JPH0643202A - Distribution line accident point survey system - Google Patents

Abstract

PURPOSE:To easily survey a grounding accident point in a short time. CONSTITUTION:When a survey signal is fed to a distribution line after a grounding fault occurs on the distribution line and the circuit breaker of a transformer station is tripped, a survey signal detecting circuit (q) detects the survey signal via a current detector and outputs a detection signal. A display switching circuit (epsilon) is turned on based on the detection signal from the survey signal detecting circuit (q), and it outputs the display drive current to display an accident on an indicator ID. A return driving circuit T outputs a display return signal to return the normal display of the indicator ID to the indicator ID after the accident is displayed on the indicator ID, and the indicator ID is returned to the normal display. To survey an accident point, a worker moves the detection position having the normal display in sequence along the distribution line from the survey signal feed position to survey the indicator ID displaying an accident, and a grounding fault point is judged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention displays a short-circuit when a short-circuit current flows in a distribution line, and when a ground fault occurs in the distribution line, it detects the ground fault point in the distribution line. The present invention relates to a distribution line fault point search system using a signal injection type short circuit / ground fault detection device that displays a ground fault based on a search signal injected from a search signal injection device into a distribution line. .

[0002]

2. Description of the Related Art Conventionally, when a ground fault occurs in a distribution line, the substation breaker is first opened and then the substation is shut off from the viewpoints of early detection of an accident section, separation of a failure section and early transmission of a sound section. The substation circuit breakers are re-closed when the faulty section is reached by re-closing the equipment and sequentially turning on the power from the divisional switches on the power supply side to re-transmit power to the healthy section. And
When the circuit breaker of the substation is reclosed again, the section switch that divides the ground fault section is locked in an open state, only the ground fault section is separated, and the power is retransmitted only in the healthy section. Searching for a faulty fault section. When a ground fault fault section can be searched, the ground fault point is detected by repeatedly executing the insulation resistance measurement of the related distribution equipment provided on each utility pole in the fault section.

[0003]

As described above, in the related art, after the ground fault fault section is known, the related power distribution equipment arranged on the utility pole or the like existing in the ground fault fault section is sequentially subjected to the insulation resistance measurement for each utility pole. However, there is a problem in that it takes a lot of time, and there is a drawback that it takes time to detect the ground fault. In order to solve the above problems, Japanese Patent Publication No. 53-26293 discloses a receiver with an antenna in which a high voltage pulse is applied to a distribution line and a pulse current flowing through the distribution line is searched for a ground fault point. Have been proposed for detection.

However, this antenna is composed of a penetrable current transformer that can be divided, and since the antenna was attached to the distribution line at the moving point and detection was performed by the receiver, it was detected at the next detection point. When moving, there was a problem that the antenna had to be removed. For this reason, the traveling time for searching inevitably requires the time for attaching / detaching the antenna to / from the distribution line, and there is a problem that it takes time to search for the accident point.

The present invention solves the above problems and makes it possible to easily search for an accident point by shortening the exploration time, and at the same time, when a short-circuit accident and a ground fault accident occur, a common display device is used. The purpose is to provide a distribution line accident point detection system that can display information.

[0006]

The signal injection type short-circuit / ground fault detector of the present invention detects a short-circuit current through a current detector when a short-circuit current flows through a distribution line and outputs a short-circuit current detection signal. And a short-circuit current output by the short-circuit detection circuit that outputs a detection signal when the search signal injected into the distribution line at the time of a ground fault is detected via the current detector. ON operation based on the detection signal or the detection signal output by the search signal detection circuit,
A display switching circuit that outputs a display drive current and causes a display to display an accident, and a return drive circuit that outputs a display return signal to the display to cause a normal display return after the display of the accident is displayed. The gist of the invention is that a signal injection type short-circuit / ground fault detection device including a control circuit integrally provided with is always attached to a detection location such as a utility pole.

[0007]

With the above construction, when a short-circuit current flows through the distribution line, the short-circuit detection circuit detects the short-circuit current via the current detector and outputs the short-circuit current detection signal. Then, the display switching circuit is turned on based on the short-circuit current detection signal, outputs the display drive current, and causes the display to display an accident.

Further, when a search signal is injected into the distribution line when a ground fault occurs in the distribution line and the circuit breaker of the substation is tripped, the search signal detection circuit causes the search signal detection circuit to detect the search signal. To detect and output a detection signal. The display switching circuit is turned on based on the detection signal from the search signal detection circuit, outputs the display drive current, and causes the display to display an accident.

Then, the return drive circuit outputs a display return signal for returning the steady display of the display unit to the display unit after the display unit displays the accident, and returns the display unit to the steady display. . Therefore, when exploring the accident point, the worker moves in sequence from the search signal injection point to the detection point where the steady display is performed along the distribution line, and searches for the indicator that displays the accident indication. The ground fault point can be identified.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment embodying the present invention will now be described with reference to FIG.
~ It demonstrates according to FIG. First, an outline of a signal injection type short-circuit / ground fault detection device H used in this system and attached for each phase will be described with reference to FIGS. 1 to 9. As shown in FIG. The device H receives a current detector 101 that detects a short-circuit current and a search signal, and a control circuit 102 that inputs various signals detected by the current detector 101 and outputs a display drive current and a return drive current based on the signals. And a display ID for returning from the steady display to the fault display and from the fault display to the steady display by the drive current and the return drive current from the control circuit 102. (Current detector 101) The current detector 101 is composed of first and second current transformers CT1 and CT2, and outputs a transformer current from the secondary side of the distribution line when a short-circuit current and a search signal flow. To do. (Control circuit 102) The control circuit 102 is roughly classified into a distribution line L.
The short-circuit detection unit that detects the short-circuit current flowing in the output and outputs the display drive current, and displays the display ID in a short-circuit, and the search signal injected into the distribution line when the circuit breaker of the substation trips at the time of a ground fault. A search signal detection unit Y that detects through the first current transformer CT1, outputs a display drive current, and drives the display ID to be displayed, and a search signal detector Y that displays the display ID and then displays the display ID. It includes a return drive circuit T that outputs a return drive current for performing display return to the display device ID. (Short-Circuit Detection Section) Explaining from the short-circuit detection section, as shown in FIG. 4, a choke coil 2, 3 is provided between both terminals P1, P2 connected to the first current transformer CT1 to form a rectifier circuit. The full-wave rectifier 4 is connected. A surge absorber 5 as a surge absorbing circuit is connected between the terminals P1 and P2.

