JPH0216474B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an overcurrent indicating device for a power distribution line.

Conventionally, when an overcurrent occurs in a distribution line due to a short-circuit accident, this is detected by an overcurrent relay, the breaker at the substation is tripped, and a re-closing relay causes the breaker to reclose after a certain period of time. If this re-closing is successful, power will continue to be supplied; if the re-closing is unsuccessful, that is, the circuit breaker trips again, a so-called fault section detection device installed on the distribution line will isolate the fault section and restore it to a healthy state. A method is adopted in which power is transmitted by re-closing the section. However, in recent years, as insulated wires have come to be used for power distribution lines, in the case of a short circuit caused by a lightning strike, even if the distribution line melts due to a concentrated arc, it is still insulated by the insulation coating. There are problems in that ground faults cannot be detected and it takes time and effort to locate the fault point, which delays recovery from the fault and lengthens power outages, making it impossible to provide a stable supply of power to customers. In addition, even if the distribution line does not melt, the damage caused by concentrated arcing may be severe and the wire may break due to subsequent mechanical external force, so it is necessary to quickly locate the fault point in the distribution line where the overcurrent has occurred. This is absolutely necessary for the maintenance and management of power distribution lines.

To solve this problem, we installed an overcurrent indicator on the distribution line, and when an overcurrent flows through the distribution line, the overcurrent relay is operated to unlock the indicator piece and display the indicator piece sticking out outside the device. Now, there are some devices that allow you to discover the abnormality during inspection, but this type of display needs to be reset manually on the pole after each display operation, and it is difficult to go up and down on the pole or with live wires. This poses a problem in that it requires a lot of time and effort, such as a return operation, and is also dangerous.

The present invention has been made in view of the above-mentioned points, and its purpose is to provide a device that has a simple configuration and can automatically recover after a certain period of time after displaying an overcurrent. There is a particular thing.

Embodiments of the present invention will be described below with reference to the drawings.
In Fig. 1, 1 is a distribution line, 2 is a through-type current transformer installed through the distribution line 1, and 3 is a current transformer 2.
This is a rectifier circuit connected to the secondary side of the diodes, which is formed into a bridge circuit using diodes to perform full-wave rectification of the input. 4 is a display capacitor connected to the output end of the rectifier circuit 3 via a resistor 6. 7 is a display element connected between the terminals of the capacitor 4 via a switching element 8 made of a thyristor. This display element 7 is an element called an electrochromic display (ECD).
It consists of a display electrode, a counter electrode, and an electrolytic solution for the movement of ions. When a voltage with a (-) polarity is applied to the display electrode and a (+) polarity is applied to the counter electrode, hydrogen ions in the electrolyte adhere to the display electrode. By applying a voltage of opposite polarity to the electrodes, the hydrogen ions are ionized and the above display is erased, and it has a memory function so that even if the voltage is removed, The display state is maintained and an electromotive force is generated in the memory. Reference numeral 9 denotes an erasing resistor inserted between the terminals of the display element 7. This resistor consumes the electromotive force of the display element 7 and restores the display after a certain period of time. This resistance 9
The recovery time can be set arbitrarily by selecting the resistance value of ing. Reference numeral 10 denotes a voltage nonlinear element, which is formed by connecting a plurality of diodes in series in the forward direction, for example. Reference numeral 11 denotes a variable resistor, the slider of which is connected to the gate of the switching element 8 to set the trigger level of the switching element 8. The voltage non-linear element 10 and the variable resistor 11 are connected to the rectifier circuit 3.
is inserted in series with the output terminal of the variable resistor 1.
The output voltage of 1 is the current flowing through the distribution line 1, for example.
It is set so that the trigger level of the switching element 8 is reached when the current exceeds 500A. Reference numeral 5 denotes a protective constant voltage element inserted between the terminals of the variable resistor 11. For example, two diodes are connected in series in the forward direction and inserted, so that the voltage between the terminals of the variable resistor 11 is the same as that of the constant voltage element 5. When the forward voltage exceeds , the forward voltage is held to protect the gate of the switching element 8, and the charging voltage of the capacitor 4 is held constant by the voltage nonlinear element 10 and the constant voltage element 5. Capacitor 4 and display element 7
It is becoming more and more protected. 12 is a noise absorbing capacitor inserted between the gate and cathode of the switching element 8, and 13 is a protection diode whose anode side is connected to the cathode of the switching element 8, and whose cathode side is connected to the gate.

