JPH0136593B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a zero-phase voltage detection capacitor used to detect a ground fault in a distribution line made of insulated wires.

Conventionally, a device that has been widely used as a zero-phase voltage detection unit is a zero-phase voltage detection capacitor that is attached directly to the core wire of a distribution line, but this type of capacitor cannot be attached to a distribution line made of insulated wire. It is difficult, especially when working with live wires. In addition, when considering a capacitor that is attached directly to the circumferential side of an insulated wire on a distribution line in consideration of removal from the distribution line, rainwater may enter between the insulated wire and the capacitor, causing a change in capacitance.
If the rate of change in capacitance is different for even one of the three phases, a voltage equivalent to the zero-sequence voltage will be generated, creating a risk of causing the ground fault relay to malfunction.

The present invention has been made by focusing on the above-mentioned problems in the prior art, and is used as a capacitor for detecting voltage to ground in a distribution line. a first conductive layer forming a first capacitor therebetween; and a second conductive layer embedded in an insulating layer integrally formed outside the first conductive layer to form a second capacitor between the first conductive layer and the first conductive layer. By making the first capacitor have a larger capacitance than the second capacitor, the influence of rainwater that enters between the first conductive layer and the outer peripheral surface of the insulated wire is reduced, and both It reduces fluctuations in capacitance as a whole when capacitors are combined, eliminating the risk of malfunctioning of ground fault relays, and also enables direct installation to distribution lines made of insulated wires even in live lines, thereby preventing ground faults. An object of the present invention is to provide a zero-sequence voltage detection capacitor that can be installed at an increased number of locations on a power distribution line in order to shorten the time required to find a fault point.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the zero-phase voltage detection capacitor of the present invention and an entire failure section detection and display device using the same will be described below with reference to the drawings. First, the outline will be explained according to FIGS. 1 and 2. The insulated wires 4 of each phase in the distribution line supported by the pin insulator 3 erected on the arm 2 of the utility pole 1 have zero phase, respectively. Voltage detection capacitor 5
is fitted, and a current detector 6 is attached to the center of the capacitor 5. A reinforcing arm provided between the telephone pole 1 and the arm 2 to support the arm 2 has a terminal for connecting the lead wire 7 led out from each capacitor 5 to one shield wire 8. In addition to the box 9 being fixed, a display 12 is fixed to the lower part of the utility pole 1 using scaffolding bolts 10 and mounting bands 11, and the display 12 is attached to the display 12 bound by the scaffolding bolts 10 at the upper position. The lead wire 13 of each detector 6 and the shield wire 8 are connected.

Next, the zero-phase voltage detection capacitor 5 will be explained in detail with reference to FIGS. It is formed so that it can be divided into two in the direction. The two capacitor pieces 21 each have a semi-cylindrical shape, and are removably opposed to each other in their planar portions and are in close contact with each other.

The inside of each capacitor piece 21 is connected to the outer peripheral surface of the insulated wire 4, and a first conductive layer 22 made of conductive rubber is formed in a semi-cylindrical shape so as to form a first capacitor between it and the core wire 4a of the wire 4. and a first insulating layer 23 made of insulating rubber and having an H-shape in front that covers the outer curved surface portion of the conductive layer 22 in a semi-cylindrical shape.
and a second insulating layer 24 made of insulating rubber having a semi-cylindrical shape that covers the curved surface portion of the insulating layer 23, and the first conductive layer 22, both insulating layers 23, A semi-cylindrical metal second conductive layer 25 buried between the two conductive layers 24 forms a four-layer structure integrally formed, and the capacitance of the first capacitor is larger than that of the second capacitor. The location and size of the second conductive layer 25 are set.

