JP3756504B2 - Plant electrical ground resistance measuring device - Google Patents

Description

  The present invention relates to a measuring device for measuring the electrical grounding resistance between a plant root and the ground.

  Since plant growth is accompanied by the development of roots, knowing the extent of root growth without digging up the roots can be useful as a method for diagnosing tree health, such as tree planting research and judgment of plant growth by tree doctors.

  In order to achieve this object, the present applicant has proposed a method for measuring electrical resistance (hereinafter referred to as a conventional method) between the ground and a plant root in Patent Document 1 below.

  Specifically, as shown in FIG. 5 and FIG. 6, the main electrode T for energization is attached at a position separated from the ground surface of the trunk 12 a of the tree 12, and the ground 14 is energized at a position sufficiently separated from the tree 12. The auxiliary electrode C is installed, the first electrode E for potential measurement is attached in the vicinity of the ground surface of the trunk 12a, and the potential distribution of the ground 14 between the tree 12 and the auxiliary electrode C for energization is obtained. After the second voltage measurement electrode P is installed in a flat region, a current i flowing through the ground 14 through the tree 12 is passed between the energizing main electrode T and the energizing auxiliary electrode C, and the potential A potential difference between the first electrode E for measurement and the second electrode P for potential measurement is measured, and the ground resistance of the tree root 12b is obtained by dividing this potential difference by the current i.

  According to this method, since it is not necessary to pass an electric current through the potential measuring circuit, it is not affected by the electrode resistance between the electrode attached to the stem or stem of the plant and the stem or stem, and the ground and the root of the plant are not affected. It becomes possible to accurately measure the electrical resistance. Therefore, with this electrical resistance, factors that have a large impact on plant growth, such as plant root tension, soil quality of the planted land, soil moisture (humidity), and the affinity between the ground and the roots, can be simplified. Based on these, it is possible to accurately determine the growth status of the plant itself without digging up the ground.

  On the other hand, needles for sewing and stainless steel nails for woodworking are usually used for the electrodes attached to the plant. However, when these are inserted into the plant, it is inevitable that the plant will be damaged more or less. Especially for young plants, the insertion of such a metallic substance is unfavorable because it affects future growth. It also leaves scars on the epidermis, which significantly reduces the value of ornamental plants. In addition to natural monuments and tourism resources trees, these trees are often old trees, which give them an opportunity for decaying fungi to enter, so that they can cause damage. Is where you want to avoid. For the above reasons, there has been a strong demand for an electrode installation method that does not affect plants other than the method of inserting electrodes into plants.

As an example of an electrode installation method in which an electrode is not inserted into a plant, in Patent Document 1, a sheet material having electrical insulation is wound around an outer peripheral surface of a tree, and a conductive material such as a metal belt or aluminum foil is formed thereon. A method has been proposed in which a strip is wound and electrical coupling is achieved by capacitive coupling.
JP-A-11-332377

  However, in the method of winding a conductive belt such as a metal belt around a tree as described in Patent Document 1, when the trunk or stem of the tree is thin, the frequency of the power source used for measurement is within several kHz. In many cases, the impedance of the electrode forming the capacitor cannot be sufficiently lowered due to the limited contact area of the metal belt to be wound, and a current sufficient for measurement cannot be passed.

  In addition, the electrical coupling between the electrode and the tree may be a conductive coupling in addition to the capacitive coupling. However, because the skin of the tree has a much higher resistivity than that of the tissue in the plant body, simply contacting the metal belt with the skin of the tree can lead to conductive coupling with the plant body as an electrode. Is insufficient. At this time, in general, in order to achieve conductive coupling between the conductive substance and the object to be measured, electrode paste is applied between the two to make the electrical coupling dense. For purposes such as measuring the ground resistance of a root, the resistance at the electrode is still high and the electrical coupling is often inadequate.

  Therefore, the main problem of the present invention is that the plant can measure the electrical grounding resistance of the plant without causing any damage to the stem or stem of the plant, and can sufficiently connect the electrode and the tree electrically. An electrical grounding resistance measuring device is provided.