A smoothing capacitor C18 and a series circuit of a b-contact RYb of a reset relay RY2, a resistor R2, a zener diode ZD1 and a resistor R6, which will be described later, are connected in parallel between the plus and minus terminals of the full-wave rectifier 4. ing. A series circuit of a resistor R1 and a diode array Da1 is connected between the negative terminal of the b-contact RYb and the negative terminal of the full-wave rectifier 4.

The smoothing capacitor C18, the resistor R1 and the diode array Da1 constitute a voltage detecting circuit h shown in FIG. In addition, b of the reset relay RY2
A resistor R40 and a capacitor C30 are provided on both terminals of the contact RYb.
An open / close surge absorbing circuit a composed of a series circuit of is connected in parallel.

Further, as shown in FIG. 4, a change-over switch S is provided between the negative terminal of the resistor R2 and the negative terminal of the full-wave rectifier 4, and a parallel circuit of a resistor R4 and a resistor R5 having different resistance values is connected in series. The circuit is connected. By switching and connecting the changeover switch S to the side of the resistor R4 or the resistor R5, this short-circuit / ground fault detection device H can be attached to the distribution line L through which different steady load currents flow. .

The Zener diode ZD1 breaks down by the full-wave rectified signal by the full-wave rectifier 4 when the short-circuit current of a predetermined value or more flows in the distribution line L and the transformation current output from the first current transformer CT1 is broken down. It is supposed to do. The AND circuit 6 is connected to the positive terminal of the resistor R6, and when the Zener diode ZD1 is pulled down, the voltage of the resistor R6 corresponding to the logical value 1 is applied to the input terminal of the AND circuit 6. In addition,
The capacitor C2 connected in parallel to both terminals of the resistor R6 is for noise prevention.

A NAND circuit 7 is connected to the positive terminal side of the diode array Da1. Then, when the circuit breaker of the substation trips due to a short circuit, a ground fault or the like on the distribution line L, the voltage between the diode arrays Da1 corresponding to the logical value 0 is input to the input terminal of the NAND circuit 7 (that is, no voltage).
Is applied. That is, the NAND circuit 7
When the logical value 0 is input, outputs a signal corresponding to the logical value 1. The capacitor C1 connected in parallel to both terminals between the diode array Da1 is for noise prevention.

A series circuit of a collector / emitter of a switching transistor Tr1 and a resistor R33 is connected between an output terminal P3 (plus terminal) of a power supply circuit Z described later and a minus terminal of the full-wave rectifier 4, and both ends of the resistor R33 are connected. A capacitor C19 is connected in parallel to the child.

As shown in FIG. 4, the NAND circuit 7, the resistor R3, and the switching transistor Tr1 constitute a no-voltage discrimination switching circuit j in FIG. 2, and the capacitor C19 and the resistor R33 form a signal memory circuit k. It is configured.

In the series circuit of the switching transistor Tr1 and the resistor R33, a diode D9 and a charging resistor R3 are provided.
4 and a series circuit of a capacitor C20 serving as a relay driving power source n are connected in parallel to constantly charge the capacitor C20.

A series circuit of a thyristor SCR4 and a set relay RY1 is connected in parallel between both terminals of the capacitor C20. When excited, the set relay RY1 opens the b-contact RYb and closes the a-contact RYa of the search signal detection unit Y described later. The thyristor SCR4 and the set relay RY1 constitute a relay drive circuit m. Further, the positive terminal of the capacitor C19 is connected to the gate terminal of the thyristor SCR4, and the anode terminal is connected to one input terminal of the AND circuit 8 as a gate circuit. The output terminal of the NAND circuit 7 is connected to the base terminal of the switching transistor Tr1 via a resistor R3.

Therefore, when the NAND circuit 7 applies a signal corresponding to the logical value 1 to the base terminal of the switching transistor Tr1, the switching transistor Tr1 becomes conductive. When the switching transistor Tr1 becomes conductive, the capacitor C19
From the signal memory circuit k of the resistor R33 to the thyristor SC
A voltage is applied to the gate terminal of R4. Then, the thyristor SCR4 becomes conductive, the electric charge of the capacitor C20 is discharged, the set relay RY1 is excited, and a signal corresponding to the logical value 1 (no-voltage detection signal) is output to one input terminal of the AND circuit 8. It is supposed to do.

A series circuit of a collector / emitter of a switching transistor Tr2 and a resistor R8 is connected between an output terminal P3 (plus terminal) of a power supply circuit Z described later and a minus terminal of the full-wave rectifier 4. The output terminal of the AND circuit 6 is connected to the base terminal of the switching transistor Tr2 via a resistor R7. Therefore,
When the AND circuit 6 applies a signal corresponding to the logical value 1 to the base terminal of the switching transistor Tr2, the switching transistor Tr2 is turned on (conducted).

Zener diode ZD1 and resistor R
6, the capacitor C2, the AND circuit 6, the resistor R7, and the switching transistor Tr2 constitute the current determination switching circuit b in FIG.

A diode D is provided between both terminals of the resistor R8.
1. A series circuit of a resistor R9 is connected, and a capacitor C3 is connected in parallel to both terminals of the resistor R9. Figure 4
The other input terminal of the AND circuit 8 is connected to the positive terminal of the resistor R9 as shown in FIG. And
When the switching transistor Tr2 is turned on (conducted), the voltage of the resistor R8 is applied to the CR circuit of the capacitor C3 and the resistor R9 via the diode D1.
The CR circuit applies a voltage (short-circuit current detection signal) corresponding to the logical value 1 to the other input terminal of the AND circuit 8 for a certain period of time according to the time constant. The capacitor C3 and the resistor R9
The above constitutes a signal memory circuit d as a short circuit current detection signal delay circuit shown in FIG. That is, the short-circuit current detection memory is obtained by the time constant of the signal memory circuit d of the capacitor C3 and the resistor R9.

Further, the AND circuit 8 has one input terminal to which the voltage (short-circuit current detection signal) corresponding to the logical value 1 is applied for a certain time by the time constant of the capacitor C3 and the resistance R9 of the CR circuit to the other input terminal. When a signal (non-voltage detection signal) corresponding to the logical value 1 is input to the input terminal, a voltage (switch signal) corresponding to the logical value 1 is applied from the output terminal.

