JP2017220983A - Line monitoring device for power line - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to always supply required power without a battery by obtaining required power in a non-contact manner from a high-voltage AC power line to activate a monitoring circuit for monitoring measurement of power line current/a state of an apparatus around the power line, and the like; and improve durability by eliminating influence of heavy-current of the power line and performing protection from corona discharge, birds, insects, rainwater, etc.SOLUTION: An induction coil 2 obtained by winding a voltage coil and current coil around an annular core 21 is encapsulated inside a weatherproof induction coil storage case Y composed of an annular metal frame 1 having a U-shaped cross section, the annular metal frame having the widely open center part, and a lid body 3 fitted to the annular metal frame through a rubber layer 31. AC electromotive voltage of the voltage coil of the induction coil 2 is input to a DC power supply unit 62, using a rectification circuit, for a semiconductor circuit 6 inside a closed vessel 5 connected to the storage case Y to supply voltage of 5 V from the power supply unit to respective circuits.SELECTED DRAWING: Figure 6

Description

  In the present invention, these monitoring devices for monitoring a current value of a power line in a high-voltage AC power line, a state of equipment around the line and a temperature, and a camera monitoring of a situation around a transformer in a tower or substation are contactlessly connected to the power line. The present invention relates to a technology that enables battery-less remote monitoring by receiving power.

  It is a monitoring device around the power line that monitors the transmission current and the temperature of the connection part of the line at an AC transmission tower or substation, and it is battery-free by obtaining the DC power used for this from the AC transmission line in a contactless manner. The present applicant has developed a device that has been made possible by eliminating the need for battery replacement. This technique is known as Patent Document 1.

  However, the transmission line is located in a high tower / high position, and the device circuit malfunctions due to corona discharge caused by high voltage, and electromagnetic induction due to a large current (occurred at the time of surge current / overcurrent / short circuit accident) It was causing electrical equipment failure. In addition, it suffers from repeated fatigue deterioration, UV deterioration, and bird insect damage due to salt damage, temperature differences. Simply wrapping the induction coil to be used with an insulating tape or covering it with a waterproof insulating film has insufficient weather resistance to solve the above problems, and its service life is short.

JP 2008-31323 A

The problem to be solved by the present invention is to solve the conventional problems, reduce the failure of electrical equipment due to a large current, is not damaged by salt damage / bird insect damage, has less UV deterioration, and has high weather resistance. An object of the present invention is to provide a line monitoring device for a batteryless power line.
And even if the induction coil is enclosed in a metal-made sealed casing with high weather resistance, the sealed casing forms a closed loop of the core inside, and the performance of generating an electromotive voltage of the induction coil and the measurement of the current value of the line The purpose of this is to prevent the accuracy of. Furthermore, there is less corona discharge and less damage caused by lightning strikes.

