JPS6346659B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to forced grounding for reducing damage caused by electric shock on ungrounded high voltage distribution lines, and particularly relates to a portable forced grounding device.

If a person is electrocuted on a 6KV ungrounded high-voltage power distribution line and a ground fault occurs, the maximum electric shock duration that will not cause death is approximately 4 to 12 ms (the occurrence of ventricular fibrillation is considered the threshold for fatality). , human body resistance 500~
1000Ω, assuming that the grid's ground-to-ground charging current is 4 to 12A). However, it is difficult to trip the circuit breakers of power distribution substations within this amount of time, and it is considered that the phase where the person was electrocuted is forcibly grounded at high speed. When performing this forced grounding, it is necessary to detect and ground only the electrocuted phase in order to avoid disturbances to the grid, and therefore the operating speed of the device is required to be extremely fast. For this reason, a method has been proposed in which the electric shock phase is closed on the low voltage side by a semiconductor switching element through a transformer for each phase at the transmission end of the distribution substation, and forcedly grounded at high speed. Since the semiconductor switching elements are opened and closed on the low voltage side via the transformer, there is a problem in that the phase potential of the electric shock phase does not drop sufficiently due to voltage drop due to leakage inductance of the transformer, etc. In addition, since the point of a ground fault due to electric shock is unstable, if the point of a ground fault is far from the transmission end, the phase potential at the point of the ground fault should be sufficiently reduced by the impedance of the line, electrostatic induction, etc. The problem is that I can't. From the perspective of improving customer services, this will accurately reduce the damage caused by electric shock if a worker receives an electric shock during so-called live line work that is completed within a limited time, such as transformer replacement work that is carried out without power outages. This could lead to problems such as death of the worker. In order to improve this problem, it is possible to install the device on the distribution line near the live line construction, but in the case of the above method, a transformer must be installed for each phase, making the device larger. Therefore, it is unsuitable as a portable type.

The present invention has been made in view of the above-mentioned points, and its purpose is to make it portable by reducing its size and weight, and to sufficiently lower the phase potential of the electric shock phase to enable forced grounding at high speed. Our mission is to provide what we believe in.

Embodiments of the present invention will be described below with reference to the drawings.
In Figure 1, 1 is an ungrounded high voltage distribution line, 2,
2' and 2'' are thyristor valves that are detachably connected between phases a, b, and c of the distribution line 1 and the ground.As shown in Fig. 2, these are thyristor valves connected to the high voltage connection terminal H.
A current-limiting fuse F, an anode reactor L, a plurality of thyristor stacks 2a, and a plurality of thyristor stacks _2a ,
2 _a ′, ... 2 _a ⁿ are inserted in series, and the gate circuit 2 _b , 2 _b ′ ... 2 _b ⁿ is configured to send gate signals to the thyristor stacks 2 _a , 2 _a ′ ... 2 _a ^n. A voltage dividing circuit _2c is inserted between the high voltage connection terminal H and the ground terminal G via a current limiting fuse F. Then, the thyristor stacks 2 _a , 2 _a ′
...2 _a ⁿ connects thyristors Th ₁ and Th ₂ in antiparallel, and connects an absorber for surge absorption in parallel with this.
A ₁ is connected to a circuit in which a resistor R ₁ for overvoltage protection between the anodes and cathodes of thyristors Th ₁ and Th ₂ and a capacitor C ₁ are connected in series. In addition, the gate circuits 2 _b , 2 _b ′...2 _b ⁿ have secondary coils S ₁ and S ₂ wound around the annular core, respectively, and the primary coils pass through the annular core to form a so-called CT penetration type. gate transformer Tr ₁ and this gate transformer Tr ₁
A rectifier circuit Rec ₁ which performs full-wave rectification by connecting diodes to the bridge of the secondary coils S ₁ and S ₂ respectively,
Rec ₂ , a constant voltage diode ZD ₁ for gate protection connected in parallel to the output ends of the rectifier circuits Rec ₁ and Rec ₂ , a resistor R ₂ for preventing malfunction, and a capacitor C ₂ . Circuit Rec ₁ , Rec ₂
The output ends of the thyristor stacks 2 _a , 2 _a ′...2 _a
ⁿ thyristors Th ₁ and Th ₂ are connected between the gates and cathodes, and gate circuits 2 _b , 2 _b ′...2 _b ⁿ gate transformer Tr ₁ 's primary coil is connected in series to gate power supply terminal G _K , _GL , and a gate signal is transmitted by a current flowing to the primary side of the gate transformer Tr ₁ through the gate power supply terminals G _K and _GL . In addition, the voltage dividing circuit 2 _c is the a of the distribution line 1,
The ground voltage of each phase b and c is divided by resistors R ₃ and R ₄ and is derived from the output terminal M. The thyristor stacks _2a , _2a ^'...2an _, gate circuits _2b , _2b '...
