JPH0157309B2 - - 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 due to a short-circuit accident in a distribution line, an overcurrent relay detects this, trips the substation's breaker, and a reclosing 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 circuit to 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. The ground fault could not be detected, and therefore, when the circuit breaker was reclosed, the circuit was successfully reclosed as if it were healthy, and power was supplied, allowing maintenance personnel to detect a temporary short circuit. Make it seem like an accident,
If the situation continues as it is, there is a risk of electric shock caused by the broken distribution line, resulting in personal injury.Also, even if the distribution line does not melt, the concentration of arcs can cause significant damage. The wire may break due to subsequent mechanical external force, and if the disconnector trips due to overcurrent, the automatic reclosing operation is locked and the fault point of the distribution line where the overcurrent has occurred can be quickly located. In terms of maintenance management of power distribution lines, it is absolutely necessary to detect and promptly restore the accident.

In order to solve this problem, an overcurrent indicator is installed on the distribution line, and when an overcurrent flows through the distribution line, a relay is operated to unlock the indicator piece and cause the indicator piece to protrude outside the device. Some display devices are designed to detect abnormalities during inspection, but these types of indicators must be manually reset on the pole each time after the display has been activated, making it difficult to climb up and down the pole or perform reset operations while the wires are live. This method requires a lot of effort and is also dangerous.

The present invention has been made in view of the above-mentioned points, and its purpose is to provide an overcurrent display with a simple configuration and an automatic recovery immediately after recovery from an accident. It's about doing.

Embodiments of the present invention will be described below with reference to the drawings.
1 is a distribution line, 2 is a current detection unit detachably attached to the distribution line 1, and is a through-type current transformer formed in two parts.
It's more familiar than CT ₁ . Reference numeral 3 denotes a control section connected to the current detection section 2 and configured to cause the display section 4 to display when an overcurrent flows through the distribution line 1. and,
A display section 4 connected to the output terminal of the control section 3 is composed of a display element called an electrochromic display (ECD). It consists of a display electrode, a counter electrode, and an electrolytic solution for ion movement. When a voltage of (-) polarity is applied to the display electrode and (+) polarity is applied to the counter electrode, hydrogen ions in the electrolyte are transferred to the display electrode. The hydrogen ions are ionized and the above display is erased by applying a voltage of opposite polarity to the above electrode, and it has a memory function to remove the voltage. The display state is maintained even when the display is in use, and the memory has an electromotive force.

