JPH0348542Y2 - - Google Patents

Description

[Detailed Description of the Invention] Technical Field This invention relates to a micro-ground fault detection device that is attached to a power distribution line made of insulated wires and detects ground faults with directionality.

Prior Art Currently, the fault point of a temporary ground fault in an overhead distribution line is detected by using a fault section detection device combined with a sectional switch, using repeated reclosing at a substation. This is done by detecting the interval in which However, for ground faults that occur due to deterioration of insulators, lightning arresters, etc., the insulation often recovers in a short time and retransmission is successful (collectively referred to as a micro-ground fault). It is difficult to discover the point of failure in such a failure.

On the other hand, as a currently widely used ground fault detection method, there is a method that provides directionality to ground fault detection by detecting zero-sequence voltage and zero-sequence current. The most commonly used device for detecting this zero-sequence voltage is a capacitor that is attached directly to the core wire of the distribution line.
Working with live wires is extremely difficult because the insulation layer must be stripped off and connected to the core wire.

Purpose This invention was made by paying attention to the problems existing in the above-mentioned prior art. By integrally forming capacitors for each layer and inputting both zero-phase components to a well-known detector (ground fault direction relay) to display directionality and ground faults, it is possible to detect live wires in distribution lines. To provide a micro-ground fault detection device which can be directly installed in the current state and which can shorten the time required to discover the fault point even in the case of a ground fault where insulation is recovered in a short time as described above. There is a particular thing.

Embodiment An embodiment embodying this invention will be described below with reference to FIGS. 1 to 9.

1 is an insulated wire for each phase installed on a utility pole 2; 3 is a micro-ground fault detection device fitted to the insulated wire 1;

First, to explain the capacitor for zero-phase voltage detection, the capacitor for zero-phase voltage detection has a cylindrical shape, and is formed so that it can be divided into two parts in the axial direction by a dividing piece 4 made of a pair of insulating rubber having the same shape. has been done. Both divided pieces 4 each have a semi-cylindrical shape with a fitting groove 4a having a semi-circular cross section formed on the inner surface, and are removably opposed to each other in their planar portions and are tightly disposed opposite to each other. Reference numeral 5 denotes a sleeve as a first conductive layer that is replaceably fitted into the fitting groove 4a of the divided piece 4, and is formed into a semi-cylindrical shape from conductive foam rubber, and has a sleeve at both ends and the center of its outer peripheral surface. As shown in FIG. 8, a flexible tape 6 is attached to the stepped portion 5a, which has a reduced diameter, and is removably attached to the divided piece 4 by the flexible tape 6. That is, the sleeve 5 is appropriately selected so that the wire clamping groove 13 formed on the inner surface is in close contact with the outer peripheral surface of the insulated wire 1, and a first capacitor is formed between the sleeve 5 and the core wire 1a of the wire 1. I'm starting to do that.

7 covers the outer periphery of the sleeve 5 in a semi-cylindrical shape with an insulating layer 8 interposed therebetween;
A semi-cylindrical metal second conductive layer is molded within the divided piece 4 so as to form a second capacitor between the two conductive layers. The location and size of the second conductive layer 7 are set so that the capacitance of the first capacitor is larger than that of the second capacitor.

Reference numeral 9 denotes a spacer made of insulating rubber that is replaceably provided at both ends of the fitting groove 4a of the divided piece 4, and is formed in a semi-cylindrical shape, and has an engaging protrusion formed in the circumferential direction of the fitting groove 4a. 10, an engagement groove 11 provided on the outer periphery
are engaged to prevent the fitting groove 4a from coming off in the axial direction, and its inner end is in contact with the end surface of the sleeve 5. This spacer 9 is connected to the engaging protrusion 10.
By rotating the engagement groove 11 in the circumferential direction, attachment and detachment can be performed.

