JPS6250671A - Voltage detector for power cable - Google Patents

Abstract

PURPOSE:To make simple the change-over between the voltage detection in normal use and the potential detection at inspection, by providing a conductor member that conducts between the detector element and the metal sleeve inside a detector cap which is removable. CONSTITUTION:A band 31 is fitted around the detection part of a power cable with a buckle 32. Inside a tube 38 of the band 31 a detector element 55 is screwed to a screw pint 53 fixed to an electrode 33, and a metal sleeve 57 is embedded to which a lead wire 35 is connected. In a detector cap 34 a tubuler metal fixture 58 is provided that conducts between the detector element 55 and the metal sleeve 57. In this configuration with the cap 34 put on, the electrode 33 and the lead wire 35 are electrically connected through the tubular metal fixture to allow the voltage detection in normal use. When a zero phase voltage detection is required, the cap 34 is removed to expose the detector element 55, and the induced voltage is thoroughly detected. Thus, the change- over can be made easily.

Description

[Detailed Description of the Invention] [Technical Field] The present invention can be used to detect the presence or absence of a energized state at a terminal connection of a power cable, or to detect a zero-phase voltage to detect an area where a ground fault occurs. The present invention relates to a voltage detector.

[Prior art and its problems]

BACKGROUND ART Conventionally, as a technique for detecting voltage at a terminal connection portion of a power cable, etc., there is a technique using capacitor voltage division, as shown in Japanese Utility Model Publication No. 48-38793. A specific example is shown in FIG.

In the figure, 11 is a cable conductor, 12 is a cable insulator, 13 is a cable outer conductive layer, 14 is a shielding copper tape,
15 is a sheath. Further, 16 is a conductor of the equipment (switch etc.), 17 is its insulator, and 18 is the cable conductor 11.
Terminal 19 is a bolt that connects the terminal I7 and the device conductor 16 by tightening. 20 is a stress cone mounted on the cable insulator 12;
1 is a conductive tape wrapping layer, 22 is an insulating tape wrapping layer, 2
Reference numeral 3 denotes a connecting tube that is installed so as to span from the stress cone 20 to the equipment insulator 17.

The connecting tube 23 is composed of an insulating layer 24, an inner conductive layer 25, and an outer conductive layer 26. The outer conductive layer 26 is separated in two places in the longitudinal direction, and the separated part has a The insulating layer 24 is exposed throughout. In other words, the intermediate external conductive layer N26a is insulated from the external conductive layers 26b and 26c on both end sides and constitutes an intermediate electrode for voltage detection, and this portion serves as a voltage detection section. External conductive layer 26b/2 on both end sides
6c is grounded, and normally a conductive cover 27 is placed over both of them, so the intermediate external conductive layer 26a is also at ground potential, but when detecting voltage, the cover 27 is removed, the intermediate external conductive layer 26a is placed in an electrically floating state, and a voltage detector is brought into contact with the intermediate external conductive layer 26a to detect voltage.

However, the above configuration is inconvenient because the cover must be removed each time voltage detection is performed. In addition, to detect the direction of a ground fault, it is necessary to detect the zero-sequence voltage and zero-sequence current that occur during a ground fault accident and to know the phase difference between them, but to do this, it is necessary to constantly detect the voltage. .

However, with the above configuration, even if the cover is removed and the voltage is constantly detected, the amount of electricity induced in the intermediate external conductive layer is small, and there is a problem in that sufficient detection cannot be performed.

In addition, as a means for constantly detecting voltage,
As shown in Figure 3 of Japanese Patent No. 8793 or Japanese Patent Publication No. 58-12808, there is a method in which a detection electrode is embedded in an insulating layer of a connecting tube. However, such a structure not only complicates the structure of the connecting tube and makes it difficult to manufacture, but also has the problem that it cannot be applied to existing railway lines. Another drawback is that it is not possible to switch between constant voltage detection and voltage detection during inspection to NJ#.