  In order to solve the above-mentioned problem, as an invention according to claim 1, a belt-shaped energizing main electrode made of felt-like metal fibers and attached so as to be wound around a plant body, and an energizing auxiliary electrode inserted and installed in the ground A first electrode for potential measurement which is made of felt-like metal fiber and is attached so as to be wound around the plant body; a second electrode for potential measurement which is inserted and installed on the ground; the main electrode for energization and the auxiliary electrode for energization; And a ground resistance measuring device body for measuring a potential difference between the first electrode for potential measurement and the second electrode for potential measurement. Is provided.

  In the first aspect of the present invention, a felt-like band electrode made of metal fibers is used as the energizing main electrode and the potential measuring first electrode. As a result, the electrode and the plant body can be conductively coupled without causing any damage to the plant stem or trunk.

  In addition, the felt-shaped belt electrode can significantly increase the contact area of the entire electrode when it is in contact with the skin of the trunk, lowering the contact resistance of the electrode, and sufficiently electrically connecting the electrode and the tree can do.

  According to a second aspect of the present invention, there is provided the plant electrical ground resistance measuring apparatus according to the first aspect, wherein steel wool is used as the felt-like metal fiber.

  In the second aspect of the present invention, steel wool is used as the felt-like metal fiber. Steel wool is commercially available for polishing utensils and metal, but the cross section of the fiber is not round but square (plate), and its corners are sharpened to make it easier to remove dirt. Therefore, the contact property when abutting against the skin of the trunk is superior to the fiber having a circular cross section, and the electrical conductivity with the skin is also increased.

  The present invention according to claim 3 includes a water-soluble viscous substance having conductivity interposed between the surface of the plant body and the main electrode for energization and the first electrode for potential measurement. An apparatus for measuring the electrical ground resistance of a plant according to claim 1 is provided.

  The present invention according to claim 3 includes a water-soluble viscous substance having conductivity, which is interposed between the surface of a plant body, the main electrode for energization and the first electrode for potential measurement. If a water-soluble viscous substance is interposed between the surface of the plant body and the main electrode for energization and the first electrode for potential measurement, the water of the water-soluble viscous substance may permeate into the epidermis and reduce the resistance of the epidermis. Even if there is a place where the felt-like metal fiber is not in contact with the epidermis, the part is filled with the water-soluble viscous substance. You will be able to get a dynamic bond.

  As described above, according to the present invention, the electrical ground resistance of a plant is measured without causing any damage to the stem or stem of the plant and in a state where the electrode and the tree can be sufficiently electrically coupled. It becomes possible to do.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a diagram showing a measurement procedure of electrical grounding resistance according to the present invention for a tree 1, and FIG. 2 is an equivalent circuit diagram thereof.

  A main electrode T for energization at a position in the vicinity of the ground surface of the trunk 1a of the tree 1 rooted with the root 1b on the ground 2, specifically 0-5 cm, preferably 0-3 cm, more preferably 0-1 cm from the ground surface. And an auxiliary current electrode C is inserted and installed in the ground sufficiently separated from the tree 1. An AC power source 3 and an ammeter 4 are provided in the circuit of the electrodes T and C.

  On the other hand, the first electrode E for potential measurement is mounted at a position above the mounting position of the main electrode T for energization of the trunk 1a and 1 to 200 cm, preferably 1 to 150 cm from the ground surface. The second electrode P for potential measurement is inserted and installed in the ground 2 between 1 and the auxiliary electrode C for energization. A voltmeter 6 is provided in the circuit of these electrodes E and P. An equivalent circuit of the measurement circuit is shown in FIG.

  Originally, the electrical grounding resistance is defined as the potential of the target electrode with respect to a point at infinity divided by the current flowing into the electrode. However, since it is actually impossible to measure at an infinite distance, it is considered that the flat portion in the voltage distribution between the energizing electrodes T and C approximates the potential distribution at infinity. An electrode P for potential measurement is installed, and the voltage between the electrodes T and P is measured.