To explain the current transformer 2 with reference to FIG. 2, reference numeral 14 denotes an iron core made by winding and laminating belt-shaped steel plates in an annular manner, and is divided into left and right sides (in FIG. 2) to form divided iron cores 14a and 14b. , one split core 14b
A secondary coil 15 is wound around the core and molded with resin, and the divided surfaces of the divided cores 14a and 14b are brought into contact with each other. Reference numerals 16 and 17 denote belt-shaped tightening bands attached to the outside of the split cores 14a and 14b, and both ends of the bands protrude vertically in parallel across the split surface, and are opposed to mounting pieces 16a and 16.
b, 17a and 17b are formed. The tips of the mounting pieces 16a and 17a are rotatably wound around the support shaft 18 by cutting one side into a slightly narrow groove and the other into a groove corresponding in size to the narrow width. Further, the mounting pieces 16a, 16b are provided with screw insertion holes, and the mounting pieces 17a, 17b are provided with screw holes opposite thereto. Reference numeral 19 denotes an extended cylindrical support fitting that is installed concentrically with the screw insertion holes of the mounting pieces 16a and 16b, and has a threaded portion at the extending end in the cylinder and a threaded portion at the tip. The tightening bolt 20 inserted through the support fitting 19
The split surfaces of the split cores 14a, 14b are fixed by screwing the threads of the tightening bolt 20 into the threads of the mounting pieces 17a, 17b and tightening them. are pressed into contact with each other. 21 is in the center part on the side of the molded split core 14b,
The receiving portion is formed into a U-shaped groove with a dividing surface opened in a direction that perpendicularly penetrates the iron core 14. 22
is a slightly deep U-shaped groove formed on the molded split core 14a side facing the receiving portion 21. Reference numeral 23 denotes a clamping piece provided in the groove 22 so as to be prevented from rotating and to be movable from side to side.
It is pivotally attached to the tip of a mounting bolt 24 that protrudes by threading into the mounting bolt 24, and when the mounting bolt 24 is tightened, the distribution line 1 is clamped between the receiving part 21 and the clamping piece 23. A hard rubber is pasted on the contact surface with the power distribution line 1 to prevent damage to the insulation coating of the power distribution line 1. Reference numeral 25 denotes a box-shaped container, into which parts such as the display element 7 are assembled, and a display window 25a is provided on the side wall so that the display of the display element 7 can be seen. The container box 25 is attached to a support part provided at the tip of the mounting piece 17b and a support member 26 hanging from the side of the split core 14b.

When installing this device formed in this way to the distribution line 1, loosen the tightening bolts 20, 20 and turn the split core 14a counterclockwise (in Fig. 2).
When the split core 14a side is rotated, the split surface is expanded around the support shaft 18. In this state, the distribution line 1 is fitted into the receiving part 21, and then the split core 14a side is rotated clockwise (clockwise) in the opposite direction as described above. 2) to bring the split surfaces into contact with each other, and by tightening the tightening bolts 20, 20, the split surfaces of the split cores 14a and 14b are pressed into contact with each other. Then, by tightening the mounting bolts 24, the distribution line 1 is firmly clamped between the clamping piece 23 and the receiving part 21 via the hard rubber.
This device is attached to the distribution line 1.

Next, the overcurrent display operation will be explained. When the distribution line 1 is in a steady state, when the charging voltage of the capacitor 4 is lower than the forward voltage of the voltage nonlinear element 10, all the secondary current of the current transformer 2 flows into the capacitor 4 via the resistor 6. The lever capacitor 4 is charged. When the charging voltage of this capacitor 4 exceeds the forward voltage of the voltage non-linear element 10 (for example, 1.8 V or more in the case of three diodes), the voltage non-linear element 10 conducts and the secondary current of the current transformer 2 is divided into the capacitor 4 and the variable resistor 11.
This shunt causes a voltage at the output terminal of the variable resistor 11.
Since V _TG is generated but does not reach the trigger level of the switching element 8, the switching element 8 remains turned off.

In this state, if a short circuit occurs in the distribution line 1 due to a lightning strike or the like and an overcurrent flows, the voltage between the terminals of the variable resistor 11 increases, and its output voltage V _TG reaches the trigger level of the switching element 8, which turns on the switching element 8. do. At this time, when the voltage between the terminals of the variable resistor 11 becomes equal to or higher than the forward voltage of the constant voltage element 5 (for example, the forward voltage of two diodes is 1.2 V or higher), the constant voltage element 5 becomes conductive and a current flows therein as well. While maintaining the voltage across the terminals of the shunt variable resistor 11 at the forward voltage (for example, 1.2V) of the constant voltage element 5,
The charging voltage of the capacitor 4 is determined by the voltage nonlinear element 10.
and the forward voltage of constant voltage element 5 (for example, 1.8V+
1.2V=3.0V).