[Means for solving problems and their effects]

The present invention provides a voltage detector for power cables that solves the problems of the prior art as described above, and its structure is such that the middle part on the inner circumferential side is an insulating rubber layer, and the inner circumferential side has an insulating rubber layer. At least one side and the outer peripheral surface are made of an integrated conductive rubber layer,
A band having a cylindrical portion protruding from the outer circumferential surface side, a fastening fitting for tightening the band, a viscoelastic sealing material attached along both sides of the inner circumferential surface of the band and along the end face abutting portion, and the above-mentioned band. an electrode provided in the middle of the insulating rubber layer on the inner circumferential surface of the band; a detector electrically connected to the electrode and led out into the cylindrical part while being insulated from the conductive rubber layer of the band; A metal member installed on the inner surface of the cylindrical part in a state insulated from the conductive rubber layer of the band and the electron probe, and a lead wire having one end connected to the metal member and the other end led out of the band. , and a voltage detecting cap that is placed over the cylindrical portion, and a conductive member is provided in the voltage detecting cap that allows the metal member to pass through the voltage sensing cap four times when the cap is placed over the cylindrical portion. It is characterized by the presence of

This voltage detector is attached by wrapping the above-mentioned band around the voltage detecting part formed on the power cable connection tube, etc., and tightening it with metal fittings. The voltage can be constantly detected on the side, and when the voltage detection cap is removed, the voltage detection electron is exposed and voltage detection can be performed.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

1 to 6 show an embodiment of a voltage detector for power cables according to the present invention. Like the cover 27 in FIG. 11, this voltage detector is used by being attached to the voltage detecting portion of the connecting tube 23, and has an appearance as shown in FIGS. 1 and 2. Reference numeral 31 is a rubber band, 32 is a buckle, 33 is an electrode, 34 is a voltage detection camp, and 35 is a lead wire. - As shown in Fig. 3, the band 31 has a thin middle part and a thick wall at both ends. is formed. In addition, there are pin holes 36 and 37 for attaching buckles to the thick parts at both ends.
is formed, and a cylindrical portion 38 for voltage detection is provided protruding from one thick portion. Furthermore, as shown in FIGS. 4 and 5, the band 31 is formed of an insulating rubber layer 39 at the middle part on the inner circumferential side and a conductive rubber layer 40 on both sides of the inner circumferential side and on the outer circumferential side.

Next, the buckle 32, as shown in FIGS. 1 and 2,
It consists of a hook-side metal fitting 43 attached to one end of the band 31 with a pin 42, and a loop-side metal fitting 45 attached to the other end with a pin 44, and as shown in the figure, the loop-side metal fitting 45 has a loop 46. Hook side metal fitting 43
When the band 31 is hooked onto the hook 47 and the lever 48 is pushed down, both end surfaces of the band 31 are brought into contact with each other. Note that 49 is a fulcrum of the lever 48, and 50 is a fulcrum of the loop 146.

Next, in order to maintain the watertightness of the inner peripheral surface of the band 31,
A groove is formed on both sides of the inner peripheral surface of the band 31, that is, on the inner surface of the conductive rubber layer 40, and a viscoelastic sealing material 51 is adhered thereto (FIGS. 4 and 5). A viscoelastic sealing material 52 is also attached to one side (Fig. 3).
. Both viscoelastic sealing materials 51 and 52 are soft rubber-based,
The viscoelastic sealing material 5 on both sides of the inner peripheral surface is easily deformed by pressure to fill the gap and exhibit a sealing effect.
1 is electrically conductive, and the viscoelastic sealing material 52 on the end face is an insulator.

Next, as shown in FIG. 4, the electrode 33 is installed at the center of the insulating rubber 1139 on the inner peripheral surface of the band 31, and is insulated from the conductive rubber layer 40. This electrode 33 is made of metal, and a screw pin 53 is welded to its back surface. The screw pin 53 passes through the center of the bottom of the cylindrical portion 38, and is fixed at that position by tightening a nut 54. Further, a detector 55 is screwed onto the head of the screw pin 53. The detector 55 has a large diameter on the base side and a small diameter on the distal end, and a pair of leaf springs 56 are fixed to the large diameter portion and extend on both sides of the small diameter portion.

On the other hand, a metal cylinder 57 is embedded inside the cylinder portion 38, and the metal cylinder 57 and the detector 55 are insulated by an insulating cylinder 58. A sleeve 59 is welded to the outer surface of the base of the metal cylinder 57, and the end of the lead wire 35 is connected to the sleeve 59.

In other words, the lead wire 35 is pulled out from the side surface of the band 31 in the axial direction. The ends of the metal cylinder 57, sleeve 59, and lead wire 35 are covered with an insulating rubber layer 39 on the outer periphery.
and is insulated from the conductive rubber layer 40.

