JPH0586127B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention displays a short circuit when a short circuit current flows through the distribution line, and when a ground fault occurs in the distribution line, it displays a short circuit on the distribution line. This relates to a control circuit for a signal injection type short circuit/earth fault detection device that displays a ground fault fault based on a search signal injected into the distribution line from a search signal injection device so as to detect the point of a ground fault that has occurred. be.

(Prior art) Conventionally, when a ground fault occurs in a distribution line, the substation circuit breaker is first opened, and then the substation circuit breaker is At the same time, the sectional switches on the power supply side are sequentially turned on to retransmit power to the healthy section, and when the section reaches the ground fault section, the substation circuit breaker is shut off again. When the circuit breaker of the substation is closed again, the section switch that separates the ground fault fault section is locked in the open state, and only the ground fault fault section is isolated, and power is retransmitted only to the healthy section. , searching for ground fault sections. Once a ground fault fault section has been found, the ground fault point is detected by repeatedly measuring the insulation resistance of related power distribution equipment installed on each utility pole in the fault section.

(Problems to be Solved by the Invention) As mentioned above, in the past, after the ground fault fault section was determined, the insulation resistance of the related power distribution equipment installed on utility poles, etc. existing in the ground fault fault section was sequentially determined for each utility pole. Since the measurement was carried out, there was an operational problem in that it required a lot of time, and there was a drawback that it took a long time to detect the ground fault point.

The present invention solves the above problems, and also provides a control circuit for a signal injection type short circuit/ground fault detection device that is easier to install, has superior insulation performance, and is lower in cost than conventional directional ground fault display devices. It is an object.

(Means for solving the problem) The signal injection type short circuit/ground fault detection device of the present invention has the following features:
When a short-circuit current flows through a distribution line, the short-circuit current is detected via a current detector, and a short-circuit current detection signal is output.If a circuit breaker in a substation trips, the current detector detects the short-circuit current and outputs a short-circuit current detection signal. A short circuit detection circuit that detects the voltage state and outputs a no-voltage detection signal;
A short-circuit current detection signal delay circuit that delays the short-circuit current detection signal, a short-circuit current detection signal delayed by the short-circuit current detection signal delay circuit, and the no-voltage detection signal are both input to output a switch signal. a gate circuit; a search signal detection circuit that outputs a detection signal when a search signal injected into the distribution line at the time of a ground fault is detected via the current detector; and a switch signal outputted by the gate circuit or the search signal. a display switching circuit that turns on based on the detection signal output by the signal detection circuit, outputs a display drive current, and causes the display to indicate an accident;
a time limit circuit that outputs a display return signal to the display to cause the display to return to normal display after a predetermined period of time has elapsed after the display displays an accident; and a power supply circuit that outputs a drive current to each of the circuits. Its gist is that it is composed of the following.

(Function) With the above configuration, when a short circuit current flows through the distribution line, the ground fault detection circuit detects the short circuit current via the current detector and outputs a short circuit current detection signal. Further, the short circuit detection circuit detects the no-voltage state of the distribution line via the current detector when the circuit breaker of the substation is tripped, and outputs a no-voltage detection signal.

The short circuit current detection signal delay circuit delays the short circuit current detection signal, and when the gate circuit receives both the delayed short circuit current detection signal and the no-voltage detection signal, it outputs a switch signal. Then, the display switching circuit is turned on based on the switch signal, outputs a display drive current, and causes the display to indicate an accident.

Furthermore, when a search signal is injected into the distribution line when a ground fault occurs in the distribution line and the circuit breaker at the substation is tripped, the search signal detection circuit receives the search signal via the current detector. Detects and outputs a detection signal. The display switching circuit is turned on based on the detection signal from the search signal detection circuit, outputs a display drive current, and displays an accident on the display.

Then, the timer circuit outputs a display return signal to the display device to cause the display device to return to normal display after a predetermined period of time has passed after the display device displays the accident display, and causes the display device to return to normal display mode. .

(Embodiment) An embodiment embodying the present invention will be described below with reference to FIGS. 1 to 8.

An overview of the signal injection type short circuit/ground fault detection device H installed for each phase is as follows.
The ground fault detection device H includes a current detector that detects a short circuit current and a search signal, and a control circuit that inputs various signals detected by the current detector and outputs a display drive current and a recovery drive current based on the signals. and a display ID that changes from a steady display to an accident display and returns to a steady display from an accident display using a drive current and a return drive current from the same control circuit.

(Current Detector) The current detector is connected to the first and second current transformers.
It consists of CT1 and CT2, and when a short circuit current and a search signal flow through the distribution line, a transformed current is output from its secondary side.

(Control circuit) The control circuit can be roughly divided into two parts: it detects the short-circuit current flowing through the distribution line L, it also detects the no-voltage state of the distribution line when the substation circuit breaker trips, outputs a display drive current, and displays the display a short circuit detection unit that displays an ID as a ground fault, and detects, via the first current transformer CT1, a search signal injected into the distribution line when the circuit breaker of the substation is tripped at the time of a ground fault;
a search signal detection unit Y that outputs a display drive current and drives the display ID; and a return drive that causes the display ID to return to display after a predetermined period of time has passed after the display ID has displayed. Current indicator
It consists of a timer circuit T that outputs to the ID, and a power supply circuit Z that outputs drive current to each of the circuits.