  Therefore, in determining the installation position of the second electrode P for potential measurement, as shown in FIG. 3 (a), the first voltage measurement electrode 10 that also serves as energization is installed in the vicinity of the tree to be measured. At the same time, the current auxiliary electrode 12 is installed on the ground sufficiently away from the ground. Next, a predetermined AC voltage e is applied from the AC power supply 13 between the first voltage measurement electrode 10 and the current auxiliary electrode 12. Then, the second voltage measuring electrode 11 is installed in order while moving between the first voltage measuring electrode 10 and the current auxiliary electrode 12, and the first voltage measuring electrode 10 and the second voltage measuring electrode are arranged. 11 is measured, the potential distribution between the first voltage measuring electrode 10 and the current auxiliary electrode 12 is obtained, and a region B in which the voltage distribution is flat (flat) is searched for. The second electrode P for potential measurement is installed at a position where the potential distribution becomes flat. Note that the potential distribution may be measured by measuring the voltage while sequentially moving the second electrode P for potential measurement using the measurement circuit shown in FIG. In this method, since a potential distribution is obtained by flowing a current through the tree 1 to which the main electrode T for energization is actually attached, a potential distribution in accordance with an actual measurement circuit is obtained. If the auxiliary electrode C for energization is located at a position about 20 m away from the tree from past experiments and the like, and the second electrode P for potential measurement is installed at a substantially central point position (position about about 10 m from the tree). I know it ’s good.

In order to measure the electrical grounding resistance of the root 1b, an AC voltage e is applied from the AC power source 3 in FIG. Then, to measure the potential difference e _x between the second electrode P for the first electrode E and the potential measuring the potential measured by the voltmeter 6. As can be seen from the equivalent circuit of FIG. 2, the electrode resistance ReE of the first electrode E for potential measurement installed on the tree 1 and the potential measurement are arranged outside the energization circuit through which the measurement current (preferably constant current) flows. The electrode resistance Rep of the second electrode P and the electrical resistance Rt of the trunk of the tree 1 exist, but since the internal resistance of the voltmeter 6 is extremely high, these electrode resistance ReE, electrode resistance Rep, and electrical resistance Rt Since almost no current flows, the trunk 1a of the tree 1 becomes equipotential with the potential of the connection part of Rr and ReT in the equivalent circuit of FIG. Therefore, in addition to being able to exclude the influence of the electrode resistance of the electrode to be placed on the stem or stem of the plant, it becomes possible to measure the potential difference e _x to exclude the influence of the electrical resistance of the tree 1 trunk 1a itself. By dividing the measured potential difference ex by the measurement current i, the electric grounding resistance Rr between the root 1b of the tree 1 and the ground 2 can be obtained. Here, the electrical resistance between the root 1b of the plant 1 and the ground 2 is obtained as a pure resistance as shown by an equivalent circuit, but there is also a coupling due to capacitance between the root of the plant and the ground. It is known that there is capacity in the root tissue itself. In such a case, in phase together with the measurement of the measured current i and the potential difference e _x, to determine a resistance between the trees roots and the earth in the form of a complex impedance. Thus, the electrical resistance referred to in the present application is a concept including pure resistance and complex impedance.

  By the way, as shown in FIG. 4, the energizing main electrode T and the potential measuring first electrode E attached to the tree 1 are made of felt-like metal fibers and wound around the trunk 1a. It is desirable to install and to fill between the strip electrodes T and E and the trunk 1a with a conductive jelly-like water-soluble viscous substance.

  As the felt-like metal fiber, for example, a steel wool marketed for polishing a cooking utensil or metal is preferably used. In general, steel wool has a square cross section (plate shape) instead of a circular cross section, and its corners are sharply processed so that dirt can be easily removed. Therefore, the contact property when contacting the skin of the trunk 1a is superior to that of a fiber having a circular cross section, and the electrical conductivity with the skin is also increased. Furthermore, even if a belt-like electrode made of a metal plate is pressed against the skin of the tree, the skin is not flat, so there is only a slight contact area, but it is possible to wrap a piece of felt-like metal fiber. For example, the contact area of the entire electrode is significantly increased, and the contact resistance of the electrode is lowered.