Next, as shown in FIG. 6, the voltage detecting cap 34 has an insulating rubber part 61 integrally provided inside a cap-shaped conductive rubber part 60, and a cylindrical metal fitting 62 at the center of the insulating rubber part 61.
(conducting member) is fixed with adhesive. When the voltage detecting cap 34 is placed over the cylindrical portion 38 protruding from the band 31, the cylindrical metal fitting 62 pushes the leaf spring 56 apart as shown in FIG. 6, and the tip of the leaf spring 56 comes into contact with the inner surface of the metal cylinder 57. Electrode 33
However, when the voltage detection cap 34 is removed, the tip of the leaf spring 56 separates from the inner surface of the metal tube 57 as shown in FIG. 4, and the electrode 33 and the metal tube 57 are insulated.

The above is the configuration of the voltage detector, and next, how to use it will be explained. First, with buckle 32 removed, band 3
1 is opened and placed over the outer surface of the voltage detecting portion of the connection tube 23 shown in FIG. 11, for example. At this time, the band 31 is connected to the electrode 33
is attached to the outer conductive layer 26a in the middle of the connecting tube 23, the inner surface of the insulating rubber layer 39 is attached to the exposed part of the insulating layer 24, and the conductive rubber layer 4 on both sides
The loop 4 of the second buckle 32 is positioned so that the inner surface contacts the outer conductive layers 26b and 26c on both sides, respectively.
6 on the hook 47, pull down the lever 48, and tighten the band 31. The band 31 has a certain degree of rubber elasticity, and its inner circumference is formed to be slightly shorter than the outer circumference of the connecting tube 23. Therefore, when the buckle 32 is tightened, elastic elongation is applied, and the connecting tube 23 is stretched around the entire circumference. It will tighten almost uniformly across the entire area. Additionally, the viscoelastic sealing material 51 on both sides of the inner peripheral surface seals the gap between the inner surface of the conductive rubber layer 41 and the external conductive layers 26b and 26C, and the viscoelastic sealing material 52 on the end surface seals the gap between the end surfaces of the band 31. Since the sealing is performed, the watertightness of the electrode 33 and the inner surface of the insulating rubber layer 39 is maintained.

In this state, if you always cover the voltage detection camp 34, the lead wire 35 and the electrode 33 will be electrically connected, so you can always detect the voltage.Normally, this voltage detector is connected to the cable of each of the three phases. attached to each terminal end, and a second
As shown in the figure, the lead wires 35 of each voltage detector are connected together to detect the zero-phase voltage. Furthermore, when detecting whether or not each cable is energized, removing the voltage detector cap 34 insulates the lead wire 35 and the electrode 33 and exposes the detector 55, so place a voltage detector there. In the above embodiment, the electrode 33 is provided in a part of the circumference, but the electrode is provided in the center of the inner surface of the insulating rubber layer 39 over the entire circumference. Although a buckle was used as a metal fitting for tightening, metal fittings or the like may also be used for band-type tightening.

FIG. 7 shows another embodiment of the present invention. In this example, the structure of the voltage detection camp 34 is different from the above embodiment, and a cylindrical shape is formed at the center of the insulating rubber part 61 at the deep inside of the voltage detection camp 34. A conductive rubber 63 (conductive member) is fixed with adhesive. The wall thickness of the cylindrical conductive rubber 63 is formed to be slightly thicker than the gap between the detector 55 and the metal cylinder 57, and the voltage detector cap 34 is connected to the cylinder portion 3.
8, the cylindrical conductive rubber 63 is pushed between the detector 55 and the metal tube 57 to establish electrical continuity between the two.

Note that the lead wire 35 is connected to the voltage detection cap 3 as shown in FIG.
Although it is possible to attach it to the fourth side, the voltage detection cap becomes larger and takes up more space, and if the lead wire is attached, it is difficult to attach or remove the voltage detection cap. Structure is preferred.

FIGS. 9 and 10 show still another embodiment of the present invention, and these figures correspond to FIGS. 4 and 5 of the above embodiment.

Generally, methods for monitoring insulation deterioration in cables include extracting the current flowing from the high-voltage conductor of the cable to the shield and monitoring insulation deterioration from the DC component, or superimposing a DC voltage on the high-voltage conductor of the cable and applying it to the shield. There is a method of separating the incoming DC component and monitoring insulation deterioration based on its fluctuations, but if a voltage detector like the one in the above example is used, the cable shield is continuous from the equipment shield, so the cable It is not possible to extract only the current flowing through the shield.

Therefore, in this embodiment, a conductive rubber layer 40a on one side of the inner peripheral surface of the band 31 and a conductive rubber layer 40b on the outer peripheral surface (this is integrated with the conductive rubber M40C on the other side of the inner peripheral surface) are used. It is insulated by an insulating rubber layer 39. In this way, the cable shield and equipment shield are insulated, so only the current flowing through the cable shield can be taken out, making it possible to constantly monitor cable insulation deterioration during live wire conditions. Become.