2 _b ⁿ and the voltage dividing circuit 2 _c are detachably connected to the phases a, b, and c of the distribution line 1, as shown in FIG. 3, and will be explained below. H is a high-voltage connection terminal, and a clamping plate made of a strip-shaped conductive spring material of the terminal fitting 4 is formed into a hook shape by stacking strip-shaped conductive plate materials and bending the tips into a V-shape. 5 is bent into a V-shape and inscribed in the V-shaped space of the clamping plate 5, and a plurality of wire clamping parts _5a , which are curved semicircularly and facing each other, are connected and clamped. The bent end of the mounting plate 5 is expanded outward and extended, and the base is attached to a support fitting 7, which will be described later, protruding from the tip of a gripping tube 6, together with the terminal fitting 4, using bolts or the like, and is attached to the distribution line. By hooking each phase a, b, and c of 1, the connection is made by clipping.
6 is FRP made of glass fiber reinforced with plastic.
It is a cylindrical gripping tube made of electrically insulating material such as.
Inside the hollow of this grip tube 6 are the thyristor stacks 2 _a + 2 _a ′...2 _a ⁿ , gate circuits 2 _b , 2 _b ′...
2 _b ⁿ , a voltage dividing circuit 2 _c , a current limiting fuse F, and an anode reactor L are housed. This is achieved by arranging a plurality of rod-shaped support frames 8 along the hollow circumference of the gripping tube 6 and extending in the longitudinal direction, and supporting plates 9 having a smaller diameter than the hollow circle diameter perpendicular to the longitudinal direction. A current limiting fuse F, an anode reactor L, a voltage dividing circuit 2c, a thyristor stack 2a, and a current limiting fuse F, an anode reactor L, a voltage dividing circuit _2c , and a thyristor stack _2a are attached to the support plate 9 from the tip to the rear end of the grip tube 6. Gate circuit _2b , thyristor stack _2a ' and gate circuit _2b ',
...The thyristor stack 2 _a ⁿ and the gate circuit 2 _b ⁿ are formed into blocks and installed in this order, and this is attached to the support frame 8 above.
The support frame 8 and the grip tube 6 are inserted into the hollow of the grip tube 6 using the guide as a guide, and the support frame 8 and the grip tube 6 are fastened and fixed with screws or the like. The rear end opening of the grip tube 6 is closed by an insulating plate 10, and this insulating plate 10 has gate power terminals G _K , G _L , an output terminal M, and a ground terminal G.
are installed and arranged. Further, a grounding wire 11 having a grounding tool 12 such as a grounding rod attached to one end is connected to the grounding terminal G. 13 is a of the distribution line 1,
A voltage dividing circuit _2c of thyristor valves 2, 2', and 2'' inserted between each phase b and c and the ground is connected,
Detects a ground fault phase caused by an electric shock and sends gate power to the gate circuit 2 _b , 2 _b ′...2 b ⁿ of any one phase of the thyristor valves 2, 2', 2 _' ' connected to the ground fault phase. This is a control device that fires the thyristors Th ₁ and Th ₂ of the thyristor stacks 2 _a , 2 _a ′...2 _a ⁿ . The ground detection circuit 14 is equipped with a detection circuit 14 and a gate switch circuit 31 that is controlled to open and close for each phase by the output signal of the ground detection circuit 14. 2″ gate circuit 2 _b , 2 _b ′...2 _b
The power supply circuit 15 is configured to supply a gate power supply to the ^gate power source. Next, the above ground detection circuit 1
4 will be explained. 16 _a , 16 _b , and 16 _c are conversion circuits in which variable resistors are inserted between the input terminals M _a , M _b , M _c and the circuit ground, and an operational amplifier formed as a voltage follower is connected to the sliders of these variable resistors. _Thyristor valves ₂ , 2 _' ,
Connect the output terminals M of the 2″ voltage divider circuit _2c ,
Voltage to ground V _a of each phase a, b, c of distribution line 1,
A voltage obtained by dividing V _b , V _c is input, and this input is impedance-converted to obtain the ground voltage V _a , V _b ,
It is designed to output a voltage V _a ′V _b ′V _c ′ corresponding to V _c . And the above variable resistor is the voltage between ground
V _a , V _b , and V _c are in equilibrium (|V _a |=|V _b |=|
This is to adjust the output voltages V _a ′, V _b ′, and V _c ′ to be balanced when the voltage V _c |). 17
is an adder circuit connected from the conversion circuits _16a , _16b , _16c , and the conversion circuit 16 is connected by an operational amplifier.