The configuration of the present invention that solves this problem is as follows.
1) An induction coil for generating an electromotive force in which a coil is wound around an annular core is arranged inside an annular metal casing having a U-shaped cross section made of a magnetically permeable and highly conductive metal. A highly conductive metal lid is fitted to the opening edge of the body via an electrical insulator to form a sealed weatherproof induction coil container, and the central opening space of the weatherproof induction coil container Penetrating the AC power transmission line, and encapsulating the slave semiconductor circuit in the weatherproof induction coil container or in a separate sealed metal container connected to it by a highly conductive metal mounting plate, A DC power supply unit that rectifies a voltage generated in the induction coil for generating an electromotive voltage as a slave circuit and generates DC power of a required voltage, and a device around a transmission line using the DC voltage of the DC power supply unit Sensor circuit or camera device A monitoring circuit of a camera control image processing circuit for processing a signal, a control signal of the direct current power supply unit or the monitoring circuit, and a radio relay device for relaying radio waves with the parent device or the parent device for managing the information from the control signal by radio waves A power line monitoring device 2 having a built-in radio communication unit for transmission and reception) A current detection induction coil capable of detecting a current in the transmission line, in which a coil is wound around the annular core, and the electromotive voltage generation induction coil Provided separately, and arranged in the annular metal casing having a U-shaped cross section in a state where the induction coil for generating electromotive force and the induction coil for current detection are wound around the annular core, and the induction coil for current detection The power line line described in 1) above, wherein a current measurement circuit that detects a flowing current value and calculates a current value flowing from the output to the transmission line is provided as one of the monitoring circuits of the slave semiconductor circuit. Monitoring device 3) The line monitoring device 4 for a power line according to 1) or 2), wherein an overvoltage protection circuit is provided for the DC voltage output from the DC power supply unit so that an excessive DC voltage is not applied to the slave device semiconductor circuit. The connection electrode plate exposed to the atmosphere of the power transmission line provided at the insulator tip of the AC power transmission line encapsulates the weatherproof induction coil container and the slave device semiconductor circuit using a conductive metal. The line monitoring device 5 for a power line according to any one of 1) to 3), wherein a temperature sensor circuit for measuring the temperature of the connection electrode plate of an AC power transmission line is used as the sensor circuit. The power line monitoring device 6) according to 4), wherein the antenna of the radio wave communication unit is an antenna extending from the outside of the hermetic metal container toward the ground surface. Line monitoring device 7) The power line track monitoring device 8) according to any one of 1) to 6), wherein the outer shape of the metal casing and the lid is rounded with no corners to reduce corona discharge. The power line track monitoring device 9) according to any one of 1) to 7), wherein the slave device semiconductor circuit in the sealed metal container is disposed inside a polycarbonate casing provided in the sealed metal container. 1) to 8) A base unit capable of bidirectionally communicating with each radio communication unit of the line monitoring device by attaching a plurality of power line monitoring devices according to any one of the above to the line of a switch of a substation of a three-phase high-voltage power line Is in the track monitoring facility in the substation.

  In the present invention, an induction coil for generating electromotive voltage is enclosed in a metal casing made of metal that is magnetically permeable and has good electrical properties, and the same electrically conductive metal lid is connected through an electrical insulator. Therefore, the metal casing and the lid are not directly connected to each other at the opening edge, and a closed loop formed by the metal casing and the lid is not formed on the inner core. As a result, the induction coil for generating an electromotive voltage or the current detecting induction coil obtains a stable voltage from the AC power line. Furthermore, a DC power supply unit, current measurement circuit, sensor circuit, or camera control image processing circuit of a slave device semiconductor circuit in a sealed metal container made of a good-electricity metal connected to the same metal casing with a good-conductive metal. The monitoring circuit and the telecommunication part circuit are enclosed, so that the malfunction of the semiconductor circuit is reduced, the weather resistance is high, the damage of salt damage, rainwater, wind, avian insects and UV deterioration are prevented, and the durability is increased. ing. Also, since there is no direct electrical connection with the transmission line, malfunctions and failures due to large currents are reduced. Furthermore, since the metal casing and the lid are indirectly connected and sealed to have the same potential, they are resistant to lightning and electric field gradients. If the semiconductor circuit is housed in a polycarbonate casing in a sealed metal container, the influence of the electric field gradient can be further reduced.

  Moreover, the DC power necessary for the circuit of the present invention is generated by an induction coil for generating electromotive voltage from the AC current of the transmission line, and rectified to secure DC power for the slave semiconductor circuit. So it can always operate without battery. Therefore, inspection and periodic replacement work of the battery are not necessary, and monitoring can be performed constantly, and it can withstand long-life use.

  Also, a current detection induction coil of a current coil for detecting the current of the line is wound around the core, and the current of the current coil is detected by a detection circuit and input to a current measurement circuit to constantly monitor the current value of the line current. If possible, management of the line current value of the power line and current control management are facilitated.