(Short Circuit Detection Section) To explain from the short circuit detection section, a full wave rectifier 4 as a rectifier circuit is connected between both terminals P1 and P2 connected to the first current transformer CT1 via chiyoke coils 2 and 3. ing. Also, both terminals P
1 and P2, a surge absorber 5 as a surge absorption circuit is connected.

Between the positive and negative terminals of the full-wave rectifier 4, a smoothing capacitor C18, a series circuit including 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. A series circuit including 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.

A voltage detection circuit h is constituted by the smoothing capacitor C18, the resistor R1, and the diode array Da1. In addition, a resistor R40 and a capacitor C are connected to both terminals of the b contact RYb of the reset relay RY2.
A switching surge absorption circuit a constituted by a series circuit with 30 is connected in parallel.

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

The Zener diode ZD1 is arranged so that when a short-circuit current exceeding a predetermined value flows through the distribution line L, the transformed current output from the first current transformer CT1 breaks down by a signal that is full-wave rectified by the full-wave rectifier 4. It's summery. An AND circuit 6 is connected to the positive terminal of the resistor R6, and when the Zener diode ZD1 goes 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, resistance R6
A capacitor C2 connected in parallel to both terminals is for noise prevention.

A NAND circuit 7 is connected to the positive terminal side of the diode array Da1. . When the substation circuit breaker trips due to a short circuit or ground fault in the distribution line L, a voltage across the diode array Da1 corresponding to a logical value of 0 (i.e., no voltage) is applied to the input terminal of the NAND circuit 7. I'm getting closer to you. That is, when the NAND circuit 7 receives the logic value 0, it outputs a signal corresponding to the logic value 1. In addition, diode array Da1
A capacitor C1 connected in parallel between both terminals is for noise prevention.

A series circuit consisting of the 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 (to be described later) and a minus terminal of the full-wave rectifier 4, and a series circuit consisting of the collector/emitter of a switching transistor Tr1 and a resistor R33 is connected to both terminals of the resistor R33. A capacitor C19 is connected in parallel.

The NAND circuit 7, the resistor R3, and the switching transistor Tr1 constitute the no-voltage discrimination switching circuit j in FIG.
A signal memory circuit k is constituted by the capacitor C19 and the resistor R33.

The switching transistor Tr1 and the resistor R
The series circuit of 33 includes a diode D9 and a charging resistor R.
34, and a series circuit of a capacitor C20 as a relay drive 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 the set relay RY1 is energized, it opens the b contact RYb and also opens the a contact RYa of the search signal detection section Y, which will be described later.
Close the circuit. This thyristor SCR4 and set relay RY1 constitute a relay drive circuit m.

Furthermore, 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 an 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.
Connected via 3.

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

A series circuit consisting of the 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 (to be 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, the AND circuit 6 outputs the signal corresponding to the logical value 1 to the switching transistor.
When applied to the base terminal of Tr2, the switching transistor Tr2 is turned on (conducted).

The Zener diode ZD1, the resistor R6, the capacitor C2, the AND circuit 6, the resistor R7, and the switching transistor Tr2 constitute the current discrimination switching circuit b in FIG.

A diode D1 is connected between both terminals of the resistor R8.
A series circuit of a resistor R9 is connected, and a capacitor C3 is connected in parallel to both terminals of the resistor R9.

The other input terminal of the AND circuit 8 is connected to the positive terminal of the resistor R9. When the switching transistor Tr2 turns on (conducts), the voltage of the resistor R8 passes through the diode D1 to the capacitor C3 and the resistor R9.
, and the CR circuit applies a voltage (short-circuit current detection signal) corresponding to the logical value 1 for a certain period of time to the other input terminal of the AND circuit 8 according to its time constant. The capacitor C3 and the resistor R9 constitute a signal memory circuit d as a short circuit current detection signal delay circuit. That is, the memory for detecting the short circuit current is obtained by the time constant of the signal memory circuit d consisting of the capacitor C3 and the resistor R9.

Also, the AND circuit 8 applies a voltage (short-circuit current detection signal) corresponding to a logical value 1 for a certain period of time to one input terminal due to the time constant of the CR circuit including the capacitor C3 and the resistor R9. When a signal corresponding to logical value 1 (no-voltage detection signal) is input, a voltage corresponding to logical value 1 (switch signal) is input.
is applied from its output terminal.

Short circuit caused by the surge absorption circuit 5, rectifier circuit 4, current discrimination switching circuit b, signal memory circuit d, voltage detection circuit h, no-voltage discrimination switching circuit j, signal memory circuit k, relay drive circuit m, relay drive power supply n, etc. A detection circuit X is configured.

Between the output terminal P3 (plus terminal) of the power supply circuit Z and the minus terminal of the full-wave rectifier 4, the collector/emitter of the switching transistor Tr3 and the resistor R are connected.
Eleven series circuits are connected. Further, a capacitor C10 is connected in parallel between both terminals of the resistor R11. The output terminal of the AND circuit 8 is connected to the base terminal of the switching transistor Tr3 via a resistor R10.

A series circuit of a diode D3, a charging resistor R12, and a capacitor C4 as a drive power source is connected between the output terminal P3 (plus terminal) of the power supply circuit Z (described later) and the minus terminal of the full-wave rectifier 6, and constantly charges the capacitor C4. I'm starting to do that. A display drive power supply charging circuit e is constituted by a series circuit of the diode D3, the charging resistor R12, and the capacitor C4 as a drive power supply.