Further, at both ends of the outer periphery of the first insulating layer 23, square plate-shaped engagement flanges 26 and 27 having different wall thicknesses are integrally formed on the upper and lower dividing surface side edges, respectively, and project in the upper and lower directions. On the side surfaces of each pair of engagement flanges 26 and 27, there are an appropriate number of locking holes 28 (four in this embodiment) each consisting of a pair of large and small holes and a slit that communicates the two holes.
are transparently installed separately. Of the upper and lower engaging flanges 26 and 27, a finger hook 29 is attached to the end of one of the thicker engaging flanges 26.
6, and its flange 2
A connecting piece 30 made of an insulating material harder than the flanges 26 and 27, such as synthetic resin such as polyethylene resin, is fitted and locked into the locking hole 28 at 6, and the outer end of the connecting piece 30 is fitted with the flange 26. A large-diameter disk-shaped locking portion 30a is formed to abut and lock on the outer surface of the locking hole 28, and a circular plate is formed in the center of the locking portion 30a to fit into the large-diameter hole portion of the locking hole 28. A columnar insertion part 30b is formed, and a conical engagement part 30c is formed at the inner end thereof.

Further, near the end of the other thin-walled engagement flange 27, a square plate-shaped finger hook piece 31 is provided to protrude in the direction in which the flange 27 extends. The finger hook piece 29 of the engaging flange 26 contacts the engaging flange 27 of one of the capacitor pieces 21 with a shift of about half.
It is used together with the finger hook piece 29 to disengage the connecting piece 30 of the other capacitor piece 21 from the locking hole 28 in the locking hole 28 .

Further, a support protrusion 32 is formed to protrude laterally near one end of the side surface of the second insulating layer 24, and the end of the lead wire 7 is integrally supported by molding on the support protrusion 32. A conducting wire 7a of the lead wire 7 is connected to the second conductive layer 25.

The inner diameter of the first conductive layer 22 is formed to be slightly smaller than the outer diameter of the insulated wire 4, so that the inner surface of the first conductive layer 22 can come into close contact with the outer peripheral surface of the insulated wire 4, and The length of the fitting part 30b of the connecting piece 30 is formed to be equal to or slightly shorter than the combined thickness of both engaging flanges 26 and 27,
The pair of capacitor pieces 21 can be brought into close contact with each other, especially at both ends thereof.

Next, the current detector 6 will be described in detail with reference to FIGS. 6 to 10, with the front side of the page in FIG. An upper frame 42 made of a plate material is fastened with bolts so as to extend to the right, and a fixing fitting 43 made of a plate material with an inverted L-shaped cross section is located slightly above the center thereof and extends to the lower left. The mounting brackets 44 are fitted and welded together as shown in FIG. A plate-shaped attachment piece 45 is fixed at its base end.

A support piece 46 made of a vertically long L-shaped plate is bolted to the left end of the fixing metal fitting 43 at its lower part, and a terminal part 47 is supported and fixed to the upper part of the support piece 46. A bottomless box-shaped terminal box 48 that covers the terminal block 47 from above with a predetermined gap is located in the center, and a box fixing base 49
, and cylindrical guide columns 50 are arranged side by side at the front and rear positions between the lower end portion and the upper frame 42, and the upper and lower ends of both guide columns 50 are connected to the upper frame 42 and the upper frame 42, respectively. It is tightened and fixed to the support piece 46 with a nut.

Each guide column 50 has a cylindrical movable body 51.
is fitted loosely so that it can move up and down, and a plate-shaped connecting piece 52 is welded between the upper ends of both movable bodies 51 to move both movable bodies 51 integrally. The upper and lower surfaces of the movable body 51 are adapted to restrict the vertical movement range of the movable body 51 by contacting the lower surface of the upper frame 42 and the upper surface of the support piece 46, respectively. A movable frame 53 extending to the right is welded to the lower end of each movable body 51 at each fork-shaped end of a connecting portion 53a forming a horizontal Y-shape in plan,
At the upper end of the distal end of the connecting portion 53a in the movable frame 53, a horizontal plate-shaped attachment portion 53b is formed so as to form a T-shape on the side with respect to the distal end of the connecting portion 53a.