Further, in the invention in which the overvoltage protection circuit is provided in the DC power supply unit, the overvoltage protection circuit does not output a high DC voltage even if an excessive voltage is input from the induction coil for inducing electromotive force. The circuit is prevented from malfunctions and failures due to overvoltage.
Also, the exposed connection electrode plate of the transmission line at the tip of the transmission line tends to become hot due to Joule heat, but if the temperature sensor can detect the temperature, the temperature of the connection electrode plate can be constantly monitored Can be.

Further, since the conductive electrode is connected to the metal case, the lid, and the metal hermetic container with the conductive metal, the heat of the connection electrode plate generates heat from the case, the lid, and the metal seal. Heat is transferred to the container and dissipated to the atmosphere, preventing the connection electrode plate from becoming extremely hot. It is also safe from lightning.
Moreover, if roundness is given to the corner part of the outer shape of a metal housing and a cover body, corona discharge will also be reduced.

FIG. 1 is a front view showing a metal casing of an induction coil container of a power line monitoring device according to an embodiment of the present invention. FIG. 2 is a partially cutaway front view showing the lid of the induction coil storage unit of the embodiment. 3 is a cross-sectional view taken along line AA of FIG. FIG. 4 is a partially cutaway side view of the induction coil storage device of the embodiment. FIG. 5: is a top view which shows the attachment state of the airtight metal container of the induction coil storage device of an Example, and a subunit | mobile_unit semiconductor circuit. FIG. 6 is a circuit diagram showing a DC power supply unit of the embodiment. FIG. 7 is a characteristic diagram showing circuit temperature characteristics of the overvoltage protection circuit of the example. FIG. 8 is a block diagram of the slave device semiconductor circuit in the sealed metal container. FIG. 9 is an explanatory view showing a state in which the power line of the embodiment is attached to the line electrode plate. FIG. 10 is an explanatory diagram showing an attachment state of the insulator upper end line of the substation of the power line monitoring apparatus of the embodiment.

  An aluminum alloy is preferable as a material for the metal casing and lid body having magnetic permeability and good conductivity according to the present invention.

  In addition, a light aluminum alloy is preferable as a material of the sealed metal container for housing the slave device semiconductor circuit.

  In addition, when inserting the induction coil of the insulated coil wire into the metal casing of the induction coil container, it is inserted through the binding band of the elastic elastic body that binds the induction coil so as not to directly contact the metal casing. It is preferable.

  The semiconductor device circuit in the sealed metal container uses a semiconductor that can withstand high temperatures. A circuit that can operate for a certain period of time even when the temperature in the sealed metal container is 100 ° C. is preferable.

  Furthermore, it is preferable to provide an overvoltage protection circuit that prevents the DC power supply unit and other slave device semiconductor circuits from failing even if there is an excessive current load on the induction coil. It is preferable to use a FET as this overvoltage protection circuit to convert a large current into heat.

  In addition, when installing the power line monitoring device of the present invention to the power line of the tower, the radio communication unit of the slave unit semiconductor circuit collects information, control, and radio communication of a plurality of slave units arranged at the same tower location. You may make it communicate with the main | base station held by the main | base station or radio | wireless relay apparatus or radio | wireless transmission / reception station close | similar to the main | base station or steel tower to perform, or the nearby supervisor. Alternatively, a monitoring information or control signal with the transmission tower line ID is sent by radio wave to a slave unit of another power line monitoring apparatus in another nearby tower, and the power line monitoring apparatus that receives this information is sent to a nearby tower. Can transmit information and control signals to multiple power tower monitoring devices by radio waves, network the slave unit or master unit of the tower, and send information and control signals of multiple tower lines to a predetermined location or centralized management facility / master unit You may do it.

  Separately from this, one master unit is installed on one tower, and the master unit monitors information / control signals of multiple power line track monitoring devices installed directly on the tower with high-power radio waves to remote centralized monitoring facilities Can be sent and received by attaching IDs to them.

  Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, measurement is possible even when a current of 2,000 A or more flows through the electrical circuit of each phase of the three-phase AC wire of a high voltage 75 KV substation, and information and control of a plurality of slave units are both performed by radio waves. A master unit for direct communication is installed in the substation so that the current of each line and the temperature of the line connection can be monitored in the substation or a management station that centrally manages the information.

(Explanation of reference numerals in embodiments)
G is a power line monitoring device according to an embodiment of the present invention, L is a 75 KV high-voltage three-phase AC transmission line, INS is an insulator that holds the connection of the line in the air, and F is a building room of a substation Is a master unit that communicates data and control with a plurality of slave units, and stores data, changes in data over time, analyzes data, and alarms using a computer. A weather-resistant induction coil housing for the power line monitoring device G, 1 is an annular metal casing having a U-shaped cross section using a magnetically-permeable and highly conductive aluminum alloy of the induction coil housing Y, and 11 is the same metal. An induction coil installation space inside the housing 1, 12 is an opening space in the center of the metal housing, 13 is a mounting surface in which the inner bottom surface of the induction coil installation space 11 is widened, and 14 is three pieces provided on the mounting surface. The through hole of the connecting bolt 17, 15 is a piece provided on the side opposite to the mounting surface 13 Perforated connecting bolt through-holes 15a, 16 are output line hole of the voltage coil 2a and the current coil 2b of the induction coil 2, 17 is a connecting bolt of good electrical conductivity. 2 is an induction coil, 2a is an induction coil (voltage coil) for generating an electromotive voltage, and 2b is an induction coil (current coil) for detecting current. 21 is an annular magnetic core in the center, 22 is an induction coil voltage coil 2a and current coil 2b coil wire coated with insulating tape on the core, and 23 is a metal casing that binds the induction coil 2 together. Bundling rubber bands 24 indicated by dotted lines in the figure that are elastically supported so as not to come into direct contact with the body 1 are output lines of the voltage coil 2a and the current coil 2b of the induction coil 2. 3 is an aluminum alloy lid, 31 is an electrically insulating rubber layer attached to the entire inner surface of the lid, 32 is a connecting bolt mounting hole provided in the lid, and 33 is a round outer periphery of the lid 3. It is a curved corner portion that is processed to prevent the generation of corona. Reference numeral 4 denotes an L-shaped, highly conductive metal mounting plate that is attached to the outside of the mounting surface 13 of the metal housing 1 by a connecting bolt 17, and 41 is a connecting bolt hole. Reference numeral 42 denotes a vertical rectangular mounting surface in which the metal mounting plate 4 is bent and the tip is widened, and 43 is an L-shaped conductive line mounting plate connected to the mounting surface. The mounting surface 42 and the bolt 44 are connected. 45 is an aluminum spacer provided between the nut of the bolt 44 and the line mounting plate 43, and 46 is a horizontal connection erected at right angles to the mounting surface 42 of the metal mounting plate 4 of the L-shaped line mounting plate 43. The power line monitoring apparatus G of the power line according to the embodiment is connected to the electrode plate 46 by a horizontal connection electrode plate 46 attached to the upper end (not shown) of the insulator INS (not shown) of one phase of the three-phase alternating current. Is fixedly supported. A temperature sensor 64 a is embedded in the hole of the spacer 45 in order to measure the temperature of the aluminum spacer 45 and the temperature of the connection portion of the line via the line attachment plate 43 thermally connected thereto. 5 is a durable and weatherproof sealed metal container that magnetically shields the slave semiconductor circuit 6 and is firmly attached to the metal mounting plate 4. 51 is a connecting bolt for connecting the sealed metal container 5 to the mounting surface 42 of the metal mounting plate 4, and 52 is an aluminum spacer provided between the sealed metal container 5 and the mounting surface 42 of the metal mounting plate 4. Is penetrated. 6 is a slave semiconductor circuit mounted in a plastic container 61 using polycarbonate in the sealed metal container 5, 62 is a DC power supply unit thereof, 62 a is an overvoltage protection circuit using an FET, and 63 is a current of the induction coil 2. The current value of the coil 2b is amplified by an operational amplifier and the output is inputted to calculate the current value of the line L. The current measurement circuit for the line L of the power line 64 is connected to the line L of the power line near the switch in the substation. The temperature sensor circuit of the temperature sensor 64a that measures the temperature of the section, 65 is a control information processing minicomputer that performs various circuit information and control processes using the CPU, and 66 is a camera monitor that controls the camera 66a that captures the periphery of the track The circuit, 67 is a radio wave communication unit that communicates information and control signals of each circuit with the main unit F, and 67a is an antenna of the radio wave so as to avoid a lightning strike toward the ground surface. That. 68 is a connector for connecting the voltage coil 2a of the induction coil 2 and the output line 24 of the current coil 2b to the DC power source 62 or the current measuring circuit 63, and 69 is a connector for connecting the sensor 64a and the sensor circuit 64. F is a parent provided in a substation for transmitting information and control signals by two-way communication with the radio wave communication unit 67 of the line monitoring device G of the power line of the plurality of embodiments installed in the substation for each three-phase line of the power line. The data of the sensors, images, current values, temperature values, etc. of the line monitoring device G of each power line is stored using a computer and stored over time so that the progress can be known. It is a system that can detect and alert the condition.