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

Therefore, the signal corresponding to the logical value 1 from the AND circuit 8 is sent to the switching transistor Tr3.
When the voltage is applied to the base terminal of the switching transistor Tr3, the switching transistor Tr3 is turned on (conducted), and a voltage is applied to the resistor R11 and the capacitor C10. As a result, the resistor R11 and capacitor C1
A voltage (switch signal) is applied from 0 to the gate terminal of the thyristor SCR1, and the thyristor
It is designed to make SCR1 conductive. and,
Due to conduction of thyristor SCR1, capacitor C
4 is discharged, and a short-circuit display drive current is output to the display ID.

A series circuit of a capacitor C11 and a resistor R24 forming a differential circuit is connected between the negative terminal of the diode D4 and the negative terminal 4 of the full-wave rectifier 4, and the positive terminal of the resistor R24 is connected to an IC23 of a timer circuit T to be described later. connected to. When the thyristor SCR1 becomes conductive, the charge in the capacitor C4 is discharged, and a display drive current is output to the display ID.
A clear control signal is output to the IC23 of the timer circuit T from the voltage dividing point of the differentiator circuit consisting of the resistor R24 and the resistor R24. The capacitor C11 and the resistor R2
4 constitutes a voltage amplification circuit g (see FIG. 1).

Furthermore, a series circuit of a capacitor C12 and a resistor R25 forming a differential circuit v 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 connected to a search signal detection section to be described later. It is connected to the gate terminal of the Y thyristor SCR2.

Then, due to the conduction of the thyristor SCR1,
The charge on capacitor C4 is discharged and the indicator
When the display drive current is output to the ID, a gate trigger voltage is applied to the gate terminal of the thyristor SCR2 from the voltage dividing point of the differentiating circuit v formed by the capacitor C12 and the resistor R25.

(display) Here, the display device ID will be explained in detail.

The display ID is composed of a plurality of magnetic reversal displays. In FIG. 5 and FIG. 6, one magnetic reversal display includes a disk 10 whose both ends are magnetized to N and S poles, rotatably supported around a rotation shaft 11, and a round bar-shaped stator 12. is formed to have a magnetic pole portion 12 a corresponding to the S pole of the disk 10 and a magnetic pole portion 12 b corresponding to the N pole of the disk 10 . Note that the stator 12 is preferably formed of a material with low coercive force. Between the two magnetic pole portions 12a, 12b, the same magnetic pole portions 12a, 12 are provided.
A drive coil 15 whose both ends are connected to the common terminal 13 and the set terminal 14 so that b is magnetized to the same polarity as the magnetic poles at both ends of the disk 10 in the state shown in FIG.
is wound.

Further, adjacent to the drive coil 15, between the two magnetic pole portions 12a and 12b, the same magnetic pole portions 12a and 12b are provided.
The return drive coil 17 is connected to the common terminal 13 and the reset terminal 16 so that it is magnetized to the same polarity with respect to both end magnetic poles of the disk 10 in the state shown in FIG.
is wound.

Front surface 10a and back surface 10b of the disk 10
Labels of different colors (in this embodiment, the front side 10a is black and the back side 10b is red) are displayed on the .

The drive coil 15 and return drive coil 17 of each magnetic reversal display are connected in parallel to each other (see FIG. 4).

Therefore, when a display drive current flows through the set terminal 14 to the display ID, each drive coil 15 is excited, and as shown in FIG. 6, the magnetic end portion 12a becomes the S pole and the magnetic pole portion 12b becomes the N pole. Each disk 10 is reversely rotated so that its N pole faces the magnetic pole part 12a (S pole) and its S pole faces the magnetic pole part 12b (N pole). The displayed signs are displayed all at once to the outside (short-circuit display).

Conversely, when a return drive current flows through the reset terminal 16 to the display ID, each return drive coil 17 is excited, and the magnetic pole portion 12 is energized as shown in FIG.
a is magnetized as a north pole, and the magnetic pole part 12b is magnetized as an south pole, and the north pole of each disk 10 is magnetized as the magnetic pole part 12a (north pole).
Then, the S pole is reversely rotated so that it faces the magnetic pole portion 12b (S pole), and the surface 10 of each disk 10 is
The signs attached to a are constantly displayed externally all at once.

(Search signal detection unit Y) To explain the search signal detection unit Y, between the plus and minus terminals of the full-wave rectifier 4 are the a contact RYa of the set relay RY1, and the smoothing capacitor C5.
series circuit is connected. A Zener diode ZD2 is connected between both terminals of the smoothing capacitor C5.
A series circuit of diode array Da2 is connected in parallel. In addition, a resistor R41 and a capacitor C are connected to both terminals of the a contact RYa of the reset relay RY1.
A switching surge absorption circuit γ composed of a series circuit with 31 is connected in parallel.

The Zener diode ZD2 is connected to the first current transformer based on the normal load current flowing in the distribution line L.
The transformed current output from the CT 1 is broken down by a signal that is full-wave rectified by the full-wave rectifier 4. The diode array Da2
An AND circuit 20 is connected to the positive terminal of , and when the Zener diode ZD2 breaks 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 consisting of the collector/emitter of a switching transistor Tr4 and a resistor R14 is connected between the output terminal P3 (plus terminal) of the power supply circuit Z (described later) and the minus terminal of the full-wave rectifier 4, and a series circuit consisting of the collector/emitter of a switching transistor Tr4 and a resistor R14 is connected to both terminals of the resistor R14. A capacitor C21 is connected in parallel.