A channel-shaped current transformer mounting base 54 is attached to the mounting portion 53b of the movable frame 53 so as to be movable up and down.
On the lower surface of the mounting base 54, support columns 55 are provided at symmetrical positions in the front and back, respectively, and extend through the mounting portion 53b of the movable frame 53 so as to be vertically movable. A locking nut 56 is screwed onto the lower end of the support column 55, and is adapted to restrict the upward movement range of the mounting base 54 by coming into contact with the lower surface of the mounting portion 53b. Pillar 5
A compression spring 57 is loosely fitted in each of the mounting portions 5 to bias the mounting base 54 upwardly with respect to the mounting portion 53b.

A semicircular lower current transformer piece 58 and a horizontal L-shaped lower core piece 59 are screwed to the front and back positions of the upper surface of the mounting base 54, respectively, and are screwed to the front and rear positions of the right end of the lower surface of the upper frame 42, respectively. The upper current transformer piece 60 has a semicircular ring shape and the upper core piece 61 has a horizontal L-shape, which are screwed together, so that they can be pressed against each other. A connecting core piece 62 whose lower surface can be pressed against the upper surface of the lower core piece 59 is protruded from the open end of the lower surface of the upper core piece 61, and a coil 63 molded with an insulator is provided on the core piece 62. spacers 64 are interposed between the upper and lower core pieces 61 and 59 and the upper frame 42 and the mounting base 54, respectively, and each of the upper and lower core pieces 61 and 59 A clamping piece 65 that clamps the zero-phase voltage detection capacitor 5 at the second insulating layer 24 portion is fixed to the inner surface, and the inner surface of the clamping piece 65 has a curved surface corresponding to the outer peripheral surface of the insulating layer 24. A fitting recess 65a is formed.

The coils in each of the current transformer pieces 58, 60 are formed of conductors having a square cross section and a pair of U-shaped cross sections, as shown in FIG. Current transformer piece 58,6
0, an annular current transformer 66 for zero-sequence current detection having an inner hole slightly smaller than the outer diameter of the second insulating layer 24 of the capacitor 5 is formed, and each of the core pieces 59, 61, 62 and The coil 63 forms a current transformer 67 for detecting overcurrent.

A plate-shaped guide piece 68 having a horizontal U-shape in plan is bolted to the mounting piece 45, and the upper current transformer piece 60 is held between the upper parts thereof, and a guide part 68a is provided at the lower end of the plate-shaped guide piece 68. is bent outward to insert and guide the lower current transformer piece 58, and both current transformer pieces 5
8 and 60 are surely placed in close contact with each other. Further, lead wires (not shown) led out from both current transformers 66 and 67 are connected to the 2-core shielded 4-core lead wire 13 in the terminal box 48,
The lead wire 13 is supported and fixed to the box fixing base 49 by a wire holding plate 69, and is inserted into the main column 41 from the center thereof and led out from the lower end.

A locking pin 71 is fitted and attached to the lower part of the connecting portion 53a of the movable frame 53 so as to protrude in the front-rear direction, and the upper end portion of the connecting link 72 is rotatably attached to both the front and rear portions of the locking pin 71. A connecting pin 73 is fitted and attached to the lower end portions of both links 72. The connecting pin 73
The upper end of a lock lever 74 having a bent shape at the lower part is rotatably connected to both ends of the lock lever 74, and the upper right end of the lock lever 74 is removably engaged with the locking pin 71. An engaging protrusion 75 is provided, and a shaft pin 76 is rotatably attached to the bent portion of the engaging protrusion 75, which is fitted and attached to both of the mounting brackets 44, and a retaining pin 77 is provided between the lower end portions of the engaging protrusion 75. is inserted and installed. The upper end of a cylindrical operating lever 78 is disposed between the lower portions of both the lock levers 74 and the pins 76, 7.
7 so that they cannot move relative to each other.