(Description of operation of the embodiment)
In this embodiment, as shown in FIGS. 9 and 10, a line L of each phase of a three-phase AC power line with a high voltage of 75 KV passes through the opening space 12 in the center of the annular weatherproof induction coil container Y of the embodiment. Wiring is done as follows. Further, the power line monitoring device G of the embodiment has the connection electrode plate 46 fixed to the tip of the insulator INS holding the line L and the L-shaped line mounting plate 43 of the embodiment as a plurality of bolts 44. The line mounting plate 43 is connected to the L-shaped metal mounting plate 4 by bolts 44, and the weather-resistant induction coil housing Y is further mounted to the L-shaped metal plate 4. The output line 24 of the induction coil 2 in the weatherproof induction coil container Y is connected to the same mounting surface 42 of the metal mounting plate 4 by the connecting bolt 51 on the opposite surface of the L-shaped line mounting plate 43 to the connection electrode plate 46. It is connected to the semiconductor circuit 6 in the attached sealed metal container 5.

  If this line monitoring device G is attached to each of the three-phase lines L of 75 KV and AC power flows through the line L, the induction coil 2 (voltage coil 2a) for generating an electromotive voltage in the weatherproof induction coil container Y is provided. An alternating magnetic field is generated by the alternating current of the line L, and an alternating electromotive force is generated in the electromotive force generating induction coil 2 (voltage coil 2a) having the magnetic core 21. In this case, the rim of the aluminum alloy metal casing 1 and the lip of the lid 3 are not directly electrically connected because the rubber layer 31 of the electrical insulator is located between them. The body 3 does not form a closed loop, the magnetic flux in the core 21 in the metal housing 1 is not affected by the metal housing 1 and the lid 3, and an alternating magnetic flux is generated according to the alternating current in the line L. An electromotive voltage is generated in the induction coil 2 of the coil wire 22 of the coil 2a.

  Thus, by enclosing the induction coil 2 for generating an electromotive voltage and for detecting a current in the weather-resistant induction coil container Y, the metal housing 1, the rubber layer 31, and the lid 3 allow rainwater, insects, birds, While being not affected by ultraviolet rays and having durability, an electromotive voltage is generated in the induction coil 2 from a high-voltage AC current of the line L and used as a power source of a DC voltage of about 5 V in the DC power supply unit 62. It can operate without a battery and can be monitored at all times and with a long life with little need for battery replacement.