The AND circuit 20 is connected to the base terminal of the switching transistor Tr4 via a resistor R13.
output terminal is connected. 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 turned on.

A voltage discrimination circuit p is constituted by the Zener diode ZD2, diode array Da2, AND circuit 20, resistor R13, and switching transistor Tr4.

A series circuit of a diode D5, a charging resistor R15, and a capacitor C6 as a relay drive current α is connected between the output terminal P3 (plus terminal) of the power supply circuit Z (described later) and the minus terminal of the full-wave rectifier 4, and the capacitor C6 is constantly connected. It is now possible to charge the battery. A series circuit of a thyristor SCR2 and a reset relay RY2 is connected in parallel between both terminals of the capacitor C6.

The reset relay RY2 constitutes a relay drive circuit w.

When the reset relay RY2 is energized, it closes the b contact RYb of the short circuit detection section X, and opens the a contact RYa. Furthermore, the positive terminal of the capacitor C21 is connected to the gate terminal of the thyristor SCR2.

Therefore, the switching transistor Tr4
When conductive, the capacitor C21 and resistor R14
A voltage is applied from the circuit to the gate terminal of the thyristor SCR2. Then, the thyristor
SCR2 becomes conductive, the charge in capacitor C6 is discharged, and reset relay RY2 is energized. The thyristor SCR2 constitutes a switching circuit u.

A resistor R1 is connected to both terminals of the smoothing capacitor C5.
6. A series circuit of resistors R17 is connected in parallel. 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. Then, when the a contact RYa closes,
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 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, and the capacitor C7
and the AND circuit 21, the search signal detection circuit q
is configured.

A series circuit consisting of the collector/emitter of a switching transistor Tr5 and a resistor R19 is connected between the output terminal P3 (plus terminal) of the power supply circuit Z (to be described later) and the minus terminal of the full-wave rectifier 4, and the base of the switching transistor Tr5 is The output terminal of the AND circuit 21 is connected to the terminal via a resistor R18. When a voltage corresponding to a logical value of 1 is applied to the base terminal of the switching transistor Tr5, the switching transistor Tr5 becomes conductive.

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

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

A capacitor C1 is connected between both terminals of the resistor R23.
0 are connected in parallel, and the emitter terminal of the switching transistor Tr7 is connected to the thyristor SCR.
It is connected to the gate terminal of 1.

the switching transistors Tr5 to Tr7,
A delay circuit t (see FIG. 1) is constituted by resistors R19 to R22, capacitor C8, and capacitor C9.

Therefore, when a voltage (detection signal) corresponding to the logical value 1 is applied from the output terminal of the AND circuit 21 to the base terminal of the switching transistor Tr5, the switching transistor Tr5 becomes conductive. Then, the voltage of the resistor R19 is applied to the circuit of the resistor R20 and the capacitor C8, and the 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.
A voltage is applied from the same 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 from the differential circuit of the resistor R23 and the capacitor C10 to the gate terminal of the thyristor SCR1.

In this way, the thyristor SCR1 is turned on with a certain time delay due to the time constant of each CR circuit. That is, the search signal detection section Y is set so that the detection time of the search signal in the search signal detection circuit q is delayed from the detection time of the retransmission current in the voltage discrimination circuit p. Therefore, when the voltage discrimination circuit p detects the retransmission current immediately after the search signal is injected, the same voltage discrimination circuit p
is working, and the display unit ID does not malfunction.

A series circuit of a capacitor C12 and a resistor R25 forming a differential 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 connected to the gate terminal of the thyristor SCR2. has been done.
Then, due to the conduction of the thyristor SCR1,
The charge on capacitor C4 is discharged and the indicator
When a display drive current is output to ID, a gate trigger voltage is applied to the gate terminal of thyristor SCR2 from the voltage dividing point of the differentiating circuit of capacitor C12 and resistor R25.

(Timed circuit T) Next, the time limit circuit T will be explained.

IC23 has a resistor R26, a capacitor C13,
An oscillation circuit β consisting of a resistor R27 is connected, and the same
The IC 23 is adapted to divide the number of oscillations of its oscillation circuit.

A diode D7, a charging resistor R31, and a capacitor C16 as a driving power source are connected between the output terminal P3 (positive terminal) of the power supply circuit Z and the terminal of the IC23.
are connected in series to constantly charge the capacitor C16. The diode D
7. A recovery drive power supply charging circuit δ is constituted by 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 a series circuit of thyristor SCR3 and diode D6, and the negative terminal of the capacitor C16 is connected to the reset terminal 16 of the display ID.
Connected to the ID common terminal.

A series circuit of a resistor R29 is connected between the output terminal P3 (plus terminal) of the power supply circuit Z and the minus terminal of the IC23 via the collector-emitter of the switching transistor Tr8. A capacitor C15 and a resistor R3 are connected to both terminals of the resistor R29.
0 series circuits are connected in parallel. The negative terminal of capacitor C15 is connected to the gate terminal of thyristor SCR3. Said capacitor C
15 and resistor R30 constitute a differentiating circuit.

