber as a material, and knitted yarn such as silver-plated chemical fiber around the outer periphery of the main body. A band-shaped edging with high silver concentration is provided, and a clip that can connect the lead wire to one part of the outer periphery provided with the rim is attached, and a connection made of a thin metal plate at another position on the rim of the outer periphery. The terminal is attached.

  Since chemical fibers with silver plating are expensive, it is actually economical to use a flexible net knitted with a combination of chemical fibers with silver plating and chemical fibers without silver plating. And preferred. Furthermore, the intersection of the fiber and the fiber in the net is required to increase the adhesion between each other and make the electrical resistance as small as possible. Therefore, as a method of knitting the net, lace knitting, fishnet knitting, etc. are preferable. In particular, it is preferable to employ Raschel knitting in which the intersections of vertical and horizontal yarns are intertwined in a complicated manner. According to this knitting method, the intersections are not easily displaced, and the strength is excellent. In addition, it is preferable that the net has a moderately open stitch because the net is more flexible and has better adhesion to the ground.

  The auxiliary electrode for measuring ground resistance according to the present invention is a flexible net knitted with chemical fibers in the main body. Therefore, when it is placed on the ground or a rock, it is familiar with the unevenness and easily adheres to the surface of the ground. In addition, since the silver-plated fiber is included, the conductivity is good and a grounding effect sufficient for grounding resistance measurement can be obtained. The auxiliary electrode made of the net is flexible and can be folded small when not in use, which is convenient for handling.

  In addition, since the outer periphery of the main body consisting of a net has a frame shape with high conductivity, it is easy to connect the external lead wire to the main body, and when the lead wire is connected to this edge, the entire net In contrast, good electrical conductivity can be secured. Further, since the clip for connecting the ground wire is attached to the frame-shaped border, the lead wire can be easily connected at the ground construction site. In addition, since a connection terminal made of a thin metal plate is integrally provided at a corner of the main body made of a net and at an appropriate position of the highly conductive border, a connection clip is provided at the end of the lead wire to be connected. If it is provided, it can be easily electrically connected by sandwiching this portion with the clip. It is also possible to directly connect the lead wire to this portion by brazing or the like without providing such a clip.

1 is an external view illustrating an embodiment of the present invention. It is an enlarged view of the principal part. It is explanatory drawing of the grounding resistance measuring method using the conventional auxiliary electrode. It is explanatory drawing showing the principle. It is sectional drawing showing the attachment method of an edge part.

  Hereinafter, embodiments of the present invention will be specifically described. As shown in FIGS. 1 and 2, the auxiliary electrode P for measuring ground resistance includes a net that is flexible enough to be bent by its own weight. The net which is the main body 1 is a knitting of vertical and horizontal yarns (made of chemical fibers in the present invention) f,... Knitted by a known knitting method such as lace knitting, fishnet knitting, Raschel knitting, etc. The intersection is intertwined firmly. As for the size of the mesh d of the net constituting the main body 1, the length of one side is about several mm. The shape of the mesh d may be a polygon (triangle, quadrangle,...) Or any other shape.

  The vertical and horizontal yarns are preferably those having high conductivity, and most preferable are those obtained by silver-plating a soft and strong chemical fiber (for example, polyester or nylon). As silver-plated chemical fibers, nylon fibers that are silver-plated are commercially available, and it is effective to use them. However, economically, it is preferable to use a combination of silver-plated chemical fibers and non-silver-plated chemical fibers (nylon, polypropylene, polyester, polyethylene, etc.) at an appropriate ratio. For example, a mixture of silver-plated nylon (hereinafter referred to as “plated yarn”) and non-plated chemical fiber (hereinafter referred to as “non-plated yarn”) in a ratio of about 1: 1 to 1: 2 is preferably used. be able to. Although plating of other metals such as copper plating and nickel plating can be employed instead of silver plating, silver plating is most preferable because it is practically unstable.

  The thickness of the vertical and horizontal threads f constituting the net is preferably about 10 to 100 denier, but is not limited thereto. Further, the shape and size of the main body 1 made of a net may be appropriate depending on the use conditions and the like. Usually, it is appropriate to use a square having a side length of 50 to 100 cm.

  On the outer periphery of the net, which is the main body 1, a band-shaped border 2 is applied like a frame. This edging 2 is a tape-like thing made of a net (sheet) having a higher conductivity than the main body 1, for example, a cloth-like tape in which a polyester thread is silver-plated more closely than the main body 1. It is configured. Unlike the main body 1, a thread that is not plated is not used, and the whole is composed of a silver-plated thread. Therefore, the conductivity and the weight per unit area are significantly higher than those of the main body 1. As shown in FIG. 5, the material for the edging 2 made of this tape is folded in half at the center in the longitudinal direction, is put on the outer peripheral portion of the main body 1, and is sewn with a sewing machine. For this reason, fraying of the edge part of the main body 1 does not easily occur, and durability is improved. The width of the edging 2 on the surface of the main body is preferably about 1 to 1.5 mm.