The sum ( _{V O} ′) obtained by adding the output voltages V _a ′, V _b ′, and V _c ′ of a , 16 _b , and 16 _c (V _a ′ + V _b ′ + V _c ′) is now sent as an output. There is. That is, when a ground fault occurs due to an electric shock to a worker in the a-phase of the distribution line 1, for example, this adder circuit 17 derives the voltage V _O ' corresponding to the zero-sequence voltage V _O caused by the unbalance. It is for the purpose of Reference numeral 18 denotes a differentiator circuit connected to the adder circuit 17, which is formed with a capacitor provided at the input end and an operational amplifier, and is configured to send out an output of dV _O '/dt. This is designed to be sent out as an output corresponding to the differential value dV _O /dt of the zero-sequence voltage V _O caused by the ground fault. 19 is a clamp circuit connected from the differentiation circuit 18,
Constant voltage diodes are connected in anti-series so that when the peak value of the input (dV _O '/dt) exceeds a certain level determined by the Zener voltage, it is clamped at a certain level and output. 20 _a , 20
_b and _20c are phase-specific adder circuits connected to the conversion circuits _16a , _16b , and _16c, respectively, and the clamp circuit 19, which are formed by operational amplifiers and add the sum of inputs for each phase. (V _a ′+
dV _O ′/dt, V _b ′+dV _O ′/dt, V _c ′+dV _O ′/dt). 21 _a , 21
_b and _21c are phase comparison circuits formed into a window comparator by two operational amplifiers, which are connected to the phase addition circuits _20a , _20b , and _20c , respectively;
Level setting circuit 22 that sends out reference voltages V _r and −V _r
are connected to the phase-specific adder circuits 20a, _20a ,
The peak value of the output voltage of 20 _b and 20 _c is the reference voltage V _r
When the level is within the level range of V r and -V _r , the output signal is "L" level, and when the level of the reference voltage V _r and -V _r is exceeded, the output signal is "H" with a pulse width corresponding to the time of exceeding the level of the reference voltage V r and -V r. It is designed to send out a level pulse signal as an output signal. The level setting circuit 22 inserts variable resistors between the constant voltage power supplies V _DD and V _EE and the circuit ground, sets the reference voltages V _r and −V _r by the sliders, and outputs them from the sliders. I'm starting to do that. _23a , _23b , and _23c are phase-specific pulse circuits connected to the phase-specific comparison circuits _21a , _21b , and _21c, respectively. This is formed into a monostable multivibrator, and when the input is at the "L" level, it sends out an output signal at the "H" level.
When the above pulse signal is input, the output signal is held at the "L" level for a certain period of time (a period corresponding to, for example, 1/2 cycle of the power supply frequency of the distribution line 1) and sent out, and the pulse signal is output within the above certain period of time. When the signal is input again, the output signal is held at the "L" level for a certain period of time from the time of input and then sent out. 24
are connected from the phase-specific pulse circuits 23 _a , 23 _b , 23 _c to form the phase-specific pulse circuits 23 _a , 23 _b , 23
When the output for each phase of _c is a "H" level signal for only one phase and "L" level signals for the other two phases,
This discrimination circuit discriminates only the phase that sends out an "H" level output signal as a ground fault phase, and sends out an "H" level output signal as a discrimination signal from the output end of that phase. This is a phase-specific pulse circuit 23 _a , 2
_AND circuits AND _a , AND _{b ,}
A knot circuit is connected to the input terminals of AND _c , and the output terminal of the phase-specific pulse circuit 23 _a .