In addition, in FIGS. 9 and 10, the conductive rubber layer 4 on one side
A similar effect can be obtained by using an insulating rubber layer as the portion 0a.

〔Effect of the invention〕

As explained above, in the voltage detector of the present invention, when a band is wrapped around the voltage detecting part formed at the end of the cable, etc., and the metal fitting is tightened, the sealing action of the viscoelastic sealing material causes the electrode to be included in the voltage detector. The inner peripheral surface can be reliably waterproofed from the outside. Furthermore, since the outer circumferential surface of the band is covered with a conductive rubber layer (ground), a large amount of electricity is induced in the external conductive layer in the middle of the voltage detection part due to the capacitor partial pressure. By keeping the lead wires conductive, it is possible to constantly detect the voltage. In addition, when voltage detection is required for inspection etc., when the voltage detection cap is removed, the voltage detection electron is insulated from the lead wire and exposed, so voltage detection can be easily performed without removing the band. I can do it.

[Brief explanation of the drawing]

1 and 2 are a front view and a side view of a voltage detector according to an embodiment of the present invention, and FIG. 3 is a front view of the band portion of the same detector with the buckle and voltage detection cap removed.
Figures 4 and 5 are the ■-IV line and V-V line in Figure 3.
6 is a cross-sectional view of the voltage detection camp portion of the detector, FIG. 7 is a sectional view of the voltage detection camp portion showing another embodiment of the present invention, and FIG. 8 is a voltage detection cap portion. 9 and 10 are sectional views of a portion corresponding to FIGS. 4 and 5 above, showing still other embodiments of the present invention, and FIG. 11 is a voltage detection 1 is a cross-sectional view of a conventional cable termination having a section. 31 - band, 32 - buckle, 33 - electrode, 34 - voltage detection camp, 35 - lead wire, 39 - insulating rubber layer, 40
~Conductive rubber layer, 43~Hook side metal fitting, 45~Loop side metal fitting, 46~Loop, 47~Hook, 48~Lever, 51
~ Viscoelastic sealing material, 52 ~ Elastic sealing material, 55 ~ Electron detector, 56 ~ Leaf spring, 57 ~ Metal cylinder, 60 ~ Conductive rubber part,
61 - Insulating rubber part, 62 - Cylindrical metal fitting, 63 - Cylindrical conductive rubber. Figure 3" V Figure 4 Figure 5 Figure 6 Figure 7 Figure 8" 533 39

Claims (5)

[Claims] (1) A band in which the middle part on the inner circumference side is an insulating rubber layer, at least one side of the inner circumference side and the outer circumference side are an integral conductive rubber layer, and a cylindrical part is protruded from the outer circumference side. , a tightening fitting for tightening the band, a viscoelastic sealing material attached along both sides of the inner circumferential surface of the band and along the abutting portions of the end faces, and an intermediate portion of the insulating rubber layer on the inner circumferential surface of the band. an electrode, a detector electrically connected to the electrode and led out into the cylindrical part in a state insulated from the conductive rubber layer of the band, and a conductive rubber layer of the band and the detector on the inner surface of the cylindrical part. It consists of a metal member installed in an insulated state from the metal member, a lead wire whose one end is connected to the metal member and whose other end is led out of the band, and a voltage detection cap that is placed over the cylindrical part. A voltage detector for a power cable, characterized in that a conductive member is provided in the voltage detecting cap to establish electrical continuity between the detecting element and a metal member when the cap is placed over the cylindrical portion. (2) The voltage detector according to claim 1, wherein the band has an integrated conductive rubber layer on both sides of the inner peripheral surface and on the outer peripheral surface. (3) The voltage detector according to claim 1, wherein the band is an integral conductive rubber layer on one side of the inner circumferential surface and the outer circumferential surface, and the other side of the inner circumferential surface and the intermediate portion are formed of a conductive rubber layer. It has an insulating rubber layer. (4) The voltage detector according to claim 1, wherein the band is an integral conductive rubber layer on one side of the inner circumference side and the outer circumference side, and the other side on the inner circumference side is insulated from the conductive rubber layer. conductive rubber layer. (5) In the voltage detector according to claim 1, the viscoelastic sealing material provided along the conductive rubber layer on the inner peripheral surface of the band is electrically conductive, and the viscoelastic sealing material provided along the conductive rubber layer on the inner peripheral surface of the band is The viscoelastic seal member provided is insulating.