And the switching transistor Tr8
The output terminal of the IC 23 is connected to the base terminal of the IC 23 via a resistor R28. In addition, resistance R2
Capacitor C14 connected in parallel to both terminals of 9
is for noise prevention.

The switching transistor Tr8, the capacitor C14, the resistor R29, the resistor R30, the capacitor C15, and the thyristor SCR3 constitute a switching circuit ε (see FIG. 1).

This IC23 has a capacitor C11 and a resistor R24.
When inputting the clear control signal from the differentiator circuit,
The division of the number of oscillations of the oscillation circuit is cleared and re-division of the number of oscillations is started. and,
When the IC23 is divided into a predetermined number, that is, after a predetermined time has elapsed, a voltage is applied to the base terminal of the switching transistor Tr8 via the resistor R28.

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, and the same voltage is applied to the gate terminal of the thyristor SCR3.
It is designed to turn on (conduct). As the thyristor SCR3 becomes conductive, the charge in the capacitor C16 is discharged, and a return drive current as a display return signal is output to the display ID.

(Power circuit Z) Next, the power supply circuit Z will be explained.

Both terminals P4 and P5 connected to the secondary side of the second current transformer CT2 have chiyoke coils 23 and 25.
A full-wave rectifier 26 as a rectifier circuit is connected through the. Further, a surge absorber 27 as a surge absorption circuit is connected between both terminals P4 and P5.

A smoothing capacitor C17 and a diode array are connected between the positive and negative terminals of the full-wave rectifier 26.
Da3 and a series circuit of a transistor Tr9, a diode D8, and a rechargeable battery B are each connected in parallel. Moreover, the transistor
A resistor R3 is connected between the collector terminal and base terminal of the Tr.
2 are connected.

The diode array Da3 constitutes the first constant voltage circuit ζ in FIG. 1, and the resistor R32 and the transistor Tr9 constitute the second constant voltage circuit η.

This power supply circuit Z performs full-wave rectification of the load current detected by the second current transformer CT2 using the full-wave rectifier 26, and further makes the forward voltage across the diode array Da3 constant using the transistor Tr9 and the like, Battery B is now being charged.

When a steady load current is flowing through the distribution line L, the backup battery B is not consumed, and the drive current is supplied to each of the parts using the load current. When the substation circuit breaker trips and load current no longer flows through the distribution line L, the backup battery B supplies the necessary drive current to each part from the output terminal P3.

Short circuit/ground fault detection circuit H configured as above
The operation of the control circuit will be explained below.

When a steady load current is flowing through the distribution line L, the second current transformer CT2 is used in the power supply circuit Z.
A small amount of transformed current is output from the transformer, and the transformed current is full-wave rectified by the full-wave rectifier 26 and then sent to the power supply circuit Z.
Charge battery B. Furthermore, the power supply circuit Z charges capacitors C4, C6, C16, and C20 as driving power sources for the respective circuits X, Y, and Z.

Also, at this time, the B contact in the short circuit detection section
RYb is closed and the first current transformer
A small amount of transformation current is also output from CT1, and after being full-wave rectified by full-wave rectifier 4, most of it is transferred to resistor R1 and diode array Da.
Consumed at 1. Note that, at this time, the a contact RYa in the search signal detection section Y is opened.

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

In this state, for example, if a short circuit current that can trip a substation circuit breaker flows through the distribution line L to which the first current transformer CT1 is attached, the first current transformer
Transformed current is output from CT1 to the short circuit detection section.
Then, this transformed current is full-wave rectified by the full-wave rectifier 4 and breaks 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,
The AND circuit 6 applies a signal corresponding to the logical value 1 to the base terminal of the switching transistor Tr2. As a result, the switching transistor Tr
2 turns on (conducts).

Then, the voltage of the resistor R8 is applied to the CR circuit of the capacitor C3 and the resistor R9 via the diode D1, and the CR circuit outputs a logical value for a certain period of time to the other input terminal of the AND circuit 8 as a gate circuit due to its time constant. 1 (short circuit current detection signal) is applied.

On the other hand, when the short circuit current trips the substation circuit breaker and, as a result, the distribution line L becomes voltageless, the short circuit detection circuit X detects this via the first current transformer CT1. That is, the diode array Da corresponding to the logical value 0 is connected to the input terminal of the NAND circuit 7.
1 (ie, no voltage) is applied.

Then, the NAND circuit 7 applies a signal corresponding to the logical value 1 to the base terminal of the switching transistor Tr1, thereby making the switching transistor Tr1 conductive. When the switching transistor Tr1 becomes conductive, the thyristor
Apply gate voltage to the gate terminal of SCR4.

Then, thyristor SCR4 becomes conductive, the charge in capacitor C20 is discharged, and set relay RY is activated.
1 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. This set relay RY1
The b contact RYb of the short-circuit detection circuit X is opened by the excitation of
RYa is closed, but at this time, the distribution line L is in a no-voltage state, so the search signal detection unit Y does not operate.

In this way, the AND circuit 8 connects one input terminal while the voltage corresponding to the logic value 1 (short-circuit current detection signal) is applied to the other input terminal for a certain period of time due to the time constant of the CR circuit including the capacitor C3 and the resistor R9. When a voltage corresponding to a logical value 1 (non-voltage detection signal) is input to the terminal, a voltage corresponding to a logical value 1 (switch signal) is applied from its output terminal.