Note that the lower surfaces of the main pillar 41 and the operating lever 78 are coated with an insulating material such as insulating rubber, and the connecting links 72 of the connecting pin 73 are coated with an insulating material such as insulating rubber.
Spacing rings are fitted between the connecting link 72 and the lock lever 74, respectively.

Next, regarding the display unit 12, FIGS.
To explain in detail according to FIG. 3, this display 12
A terminal box 82 is provided at the bottom of the case 81, and a metal outlet 8 is provided at the top inside the terminal box 82 for connecting the lead wires 13 and shielded wires.
2, 84 are provided, and the case 81
At the top of the lid, there is a ground fault directional relay DG on the front inside the lid.
In addition, an integration counter 85 for measuring the number of ground fault failures is provided on the front center of the case 81, and an indicator bar 86a for ground fault direction and overcurrent display is installed outside the case 81 in the center of the case 81. A solenoid 86 is provided for protruding to. Further, on the upper surface of the case 81, a ground terminal 87 and a mounting fitting 88 for hanging the case 87 from the scaffolding bolt 10 are provided, and on the back thereof, a fitting 89 for attaching to the mounting band 11 is provided.

The case 81 of the display 12 has built-in electrical components corresponding to the electrical circuit surrounded by the dashed line in FIG. The currents are passed through a transformer and a rectifier circuit, and the output currents are combined and smoothed for each phase, and the overcurrent relay 90
There is an overcurrent detection circuit connected to the Further, the current from the zero-phase current detection current transformer 66 in each phase is combined for three phases and the terminal of the ground fault direction relay DG is
There is a ground fault direction detection circuit that includes a circuit that inputs to Z ₁ and Z ₂ and a circuit that inputs the zero-sequence voltage from the shielded wire 8 to the terminal N of the relay DG. Further, the operating power input to the relay DG at terminals P ₁ and P ₂ via the surge absorber is input to the transformer, and the output of the transformer is rectified and
It is smoothed and input to the no-voltage detection relay 91 as an operating DC power source, and on the other hand, it is connected to the integration counter 85, the power supply capacitor C, and the solenoid 86 via the output terminals A and C of the relay DG. and a diode D for backflow prevention between the counter 85 and the capacitor C.
There is a circuit in which the normally closed contact X ₁ b of the relay 91 is connected between the capacitor C and the solenoid 86, and on the other hand there is a circuit in which the normally closed contact X 1 b of the overcurrent relay 90 is connected to the solenoid 86 through the normally open contact X ₀ a of the overcurrent relay 90. There is a circuit for connecting to the operating DC power source.

When the current input to the relay 90 exceeds the set value, the contact X ₀ a of the relay 90
is closed, and the contact _X1b of the relay 91 is opened when there is no power input thereto, and further, when a ground fault is detected between contacts A and C of the relay DG. The substation is now shorting for a longer period of time than it takes for the substation to trip.

Next, the operation of the entire failure section detection and display device configured as described above will be explained. First, the zero-phase voltage detection capacitor 5 will be explained. This capacitor 5 is constructed by fitting a pair of capacitor pieces 21 facing each other to the insulated wires 4 of each phase. The mating flanges 26 and 27 are brought into close contact with each other. Then, each capacitor piece 21 is immovably attached to the outer peripheral surface of the insulated wire 4 on the inner surface of the first conductive layer 22, and a second capacitor is formed between the capacitor piece 21 itself and the core wire 4a of the insulated wire 4 together with the second capacitor in the capacitor piece 21 itself. One capacitor is formed. The capacitors 5 of each phase installed in this manner detect the ground voltage of each phase, and a zero-phase voltage obtained by combining the respective ground voltages is inputted to the shielded wire 8.