As shown in FIG. 2, the surge absorbing circuit 5,
The rectifier circuit 4, the current discrimination switching circuit b, the signal memory circuit d, the voltage detection circuit h, the no-voltage discrimination switching circuit j, the signal memory circuit k, the relay drive circuit m, the relay drive power supply n, and the like constitute a short circuit detection circuit X. ing.

As shown in FIG. 4, the output terminal P of the power supply circuit Z
A series circuit of the collector / emitter of the switching transistor Tr3 and the resistor R11 is connected between 3 (plus terminal) and the minus terminal of the full-wave rectifier 4. A capacitor C10 is connected in parallel between both terminals of the resistor R11. And the switching transistor T
The output terminal of the AND circuit 8 is connected to the base terminal of r3 via a resistor R10.

A series circuit of a diode D3, a charging resistor R12, and a capacitor C4 as a driving power source is connected between the output terminal P3 (plus terminal) of the power supply circuit Z described later and the negative terminal of the full-wave rectifier 6, and is always a capacitor. It is designed to charge C4. A display driving power supply charging circuit e shown in FIG. 2 is configured by a series circuit of the diode D3, the charging resistor R12, and the capacitor C4 as a driving power supply.

A series circuit of a thyristor SCR1 as a display switching circuit f and a diode D4 is connected between the positive terminal of the capacitor C4 and the set terminal 14 of the display ID shown in FIG. 4, and the negative terminal of the capacitor C4 is shown in FIG. 5 is connected to the common terminal 13 of the display ID. Then, the switching transistor Tr3
The emitter terminal of is connected to the gate terminal of thyristor SCR1.

Therefore, when a signal corresponding to the logical value 1 is applied from the AND circuit 8 to the base terminal of the switching transistor Tr3, the switching transistor Tr3 is turned on (conducted), and the resistor R11 and the capacitor C10 are connected. Apply voltage. As a result, the thyristor SCR1 is connected to the resistor R11 and the capacitor C10.
A voltage (switch signal) is applied to the gate terminal of the thyristor SCR1 to make it conductive. Then, due to the conduction of the thyristor SCR1, the capacitor C4
Are discharged, and a short-circuit display drive current is output to the display ID.

As shown in FIG. 5, a series circuit of a capacitor C11 and a resistor R24 forming a differentiating circuit is connected between the minus terminal of the diode D4 and the minus terminal 4 of the full-wave rectifier 4, and the plus terminal of the resistor R24. Is connected to the IC 23 of the time limit circuit T described later. And
Due to the conduction of the thyristor SCR1, the capacitor C4
When the display drive current is output to the display ID, the clear control signal is sent from the voltage dividing point of the differentiation circuit of the capacitor C11 and the resistor R24 to the IC2 of the time circuit T.
It is designed to output to 3. The capacitor C11
And the resistor R24 form a voltage amplifier circuit g (see FIG. 2).

Further, as shown in FIG. 5, between the minus terminal of the diode D4 and the minus terminal of the full-wave rectifier 4, a capacitor C12 and a resistor R25 which form a differentiating circuit v.
Is connected in series, and the positive terminal of the resistor R25 is connected to the gate terminal of the thyristor SCR2 of the search signal detecting section Y described later.

The conduction of the thyristor SCR1 discharges the electric charge of the capacitor C4, and the display I
When the display drive current is output to D, the gate trigger voltage is applied to the gate terminal of the thyristor SCR2 from the voltage dividing point of the differentiation circuit v of the capacitor C12 and the resistor R25. (Display ID) Here, the display ID will be described in detail with reference to FIGS.

The display ID is composed of a plurality of magnetic reversal displays. In FIG. 8A and FIG. 8B, one magnetic reversal display has a disk 1 whose both ends are magnetized to have N and S poles.
0 is rotatably supported around a rotating shaft 11, and a round bar-shaped stator 12 has a magnetic pole portion 12a corresponding to the S pole of the disk 10 and a magnetic pole portion 12 corresponding to the N pole of the disk 10.
b is formed. The stator 12 is preferably made of a material having a small coercive force.
Between the magnetic pole portions 12a, 12b, the magnetic pole portions 12a, 1
A drive coil 15 having both ends connected to the common terminal 13 and the set terminal 14 is wound so that 2b is magnetized to have the same polarity with respect to the magnetic poles at both ends of the disk 10 in the state of FIG. 8A.

Further, between the magnetic pole portions 12a and 12b adjacent to the drive coil 15, the magnetic pole portions 12a and 12b are in the state of FIG.
A return drive coil 17 connected to the common terminal 13 and the reset terminal 16 so as to be magnetized in the same polarity is wound. Marks of different colors are displayed on the front surface 10a and the back surface 10b of the disk 10 (in this embodiment, the front surface 10a is black and the back surface 10b is red). Then, the drive coil 15 and the return drive coil 1 of each magnetic reversal display
7 are connected in parallel with each other (see FIG. 7).

Therefore, when a display drive current flows to the display ID through the set terminal 14, each drive coil 15 is excited, and the magnetic pole portion 12a becomes the S pole as shown in FIG. 8B.
The magnetic pole portion 12b is magnetized to the N pole, and the N pole of each disk 10 is the magnetic pole portion 12a (S pole) and the S pole thereof is the magnetic pole portion 12.
The disc 10 is rotated reversely so as to face b (N pole), and the marks provided on the back surface 10b of each disk 10 are simultaneously displayed to the outside (short-circuited display) as shown in FIG. 9B.

On the contrary, the reset terminal 16 is added to the display ID.
When a return drive current flows through the
7 is excited, the magnetic pole portion 12a is magnetized to the N pole and the magnetic pole portion 12b is magnetized to the S pole as shown in FIG.
0 is inverted and rotated so that its N pole faces the magnetic pole portion 12a (N pole) and its S pole faces the magnetic pole portion 12b (S pole), and a mark attached to the surface 10a of each disk 10 is shown in FIG. (A)
As shown in, it is constantly displayed to the outside. (Search signal detecting unit Y) The search signal detecting unit Y will be described. Between the plus and minus terminals of the full-wave rectifier 4 shown in FIG.
A series circuit of a contact RYa and a smoothing capacitor C5 is connected. A series circuit of a Zener diode ZD2 and a diode array Da2 is connected in parallel between both terminals of the smoothing capacitor C5. The reset relay RY1
A-contact RYa has a resistor R41 and a capacitor C on both terminals.
The switching surge absorbing circuit γ shown in FIG. 3, which is composed of a series circuit with the circuit 31, is connected in parallel.