The output terminal of NOT _a is connected to the input terminal of AND circuits AND _b and AND _c , and similarly, the output terminal of NOT circuit NOT _b connected from the output terminal of the phase-specific pulse circuit 23 _b is connected to the input terminal of AND circuits AND _a and AND _c . A knot circuit connected to the input terminal and from the output terminal of the phase-specific pulse circuit _23c .
The output end of NOT _c is connected to the input end of AND circuits AND _a and AND _b , respectively, and phase-specific pulse circuits 23 _a ,
When only one phase of the output signal of 23 _b or 23 _c is at the "H" level, a "H" level is output from the output terminal of any one of the corresponding AND circuits AND _a , AND _b , AND _c The signal is sent out as a discrimination signal. 25 is connected from the discrimination circuit 24 and displays the ground fault phase caused by electric shock, and also displays the thyristor valve 2,
This is a display circuit that sends a control signal to a gate switch circuit 31 that controls opening and closing of gate power supplied to gate circuits 2', ₂ '', 2b, _{2b '} ^... 2bn.This is a discriminator circuit. 24 AND circuits
The set input terminals S of flip-flop circuits FF _a , FF _b , and FF _c are connected to the output terminals of AND a , AND _b , _{and AND c ,} respectively, and the flip-flop circuits FF _a ,
The base of a transistor _Q1 whose emitter is grounded is connected to the output terminal Q of FF _b and FF _c via a resistor _R3 , and the collector of this transistor _Q1 is connected to a light emitting diode.
Constant voltage power supply by connecting LED ₁ and resistor R ₄ in series
The base of the transistor Q ₂ connected to V _DD and whose emitter is connected to this constant voltage power supply V _DD is connected to the connection point between the resistor R ₄ and the light emitting diode LED ₁ via the resistor R ₅ , and the base of the transistor Q ₂ is A capacitor C ₃ and a resistor R ₇ are inserted in parallel between the resistor R ₆ connected to the collector and the emitter of the transistor Q ₁ to form switch control circuits 26 _a , 26 _b , 26 _c . Control circuits 26 _a , 26 _b , 26
Collector of transistor Q ₂ of _c and transistor Q ₁
A control signal is sent to the gate switch circuit 31 from the emitter of the gate switch. 27 are flip-flop circuits FF _a , FF _b ,
In the manual reset circuit that resets FF _c , switch SW ₁ , capacitor C ₄ , and resistor R ₈ are inserted in series between the constant voltage power supply V _DD and the circuit ground.
The connection point between C ₄ and resistor R ₈ is a flip-flop circuit.
The flip-flop circuits FF _a , FF _b , and FF _c are connected to reset input terminals R of FF a , FF b , and FF c , respectively, so that flip-flop circuits FF _a , FF _b , and FF _c can be reset by manually turning on a switch SW ₁ .

Next, the power supply circuit 15 will be explained. 28 is a DC-AC inverter that converts DC input into AC input, and the battery of the mobile work vehicle is connected to input terminals P and N. This inverter 2
The output of 8 is the power frequency of distribution line 1 (e.g. 60Hz)
It is designed to transmit at the same frequency as the 29
is a constant voltage power supply circuit connected from the inverter 28, which converts the AC input into a DC constant voltage and supplies constant voltage power supplies V _DD and V _EE from the output terminal to the ground detection circuit 14 as operating control power supplies. ing. 30 is connected from the inverter 28,
Gate circuit 2 _b of thyristor valve 2, 2', 2'',
2 _b ′...A gate power supply circuit that supplies gate power to 2 _b ⁿ , smoothing the AC input and generating a frequency higher than the input frequency (for example, 400Hz) using a Royer oscillator, etc.
A square wave pulse signal is sent out as the gate power supply. Reference numeral 31 denotes a gate switch circuit connected to the gate power supply circuit 30, and one of the output terminals of the gate power supply circuit 30 has a bidirectional thyristor (hereinafter referred to as triax) T _a ,
The main terminals T ₁ of Th _b and Th _c are connected respectively, and the main terminal T ₂ of these triacs _Tha , Th _b and Th _c is the output terminal.
GL _a , GL _b , GL _c respectively, the other output terminal _of the gate power supply circuit 30 is connected to the _output terminal G _K , _and the switch control circuit 26 _a , 26 _b , 26 _c transistor Q ₁
Connect the emitters of , respectively, and make the triax T _a ,
The switch control circuit 26 _a is connected to the main terminal T ₁ of Th _b and Th _c .
