JPH0381102B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a power detector used for detecting a zero-sequence voltage in order to detect a ground fault section at a terminal connection portion of a power cable.

[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, and 14 is a cable conductor.
1 is a shielding copper tape, and 15 is a sheath. 16 again
17 is a conductor of a device (such as a switch), 17 is an insulator thereof, 18 is a terminal compressed and connected to the cable conductor 11, and 19 is a bolt/nut for tightening and connecting the terminal 17 and the device conductor 16. 20 is a stress cone mounted on the cable insulator 12, 21 is a conductive tape wrapping layer, 22 is an insulating tape wrapping layer, and 23 is a connecting tube installed so as to span from the stress cone 20 to the equipment insulator 17. It is.

The connection tube 23 includes an insulating layer 24 and an internal conductive layer 25.
and an outer conductive layer 26, but the outer conductive layer 26 is separated at two places in the longitudinal direction, and the insulating layer 24 is exposed over the entire circumference at the separated part. In other words, the intermediate external conductive layer 26a is insulated from the external conductive layers 26b and 26c at both ends, and constitutes an intermediate electrode for detecting voltage, and this portion serves as a detecting portion. External conductive layers 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 also has a 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 of constantly detecting voltage,
As shown in Figure 3 of Japanese Patent No. 48-38793 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.

[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. A band whose at least one side and the outer peripheral surface side are made of an integrated conductive rubber layer, and a hook side metal fitting attached to one end of the band, hook the loop side metal fitting attached to the other end of the band, and then A buckle that tightens the end surfaces of the band while applying tension to the band, a viscoelastic sealing material attached to both sides of the inner circumferential surface of the band and along the abutting portion of the end surfaces, and insulation on the inner circumferential surface of the band. The band is characterized by comprising an electrode provided in the middle of the rubber layer, and a conductive member electrically connected to the electrode and led out of the band while being insulated from the conductive rubber layer of the band. It is something.

This voltage detector is attached by wrapping the above-mentioned band around a voltage detecting part formed on a power cable connection tube, etc., and tightening it with a buckle, and detects voltage without removing the band using a conductive member led out of the band. This is what we do.

〔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
34 is an electrode, 34 is a voltage detection cap, 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. It is formed. In addition, there are pin holes 3 in the thick parts at both ends for attaching buckles.
6 and 37 are 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, as shown in FIGS. 1 and 2, the buckle 32 has 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. It consists of a loop side metal fitting 4 as shown in the figure.
When the loop 46 of the band 31 is hooked onto the hook 47 of the hook-side metal fitting and the lever 48 is pushed down, both end surfaces of the band 31 are brought into contact with each other. Furthermore, 49
is the fulcrum of the lever 48, and 50 is the fulcrum of the loop 46.

Next, in order to maintain the watertightness of the inner circumferential surface of the band 31, grooves are formed on both sides of the inner circumferential 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. (Figures 4 and 5),
A viscoelastic sealing material 52 is also attached to one end face of the band 31 (FIG. 3). The viscoelastic sealing materials 51 and 52 are both made of soft rubber and are easily deformed under pressure to fill the gap and exhibit a sealing effect, but the viscoelastic sealing materials 51 on both sides of the inner peripheral surface are conductive. The viscoelastic sealing material 52 on the end face is an insulator.

Next, the electrode 33 is connected to the band 3 as shown in FIG.
1, and is disposed at the center of the insulating rubber layer 39 on the inner circumferential surface of the conductive rubber layer 40, and is insulated from the conductive rubber layer 40. This electrode 33 is made of metal, and a screw pin 53 is attached to the back side of the electrode 33.
is welded. The screw pin 53 is connected to the cylindrical portion 38.
It passes through the center of the bottom of the hole and is fixed in 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 53 are fixed to the large diameter portion and extend on both sides of the small diameter portion.

On the other hand, a metal tube 57 is embedded inside the cylindrical portion 39, and an insulating tube 58 provides insulation between the metal tube 57 and the probe 55. 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 tube 57, the sleeve 59, and the lead wire 35 are covered with an insulating rubber layer 39 on their outer peripheries and are insulated from the conductive rubber layer 40.

Next, as shown in FIG. 6, the voltage detection cap 34 is
An insulating rubber part 61 is integrally provided inside the cap-shaped conductive rubber part 60, and the insulating rubber part 61
A cylindrical metal fitting 62 is adhesively fixed to the center. When the voltage detection cap 34 is placed over the cylindrical portion 38 protruding from the band 31, the cylindrical metal fitting 6
2 pushes the leaf spring 56 apart, the tip of the leaf spring 56 contacts the inner surface of the metal tube 57, and the electrode 33 and the metal tube 5
7 is conductive, but when the voltage detection cap 34 is removed, the tip of the leaf spring 56 is connected to the metal tube 5 as shown in FIG.
The electrode 33 and the metal tube 57 are insulated apart from the inner surface of the metal tube 7 .

The above is the configuration of the voltage detector, and next, how to use it will be explained. First, with the buckle 32 removed, both ends of the band 31 are opened and placed over, for example, the outer periphery of the voltage detection portion of the connection tube 23 in FIG. 11. At this time, the band 31 has an electrode 33 on the outer conductive layer 26a in the middle of the connecting tube 23, an inner surface of the insulating rubber layer 39 on the exposed part of the insulating layer 24, an inner surface of the conductive rubber layer 40 on both sides on the outer conductive layer 26b on both sides, 26c, respectively. Next, the loop 46 of the buckle 32 is hooked onto the hook 47, the lever 48 is pushed down, and the band 31 is tightened. The band 31 has a certain degree of rubber elasticity, and its inner circumference length is slightly shorter than the outer circumference length of the connecting tube 23. Therefore, the band 31 is elastically stretched when tightened by the buckle 32, and extends around the entire circumference of the connecting tube 23. The tightening becomes almost uniform across the entire area. In addition, the viscoelastic sealing material 51 on both sides of the inner peripheral surface seals the gap between the conductive rubber layer 41 surface 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. For sealing, electrode 33 and insulating rubber layer 39
The watertightness of the inner surface will be maintained.