The Zener diode ZD2 is a distribution line L.
The first current transformer C based on the normal load current flowing in
The transformed current output from T1 is broken down by the signal that is full-wave rectified by the full-wave rectifier 4. An AND circuit 20 is connected to the positive terminal of the diode array Da2, and the Zener diode ZD2 is connected.
When is broken down, the voltage of the diode array Da2 corresponding to the logical value 1 is applied to the input terminal of the AND circuit 20.

A series circuit of a collector / emitter of a switching transistor Tr4 and a resistor R14 is connected between an output terminal P3 (plus terminal) of a power supply circuit Z described later and a minus terminal of the full-wave rectifier 4, and both ends of the resistor R14 are connected. A capacitor C21 is connected in parallel to the child. The output terminal of the AND circuit 20 is connected to the base terminal of the switching transistor Tr4 via a resistor R13. Then, when a signal corresponding to the logical value 1 is applied from the AND circuit 20 to the base terminal of the switching transistor Tr4, the switching transistor Tr4 is
Is turned on.

The Zener diode ZD2, the diode array Da2, the AND circuit 20, the resistor R13 and the switching transistor Tr4 constitute a voltage discriminating circuit p shown in FIG.

As shown in FIG. 5, a diode D5, a charging resistor R15 and a capacitor C6 as a relay driving power source α are provided between the output terminal P3 (plus terminal) of the power supply circuit Z described later and the negative terminal of the full-wave rectifier 4. A series circuit is connected to constantly charge the capacitor C6. A thyristor SC is placed between both terminals of the capacitor C6.
A series circuit of R2 and reset relay RY2 is connected in parallel.

The reset relay RY2 constitutes a relay drive circuit w shown in FIG. When the reset relay RY2 is excited, it closes the b contact RYb of the short-circuit detector X and opens the a contact RYa.
Further, the positive terminal of the capacitor C21 is connected to the gate terminal of the thyristor SCR2.

Therefore, the switching transistor T
When r4 becomes conductive, a voltage is applied from the circuit of the capacitor C21 and the resistor R14 to the gate terminal of the thyristor SCR2. Then, the thyristor SCR2 becomes conductive, the charge of the capacitor C6 is discharged, and the reset relay RY
It is designed to excite 2. Said thyristor SCR
2 forms the switching circuit u shown in FIG.

As shown in FIG. 5, the smoothing capacitor C5
A series circuit of resistors R16 and R17 is connected in parallel to both terminals of. A capacitor C7 is connected in parallel to both terminals of the resistor R17, and an input terminal of an AND circuit 21 is connected to the positive terminal of the capacitor C7. When the a-contact RYa is closed, the logical value 1
Is applied to the input terminal of the AND circuit 21, and the voltage (detection signal) corresponding to the logical value 1 is applied from the output terminal of the AND circuit 21.

The resistor R16, the resistor R17, the capacitor C7, and the AND circuit 21 constitute a search signal detecting circuit q shown in FIG. As shown in FIG. 5, a series circuit of a collector / emitter of a switching transistor Tr5 and a resistor R19 is connected between an output terminal P3 (plus terminal) of a power supply circuit Z described later and a minus terminal of the full-wave rectifier 4 for switching. The output terminal of the AND circuit 21 is connected to the base terminal of the transistor Tr5 via the resistor R18. Then, when a voltage corresponding to the logical value 1 is applied to the base terminal of the switching transistor Tr5, the switching transistor Tr5 becomes conductive.

A series circuit of a collector / emitter of a switching transistor Tr6 and a resistor R21 is connected between an output terminal P3 (positive terminal) of a power supply circuit Z and a negative terminal of the full-wave rectifier 4, which will be described later. The plus terminal of the resistor R19 is connected to the base terminal via the resistor R20. A capacitor C8 is connected between the negative terminal of the resistor R19 and the negative terminal of the resistor R20.

Similarly, an output terminal P3 of the power supply circuit Z described later is also provided.
A series circuit of the collector / emitter of the switching transistor Tr7 and the resistor R23 is connected between the (plus terminal) and the negative terminal of the full-wave rectifier 4, and the resistor R21 is connected to the base terminal of the switching transistor Tr7 via the resistor R22. The positive terminal of is connected. or,
A capacitor C9 is connected between the negative terminal of the resistor R21 and the negative terminal of the resistor R22.

A capacitor C10 is connected in parallel between both terminals of the resistor R23, and an emitter terminal of the switching transistor Tr7 is connected to a gate terminal of the thyristor SCR1.

The switching transistors Tr5 to T
A delay circuit t (see FIG. 1) shown in FIG. 3 is configured by r7, resistors R19 to R22, a capacitor C8, and a capacitor C9.

Therefore, when a voltage (detection signal) corresponding to a logical value 1 is applied to the base terminal of the switching transistor Tr5 from the output terminal of the AND circuit 21 shown in FIG. 5, the switching transistor Tr5 becomes conductive.
Then, the voltage of the resistor R19 changes to the resistor R20 and the capacitor C.
8 is applied to the circuit, and a voltage is applied from the CR circuit to the base terminal of the switching transistor Tr6. Then, the switching transistor Tr6 becomes conductive, and the voltage of the resistor R21 is similarly applied to the circuit of the resistor R22 and the capacitor C9, and the voltage is applied from the CR circuit to the base terminal of the switching transistor Tr7.

Subsequently, the switching transistor Tr7
Becomes conductive, and a voltage (switch signal) is applied to the gate terminal of the thyristor SCR1 from the differentiating circuit of the resistor R23 and the capacitor C10.

As described above, the thyristor SCR1 is rendered conductive by being delayed for a certain time by the time constant of each CR circuit. That is, the search signal detector Y shown in FIG. 3 is set so that the search signal detection time in the search signal detection circuit q is delayed from the retransmission current detection time in the voltage determination circuit p. Therefore, when the voltage discriminating circuit p detects the retransmitted current immediately after the search signal is injected, the voltage discriminating circuit p operates and the display ID does not malfunction.

As shown in FIG. 5, a series circuit of a capacitor C12 and a resistor R25 forming a differentiating circuit is connected between the negative terminal of the diode D4 and the negative terminal of the full-wave rectifier 4, and the positive terminal of the resistor R25 is It is connected to the gate terminal of the thyristor SCR2. When the thyristor SCR1 is turned on to discharge the electric charge of the capacitor C4 and output the display drive current to the display ID, the gate trigger voltage is changed from the voltage dividing point of the differential circuit of the capacitor C12 and the resistor R25. It is designed to be the gate terminal of SCR2. (Return drive circuit T) Next, the return drive circuit will be described.