The collectors of transistors Q ₂ of 26 _b and 26 _c are connected to resistors.
Connect each through R ₆ , output terminal GL _a , GL _b , GL _c
Connect the gate power terminals G _L of the thyristor valves 2, 2', 2'' to the output terminal G _K , and connect the gate power terminal G _K of the thyristor valves 2, 2', 2'' to the output terminal G _K. When a negative gate current flows through the gates of , Th _b , Th _c , the tri-activation occurs.
By turning on Th _a , Th _b , Th _c , gate circuits 2 _b , 2 b ′ of thyristor valves 2, 2', 2 _' '...
2 _b ⁿ is supplied with gate power from the gate power supply circuit 30.

Next, its operation will be explained. Load this device into a mobile work vehicle and transport it to the location where live line work is to be carried out, and then
Hook the clamping plate 5 of the high voltage connection terminal H attached to the tip of the thyristor valve 2, 2', 2'' to each phase of the
The conductor of the distribution line 1 is clamped and connected to the wire clamping portion 5a of the clamping plate ₅ by elastic force, and the thyristor valve 2,
2', 2'' are suspended and supported. Then, the grounding tool 12 attached to the ground wire 11 of the thyristor valves 2, 2', 2'' is grounded to the earth, and the thyristor is connected between each phase of the distribution line 1 and the earth. Insert and connect valves 2, 2', and 2''.For ease of understanding, insert and connect thyristor valves 2, 2', and 2'' to the a-phase of the distribution line 1, and the thyristor valve 2 to the b-phase of the distribution line 1. 2',
The following explanation assumes that the thyristor valves 2'' are connected to the c phase.Next, the output terminal _M of the gate circuit 2c of the thyristor valves 2, 2', 2'' is connected to the c phase.
the input terminal M _a of the ground detection circuit 14 of the control device 13,
Connect M _b and M _c respectively, connect the battery terminal of the mobile work vehicle to the input terminals P and N of the power supply circuit 15, and connect the output terminals GL _a , GL _b , and GL _c of the power supply circuit 15 to the thyristor valve 2 and 2′, 2″ gate power supply terminal
At the same time, the output terminals _GK of the power supply _circuit 15 are connected to the gate power supply terminals _GK of the thyristor valves 2, 2', 2'', respectively.Control device 13
is the inverter 28 by connecting to the above battery.
Control power for operation is supplied from the constant voltage power supply circuit 29 to each circuit of the ground detection circuit 14 through the converter circuits 16 _a , 16 _b , 16 _c . voltage divider circuit 2 _c to ground voltages V _a , V b , V _c of each phase a, _b , c of distribution line 1
Input the voltage divided by resistors R ₃ and R ₄ (R ₄ / R ₃ + R ₄ V _a , R ₄ / R ₃ + R ₄ V _b , R ₄ / R ₃ + R ₄ V _c ), and set this as the impedance. The output voltages V _a ′, V _b ′, and V _c ′ are converted into the adder circuit 17 and the phase-specific adder circuits 20 _a , 20
_b , _20c . Addition circuit 17 that receives this
If the ground voltages V _a , V _b , and V _c of each phase above are in equilibrium, there is a relationship of |V _a |= |V _b |= |V _c |, so the input V _a ′, V _b ′ , V _c ′, the output becomes zero. The output of the differentiating circuit 18 that received this is also zero,
The clamp circuit 19 also outputs the output as it is, and the phase-specific adder circuits _20a , 20 that receive this output
The output added by _b and 20 _c is the input voltage V _a ′,
V _b ′, V _c ′ are sent out for each phase, and the phase comparison circuits 21 _a , 21 _b , 21 _c receive the reference voltages V _r , 21 c sent from the level setting circuit 22 .
−V _r . At this time, the input voltages V _a ′, V _b ′,
Since V _c ' is within the level range of the reference voltage V _r and -V _r , the output signals of the phase comparison circuits 21 _a , 21 _b , 21 _c are sent out at "L" level, and the phase The pulse circuits 23 _a , 23 _b , 23 _c send output signals of "H" level to the discrimination circuit 24 . Therefore, the AND circuit of the discrimination circuit 24
AND _a , AND _b , AND _c have NOT circuits NOT _a ,
Since they each receive the inputs inverted by NOT _b and NOT _c , the AND circuits AND _a , AND _b , AND _c
All outputs become "L" level signals, and the switch control circuits 26 _a , 26 _b , 26 _c of the display circuit 25
The light-emitting diode LED ₁ remains off and displays "no ground fault phase", the triactors _Tha , Th _b , and Th _c of the gate switch circuit 31 of the power supply circuit 15 remain turned off, and the thyristor valves 2, 2',
2″ gate circuits 2 _b , 2 _b ′, ... 2 _b ⁿ are not supplied with gate power, and the thyristor stacks 2 _a , 2
The thyristors Th ₁ and Th ₂ of _a '...2 _a ⁿ remain turned off.