When a signal corresponding to a logical value of 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 a voltage is applied to the capacitor C10 and the resistor R11. do. As a result, a voltage (switch signal) is applied to the gate terminal of the thyristor SCR1 from the differentiating circuit of the capacitor C10 and the resistor R23, and the voltage (switch signal) is applied to the gate terminal of the thyristor SCR1.
conduction.

As the thyristor SCR1 becomes conductive, the charged capacitor C4 is discharged, and a display drive current is output to the display ID.

This display drive current causes the display ID to display a short circuit. Also, at the same time as the display drive current is output to the display ID, the capacitor C11 and the resistor R24
A clear control signal is output from the voltage division point of the differentiating circuit to the IC23 of the time limit circuit T. Also, capacitor C1
A gate trigger voltage is applied to the gate terminal of the thyristor SCR2 from the voltage dividing point of the differentiator circuit consisting of the resistor R25 and the resistor R25. Then, the thyristor SCR2 is made conductive, and the charge in the capacitor C6 is discharged to excite the reset relay RY2, thereby closing the b contact RYb of the short circuit detection circuit X and opening the a contact RYa. That is, the short circuit detection circuit X enters a standby state.

On the other hand, when IC23 inputs the clear control signal,
The division of the number of oscillations of the oscillation circuit β is cleared and re-division of the number of oscillations is started. Then, when the IC23 is divided a predetermined number of times, that is, after a predetermined time elapses,
Switching transistor via resistor R28
Apply voltage to the base terminal of Tr8.

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, and the same voltage is applied to the gate terminal of the thyristor SCR3.
turns on (conducts). This thyristor
As the SCR3 becomes conductive, the charge in the capacitor C16 is discharged, and a return drive current as a display return signal is output to the display ID after a certain period of time.

This return drive current resets the display ID and returns to the normal display state.

Next, a case where a ground fault occurs in the power distribution line L will be described.

When a ground fault occurs in the distribution line L and the circuit breaker at the substation is tripped, the short circuit current flows and the distribution line L becomes voltageless, similar to when the circuit breaker at the substation is tripped. Then, the NAND circuit 7 of the short circuit detection circuit X makes the switching transistor Tr1 conductive, and furthermore, the switching transistor Tr
1 becomes conductive, the capacitor C19 and resistor R3
3 to apply a gate voltage to the gate terminal of thyristor SCR4.

Then, thyristor SCR4 becomes conductive, the charge in capacitor C20 is discharged, and set relay RY is activated.
1 is excited. By energizing 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 section Y is closed.

Then, when a search signal is injected into the distribution line L in this state, the search signal detection section Y 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 voltage corresponding to the logical value 1 is applied from the output terminal of the AND circuit 21 to the switch. is applied to the base terminal of the switching transistor Tr5. Then, the switching transistor Tr5 becomes conductive, and the voltage across the resistor R19 changes to the resistor R.
20・Applied to the circuit of capacitor C8, the same CR
A voltage is applied from the circuit to the base terminal of the switching transistor Tr6. Subsequently, the switching transistor Tr6 becomes conductive, and the resistor R21 similarly becomes conductive.
The voltage is applied to the circuit consisting of the resistor R22 and the capacitor C9, and the voltage is applied from the same CR circuit to the base terminal of the switching transistor Tr7.

Then, 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.

In this way, a voltage (switch signal) is applied to the gate terminal of the thyristor SCR1 after being delayed for a certain period of time by the time constant of each CR circuit.

When the thyristor SCR1 is made conductive, the charge in the capacitor C4 is discharged and the display is
Display drive current is output to ID. This display drive current causes the display ID to display an accident.

Also, at the same time as the display drive current is output to the display ID, a clear control signal is sent to the time limit circuit T from the voltage dividing point of the differentiating circuit of capacitor C11 and resistor R24.
Output to IC23. Further, a gate trigger voltage is applied to the gate terminal of the thyristor SCR2 from the voltage dividing point of the differentiating circuit of the capacitor C12 and the resistor R25.

Then, in the same way as when the short-circuit current flows to the distribution line L, the thyristor SCR2 becomes conductive, and the charge in the capacitor C6 is discharged, and the reset relay RY
2, 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 enters a standby state.

On the other hand, the timer circuit T operates as a timer in the same way as when the short-circuit current flows, and after a predetermined period of time, the indicator appears.
Outputs return drive current to ID after a certain period of time.

This return drive current resets the display ID and returns to the normal display state.

Note that if a ground fault occurs in the distribution line L and the substation circuit breaker trips, and the substation successfully retransmits power without detecting the search signal, the a contact of the search signal detection section Y Power will be retransmitted while RYa is closed. That is,
Power is retransmitted from the substation with the a contact RYa of the search signal detection unit Y being closed.
At this time, a normal load current flows through the distribution line L.

Then, the Zener diode ZD2 of the voltage discrimination circuit p in the search signal detection 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.
Subsequently, 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, thyristor SCR2 becomes conductive, the charge in capacitor C6 is discharged, and reset relay RY2 is energized.

By energizing the reset relay RY2, the b contact RYb of the short circuit detection circuit X is closed and the a contact RYa is opened, and the short circuit/ground fault display device enters a state of waiting for short circuit current fault detection.