As shown in FIG. 5, the IC 23 has a resistor R2.
Oscillation circuit β consisting of 6, capacitor C13 and resistor R27
Are connected, and the IC 23 divides the number of oscillations of the oscillation circuit.

Output terminal P3 of the power supply circuit Z (plus terminal)
A serial circuit of a diode D7, a charging resistor R31, and a capacitor C16 as a driving power source is connected between the terminal of the IC23 and the IC23 so that the capacitor C16 is always charged. A recovery drive power supply charging circuit δ is composed of the diode D7, the charging resistor R31 and the capacitor C16 as a drive power supply. The positive terminal of the capacitor C16 is connected to the reset terminal 16 of the display ID through the series circuit of the thyristor SCR3 and the diode D6, and the negative terminal of the capacitor C16 is connected to the common terminal of the display ID.

Output terminal P3 of power circuit Z (plus terminal)
And a negative terminal of the IC23 through a collector / emitter of a switching transistor Tr8 to a resistor R2.
9 series circuits are connected. A series circuit of a capacitor C15 and a resistor R30 is connected in parallel to both terminals of the resistor R29. The negative terminal of the capacitor C15 is connected to the gate terminal of the thyristor SCR3. A differential circuit is configured by the capacitor C15 and the resistor R30.

The switching transistor T
The output terminal of the IC 23 is a resistor R at the base terminal of r8.
It is connected via 28. The capacitor C14 connected in parallel to both terminals of the resistor R29 is for noise prevention.

The switching transistor Tr8, the capacitor C14, the resistor R29, the resistor R30, the capacitor C15 and the thyristor SCR3 form a switching circuit ε (see FIG. 3).

This IC 23 has a capacitor C11 and a resistor R.
When the clear control signal from the 24 differentiating circuit is input, the division of the oscillation number of the oscillation circuit is cleared and the division of the oscillation number is started. When the IC 23 is divided into a predetermined number, that is, when a predetermined time has passed, the resistance R2
A voltage is applied to the base terminal of the switching transistor Tr8 via 8.

Then, the switching transistor Tr8
Is turned on (conducted), and a voltage is applied to the differentiation circuit of the capacitor C15 and the resistor R30. As a result, a voltage is applied to the gate terminal of the thyristor SCR3 from the differentiating circuit, and the thyristor SCR3 is turned on (conducting). The electric charge of the capacitor C16 is discharged by the conduction of the thyristor SCR3, and a return drive current as a display return signal is output to the display ID. (Power Supply Circuit Z) Next, the power supply circuit Z that serves as a power supply for each circuit constituting the control circuit will be described.

As shown in FIG. 6, the second current transformer CT2
A full-wave rectifier 2 as a rectifier circuit is connected to both terminals P4 and P5 connected to the secondary side of the circuit through choke coils 23 and 25.
6 is connected. A surge absorber 27 as a surge absorbing circuit is connected between the terminals P4 and P5.

A smoothing capacitor C17 and a diode array Da are provided between the plus and minus terminals of the full wave rectifier 26.
3 and a series circuit of the transistor Tr9, the diode D8, and the rechargeable battery B are connected in parallel. A resistor R32 is connected between the collector terminal and the base terminal of the transistor Tr.

The diode array Da3 constitutes the first constant voltage circuit ζ shown in FIG.
A second constant voltage circuit η is formed by 32 and the transistor Tr9.

This power supply circuit Z includes a second current transformer CT2.
After the full-wave rectification of the load current detected by the full-wave rectifier 26, the forward voltage across the diode array Da3 is further made constant by the transistor Tr9, etc.
Is supposed to charge. Then, when a steady load current is flowing in the distribution line L, the backup battery B is not consumed, and the drive current is supplied to each of the parts by the load current. When the circuit breaker at the substation trips and the load current no longer flows through the distribution line L, the battery B for back-up supplies the required drive current to each part from the output terminal P3.

The operation of the control circuit of the short circuit / ground fault detection device H configured as described above will be described. When a steady load current is flowing in the distribution line L, in the power supply circuit Z, a small amount of transformation current is output from the second current transformer CT2, and the transformation current is full-wave rectified by the full-wave rectifier 26. The battery B of the power supply circuit Z is charged. Further, the power supply circuit Z charges the capacitors C4, C6, C16 and C20 as the drive power supplies for the circuits X, Y and Z.

At this time, in the short-circuit detecting section, the b contact RYb shown in FIG. 4 is closed, and a slight amount of the transformation current is output from the first current transformer CT1 as well. The transformation current is the full-wave rectifier 4 After being full-wave rectified at, most of it is consumed by the resistor R1 and the diode array Da1. At this time, in the search signal detection unit Y, the a contact R
Ya is open circuit.

In this state, the circuit breaker of the substation has not tripped, and the thyristors SCR1 to SCR1 of each circuit are not tripped.
Since the anode partial pressure and the gate voltage applied to the thyristor SCR4 are minute (below the gate trigger voltage), the thyristors SCR1 to SCR4 are in the off state.

In this state, for example, the first current transformer CT1
When a short-circuit current capable of tripping the circuit breaker of the substation flows through the distribution line L to which is attached, the first current transformer CT1 outputs the transformation current to the short-circuit detector. Then, this transformed current is full-wave rectified by the full-wave rectifier 4 to break down the Zener diode ZD1. Then, the voltage of the resistor R6 corresponding to the logical value 1 is applied to the input terminal of the AND circuit 6, and the AND circuit 6 applies the signal corresponding to the logical value 1 to the base terminal of the switching transistor Tr2. As a result, the switching transistor Tr2 turns on (conducts).

Then, the voltage of the resistor R8 changes to the diode D1.
Is applied to the CR circuit of the capacitor C3 and the resistor R9 via the time constant, and the CR circuit causes the other input terminal of the AND circuit 8 as a gate circuit to output the voltage corresponding to the logical value 1 for a certain time (short circuit current detection). Signal) is applied. On the other hand, the circuit breaker of the substation trips due to the short-circuit current,
As a result, when the distribution line L has no voltage, the short circuit detection circuit X detects it via the first current transformer CT1. That is, the voltage (that is, no voltage) between the diode arrays Da1 corresponding to the logical value 0 is applied to the input terminal of the NAND circuit 7.