In this state, live line work such as transformer replacement work is carried out, and during this work (for example, at time t in Figure 5), a worker receives an electric shock on the a phase of distribution line 1, resulting in a single line ground fault. Explain what happens when an accident occurs. This ground fault causes the ground voltages V _a , V _b , and V _c to become unbalanced, resulting in a zero-sequence voltage _VO . A conversion circuit _16a inputs this from the voltage dividing circuit _2c of the thyristor valves 2, 2', 2'', converts the impedance, and sends it out.
The outputs of 16 _b and 16 _{c are shown} in Figure 5 _.
As can be seen from the figure, the a-phase, which is the phase that was electrocuted after the accident occurrence, has a waveform with a slightly lower peak value than before the accident, and the b and c phases have waveforms with slightly higher peak values than before the accident. , conversion circuit 16 _a ,1
6 _b and 16 _c . Upon receiving this, the adder circuit 17 adds the input voltages V _a ′, V _b ′, and V _c ′ and sends an output V _O ′ corresponding to the zero-phase voltage V _O to the differentiating circuit 18 . (Fig. 5 17) Differentiator circuit 1 that receives this
8 differentiates the input V _O ' and outputs (dV _O '/dt).

This differential value (dV _O ′/dt) and the corresponding differential value (dV _O /dt) of the zero-sequence voltage V _O are calculated by calculating the ground capacitance of each phase of distribution line 1 by C, and the electric shock of the worker. If the ground fault resistance that occurs is R _g , the above (dV _O /dt) will be expressed as dV _O /dt=-V _a /3CR _g . Therefore, (dV _O '/dt) corresponds to -V _a /3CR _g above, and the output of the differentiating circuit 18 has a relatively low rise at time t when the accident occurred, as shown in Figure 5.18. It becomes a large waveform. In response to this, the clamp circuit 19 outputs the output as is unless the peak value of the output (dV _O '/dt) of the differentiating circuit 18 exceeds a certain level determined from the constant voltage diode, and when it exceeds the peak value at a certain level. are clamped and sent to phase-specific adder circuits _20a , _20b , and _20c , respectively. The phase-specific addition circuit _20a that received this,
20 _b , 20 _c are the conversion circuits 16 _a , 16 _b , 16 _c
V _a ′+(dV O ′/dt)V _{b ′} +(dV _O ′/dt), V _{c ′} +(dV _{O ′} /dt ₎ '/dt)) Output. As shown in Fig. 5, _20a , _20b , and _20c , this output has a significantly lower peak value in phase a, where the electric shock occurred, than in phases b and c (|v _a ′+(dV _O ′/dt)｜≪｜V _b ′＋(dV _O ′/dt)｜
, | V _c ′ + (dV _O ′/dt) |) waveform. This is because the voltage (dV _O '/dt) is in opposite phase to the a-phase voltage V _a '. Then, the phase-specific addition circuits _20a , 2
Phase comparison circuits 21 a and 21 _a receiving the outputs of 0 _b and 20 _c
21 _b and 21 _c are compared with reference voltages V _r and -V _r sent out from the level setting circuit 22 for each phase. At this time, the phase-specific comparator circuit _21a outputs the phase-specific adder circuit _20a (V _a ′+(dV _{O ′} /dt)), as shown in _{FIG .} Since the output signal is within the level range of "L" as shown in Figure 5, _21a ,
level. Further, the phase comparison circuits 21 _{b and 21 c} have reference voltages V _{r and -} , as shown in FIG.
Since the level of V _r is exceeded, a pulse signal having a pulse width corresponding to the time during which the level is exceeded is sent out as an output signal when the level is exceeded (FIG. 5, 21 _b and 21 _c ).

The phase-specific pulse circuit _23a receiving the output of the phase-specific comparison circuit _21a is set to "H" as shown in FIG. 5 _23a .