The electromotive voltage / current of the induction coil 2 is input to the DC power source 62 and the current measuring circuit 63 of the semiconductor circuit 6 in the plastic container 61 in the sealed metal container 5 via the output line 24.
The DC power source 62 is of the circuit shown in FIG. 6, and the output voltage of the induction coil 2 is converted to DC by a rectifier circuit, and a constant voltage can be stably output at a stable 5 V by an overvoltage protection circuit 62a using an FET. I made it. Further, it withstood continuous overcurrent with a line current of 2,000 A in the line L. The temperature rise value dTf of the FET of the overvoltage protection circuit 62a was 30 ° C. The relationship between the line current I1 (L), the output voltage, and the temperature rise value dTf of the FET is shown in the operation characteristic diagram of FIG. As a result, it was confirmed that the overvoltage protection circuit 62a and the slave semiconductor circuit 6 do not fail when the line current I1 continuously flows over 1,000 A.

  In addition, since the semiconductor circuit 6 is sealed in the plastic container 61 made of polycarbonate in the sealed metal container 5, an induced voltage is generated in the closed loop of the electronic circuit due to a strong magnetic field with a short-circuiting large current in the circuit and the CPU being used. It was made not to break down due to or current. In addition, the gradient of the electric field can be reduced and the influence is prevented.

The DC power supply 62 of the semiconductor circuit 6 supplies 5V DC, and the current measuring circuit 63 detects and amplifies the current value generated in the current coil 2b of the induction coil 2, and according to the input value. The current value of the line I1 is calculated and output. The sensor circuit 64 obtains temperature information of the temperature sensor 64a embedded in the aluminum spacer 45 which is crimped by the line mounting plate 43 and the bolt 44, and the temperature generated in the line (board) is determined as the connection electrode plate 46 / spacer. 45 is detected by the temperature sensor 64a and measured as the temperature of the connection portion of the line.
In addition, this sealed metal container 5 is provided with a camera 66a capable of photographing a portion to be observed outside the required line (bird's nest, line due to strong wind, power line breakage, bending, etc.), and the state around the line as an image. It can be output.

  The DC voltage value, the line current value, the temperature value of the line connection part, and the information output from the camera image of these semiconductor circuits 6 are input to the control information processing mini-computer 65, and the necessary information is output to the radio wave communication part 67. It can be transmitted to the machine F by radio waves. Since the antenna 67a of the radio wave communication unit 67 faces downward, lightning can be avoided, and corners are eliminated from the outer periphery of the metal housing 1 and the lid 3 to provide roundness (curvature), thereby reducing corona discharge. ing. The semiconductor circuit 6 is also operated according to the control signal in response to the control signal / information output control signal from the master unit F.

In this embodiment, a specific low-power radio frequency of 429 MHz is used as a radio wave, and the radio wave can be seen in a communication distance of 200 m to 300 m. Therefore, it is possible to obtain information from a power transmission tower.
A plurality of slave units can be provided, and the master unit F obtains the above-mentioned information about the track from each slave unit (track monitoring device) by a polling method of about 1 sec / slave unit, and stores and saves it. Software inspections and alarms can be displayed if there are any abnormalities so that the location of abnormalities and abnormal states can be displayed.

  As described above, this embodiment can withstand severe power environments (high voltage environment, material deterioration due to corona discharge, malfunction of electronic circuits, surge current, overcurrent, excessive current during short circuit accident), salt damage, As a battery that can effectively protect against heat cycle deterioration, UV light deterioration, and bird damage, it has long life and can operate without batteries.

  The present invention can monitor lines in places such as high-voltage current transmission towers and underground spaces other than substations without batteries (replacement of batteries is not necessary). It can measure the strain and stress values of currents and structures, and can be used to observe the camera around the track by attaching a camera.