Thus, in this embodiment, the first current transformer
Since it is an internal power supply type that constants the forward voltage across the diode array Da2 detected by CT1 and charges battery b, a separate power supply is not required.

In addition, in the short circuit detection circuit X, the diode array Da
Since no voltage is detected based on the presence or absence of forward voltage between 1 and 1, there is no need to detect the potential between PT or ground, and therefore there is no risk of insulating performance.

Furthermore, in the short-circuit detection circuit X, the memory for short-circuit current detection is obtained by the time constant of the memory circuit of the capacitor C3 and the resistor R9, so that the memory time can be effectively saved without loss.

In addition, the display ID is displayed due to the discharge of capacitor C4.
The display is driven and the set relay
RY1 and reset relay RY2 are capacitor C
Since it is operated by discharging the transistors 20 and C6, it is possible to consume almost no current for driving.

In addition, in this embodiment, since the display ID is electrically connected in parallel with the magnetic reversal display, the circuit impedance is reduced, and the capacitor C4 used as the drive power source and the capacitor C16 of the timer circuit T are
The discharge efficiency is improved, and display drive and return display drive are ensured.

Furthermore, 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 interfere with display drive, and outputs a clear control signal from the CR voltage division point to the IC23. Therefore, the time period from when the display is driven to when it is reset is accurate.

Furthermore, since the control circuit uses an IC as described above, there is an advantage that the current consumption of the control circuit is small.

Application Example Next, an example in which this signal injection type short circuit/ground fault detection device is applied to a ground fault detection system will be described with reference to FIGS. 9 to 12.

In the figure, 30 is a power transmission line, 31 is a substation circuit breaker (hereinafter referred to as CB), and the distribution line L is connected to the power transmission line 1 via CB31, and each phase is connected as shown in Figure 9. is expressed as La, Lb, and Lc.

32 is a zero-phase current transformer (hereinafter referred to as ZCT) of the substation installed on the immediate load side of the CB 31, and 33 is a grounding transformer (hereinafter referred to as GPT) installed on the power transmission line 1.
A single line ground fault occurring in the distribution line L is detected by both 32 and 33, and the directional ground fault relay 34 is activated.
is activated to trip the CB 31 and disconnect the power distribution line L from the power transmission line 30.

A large number of section switches SS are arranged on the distribution line L, and the section switches SS connect many sections An.
(n=1, 2, 3......) are classified.

This section switch SS is a conventionally known section switch, and as shown in Fig. 11, when a ground fault occurs in a certain section (time T1), the substation CB31 selectively cuts off the faulty line (time T2). time), when the fault line becomes non-voltage, each section switch opens after a delay opening time Z.
SS is set to open circuit (at T6).
Then, when voltage is applied by re-closing CB31 (at T3), CB31 closes after X hours (at T7).
The first section switch SS adjacent to is closed,
Thereafter, when voltage is sequentially applied to the load-side section switches SS, each section similarly closes after X hours.

In this way, power is turned on sequentially from the section switch SS on the power supply side and retransmitted to the healthy section, and when it reaches the ground fault section, substation CB31 is shut off again (T4
time) to be done. When CB31 of the substation is closed again (time T5), the section switch SS that separates the ground fault section is locked in the open state, so that only the ground fault section is isolated. There is.

Reference numeral 35 denotes a search signal injection device connected to the distribution line L of each phase at the nearest load side of the ZCT 32, and is grounded (see FIG. 9). The search signal output from the search signal injection device 35 has a full-wave current waveform (see FIG. 12). The reason why the full-wave current waveform is adopted as the search signal is so that the current transformers CT1 and CT2 of the short circuit/earth fault detection circuit H can detect both the short circuit current and the search signal. Also, when this full-wave current waveform search signal is injected into the high-voltage distribution line, the loss current due to the distribution line stray capacitance is small (only the leakage current due to the CR time constant).
It's for a reason.

This search signal injection device 35 inputs a trip signal from CB 21 when substation CB 31 is cut off (time T2), and based on the trip signal, CB 31
The search signal is injected into the three phases at once using the delayed opening time Z from the time when the first section switch SS is cut off (T2 o'clock) to the time when the first section switch SS is opened (T6 o'clock).

The injection of the search signal is set to end before the first section switch SS is opened (time from T8 to T9 shown in FIG. 11). A driving power source for this search signal injection device 35 is constituted by a transformer Tr connected to the power source side of the CB 31.

As shown in FIG. 9, a plurality of short circuit/ground fault detection 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 explained.

Now, in FIG. 10, it is assumed that a single line ground fault occurs at point m of phase a in section A3 of distribution line L (time T1). In addition. For convenience of explanation, only the a-phase La of the distribution line L is illustrated in FIG. 10.

Then, ZCT32 at the substation transmits the zero-sequence current,
GPT33 outputs zero-sequence voltage as a ground fault signal,
A trip signal is sent to CB31 through relay 34, and substation CB31 is opened (at time T2).

Then, the search signal injection device 35 inputs the trip signal from the CB 31, and based on the trip signal, the delay opening time Z from the time when the CB 31 is cut off (at T2) to the time when the section switch SS is opened (at T6) is calculated. The search signal is sent to each phase of the distribution line La, Lb,
Lc (time from T8 to T9 shown in FIG. 11).

Then, the search signal injection device 35, the power distribution line La,
A circulating current flows in a closed loop path passing 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, A1 section and A2
Section detection device H1 etc. and A3 section detection device H
2, H3 is displayed.