Send out a level output signal, phase-specific pulse circuit 23
_b , _23c , the output signal inverts from "H" to "L" level when the above pulse signal is input, holds it for a certain period of time (for example, the time of 1/2 cycle of the power supply frequency of distribution line 1), and outputs it. do. This output signal is held for a certain period of time every time a pulse signal is input, so as shown in Fig. 5, 23 _b and 23 _c ,
Set the output signal to “L” at the time of inputting the first pulse signal.
It will be inverted to the level, held and transmitted. Then, “H” of the phase-specific pulse circuit 23 _a
Level output signal and phase-specific pulse circuit 23 _b , 2
The discriminating circuit 24 that receives the "L" level output signal of _3c receives the input after the AND circuits AND _a , AND _b , AND _c are inverted by the NOT circuits NOT _a , NOT _b , and NOT _c . , the above AND circuit
Only the inputs of AND _a are all "H" level signals, and the AND circuit AND _a determines that phase a is a ground fault phase, and sends an "H" level output signal to the display circuit 25 as a determination signal. In response to this, the flip-flop circuit FF _a of the display circuit 25 is set, and an output signal of "H" level is sent from its output terminal Q to the base of the transistor Q ₁ of the switch control circuit 26 _a , thereby causing the transistor Q ₁ turns on and lights up light emitting diode LED ₁ .
At the same time, transistor _Q2 is turned on to indicate that the phase is a ground fault phase, and the power supply circuit 15 is turned on.
A negative gate current is passed through the gate of the triax T _a of the gate switch circuit 31 to turn it on. By turning on the triax T _a , the gate circuits 2 _b and 2 _b ′ of the thyristor valve 2 are turned on.
Gate power is supplied from the gate power supply circuit 30 to the primary side of the gate transformer Tr ₁ of 2 _b ⁿ , and the current flowing to the primary side of the gate transformer Tr ₁ is induced in the secondary coils S ₁ and S ₂ . Rectifier circuit for secondary voltage
Full-wave rectification ^is performed by Rec ₁ and Rec ₂ to turn on _{the thyristors Th 1 and} Th ₂ of the thyristor stacks 2 a , 2 _{a ′} . This forced grounding point will be near the accident point, so
The phase potential at the fault point can be sufficiently lowered without being affected by line impedance, electrostatic induction, etc. After the above-mentioned forced grounding, if the ground fault due to electric shock is canceled by tripping the disconnector (not shown) at the distribution substation, the manual reset circuit 27 is reset.
Manually turn on the switch SW ₁ to reset the flip-flop circuit FF _a of the display circuit 25. As a result, the output signal from the output terminal Q of the flip-flop circuit FF _a is inverted from "H" to "L" level, turning off the transistor Q ₁ of the switch control circuit 26 _a and extinguishing the light emitting diode LED ₁ . The transistor _Q2 is turned off, and the triax T _a of the gate switch circuit 31 is turned off when the gate power supply waveform passes the zero point. As a result, the gate circuits _2b , 2 of the thyristor valve 2
_b ′...2 The gate power supply to _b ⁿ is cut off,
Along with this, thyristor stacks 2 _a , 2 _a ′
...2 _a ⁿ thyristors Th ₁ and Th ₂ have a voltage to ground V _a
When it passes the zero point, it turns off and returns to the state before the ground fault occurred, preparing for the next forced grounding operation.

Although the embodiment has been described as forced grounding due to electric shock in the a-phase of the power distribution line 1, it goes without saying that the operation is similar in the case of the b- and c-phases. Furthermore, in the embodiment, the input end of the power supply circuit 15 was explained as being connected to the mobile worker's battery, but if there is an AC power source near the work place, this AC power source can be connected to the output end of the inverter 28. Try to connect,
The control power source and the gate power source for operation may be configured to be supplied by both AC and DC power sources.

As described above, the present invention includes a high-voltage connection terminal that is detachably connected to an ungrounded high-voltage distribution line by attaching it to the tip of a cylindrical gripping tube made of an electrically insulating material.