Reference numeral 12 denotes a semicircular clamping recess formed on the inner surface of the spacer 9 with a diameter slightly larger than that of the wire clamping groove 13 formed on the inner surface of the sleeve 5, and the central part thereof in the circumferential direction is A pair of clamping protrusions 14 having the same diameter as the clamping groove 13 are formed parallel to each other. Reference numeral 15 denotes a draining ridge that is integrally formed to extend in the longitudinal direction symmetrically on the upper part of the plane part of one of the divided pieces 4, and is designed to improve the waterproof performance of the insulated wire 1. ing.
The both ends thereof are arranged to correspond to the grooves between the clamping protrusions 14 of the spacer 9, and the central part is arranged outward so as to bypass a cut surface 22 of a cut core 21, which will be described later. Note that the draining ridges 15 of the other divided piece 4 are similarly provided at the lower part of the flat portion, and are brought into close contact with the flat portion of the one divided piece 4 to improve waterproof performance.

Reference numeral 16 denotes an engagement flange integrally formed to project upwardly and downwardly in each direction at both ends of the divided piece 4, and 17 indicates an upper and lower both sides edges of the central part of the divided piece 4 so as to be adjacent to both sides of the expansion section 20, which will be described later. These are engagement flanges that are integrally formed to extend upwardly and downwardly, respectively. Each engagement flange 16,1
Insertion holes 16a and 17a are transparently provided in the side surfaces of 7, respectively.

Reference numeral 18 shown in FIG.
By tightening the nut 19, which is a mounting bolt inserted through the insertion holes 16a and 17a of the sleeve 5 and the nut 19 screwed into the tip, the two divided pieces 4 are separated with the insulated wire 1 being clamped between the sleeve 5 and the spacer 9. They are closely attached to each other.

The sleeve 5, the insulating layer 8, and the second conductive layer 7 constitute a zero-phase voltage detection capacitor.

To explain the zero-sequence current generator integrally molded into the divided piece 4 of this zero-sequence voltage detection capacitor, 21 is a cut core molded inside the expansion part 20 formed on the outside of the central part of the divided piece 4. , are arranged so as to straddle the second conductive layer 7.
Reference numeral 22 denotes cut surfaces exposed at the top and bottom of the plane portion of the divided piece 4, which are formed in a comb blade shape and can engage with the cut surfaces of the cut core 21 molded on the other divided piece 4. . Reference numeral 23 denotes a pair of regulating members made of synthetic resin that are attached to both ends of the cut core 21 with bolts 21a in one of the divided pieces 4, and are formed in a channel shape so as to cover three side surfaces of the end of the cut core 21. Its tip protrudes inward from the cut surface 22 and the divided piece 4
The guide surface 23a is slanted so that it is flush with the flat part of the guide surface 23a, and its inner surface becomes narrower toward the inside.
is formed.

When the divided pieces 4 are brought into close contact with each other by this regulating member 23, the cut core 2 in the other divided piece 4
It is designed to guide the end of 1. 24 is a protective tape wrapped around the entire cut core 21 except for both ends, and 25 is a coil wound around the center of the cut core 21 with the protective tape 24 in between.

26 is a control branch line led out from the expansion section 20, through which a lead wire (not shown) connected to the coil 25 and a lead wire (not shown) connected to the second conductive layer 7 are inserted. has been done.
Furthermore, the control branch line 2 derived from one of the divided pieces 4
6 is a control branch line 2 derived from the other divided piece 4
6 and molded portion 27 to form a control line 28 extending downward.

29 is a scaffolding bolt 30 attached to the lower part of the utility pole 1.
and an indicator fixed by a mounting band 31, to which the lower end of the control line 28 led out from the micro-ground fault detection device 3 is connected for each set.

Note that the sleeve 5 and spacer 9 attached to the divided piece 4 as described above are wires that are normally used (diameter 5
mm to 125 mm) and can be arranged in advance so that they can be replaced.

Next, in order to attach the micro-ground fault detection display device formed as described above to the insulated wire 1, first, a pair of divided pieces 4 are placed opposite each other to the insulated wire 1 of each phase, and the cut surface 22 of the cut core 21 is are fitted while engaging each other. And the engagement flange 1
Attachment bolts 1 are inserted into the insertion holes 16a and 17a of 6 and 17.
8 and tightening the tip of the bolt 18 with the nut 19, the engaging flange 16,
17 in close proximity to each other. Then, the planar parts of each divided piece 4 are brought into close contact with each other via the draining ridges 15, and the inner surface of the sleeve 5 and the spacer 9
The clamping protrusion 14 is immovably attached to the outer peripheral surface of the insulated wire 1 in a watertight manner, and the core wire 1a of the insulated wire 1 is attached together with the second capacitor in the split piece 4 itself.
A first capacitor is formed between the first capacitor and the second capacitor.