Note that when detecting this ground voltage, if there is a change in the capacitance of at least one phase of the capacitors 5 for each phase, a zero-sequence current will flow to the shielded wire 8 even if there is no ground fault. There is a risk that the output will cause the ground fault directional relay DG to malfunction.
In each capacitor piece 21 of this embodiment, the capacitance of the first capacitor, which is at risk of changing capacitance due to rainwater entering between the insulated wire 4 and the first conductive layer 22, is set higher than that of the second capacitor. The capacitance as a whole is approximated to the capacitance of the second capacitor, which has no change in capacitance.

In addition, when removing the capacitor 5 from the insulated wire 4, the finger hook pieces 29 and 31 of the different capacitor pieces 21 are spread apart, and the engaging portion 30c of the connecting piece 30 provided on one of the engaging flange 26 is removed.
Since it comes off from the locking hole 28 of the other engaging flange 27, the capacitor piece 21 is separated into two parts and removed from the insulated wire 4.

Next, the current detector 6 will be explained. The operating lever 78 of this detector 6 is rotated to open and close relative to the main column 41 around the shaft pin 76, and due to this rotation, the operating lever 78 is integrally connected to the operating lever 78. The axis of the connecting pin 73 that connects the lock lever 74 and the connecting link 72 attached to the lock lever 74 connects the axis of the locking pin 71 that connects the connecting link 72 and the movable frame 53 with the axis of the shaft pin 76. Dead center D (Fig. 6 and 10)
(indicated by a dashed line in the figure) in the vertical direction. Further, the rotation of the operating lever 78 is converted into vertical movement of the movable frame 53 via the lock lever 74 and the connecting link 72, and the vertical movement is performed linearly by the guide column 50 via the movable body 51.

The upward movement of the movable frame 53 is transmitted to the current transformer mount 54 against the spring force of the compression spring 57, and the upward movement of the mount 54 causes the lower current transformer piece 58 to be guided by the guide piece 68. The spring 57 can be moved without any displacement in the front and rear and lateral directions with respect to the upper current transformer piece 60.
At the same time, the lower core piece 59 is pressed against the upper core piece 61, and the zero-sequence current detection current transformer 66 and the overcurrent detection current transformer 67
form. Note that the upward movement of the movable frame 53 is toggled and locked when the engaging protrusion 75 of the locking lever 74 is engaged with the locking pin 71, and when both the core pieces 50 and 61 are pressed together, the connecting core piece The lower surface of 62 is pressed against the lower core piece 59 to form a core with low magnetic resistance.

On the other hand, the downward movement of the movable frame 53 is carried out with the help of the spring force of the compression spring 57 as soon as the axis of the connecting pin 73 passes the dead center D, and the downward movement is carried out when the lower surface of the movable body 51 touches the upper surface of the lower part of the support piece 46. The current transformer pieces 58 and 60 (both core pieces 59 and 61
The same applies to the case of 2)), which is larger than the outer diameter of the simple cylindrical central portion of the capacitor 5.

Now, when attaching this current detector 6 to the insulated wire 4, first, as shown in FIG.
The capacitor 5 is loosely fitted into the center of the capacitor 5 from the outside using its dielectric strength, and the upper current transformer piece 60 and the upper clamping piece 65 are fitted and locked from above. In this state, the operating lever 78 is closed by tilting it at a predetermined angle with respect to the vertical line, if necessary, taking into account the influence of wind and rain. Then, the center portion of the capacitor 5 is held between the current transformer pieces 58, 60 and the holding pieces 65 in a slightly contracted state, so that the current detector 6 is fixed to the capacitor 5, and the current detector 6 is fixed to the capacitor 5. Both current transformers 66 and 67 are formed, and each current transformer 66 and 67 outputs a transformed current to the display 12, respectively.

Note that if the operating lever 78 is opened in the above state, the output to the display will disappear and the capacitor 5 can be removed, and the operating lever 78
In the case where the capacitor 5 is opened and locked, or when the capacitor 5 is clamped, the engagement flanges 2 at both ends of the capacitor 5 remain even if the current detector 6 is moved in the axial direction with respect to the capacitor 5.
6, 27 prevents the current detector 6 from coming off the capacitor 5.