Inside the hollow of this holding tube, a plurality of thyristor stacks each having thyristors connected in anti-parallel are connected in series, one end of which is connected to the high voltage connection terminal, and a CT through type is connected to the gate of the thyristor of the thyristor stack. A plurality of gate circuits each configured to send out a gate signal by the output of the gate transformer are connected to the thyristor stack in correspondence with each other, a voltage dividing circuit is connected to the high voltage connection terminal for storage, and the grip tube is connected to the thyristor stack. Each phase is equipped with a thyristor valve consisting of the other end of a plurality of thyristor stacks connected in series at the rear end and a voltage dividing circuit connected to a ground wire equipped with a grounding device via a ground terminal. The differential value of the zero-sequence voltage connected from the output end of the voltage circuit and caused by the unbalance of the voltage to ground is added to the voltage to ground of each phase, and the sum is calculated as follows: The above thyristor valve is equipped with a ground detection circuit that detects this as a ground fault phase when it is small, and a gate switch circuit that controls the opening and closing of the gate power supplied to the gate circuit for each phase based on the output of this ground detection circuit. is connected between each phase of the distribution line near live line work and the ground, so that it can be grounded in the event of an electric shock.Forced grounding is performed on the high voltage side using a thyristor, so There is no need to install a transformer at all, and the thyristor valve can be made small and lightweight and can be carried freely.Moreover, the thyristor valve has multiple thyristor stacks, gate circuits, and voltage dividing circuits in a cylinder made of insulating material. It is housed in a shaped gripping tube, and has a high-voltage connection terminal attached to the tip that can be detachably connected to the distribution line, making it easy to connect and disconnect from the distribution line, and to protect the ground in the event of an electric shock accident. To detect a phase fault, the sum of the differential value of the zero-sequence voltage and the ground-to-ground voltage of each phase is compared, and if one phase is smaller than the other two phases, the smaller phase is determined to be a ground fault phase. The structure is simple, and the detection can be performed within one cycle of the power frequency from the time of occurrence of an accident, reducing the amount of time the person receives an electric shock.Moreover, the device is portable. Since forced grounding is performed near the accident point, the potential at the accident point can be sufficiently lowered without being affected by line impedance, electrostatic induction, etc.
The damage caused by electric shock to workers can be significantly reduced, and the safety of workers in live line construction can be further improved.

[Brief explanation of drawings]

Fig. 1 is a block diagram explaining the basic configuration of the present invention, Fig. 2 is a circuit diagram showing an embodiment of the thyristor valve shown in Fig. 1, and Fig. 3 is an outline drawing of Fig. 2.
Figure A is a partially cutaway front view, and Figure B is a view taken along arrow F in Figure A. 4 is a block diagram showing an embodiment of the control device shown in FIG. 1, and FIG. 5 is a time chart explaining ground fault phase detection in FIG. 4. 2, 2', 2'': Thyristor valve, 2 _a , 2 _a '
...2 _a ⁿ : thyristor stack, 2 _b , 2 _b '...
2 _b ⁿ : gate circuit, 2 _c : voltage dividing circuit, 6: gripping tube,
14: Ground detection circuit, 31: Gate switch circuit, H: High voltage connection terminal, G _K , G _L : Gate power supply terminal, M: Output terminal.

Claims (1)

[Claims] 1 A plurality of thyristor stacks in which thyristors are connected in anti-parallel are connected in series, and a gate circuit for sending a gate signal to the gate of the thyristor is connected in correspondence with the plurality of thyristor stacks, and the plurality of thyristor stacks connected in series are connected in series. A voltage dividing circuit is connected to both ends of the thyristor stack, and these are housed in the hollow of a vertically long cylindrical grip tube made of electrically insulating material.
A high-voltage connection terminal that is removably connected to the power distribution line is attached to the upper part of this gripping tube, and a grounding terminal to which a ground wire equipped with a grounding tool is connected is installed at the lower part, and a thyristor is installed between the above-mentioned high-voltage connection terminal and the grounding terminal. A thyristor valve consisting of a stack and a voltage divider circuit is installed for each phase of the distribution line, and the differential value of the ground voltage and zero-sequence voltage of each phase is connected to the output end of the voltage divider circuit of the thyristor valve. When the sum of the additions of only one phase is smaller than the other two phases, a grounding detection circuit is connected that detects the smaller phase as a ground fault phase, and the output of this grounding detection circuit is used to control the opening and closing of each phase. A gate switch circuit is interposed between the gate power source and the above gate circuit, and the above thyristor valve is connected between each phase of the distribution line near the live line construction and the earth for forced grounding. Features forced earthing device.