Next, the control section 3 will be explained. DB ₁ is a rectifier circuit connected to the secondary side of current transformer CT ₁ , and is designed to perform full-wave rectification by bridge-connecting diodes. At the output end of this rectifier circuit DB ₁ , a diode D ₁ and a resistor P ₁ inserted in the forward direction are connected.
A charging circuit with a display capacitor C ₁ connected in series, a voltage nonlinear element NLE with multiple diodes (5 in this example) connected in series in the forward direction, and a variable resistor VR ₁ for overcurrent detection are connected in series. The connected circuit and
A constant variable resistor that restores the display on the display section 4
Insert VR ₂ in parallel and connect the above display capacitor.
A display unit 4 is connected between the terminals of C ₁ via the emitter-collector of a PNP main transistor Q ₁ , and diodes D ₂ and D ₃ are connected between the terminals of this display unit 4 to protect the display unit 4 from overvoltage. A circuit in which these are connected in series in the forward direction is inserted in parallel between the collector and emitter of the display recovery transistor Q ₂ , and a resistive VR ₂ slider (output end) is connected to the base of this transistor Q ₂ .
is connected through resistor R ₃ and above transistor Q ₁
Insert resistors R ₄ and R ₅ between the emitter and base of
The conduction of the transistor _Q1 closes the discharge circuit of the capacitor _C1 , and the discharge of the capacitor _C1 causes the display section 4 to display color.
The above-mentioned colored display is made to disappear when _Q2 becomes conductive. In addition, between the terminals of the variable resistor VR ₁ , there is a protective constant voltage element CVE, which is formed by connecting a plurality of diodes (two in this example) in series in the forward direction.
and a resistor _R8 having a lower resistance than the variable resistor VR ₁ (for example, 1/100 in terms of resistance value ratio) are inserted in parallel so that the voltage between the terminals of the variable resistor VR ₁ is equal to or higher than the forward voltage of the constant voltage element CVE. When this happens, the forward voltage is held to protect the output side of the variable resistor VR ₁ , and the voltage non-linear element NLE and constant voltage element CVE prevent the charging voltage of the capacitor C ₁ from rising above a certain value. It is designed to be suppressed and protected.
In addition, the base of a transistor Q ₃ whose emitter is connected to the (-) side output terminal of the rectifier circuit DB ₁ is connected to the slider of the variable resistor VR ₁ via a resistor R 5, and the collector of this transistor Q ₃ is connected to the slider of the variable resistor VR 1 through a resistor R ₅ . , the above variable resistor
The base of transistor Q ₄ whose collector is connected to the slider of VR ₁ through resistor R ₆ is connected through resistor R ₇ , the emitter of transistor Q ₄ is connected to the emitter of transistor Q ₃ , and transistor Q ₃ The collector of is connected to the slider of the variable resistor VR ₂ , so that transistors Q ₄ and Q ₂ are normally conductive, and when an overcurrent occurs, transistor Q ₃ is conductive, making transistors Q ₄ and Q ₂ non-conductive. It's getting old. Furthermore, the base of a transistor _Q5 is connected to the collector of the transistor _Q4 , and the emitter of this transistor _Q5 is connected to the emitter of the transistor _Q4 , and a capacitor _C2 is inserted between the base and emitter of the transistor _Q5 . collector
The collector of transistor Q ₆ is connected to the base of transistor _{Q 5 ,} and the emitter of transistor Q ₆ is connected to the resistor R ₄ and R inserted between the emitter and base of transistor Q ₁ . ₅ , the non-conduction of transistor Q ₄ makes transistor Q 5 conductive, which makes transistor Q ₆ conductive, and the transistor Q ₅ becomes conductive.
A switching circuit with a latch function that allows the collector current of Q ₆ to flow into the base of transistor Q ₅ and continues conduction even when the output voltage of variable resistor VR ₁ becomes zero is formed by transistors Q ₅ and Q ₆ . However, due to the conduction of this, the transistor _Q1 is made conductive, the discharge circuit of the capacitor _C1 is closed, and the discharge voltage of the capacitor _C1 is applied to the display section 4, so that the display section 4 becomes colored. ing. Furthermore, when the current flowing through the distribution line 1 exceeds, for example, 500 A, the output voltage of the variable resistor VR ₁ is determined by the base voltage applied via the resistors R ₅ and R ₆ to the transistors Q ₃ ,
_Q5 is set to conduct.

Next, the current detection unit 2 will be explained with reference to FIG. 2. Reference numeral 5 denotes an iron core made by winding and laminating belt-shaped steel plates in an annular manner, which is divided into left and right parts (in FIG. 2) to form divided iron cores 5 _a and 5 _b . A secondary coil 6 is wound around one of the split cores 5 _b and resin molded, and the split surfaces of the split cores 5 _a and 5 _b are brought into contact with each other. Reference numerals 7 and 8 denote belt-shaped tightening bands attached to the outside of the split cores 5 _a and 5 _b , and both ends of the bands protrude vertically in parallel across the split surface, and are attached to mounting pieces 7 _a facing each other. , 7 _b and 8 _a , 8 _b are formed.
The ends of the mounting pieces 7 _a and 8 _a are made into a slightly narrow groove on one side and a groove corresponding to the narrow width on the other side, and are rotatably wound around the support shaft 9 . is. Further, screw holes are provided in the mounting pieces 7 _a and 7 _b in a protruding manner, and screw holes are provided in the mounting pieces 8 _a and 8 _b in opposition thereto. Reference numeral 10 denotes a cylindrical support fitting that is installed concentrically with the screw insertion holes of the mounting pieces 7 _a and 7 _b and extends, with a threaded part provided at the extending end in the cylinder and a threaded part at the tip. The tightening bolt 11 inserted through the support fitting 10 is received by the threaded part of the support fitting 10 to prevent it from coming off outward.
The divided surfaces of the divided cores 5 a and 5 _b are brought into pressure contact with each other by screwing the threaded portions of the split iron cores 5 _a and 5 _b with the threaded portions of the mounting pieces 8 _a and 8 b and tightening them.
Reference numeral 12 denotes a receiving portion formed in the center of the molded split core 5 _b side with a split surface opening in a direction perpendicularly passing through the core 5 and formed into a U-shaped groove.
Reference numeral 13 denotes a slightly deep U-shaped groove formed on the molded split core _5a side facing the receiving portion 12. Reference numeral 14 denotes a clamping piece provided in the groove 13 so as to be prevented from rotating and to be movable from side to side.
_It is pivotally attached to the tip of a protruding mounting bolt 15 that is threaded into the mounting bolt 15, and by tightening the mounting bolt 15, the distribution line 1 is clamped between the receiving part 12 and the clamping piece 14, A cushioning material such as hard rubber is attached to the contact surface with the distribution line 1 to prevent damage to the insulation coating of the distribution line 1. Reference numeral 16 denotes a box-shaped container in which the control section 3 and display section 4 are incorporated, and a display window 16 _a is provided on the side wall at a position where the display section 4 can be easily viewed. and,
This container 16 includes a support provided at the tip of the mounting piece 8 _b and a support 17 hanging from the side of the split iron core 5 _b .
It is installed in