Next, the indicator 12 that receives the outputs of the capacitors 5 and detectors 6 for each phase will be explained. First, if a ground fault occurs in the distribution line where the insulation recovers in a shorter time than it would take for the substation to trip. Since the operating power is not lost, the contact _X1b remains open, and the terminals A and C of the ground fault direction relay DG are short-circuited, so the integration counter 85
works and counts one time.

Next, when a ground fault that trips the substation occurs in the distribution line, no current flows to the no-voltage detection relay 91, so its contact X ₁ b closes, and the current is stored in the power supply capacitor C. Flowing electricity through the solenoid 86 causes the indicator bar 86a to become the indicator 1.
The second case 81 is protruded and locked, and the counter 85 counts the number in the same manner as described above.

Furthermore, when an overcurrent flows in the distribution line, the current flowing through the overcurrent relay 90 exceeds the set value, so the relay 90 operates and contacts X ₀ a
is closed, and the solenoid 86 is operated to project the display bar 86a.

As described in detail above, the zero-phase voltage detection capacitor of the present invention includes a first conductive layer that is closely attached to the outer peripheral surface of an insulated wiring in a distribution line and forms a first capacitor between the core wire of the insulated wire; Consisting of an insulating layer integrally formed on the outside of a conductive layer, and a second conductive layer embedded within the insulating layer to form a second capacitor with a smaller capacitance than the capacitor between the conductive layer and the conductive layer. This reduces the influence of rainwater that enters between the first conductive layer and the outer peripheral surface of the insulated wire, making the overall capacitance less susceptible to external influences, and reducing the risk of malfunctioning of the ground fault relay. This eliminates the problem of ground faults, enables live-line work to be carried out on distribution lines, increases the number of locations on distribution lines that can be installed, and contributes to shortening the time required to find fault points in the event of ground faults. This invention is preferable for industrial use as a zero-phase voltage detection capacitor for fault detection.

Note that the present invention is not limited to the above embodiments, and may include integrating the first and second insulating layers,
Any changes can be made without departing from the spirit of the invention, such as forming the second conductive layer from conductive rubber or changing the shape of each part as necessary.

[Brief explanation of drawings]

FIG. 1 is a front view showing the installed state of an embodiment of the present invention together with the entire failure section detection and display device, FIG. 2 is a side view similarly showing the installed state, and FIGS. A phase voltage detection capacitor is shown, with FIG. 3 being an exploded perspective view thereof, FIG. 4 being a plan sectional view thereof, and FIG. 5 being a side sectional view thereof.
Figures 6 to 10 similarly show the current detector, Figure 6 is its front view, and Figure 7 is approximately X-X of Figure 6.
8 is a side view thereof, FIG. 9 is a sectional view taken approximately along the line Y--Y in FIG. 8, and FIG. 10 is a front view showing the opened state. Figures 11 and 12 also show the display unit, and Figure 11 is its front view, and Figure 1
Figure 2 is a side view of the same. FIG. 13 is also an overall electrical circuit diagram. Insulated wire 4, core wire 4a, zero-phase voltage detection capacitor 5, first conductive layer 22, first insulating layer 23, second insulating layer 24, second conductive layer 25.

Claims (1)

[Scope of Claims] 1. A first conductive layer that is closely attached to the outer circumferential surface of an insulated wiring in a distribution line and forms a first capacitor between it and the core wire of an insulated wire, and an insulating layer that is integrally formed on the outside of the conductive layer. and a second conductive layer that is embedded in the insulating layer and forms a second capacitor with a smaller capacitance than the capacitor between the conductive layer and the conductive layer. capacitor. 2. The zero-sequence voltage detection capacitor according to claim 1, wherein both the conductive layer and the insulating layer have a cylindrical shape and are formed so as to be able to be divided into two in the axial direction. 3. The zero-phase voltage detection capacitor according to claim 1 or 2, wherein the first conductive layer is made of conductive rubber.