Then, the NAND circuit 7 applies a signal corresponding to the logical value 1 to the base terminal of the switching transistor Tr1 to cause the switching transistor Tr1 to be switched.
1 conducts. When the switching transistor Tr1 is turned on, the capacitor C19 and the resistor R33 are connected.
The gate voltage is applied to the gate terminal of the thyristor SCR4 from the differentiating circuit of.

Then, the thyristor SCR4 becomes conductive, the charge of the capacitor C20 is discharged, and the set relay RY1.
And a signal corresponding to a logical value 1 (no-voltage detection signal) is output to one input terminal of the AND circuit 8. By exciting the set relay RY1, the b contact RYb of the short circuit detection circuit X is opened and the a contact RYa of the search signal detection unit Y is closed. At this time, however, the distribution line L is in a non-voltage state, so the search signal is not detected. The detector Y does not operate.

As described above, the AND circuit 8 has a voltage (short-circuit current detection signal) corresponding to the logical value 1 for a certain period of time depending on the time constant of the CR circuit of the capacitor C3 and the resistor R9 at the other input terminal.
When a voltage (non-voltage detection signal) corresponding to the logical value 1 is input to one of the input terminals while the voltage is applied, the voltage (switch signal) corresponding to the logical value 1 is applied from the output terminal.

When a signal corresponding to a logical value 1 is applied from the AND circuit 8 to the base terminal of the switching transistor Tr3, the switching transistor Tr3 is applied.
Is turned on (conducted), and a voltage is applied to the capacitor C10 and the resistor R11. As a result, the capacitor C10
A voltage (switch signal) is applied to the gate terminal of the thyristor SCR1 from the differentiating circuit of the resistor R23 to make the thyristor SCR1 conductive.

Due to the conduction of this thyristor SCR1, the charged electric charge of the capacitor C4 is discharged, and the display drive current is output to the display ID shown in FIG. This display drive current causes the display ID to display a short circuit. At the same time that the display drive current is output to the display device ID, a clear control signal is output to the IC 23 of the time limit circuit T from the voltage dividing point of the differentiation circuit of the capacitor C11 and the resistor R24. Further, the gate trigger voltage is applied to the gate terminal of the thyristor SCR2 from the voltage dividing point of the differentiation circuit of the capacitor C12 and the resistor R25. Then, the thyristor SCR2 is turned on, the charge of the capacitor C6 is discharged, and the reset relay RY2 is excited, so that the b contact RYb of the short-circuit detection circuit X is closed and the a contact RYa is opened. That is, the short circuit detection circuit X is in a standby state.

On the other hand, when the clear control signal is input, the IC 23 clears the division of the oscillation number of the oscillation circuit β and starts the division of the oscillation number again. Then, the IC 23 applies a voltage to the base terminal of the switching transistor Tr8 via the resistor R28 when the IC 23 is divided a predetermined number of times, that is, when a predetermined time elapses.

Then, the switching transistor Tr8
Is turned on (conducted), and a voltage is applied to the differentiation circuit of the capacitor C15 and the resistor R30. As a result, a voltage is applied from the differentiating circuit to the gate terminal of the thyristor SCR3 to turn on (conduct) the thyristor SCR3. Due to the conduction of the thyristor SCR3, the charge of the capacitor C16 is discharged, and a return drive current as a display return signal is output to the display ID after a fixed time.

The display drive ID is reset by this return drive current, and the display returns to the steady display state. Next, a case where a ground fault occurs in the distribution line L will be described.

When a ground fault occurs in the distribution line L and the circuit breaker at the substation trips, the distribution line L becomes a no-voltage as in the case where the short-circuit current flows and the circuit breaker at the substation trips. Then, the NAND circuit 7 of the short-circuit detection circuit X makes the switching transistor Tr1 conductive, and when the switching transistor Tr1 becomes conductive, a gate voltage is applied from the capacitor C19 / resistor R33 to the gate terminal of the thyristor SCR4.

Then, the thyristor SCR4 becomes conductive, the charge of the capacitor C20 is discharged, and the set relay RY1 is discharged.
To excite. Due to the excitation of the set relay RY1, the b contact RYb of the short circuit detection circuit X is opened and the a contact of the search signal detection unit Y is closed RYa. And
When the search signal is injected into the distribution line L in this state, the search signal detection unit Y shown in FIG. 5 detects the search signal via the first current transformer CT1.

That is, when the a-contact RYa is closed, the voltage of the resistor R17 corresponding to the logical value 1 is applied to the input terminal of the AND circuit 21, and the AND circuit 21 is connected.
A voltage corresponding to the logical value 1 is applied to the base terminal of the switching transistor Tr5 from the output terminal of the. Then, the switching transistor Tr5 is turned on, the voltage of the resistor R19 is applied to the circuit of the resistor R20 and the capacitor C8, and the switching circuit T5 is switched from the CR circuit.
A voltage is applied to the base terminal of r6. Then, the switching transistor Tr6 becomes conductive, and the voltage of the resistor R21 is applied to the circuit of the resistor R22 and the capacitor C9 in the same manner.
A voltage is applied from the CR circuit to the base terminal of the switching transistor Tr7.

Then, the switching transistor Tr7
Are conducted, and a voltage (switch signal) is applied to the gate terminal of the thyristor SCR1 from the differentiation circuit of the resistor R23 and the capacitor C10. In this way, the voltage (switch signal) is applied to the gate terminal of the thyristor SCR1 with a certain time delay due to the time constant of each CR circuit.

When the thyristor SCR1 is turned on, the electric charge of the capacitor C4 is discharged and the display ID
The display drive current is output to. The display drive current causes the display ID to display an accident. Also, the display ID
At the same time that the display drive current is output to the capacitor C11
And a clear control signal from the voltage dividing point of the differentiation circuit of the resistor R24 to the IC23 of the return drive circuit T. Further, the gate trigger voltage is applied to the gate terminal of the thyristor SCR2 from the voltage dividing point of the differentiation circuit of the capacitor C12 and the resistor R25.

Then, as in the case where the short-circuit current flows through the distribution line L, the thyristor SCR2 is turned on, the charge of the capacitor C6 is discharged, and the reset relay RY2 is excited, whereby the b-contact RYb of the short-circuit detection circuit X is excited. Is closed and the a-contact RYa is opened. That is, the short circuit detection circuit X is in a standby state.