When installing this device configured in this way on the distribution line 1, loosen the tightening bolts 11, 11, remove them from the screw holes of the mounting pieces _8a , _8b , and rotate the split iron core _5a side counterclockwise (second ) in the figure, the split surface of the split core _5a side is expanded around the support shaft 9,
In this state, fit the distribution line 1 into the receiving part 12, and then rotate the split iron core _5a side clockwise (in Fig. 2) in the opposite direction as described above to bring the split surfaces into contact with each other, and tighten the tightening bolts 11, 11. By screwing the mounting pieces 8 _a and 8 _b into screw holes and tightening them, the split surfaces of the split cores 5 _a and 5 _b are pressed into contact with each other. And mounting bolt 1
5, the distribution line 1 is clamped between the clamping piece 14 and the receiving part 12, and the present device is attached to the distribution line 1.

Next, the overcurrent display operation will be explained. When this device is installed on the distribution line 1 which is currently in a steady state,
The secondary current of current transformer CT ₁ of current detection unit 2 is rectified by a rectifier circuit.
Since it flows through DB ₁ to variable resistor VR ₂ , the output voltage of variable resistor VR ₂ is applied to the base of transistor Q ₄ through resistor R ₇ and to the base of transistor Q ₂ through resistor R ₃ . and transistors Q ₄ and Q ₂ become conductive. Meanwhile above current transformer CT ₁
The secondary current of capacitor C1 also flows through the capacitor _C1 .
When the charging voltage to C ₁ is less than the forward voltage of the voltage non-linear element NLE, it flows through the diode D ₁ and the resistor R ₁ and charges the capacitor C ₁ . and,
The charging voltage of capacitor _C1 is a voltage nonlinear element.
NLE forward voltage or higher (e.g. forward voltage
0.6V (for 5 diodes in this example, 3.0V or more), the voltage nonlinear element
NLE becomes conductive, and the current flows through the voltage nonlinear element NLE to the resistor R ₈ and the variable resistor VR _1. However, the resistor R ₈ has a lower resistance than the variable resistor VR ₁ (e.g. 1/100), the output of the variable resistor VR ₁ is approximately zero, and the transistors Q ₃ and Q ₅ are not conductive. Therefore, the transistors Q ₆ and Q ₁ remain non-conductive, and the display section 4 is short-circuited and does not display due to the conduction of the transistor Q ₂ .

In this state, a short circuit accident occurs in the distribution line 1 due to a lightning strike, etc. at time _t1 in Figure 3, and when an overcurrent flows, the variable resistance
The voltage across VR ₁ increases, which causes the base voltage of transistor Q ₃ to increase, causing transistor Q ₃ to conduct. This results in transistor Q ₄ ,
The base voltage of Q ₂ decreases and transistors Q ₄ and Q ₂ become non-conductive. At this time, the voltage between the terminals of the variable resistor VR ₁ is equal to or higher than the forward voltage of the constant voltage element CVE (for example, if the forward voltage of the diodes is 0.6 V and there are two diodes as in this example, it is 1.2 V or higher). Then, the constant voltage element CVE becomes conductive and the current is shunted to this as well, maintaining the voltage between the terminals of the variable resistor VR ₁ at the forward voltage (for example, 1.2V) of the constant voltage element CVE, and reducing the charging voltage of the capacitor C ₁ . Voltage nonlinear element NLE
and the forward voltage of constant voltage element CVE (e.g. 4.2V)
to hold. Then, when the transistor Q ₄ becomes non-conductive, the base voltage of the transistor Q ₅ increases and the transistor Q ₅ becomes conductive, which causes the base voltage of the transistor Q ₆ to decrease and the transistor Q ₆ also becomes conductive. When this transistor Q ₆ becomes conductive, the collector current of the transistor Q ₆ flows into the base of the transistor Q ₅ .
Transistors Q ₆ and Q ₅ are latched and become variable resistors.
Maintains conduction even if the output voltage of VR ₁ becomes zero. Further, due to the conduction of the transistors Q ₆ and Q ₅ , the base voltage of the transistor Q ₁ decreases, and the transistor Q ₁ becomes conductive. Thereby, the discharge circuit of the capacitor C ₁ is formed by the circuit of C ₁ -Q ₁ -4-C ₁ , and the discharge voltage of the capacitor C ₁ is applied to the display section 4. In response to this, the display element of the display unit 4 becomes blue as the hydrogen ions in the electrolyte adhere to the display electrode due to reduction and display the occurrence of overcurrent (third
Figure 4). On the other hand, at the substation, the overcurrent relay detects the overcurrent that has occurred in the distribution line 1, and the circuit breaker trips (time _t2 in Figure 3), stopping the power supply. After the current is generated and before the circuit breaker trips, the transistor Q ₅ ,
Capacitor C 1 continues to discharge as Q ₆ conducts and holds it, causing transistor Q ₁ to remain conductive, and as the discharge voltage decreases, transistor Q ₁ continues to conduct.
The base-emitter voltage of Q ₁ decreases and transistor Q ₁ becomes non-conductive. As a result, the applied voltage is removed from the display section 4, but since the display section 4 has a memory function, the display indicating that an overcurrent has occurred is maintained. Due to the non-conduction of the transistor Q ₁ , the capacitor C ₁ is discharged through the transistors Q ₆ and Q ₅ , and when the discharge voltage becomes lower than the forward voltage of the transistors Q ₆ and Q ₅ , the emitter voltage of the transistor Q ₆ becomes As a result, transistors Q ₆ and Q ₅ become non-conductive.