The zero-phase voltage detection capacitors 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 control line 28.

Note that when detecting this ground voltage, if there is a change in the capacitance of at least one phase of the zero-phase voltage detection capacitors of each phase, the control line 28 will be detected even if there is no ground fault. Since a zero-sequence current is output and there is a risk of malfunctioning the ground fault direction relay in the indicator 29, in each divided piece 4 of this embodiment, there is a The capacitance of the first capacitor, which is at risk of changing capacitance due to intrusion of rainwater, is made larger than the second capacitor, and the overall capacitance is set to the capacitance of the second capacitor, which has no change in capacitance. It is approximated.

On the other hand, the cut core 21 forms a zero-phase current transformer by having its cut surfaces 22 engaged with each other when the divided pieces 4 are brought into close contact with each other.

The current transformer installed in this manner outputs a transformed current to the display 29 via the control line 28 when a ground fault current flows.

In addition, when removing this slight ground fault detection device 3 from the insulated wire 1, the clamping bolt 1 on both divided pieces 4
8 and the nut 19, it can be removed from the insulated wire 1.

Since this micro-ground fault detection device 3 only requires fitting the divided piece 4 of the zero-phase voltage detection capacitor to the insulated wire 1, the installation work is easier than when the zero-phase current transformer is installed separately. It will be easy. Since the zero-phase voltage detection capacitor and the zero-phase current transformer are integrated, it is possible to reduce variations in performance due to installation when compared with a case where the zero-phase current transformer is separate. Further, when the wire is attached to an insulated wire, the influence of external influences due to environmental changes can be reduced by integrating the wire.

As detailed above, this invention consists of a conductive layer that is closely attached to the outer peripheral surface of an insulated wire in a distribution line, and an insulating layer on the outside of the conductive layer, and the conductive layer and the insulating layer are arranged in the axial direction. A zero-phase voltage detection capacitor is formed so that it can be divided into two parts, and is removably fitted onto the insulated wire. The zero-phase current transformer is equipped with a pair of cut cores that are placed at It does not cause errors even when installed in areas where large load currents flow, such as outlet openings, and since it uses a split current transformer, it is less susceptible to external magnetic fields and can be installed on multi-circuit distribution lines. . Furthermore, even in the case of a ground fault where the insulation recovers in a short period of time, the present invention has an excellent effect of shortening the time required to find the fault point, and is an excellent invention in terms of a utility model.

[Brief explanation of the drawing]

Fig. 1 is an overall perspective view showing the installed state of a micro-ground fault detection device according to an embodiment embodying this invention, Fig. 2 is a front view similarly showing the installed state, and Fig. 3 is a plan view similarly showing the installed state. Figure 4 is a front view of the divided piece of the zero-phase voltage detection capacitor, Figure 5 is a plan sectional view, and Figure 6 is a cross sectional view of the cut core.
FIG. 7 is a longitudinal sectional view of the end of the cut core, FIG. 8 is a perspective view of the sleeve, and FIG. 9 is a perspective view of the spacer. Insulated wire 1, core wire 1a, first conductive layer (sleeve) 5, second conductive layer 7, insulating layer 8, spacer 9,
Cut core 21, control line 28, display 29.

Claims (1)

[Claims for Utility Model Registration] Consisting of a conductive layer closely attached to the outer peripheral surface of an insulated wire in a distribution line, and an insulating layer provided on the outside of the conductive layer, the conductive layer and the insulating layer are centered A zero-phase voltage detection capacitor formed to be split into two in the direction and removably fitted onto the insulated wire; 1. A micro-earth fault detection device comprising a zero-phase current transformer having a pair of cut cores arranged so as to