On the other hand, the recovery drive circuit T operates in the same manner as when the short circuit current flows, and outputs the recovery drive current to the display device ID after a predetermined time after a predetermined time. The display drive ID is reset by the return drive current, and the display is returned to the steady display state.

When a ground fault occurs in the distribution line L, the circuit breaker of the substation trips, and the search signal is not detected thereafter, and the re-transmission of the substation succeeds, the search signal detection unit Y is detected. Re-power transmission is performed in a state where the a-contact RYa is closed. That is, the substation retransmits power while the a-contact RYa of the search signal detection unit Y is closed, and a normal load current flows through the distribution line L at this time.

Then, the Zener diode ZD2 of the voltage discriminating circuit p in the search signal detecting section Y breaks down and the voltage of the diode array Da2 corresponding to the logical value 1 is applied to the input terminal of the AND circuit 20. Then, the AND circuit 20 applies a signal corresponding to the logical value 1 to the base terminal of the switching transistor Tr4, and the switching transistor Tr4 is turned on (conducted).

When the switching transistor Tr4 is turned on, a voltage is applied from the circuit of the capacitor C21 and the resistor R14 to the gate terminal of the thyristor SCR2. Then, the thyristor SCR2 becomes conductive, the charge of the capacitor C6 is discharged, and the reset relay RY2 is excited.

By exciting the reset relay RY2,
The b contact RYb of the short circuit detection circuit X is closed and a
The contact RYa is opened, and the short-circuit / ground-fault display device is in a state of waiting for an accident detection of a short-circuit current.

As described above, in this embodiment, since the forward voltage between the diode arrays Da2 detected by the first current transformer CT1 is made constant and the battery b is charged, the internal power source type is used. Is unnecessary.

Further, since the short-circuit detection circuit X detects no voltage depending on the presence / absence of the forward voltage across the diode array Da1, it is not necessary to detect the potential of PT or the ground, and therefore the insulation performance may be a concern. There is no. Further, since the short-circuit current detection memory in the short-circuit detection circuit X is obtained by the time constant of the memory circuit of the capacitor C3 and the resistor R9, the memory time can be effectively taken without loss.

Further, the display ID is driven by the discharge of the capacitor C4, and the set relay RY1 and the reset relay RY2 are operated by the discharge of the capacitors C20 and C6.
It consumes almost no current for driving. Further, in this embodiment, since the display ID electrically connects the magnetic reversal display in parallel, the circuit impedance is lowered,
The discharge efficiency of the capacitor C4 used as the drive power source and the capacitor C16 of the recovery drive circuit T is improved, and the display drive and the recovery display drive are ensured.

Further, the drive coil 15 of the display ID is connected in parallel to the series circuit of the capacitor C11 and the resistor R24 so as not to hinder the display drive, and the clear control signal is sent from the CR voltage dividing point to the IC23. Since the output is output, the time period from the display driving of the display to the reset is accurate. Further, since the control circuit uses the IC as described above, there is an advantage that the current consumption of the control circuit can be small.

Next, a ground fault point detection system using the signal injection type short circuit / ground fault detection device will be described with reference to FIGS. In the figure, 30 is a power transmission line, 31 is a circuit breaker (hereinafter, referred to as CB) in a substation, a distribution line L is connected to the power transmission line 1 via the CB 31, and each phase is as shown in FIG. Represented by La, Lb, and Lc.

Reference numeral 32 is a zero-phase current transformer (hereinafter, referred to as ZCT) of the substation provided on the closest load side of the CB 31, and 33 is a grounding transformer (hereinafter, referred to as GPT) provided in the transmission line 1. The both lines 32 and 33 detect a one-line ground fault that occurs in the distribution line L, operate the directional ground fault relay 34 to trip the CB 31, and disconnect the distribution line L from the transmission line 30.

A large number of section switches SS are arranged on the distribution line L, and a large number of sections An are provided by the section switches SS.
(N = 1, 2, 3, ...) Are classified. This section switch SS is a conventionally known section switch, and when a ground fault occurs in a certain section as shown in FIG. 12, (T1
Substation CB31 selectively cuts off the faulty line (T2
When the fault line has no voltage, each section switch SS opens the circuit after the delay open time Z (at T6). Then, when a voltage is applied by reclosing the CB31 (at T3), the first partition switch SS adjacent to the CB31 is closed after X hours (at T7), and the load side partition switches are sequentially connected. When a voltage is applied to SS, the circuits are similarly closed after X hours.

In this way, power is sequentially supplied from the partition switch SS on the power supply side to re-transmit power to a healthy section, and when the ground fault section is reached, the substation CB31 is re-cut off (at T4). When the CB31 of the substation is closed again (at T5), the partition switch SS that partitions the ground fault section is locked in an open state so that only the ground fault section is separated. There is.

Reference numeral 35 denotes ZCT3 for the distribution line L of each phase.
A search signal injection device coupled on the nearest load side of 2, which is grounded (see FIG. 10). The search signal output from the search signal injection device 35 is a full-wave current waveform (see FIG.
3)). The reason for using the full-wave current waveform as the search signal is that the current transformer CT of the short circuit / ground fault detector H is used.
This is because 1 and CT2 can detect both the short circuit current and the search signal. This is also because the loss current due to the distribution line stray capacitance is small (only the leakage current due to the CR time constant) when the search signal of this full-wave current waveform is injected into the high-voltage distribution line.

This search signal injection device 35 is installed in the substation CB3.
When 1 is cut off (at T2), a trip signal from CB31 is input, and based on the trip signal, from when CB31 is cut off (at T2) to when the first section switch SS is opened (at T6). The search signals are collectively injected in three phases using the delay open time Z of.

The injection of the search signal is set so as to be completed before the first section switch SS is opened (time from T8 to T9 shown in FIG. 12).
The drive power supply of the search signal injection device 35 is composed of a transformer Tr connected to the power supply side of the CB 31.

As shown in FIG. 10, a plurality of short circuit / ground fault detecting devices H are attached to each phase in each section An of the distribution line L and are arranged at a predetermined distance from each other. In addition,
In FIG. 10, AS is a normally closed switch.

Next, the operation of the system configured as described above will be described. Now, in FIG. 11, it is assumed that a one-line ground fault occurs at the point m of the phase a in the section A3 of the distribution line L (at T1). Incidentally. For convenience of explanation, only the a-phase La of the distribution line L is shown in FIG.