Then, due to the above-mentioned trip caused by the overcurrent of the shino breaker, maintenance personnel searched for the fault point, and when the fault recovery was completed and the shiya breaker of the substation was turned on (as of t ₃ in Figure 3). , the output of the variable resistor VR ₂ makes transistors Q ₄ and Q ₂ conductive, which causes the display section 4 to become conductive.
are short-circuited, the electromotive force of the display element is consumed, hydrogen ions adhering to the display electrodes are ionized, and the colored display is erased. That is, the overcurrent display is automatically restored (FIG. 3, 4).

According to the present invention, when an overcurrent is detected through a current transformer attached to a distribution line, the main transistor inserted into the discharge circuit of the capacitor that is normally charged is activated before the substation circuit breaker trips. It is made conductive and maintained, and the display element is colored to indicate an overcurrent due to the discharge pressure of the capacitor, so even if the power supply is stopped due to a circuit breaker trip, It is possible to accurately display the occurrence of overcurrent, and since the display element has a memory function, the overcurrent display can be maintained even when there is no voltage.
This makes it possible to easily find overcurrent distribution lines during inspection and speed up accident recovery. In addition, a transistor is inserted between the terminals of the display element, and the output terminal of a variable resistor connected to the secondary side of the current transformer via a rectifier circuit is connected to the base of the transistor, so that the display element is immediately connected to the power supply from the distribution line. Since the overcurrent display is reset by shorting the terminals of the The display recovery transistor inserted between the terminals of the display element is configured to conduct only when the main transistor, which is conductive when an overcurrent occurs, is nonconductive, so that the overcurrent display is not displayed. There is no interruption at all, and operations can be performed that correspond to the maintenance and operation of power distribution lines. In addition, since the configuration is stationary, it not only responds quickly but also consumes little power and can be made smaller and lighter, allowing it to be freely installed directly at any location on the distribution line. It has many advantages, such as being easy to install.

[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. FIG. 3 is a time chart showing the relationship between the overcurrent display in FIG. 1 and the operation of the shroud breaker. 1: Distribution line, 2: Current detection section, 3: Control section,
4: Display section, C ₁ : Display capacitor, Q ₂ : Transistor for display recovery, Q ₁ : Main transistor,
VR ₁ : Variable resistor for overcurrent detection, VR ₂ : Variable resistor for constant use.

Claims (1)

[Claims] 1 A current transformer divided into two parts is removably sandwiched and connected to the distribution line from both sides, and a voltage nonlinear element and a variable resistor for overcurrent detection are connected to the secondary side of the current transformer via a rectifier circuit. A circuit in which these are connected in series, a display capacitor, and a constant variable resistor are connected in parallel.
A display element is connected between the terminals of the capacitor through a PNP type main transistor, and a display recovery transistor whose base is connected to the output terminal of the constant variable resistor is inserted between the terminals of the display element. The collector of a transistor made conductive by the output of the variable resistor for overcurrent detection is connected to the base of the transistor for display recovery, and the output terminal of the variable resistor for overcurrent detection has a latch function. A distribution line overcurrent indicating device connected to the base of the main transistor via a switching circuit.