  Since the resistance of the epidermis is considerably higher than that of the internal tissue, a water-soluble viscous substance should be interposed between the surface of the plant body and the felt-like band electrode in order to achieve a sufficient conductive bond with the tree. Is desirable. When the water-soluble viscous substance is interposed, moisture of the water-soluble viscous substance penetrates into the epidermis, the resistance of the epidermis can be lowered, and even if there is a place where the metal fiber is not in contact with the epidermis, Since it is filled with the water-soluble viscous substance, it is possible to achieve conductive coupling throughout the entire surface of the skin due to its conductivity, and a desired electrical coupling can be obtained.

  As the water-soluble viscous substance, in order to achieve acoustic coupling between a living body and a probe for ultrasonic diagnosis, the viscosity is mainly composed of glycerin sold under the trade name “Ultrasonic Jelly”. A water-soluble viscous substance such as Sonicoat or Sonozerie (trade name [manufactured by Toshiba Medical Supplies Co., Ltd.]) used as a contact medium with a measurement object in ultrasonic survey can be suitably used. In addition, the water-soluble viscous substance may be used as a synthetic paste mainly composed of polyvinyl alcohol, which is commercially available as office supplies, or a polyvinyl alcohol aqueous solution alone.

  By the way, it is conceivable to use saline or water alone as the conductive substance instead of the water-soluble viscous substance, but since these have no viscosity, the liquid flows out into the skin of the tree, Since the surface of the skin is wetted, measurement current leaks, making accurate measurement difficult. In addition, the use of saline solution should be avoided because it is unavoidable that it will soak into the root ground when washing the tree skin after measurement, and this will have an undesirable effect on plant growth. Furthermore, an electrode paste that can be electrically coupled with a living body is conceivable. However, in many cases, an electrode paste contains an electrolyte in order to increase conductivity, which is preferable because it causes a problem after washing as in the case of saline. Absent.

It is a measurement outline figure of electric ground resistance concerning tree 1 concerning the present invention. It is a figure which shows the equivalent circuit. (a) is a measurement procedure diagram of the ground potential distribution, (b) is a graph showing the potential distribution measurement results. It is a figure which shows the attachment state to the tree 1 of the main electrode T for electricity supply, and the 1st electrode E for electric potential measurement. It is an electrical grounding resistance measuring procedure figure concerning the conventional method. It is the equivalent circuit diagram.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Tree, 1a ... Trunk, 1b ... Root, 2 ... Ground, 3 ... AC power supply, 4 ... Ammeter, 5 ... Current circuit, 6 ... Voltmeter, 7 ... Potential measuring circuit, T ... Main electrode for energization, C ... Auxiliary electrode for energization, E ... First electrode for potential measurement, P ... Second electrode for potential measurement

Claims (3)

  A strip-shaped main electrode made of felt-like metal fibers that is attached to the plant body and attached to the ground, a current-carrying auxiliary electrode that is inserted and installed on the ground, and a felt-like metal fiber that is wrapped around the plant body. The first electrode for potential measurement, the second electrode for potential measurement inserted and installed on the ground, and the first electrode for potential measurement while passing a current between the main electrode for energization and the auxiliary electrode for energization And a ground resistance measuring device main body for measuring a potential difference between the second electrode for potential measurement and the second electrode for potential measurement.   The plant electric grounding resistance measuring apparatus according to claim 1, wherein steel wool is used as the felt-like metal fiber. The electrical ground resistance of the plant according to claim 1, comprising a water-soluble viscous substance having electrical conductivity, which is interposed between the surface of the plant body and the main electrode for energization and the first electrode for potential measurement. measuring device.

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