Then, the ZCT 32 of the substation outputs the zero-phase current and the GPT 33 outputs the zero-phase voltage as a ground fault signal, and the relay 34 is disengaged to send a trip signal to the CB31 to open the substation CB31 ( At T2). Then, the search signal injecting device 35 inputs the trip signal from the CB31, and when the sectional switch SS is opened (T6) from when the CB31 is cut off (T2) based on the trip signal.
The search signal is injected into each phase La, Lb, Lc of the distribution line by using the delay open time Z up to (see T shown in FIG. 12).
Time from 8 to T9).

Then, the search signal injection device 35 and the distribution line L
a, a circulating current flows in a closed loop path through the ground fault point m and the search signal injection device 35, and as a result, a detection device disposed between the injection point of the search signal injection device 35 and the ground fault point P, That is, the detection devices H1 and the like in the A1 and A2 sections and the detection devices H2 and H3 in the A3 section are displayed.

On the other hand, for the b and c phases, a closed loop including the ground capacitance of the distribution line L is formed instead of the ground fault point m, but the impedance of this loop is high and the flowing search signal level is low. The detection devices H arranged in the other two phases Lb and Lc remain in the steady display. Further, even if the detection device is attached to the a-phase, the search signal does not reach a certain level or higher, so that the detection device H4 and the like provided on the load side from the ground fault point m remain in the steady display.

In this way, the search signal injection device 35 displays the ground fault on the display device up to the ground fault point m. The search signal is injected before the section switch SS is opened (T9).
End). As described above, after the search signal injection device 35 injects the search signal (that is, after Z time has passed since the substation CB31 was cut off), the sectional switch SS is opened (at T6). Then re-closed CB31 (T3
When the voltage is applied for the first time, the first segment switch SS adjacent to the substation CB31 is closed after X hours (at T7), and the voltage is sequentially applied to the load side segment switch SS. Then, the circuit is closed after X hours.

In this way, the sub-switches SS on the power source side are sequentially turned on to re-transmit power to the healthy section, and when the ground fault section is reached, the substation CB31 is re-cut off (T4).
Time). Then, when the CB31 of the substation is closed again (at T5), the partition switch SS that partitions the ground fault section A3 is locked in an open state, and only the ground fault section A3 is separated, and a sound section. Only the power is retransmitted.

As described above, the ground fault fault section A3 can be detected by the division switch SS being locked in the open state. Therefore, the worker starts from the power supply side toward the load side in the ground fault fault section. To do. Then, if the detection device H in the accident (ground fault) display state is sequentially searched, it is detected from the point where the detection device H3 in the ground fault display, which is one before the detection device H4 that is not displaying the accident, is arranged. Device H4
It is possible to determine that there is a ground fault point m between the points where is arranged.

In searching for the ground fault point m, the branch point α
In the above, the detecting device H5 provided on the branch line on one load side and the detecting device H5 provided on the branch line on the other load side.
3 and the detection device H may proceed along the branch line on the side where the accident (ground fault) is displayed.

The present invention is not limited to the above embodiment, and for example, the first current transformer CT1 and the second current transformer CT1 in which a pair of current transformers are provided in the above embodiment are used.
2 may be configured as a single current transformer as a common current transformer, and may be arbitrarily changed without departing from the spirit of the present invention.

[0109]

As described in detail above, the present invention does not require a grounding transformer and has a simple structure of a short circuit detection circuit, a search signal detection circuit and a time limit circuit. The cost can be reduced, and further,
Since it is configured to operate by the search signal, it is a large practical point that the worker can easily identify the ground fault point without taking time only by making a primary round from the power supply side to the load side in order in the ground fault fault section. There are advantages, and if many short-circuit / ground fault detectors are installed on the distribution line, it will be effective in shortening the time required to search for a fault point, and in the early recovery. It has an excellent effect of being able to display an accident display on a container.

[Brief description of drawings]

FIG. 1 is an electric block circuit diagram of a short-circuit / ground fault detection device according to an embodiment of the invention.

FIG. 2 is an electric block circuit diagram of a short-circuit detection unit of the short-circuit / ground fault detection device.

FIG. 3 is a block circuit diagram of a search signal detection unit and a power supply circuit of the short circuit / ground fault detection device.

FIG. 4 is a circuit diagram of a short-circuit detection unit of the short-circuit / ground fault detection device.

FIG. 5 is a circuit diagram of a search signal detection unit and a return drive circuit of the short circuit / ground fault detection device.

FIG. 6 is a power supply circuit diagram of the short circuit / ground fault detection device.

FIG. 7 is an electric circuit of a display of the short circuit / ground fault detection device.

8A and 8B are schematic diagrams of a display.

9A and 9B are bottom views of the display.

FIG. 10 is a distribution line system diagram.

FIG. 11 is a distribution line diagram for explaining the operation.

FIG. 12 is a time chart.

FIG. 13 is a waveform diagram of a search signal.

[Explanation of symbols]

4 ... Full wave rectifier, 6 ... AND circuit, 7 ... NAND circuit, 8
... AND circuit, 20, 21 ... AND circuit, 23 ... IC,
26 ... Full wave rectifier, d ... Signal memory circuit (short circuit current detection signal delay circuit), H ... Short circuit / ground fault detection device, X ... Short circuit detection circuit, Y ... Search signal detection section, T ... Return drive circuit, ID
... indicator, CT1 ... first current transformer, CT2 ... second current transformer, L ... distribution line.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsunori Aoki No. 1 Kamikomenee, Inuyama City, Aichi Prefecture Takamatsu Denki Seisakusho Co., Ltd. (72) Mitsuharu Kutomi No. 1 Kamikonee, Inuma City, Aichi Takamatsu Corporation Inside the Electric Works

Claims (1)

[Claims] 1. A short-circuit detection circuit which detects a short-circuit current through a current detector when a short-circuit current flows through the distribution line and outputs a short-circuit current detection signal, and a search signal which is injected into the distribution line when a ground fault occurs. Is detected via the current detector, a search signal detection circuit that outputs a detection signal, and a short-circuit current detection signal output by the short-circuit detection circuit or a detection signal output by the search signal detection circuit is turned on. Then, a display switching circuit that outputs a display drive current and displays an accident on the display unit, and a display recovery signal that outputs a display recovery signal for performing steady display recovery after the display on the display unit is displayed. A distribution line fault point detection system characterized in that a signal injection type short-circuit / ground fault detection device including a control circuit integrated with a drive circuit is always attached to a detection location such as a utility pole.