Then, by turning on the switching element 8, a discharge circuit of the capacitor 4 is formed, and the discharge voltage of the capacitor 4 is applied to the display element 7. In the display element 7 that receives this, the hydrogen ions in the electrolyte adhere to the display electrode due to reduction and develop a blue color.
Displays overcurrent occurrence. At this time, at the substation, the overcurrent generated in the distribution line 1 causes the breaker to trip and stop the power supply, but before the overcurrent occurs and the breaker trips, Switching element 8 is triggered. The switching element 8 is turned off when the circuit current due to the discharge of the capacitor 4 becomes less than the holding current. As a result, the applied voltage is removed from the display element 7, but since it has a memory function, the overcurrent indication is maintained as it is. However, since the display element 7 has an electromotive force during memory, this electromotive force is transferred to the resistor 9 inserted between the terminals of the display element 7.
The hydrogen ions that are consumed through the display and adhered to the display electrode are ionized, and after a period of time determined by the resistance value of the resistor 9 (for example, 3 hours), the blue display disappears, that is, the overcurrent display is automatically restored. do.

According to the present invention, when an overcurrent is detected through a current transformer attached to a distribution line, a switching element is triggered before a substation circuit breaker trips, and a capacitor charged in a steady state is discharged. Since the overcurrent is displayed by coloring the display element, it is possible to accurately display the overcurrent even if the power supply is stopped due to a circuit breaker trip. Since it has a memory function, it is possible to maintain the overcurrent display even when there is no voltage, and as a result, it is possible to detect overcurrent distribution lines at the time of inspection.
In addition, a resistor is inserted between the terminals of the display element to erase the electromotive force in the memory, and the coloring is erased by an oxidation reaction, so even if there is no power supply for recovery from the distribution line, it can be used again. , the overcurrent display can be automatically reset without manual reset operation. Furthermore, the distribution line is clamped by tightening the mounting bolt via hard rubber between the receiving part and the clamping piece provided on the dividing surface of the current transformer, which is divided into two parts, so that the wire diameter can be adjusted. Even if the wires are different, the distribution wire can be securely clamped without damaging the insulation coating. This means that even if this device is suspended and attached to a power distribution line, the distribution line will vibrate due to external force and the attachment point will not move.Moving the attachment point will damage the insulation coating and allow rainwater to flow from there. Rainwater infiltrates and accumulates between the insulation coating and the conductor at low points on the overhead wire, corroding the conductor, causing local heat generation, causing deterioration over time, causing the wire to break due to mechanical external force, or concentrating on arcs caused by lightning and causing it to melt. It has great utility in that it can prevent such things from happening. Furthermore, display capacitors can be configured with a small capacity because they only need to be discharged for a sufficient period of time for the display element to develop color due to reduction, and the time required for charging is short, making it possible to connect them to the same distribution line. Even if an accident occurs at short intervals, overcurrent display can be performed accurately for a predetermined period of time, and when searching for a fault point, the fault point can be accurately found without causing misunderstanding by an inspector. In addition, the configuration can be simplified and stationary, which not only speeds up the response when overcurrent is detected, but also reduces the size and weight without causing malfunctions since there are no moving parts. , which allows for direct installation on power lines, and
By installing it at each branch point of the power distribution line, it is possible to easily search for the point of a fault, thereby enabling early detection of the disconnection point and early recovery from the fault, and streamlining the maintenance management of the power distribution line.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is an external view of FIG. 1, with A being a front view and B being a side view. 1: Distribution line, 2: Current transformer, 4: Display capacitor, 7: Display element, 8: Switching element,
9: Erasing resistor.

Claims (1)

[Claims] 1 The upper part of the two split cores, each of which is resin-molded by dividing the core into two parts so that the distribution line can be attached and detached from both sides, is attached integrally to the outside of the two split cores, with the split surfaces sandwiched between them. A receiving part that is rotatably attached via mounting pieces that protrude vertically and parallel to each other, and has a splitting surface opening in one of the central parts of the splitting surfaces of the two split iron cores in a direction perpendicular to the core and penetrating through the core. At the same time, a slightly deep U-shaped groove is opened on the other side of the central part facing the receiving part, and a movable clamping piece is interposed in this U-shaped groove to prevent rotation. Then, the split iron core with the U-shaped groove is screwed onto this clamping piece, the tips of the protruding mounting bolts are pivotally connected, and the mounting pieces protruding above and below are connected to each other through the tightening bolts. A current transformer in which the divided surfaces are pressed into contact with each other by tightening, and the distribution line is firmly clamped between the receiving part and the clamping piece through hard rubber by tightening the mounting bolt. , a support fitting that is integrally attached to the outside of one of the split iron cores of the current transformer and hangs vertically, and a container having a display window attached to the mounting piece, and inside the container, the above-mentioned transformer is installed. A circuit in which a voltage nonlinear element and a variable resistor are connected in series and a display capacitor are connected in parallel to the secondary side of the current flow device via a rectifier circuit, and the above-mentioned capacitor is connected between the terminals of the display capacitor. A display element consisting of an electrochromic display placed close to the display window and a switching element are inserted in series, the output terminal of the variable resistor is connected to the gate of the switching element, and a constant voltage element is connected between the terminals of the variable resistor. An overcurrent display device for a power distribution line, in which an erasing resistor is inserted between the terminals of the display element.