In this state, the voltage detection cap 34 is always covered. Then, since the lead wire 35 and the electrode 33 are electrically connected, normal voltage detection can be performed. usually,
This voltage detector is attached to the cable end of each of the three phases, and as shown in Figure 2, the lead wires 35 of each voltage detector are connected together to detect the zero-phase voltage. . In addition, when detecting whether or not each cable is energized, when the voltage detection cap 34 is removed, the lead wire 35 and the electrode 33 are insulated and the voltage detector 55 is exposed, so a voltage detector is installed there. If you hit the target, you can easily detect the presence or absence of the energized state.

In the above embodiment, the electrode 33 is provided in a part of the circumferential direction, but the electrode may be provided in the center of the inner surface of the insulating rubber layer 39 over the entire circumference.

FIG. 7 shows another embodiment of the invention. In this example, the structure of the voltage detecting cap 34 is different from that of the above embodiment, in that a cylindrical conductive rubber 63 is adhesively fixed to the center of an insulating rubber portion 61 at the deep inside of the voltage detecting cap 34. The thickness of the cylindrical conductive rubber 63 is determined by the detector 55.
When the voltage sensing cap 34 is placed over the cylindrical portion 38, the cylindrical conductive rubber 63 is pushed between the sensing element 55 and the metal cylinder 57, establishing electrical continuity between the two. It's becoming like that.

FIG. 8 shows yet another embodiment of the invention. In this example, a lead wire 35 is attached to the voltage detection cap 34 side. Even in this case, if the voltage detection cap 34 is covered, voltage can be detected at all times, and if the voltage detection cap 34 is removed, the detection electron 55 is exposed and voltage detection can be performed.

FIGS. 9 and 10 show still another embodiment of the present invention. These two 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 to separate the incoming DC component and monitor 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, the conductive rubber layer 40a on one side of the inner peripheral surface of the band 31 and the conductive rubber layer 40b on the outer peripheral surface side (this is integrated with the conductive rubber layer 40c on the other side on the inner peripheral surface). is insulated by an insulating rubber layer 39. By doing this, 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 under live wire conditions. .

Note that in FIGS. 9 and 10, the same effect can be obtained even if the conductive rubber layer 40a on one side is replaced with an insulating rubber layer.

〔Effect of the invention〕

As explained above, the voltage detector of the present invention can be easily installed by simply wrapping a band around the voltage detection part formed at the end of the cable and tightening the buckle. By tightening with rubber elasticity and sealing action with viscoelastic sealing material, the inner circumferential surface including the electrode can be reliably waterproofed from the outside. Since a conductive member led out from the band is electrically connected to the electrode while being insulated from the conductive rubber layer of the band, voltage detection can be performed without taking out the band. Furthermore, since the outer circumferential surface of the band is covered with a conductive rubber layer (ground), the amount of electricity induced in the external conductive layer in the middle of the voltage detection part increases due to the gondensor partial pressure, making it difficult to constantly detect voltage. It becomes possible.

[Brief explanation of drawings]

1 and 2 are a front view and a side view of a voltage detector according to an embodiment of the present invention, FIG. 3 is a front view of the band portion of the same detector with the buckle and voltage detection cap removed, and FIG. Figures and Figure 5 are the third
6 is a sectional view of the voltage detection cap portion of the same detector, FIG. 7 is a sectional view of the voltage detection cap portion showing another embodiment of the present invention, and FIG. The figure is a partial sectional view of the voltage detection cap portion showing still another embodiment of the present invention, and FIGS. 9 and 10 correspond to the above-mentioned FIGS. 4 and 5 showing still other embodiments of the present invention. FIG. 11 is a cross-sectional view showing a conventional cable termination having a voltage detecting section. 31 - Band, 32 - Buckle, 33 - Electrode,
34 - Voltage detection cap, 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 - Viscoelastic sealing material, 55 - Microscope, 56 - Leaf spring, 57 - Metal cylinder, 60 - Conductive rubber part, 61 -
Insulating rubber part, 62 ~ cylindrical metal fitting.

Claims (1)

[Scope of Claims] 1. A band having an insulating rubber layer in the middle part on the inner circumferential side and an integrated conductive rubber layer on at least one side of the inner circumferential side and the outer circumferential side, and attached to one end side of the band. The loop side metal fitting attached to the other end of the band is hooked onto the hook side metal fitting, and the buckle is tightened so that the end surfaces of the band butt against each other while applying tension to the band, and the inner peripheral surface of the band. A viscoelastic sealing material attached along both sides and the end face abutting portion, and an electrode provided in the middle of the insulating rubber layer on the inner peripheral surface of the band, electrically connected to this electrode, and the conductive material of the band. A voltage detector for a power cable, comprising a rubber layer and a conductive member led out of the band in an insulated state. 2. The voltage detector according to claim 1, wherein the band is formed of 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 made of an integral conductive rubber layer on one side of the inner peripheral surface and the outer peripheral surface, and an insulating rubber layer on the other side of the inner peripheral surface and the intermediate part. Something that is layered. 4. 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 is insulated from the conductive rubber layer. A 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 circumferential surface of the band is electrically conductive, and the viscoelastic sealing material provided along the end face abutting portion of the band The viscoelastic seal member provided is insulating.