G Line Monitoring Device for Power Line of Example F Master Unit L Line INS Insulator Y Weatherproof Induction Coil Container 1 Metal Housing 11 Induction Coil Installation Space 12 Opening Space 13 Mounting Surface 14 Through Hole 15 Connecting Bolt Through Hole 15a Piece Member 16 Hole for output line 17 Connecting bolt 2 Induction coil 2a Voltage coil (Induction coil for generating electromotive voltage)
2b Current coil (Induction coil for current detection)
21 Core 22 Coil wire 23 Bundling rubber band 24 Output line 3 Lid 31 Rubber layer 32 Hole 33 Curved corner 4 Metal mounting plate 41 Bolt hole 42 Mounting surface 43 Line mounting plate 44 Bolt 45 Spacer 46 Connection electrode plate 5 Sealed metal container 51 connecting bolt 52 spacer 6 semiconductor circuit 61 plastic container 62 DC power supply unit 62a overvoltage protection circuit 63 current measurement circuit 63a current detection circuit 64 temperature sensor circuit 64a temperature sensor 65 control information processing mini-computer 66 camera monitoring circuit 66a camera 67 radio wave communication unit 67a Antenna 68, 69 connector

Claims (9)

  An induction coil for generating an electromotive voltage in which a coil is wound around an annular core is arranged inside an annular metal casing having a U-shaped cross section made of a magnetically permeable and highly conductive metal. A highly conductive metal lid is fitted to the opening edge via an electrical insulator to form a sealed weatherproof induction coil container, and AC is connected to the central opening space of the weatherproof induction coil container. Pass the power transmission line, enclose the slave device semiconductor circuit in the weatherproof induction coil container or in a separate sealed metal container connected to it by a highly conductive metal mounting plate. DC power supply unit that rectifies the voltage generated in the induction coil for generating electromotive force as a semiconductor circuit to generate DC power of a required voltage, and the state of equipment around the transmission line using the DC voltage of the DC power supply unit Sensor circuit or camera device electrical signal to monitor The control circuit of the camera control image processing circuit to be processed, the control signal of the DC power supply unit or the monitoring circuit and the information from them are transmitted / received to / from the base unit for managing them or the radio relay device for relaying the radio with the base unit A power line monitoring device with a built-in radio communication unit.   A current detecting induction coil capable of detecting a current of the transmission line in which the coil is wound around the annular core is provided separately from the electromotive voltage generating induction coil, and the electromotive voltage generating induction coil and current are provided in the annular core. In the state where the detection induction coil is wound, the coil is disposed in the annular metal casing having a U-shaped cross section, and the current value flowing through the current detection induction coil is detected and flows from the output to the transmission line. The line monitoring device for a power line according to claim 1, wherein a current measuring circuit for calculating a current value is provided as one of the monitoring circuits for the slave semiconductor circuit.   The line monitoring device for a power line according to claim 1 or 2, wherein an overvoltage protection circuit is provided for the DC voltage output from the DC power supply unit so that an excessive DC voltage is not applied to the slave device semiconductor circuit.   The sealing in which the weather-resistant induction coil container and the slave device semiconductor circuit are encapsulated using a conductive metal on a connection electrode plate exposed to the atmosphere of the transmission line line provided at the insulator tip of the AC power transmission line The line monitoring device for a power line according to any one of claims 1 to 3, wherein the metal container is connected and supported.   The line monitoring device for a power line according to claim 4, wherein the sensor circuit includes a temperature sensor circuit for measuring a temperature of the connection electrode plate of an AC power transmission line.   The line monitoring device for a power line according to any one of claims 1 to 5, wherein the antenna of the radio wave communication unit is an antenna extending from the outside of the sealed metal container toward the ground surface.   The line monitoring device for a power line according to any one of claims 1 to 6, wherein corona discharge is reduced as an outer shape of the metal casing and the lid having a rounded outer shape.   The line monitoring device for a power line according to any one of claims 1 to 7, wherein the slave device semiconductor circuit in the sealed metal container is disposed inside a polycarbonate casing provided in the sealed metal container.   A parent capable of bidirectionally communicating with each radio wave communication unit of the line monitoring device by attaching a plurality of power line monitoring devices according to any one of claims 1 to 8 to a switch line of a substation of a three-phase high-voltage power line. Line monitoring equipment in a transformer station with a machine installed in a substation.

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