On the other hand, for phases b and c, a closed loop including the ground capacitance of the distribution line L instead of the ground fault point m is formed, but the impedance of this loop is high, the level of the flowing search signal is low, and the other two Phase Lb,
The detection device H placed at Lc remains in steady display.

In addition, even if the detection device is installed on the a phase, the search signal does not reach a certain level or higher, so the ground fault point m
The detection device H4, etc. provided closer to the load side remains at a steady display.

In this way, the search signal injection device 35 displays a ground fault on the display device up to the ground fault point m, but the injection of the search signal ends before the section switch SS is opened (at time T9).

After the search signal injection device 35 injects the search signal as described above (that is, after Z time has passed since the substation CB31 was cut off), the section switch SS
operates to open the circuit (at T6). Next, when voltage is applied by re-closing CB31 (at time T3), the first section switch SS adjacent to substation CB31 closes after X hours (at time T7), and then the section switches on the load side are sequentially closed. When a voltage is applied to the circuit SS, it similarly closes after X hours.

In this way, power is sequentially turned on from the section switch SS on the power supply side to retransmit power to the healthy section, and when it reaches the ground fault section, the substation CB31 is shut off again (at time T4). Then, when CB31 of the substation is closed again (at T5), the ground fault section A3
Only the short-circuit fault section A3, in which the section switch SS that separates the section is locked in the open state, is separated, and power is retransmitted only to the healthy section.

As mentioned above, the ground fault section A3 is a sectional switch.
Since the SS can be detected by being locked open, the worker then leaves from the source side to the load side in that ground fault section. Then, if the detection devices H displaying an accident (ground fault) are sequentially searched, the detection device H3 displaying a ground fault, which is one step before the detection device H4 not displaying an accident, will be detected.
It can be determined that there is a ground fault point m between the point where the detection device H4 is placed and the point where the detection device H4 is placed.

In addition, in searching for the ground fault point m, at the branch point α, the detection device H5 installed on the branch line on one load side is compared with the detection device H3 installed on the branch line on the other load side, and the detection It is sufficient to proceed along the branch line on the side where device H is displaying an accident (ground fault) indication.

Note that the present invention is not limited to the above-mentioned embodiment, and for example, the first current transformer CT1 and the second current transformer CT2, which are provided as a pair of current transformers in the above-mentioned embodiment, may be used as a common current transformer. It may be configured with a single current transformer, and any changes may be made without departing from the spirit of the invention.

(Effects of the Invention) As detailed above, the present invention does not require a grounding transformer and requires only a simple configuration of a short circuit detection circuit, a search signal detection circuit, and a time limit circuit, making the entire device smaller, lighter, and lighter. It is possible to reduce costs, and since it is configured to be activated by a search signal, workers can detect ground faults in a short period of time by simply making a temporary tour from the power supply side to the load side in the area where a ground fault has occurred. It has the great practical advantage of being able to easily identify short-circuit/ground fault detection devices, and by placing many of these short-circuit/ground fault detection devices on distribution lines, it will have a great effect on shortening the time to search for the fault point and, in turn, on early recovery. This has an excellent effect of indicating a short circuit.

[Brief explanation of the drawing]

FIG. 1 shows the short-circuit and
The electrical block circuit diagram of the ground fault detection device, Fig. 2 is the electrical circuit diagram of the short circuit/ground fault detection device, Fig. 3 is the power supply circuit diagram, Fig. 4 is the electrical circuit diagram of the display, and Fig. 5 is the electrical circuit diagram of the display. Fig. 6 is an explanatory diagram for the operation, Fig. 7 is a bottom view of the display, Fig. 8 is a bottom view of the display in the accident display state, and Fig. 9 is a distribution line system diagram. , FIG. 10 is a power distribution diagram for explaining the operation,
FIG. 11 is a time chart, and FIG. 12 is a waveform diagram of the search signal. 4...Full wave rectifier, 6...AND circuit, 7...NAND circuit, 8...AND circuit (gate circuit), 20,2
1...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 unit, Z...Power supply circuit, T...Time limit circuit, ID...Display device , CT1...first current transformer, CT2...second current transformer, L...distribution line.

Claims (1)

[Claims] 1. When a short-circuit current flows through a distribution line, the short-circuit current is detected via a current detector, and a short-circuit current detection signal is output, and when a circuit breaker in a substation is tripped, the current detector detects the short-circuit current. a short-circuit detection circuit that detects a no-voltage state of the distribution line and outputs a no-voltage detection signal via the short-circuit current detection signal delay circuit that delays the short-circuit current detection signal; A gate circuit that outputs a switch signal when both the delayed short-circuit current detection signal and the no-voltage detection signal are input, and a search signal that is injected into the distribution line in the event of a ground fault is detected via the current detector. When this happens, a search signal detection circuit that outputs a detection signal and a switch signal output from the gate circuit or a detection signal output from the search signal detection circuit turn on based on the detection signal output, outputting a display drive current, and driving the display device. a display switching circuit that displays an accident; a timer circuit that outputs a display return signal to the display to cause the display to return to normal display after a predetermined period of time has passed after the display displays an accident; 1. A control circuit for a signal injection type short circuit/ground fault detection device, comprising a power supply circuit that outputs a drive current to each circuit.