  The edging 2 is formed in a frame shape over the entire circumference of the main body 1, and a current-carrying clip 3 is attached to one corner portion of the frame-shaped edging. The clip 3 is connected to the edging 2 and is preferably detachable from the edging 2. For example, it is preferable that the connection terminal fixed to the edge can be attached and detached by fitting, screwing or the like. In the illustrated example, the clip 3 is attached to the corner portion and is convenient for handling. However, depending on the case, the clip 3 is not limited to the corner portion, but may be another position (appropriate position) of the outer peripheral portion of the main body 1. . The clip 3 is commonly used for connection of a conducting wire, and its base is connected to the edge portion 2 having high conductivity, and the opposite free end is a mouth-open mouth. The clip includes a lever for opening the mouth, and by pressing the lever, the mouth of the clip can be opened against the elasticity of a torque spring (not shown).

  Connection terminals 5 made of a thin conductive metal sheet (plate or foil) are attached to other positions on the outer periphery of the frame-shaped rim 2, in the illustrated example, at three corners other than the clip attachment part. . For example, the connection terminal 5 may be fixed to the edge 2 by means of a stapler, a rivet or the like. In short, it only has to be electrically connected to the edging 2. In the illustrated example, a thin copper plate having a thickness of 1 mm or less is used as the connection terminal 5. The connection terminal 5 has a side length of several millimeters to several tens of millimeters and is generally rectangular in the illustrated example, but may be a key shape extending over two sides or an elliptical shape. The connecting terminals 5 are not limited to three places, but may be provided in an appropriate number at appropriate places (other than the corners) other than the part where the clip 3 is attached in the edging 2.

  The ground resistance measuring auxiliary electrode P is used by being placed on the ground. In this case, since the auxiliary electrode itself is made of a flexible net, it is well adapted to the unevenness of the ground and has good adhesion to the ground. In addition, since the outer peripheral portion is provided with the edge 2 having a high silver concentration and a large weight, and the connection terminal 5, it is difficult to roll up when covered with the ground, and the adhesion to the ground is improved. When measuring the ground resistance, the lead wire may be connected by the connection clip 3 attached to the corner portion of the main body 1 or the lead wire may be connected to the connection terminal 5 provided at the other corner portion by soldering or the like. Good. When a clip is attached to the end of the lead wire, the connection terminal 5 may be sandwiched between the clips. In addition, in order to reduce ground resistance, it is preferable to pour water over the net. When the measurement is completed, the flexible main body 1 can be folded to an appropriate size to reduce the volume.

  Silver plated nylon fiber (trade name “X-static 30XS10”) manufactured by Sauquiit, USA, is used as the plating thread, and it is made of a net by raschel knitting in combination with a non-plating thread made of non-plated nylon fiber at a ratio of 1: 1. Made the material. This net has an electric resistance of 100Ω or less, cut into a 70 cm square to form a main body 1, connected to a ground wire, and measured using a ground resistance meter 3235 manufactured by Yokogawa Electric Corporation. When the ground resistance of the ground electrode was measured, the ground resistance could be measured well on the rock.

  This auxiliary electrode for ground resistance measurement is mainly composed of a flexible net knitted using silver-plated chemical fibers, and is not only highly conductive, but also has good adhesion to the ground. The ground resistance can be measured easily and accurately even on the ground where the conventional auxiliary electrode made of a ground rod cannot be driven. In addition, since the outer peripheral portion is provided with an edge having a high specific gravity and high conductivity, and a clip for connecting the conductive wire is also provided at an appropriate position, the net is not easily drawn up and is convenient for connecting the conductive wire.

1 Body 2 Border 3 Clip 5 Connection terminal P Auxiliary electrode f Thread (chemical fiber)
d Mesh E Grounding terminal

Claims (3)

A flexible net knitted from silver-plated chemical fibers is used as the main body, and a belt-like edge with a high silver concentration is formed on the outer periphery of the main body by knitting silver-plated chemical fibers. Attaching a clip that can connect a lead wire to one location on the outer periphery and attaching a connection terminal made of a thin metal plate to another position on the outer periphery electrode. 2. The auxiliary electrode for measuring ground resistance according to claim 1, wherein the main body is formed of a flexible net knitted by combining a chemical fiber subjected to silver plating and a chemical fiber not subjected to silver plating. The auxiliary electrode for measuring ground resistance according to claim 1 or 2, wherein the net of the main body is knitted by Raschel knitting.

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