JP2011141212A - Method of measuring surface pressure of interface between cable insulator and rubber block - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of measuring a surface pressure in which a case of going into a measurement incapable condition hardly occurs in a case where measuring of the surface pressure of an interface between a cable insulator and a rubber block is performed for a long time period. <P>SOLUTION: A rigid holder 6 is used that has a support 6a supporting a surface at the opposite side of the pressure receiving surface 4a of a surface pressure sensor 4, a frame 6b surrounding the periphery of the surface pressure sensor 4 and a housing 6c accommodating a lead wire 5 of the surface pressure sensor 4. The surface pressure sensor 4 is fitted into a recess formed by the support 6a and the frame 6b of the holder 6 so as to be held thereby, and the lead wire 5 in the vicinity of the surface pressure sensor 4 is accommodated in the housing 6c by giving slack to the lead wire 5. The holder 6 having the surface pressure sensor 4 and the lead wire 5 built therein is fitted into a recess 1a formed at a part of the outer peripheral face of the cable insulator 1, and the rubber block 2 is covered thereon, and then a surface pressure of the interface 3 between the cable insulator 1 and the rubber block 2 is measured. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for measuring the surface pressure at the interface between a cable insulator and a rubber block when a power cable connecting portion is formed using a cold-shrinkable rubber block.

  For the power cable connection part using the normal temperature shrinkable rubber block, the cylindrical rubber block held in the expanded state is placed around the conductor connection part and the cable insulation on both sides, and then the expanded member is removed. Thus, the rubber block is contracted, and the rubber block is brought into close contact with the conductor connecting portion and the outer peripheral surface of the cable insulator by the contraction force (see Patent Document 1).

  In such a power cable connection part, the surface pressure at the interface between the cable insulator and the rubber block due to the contraction force of the rubber block ensures the necessary insulation performance. It is necessary to grasp the magnitude of the pressure in advance. For this reason, conventionally, a surface pressure sensor is installed at the interface between the cable insulator and the rubber block, and the surface pressure is measured in a state where a heat cycle of room temperature to high temperature (90 ° C. to 105 ° C.) is applied.

  Specifically, for example, in the case of a 66 kV to 154 kV class high voltage power cable connection part, the thickness of the cross-linked polyethylene insulator of the cable is thin (9 to 17 mm), and the volume of the rubber block is small. A counterbore hole is formed to allow the surface pressure sensor to enter, and after installing the surface pressure sensor, cover the rubber block and connect the lead wire of the surface pressure sensor to a measuring instrument installed outside the rubber block. Then, the surface pressure was measured.

JP 2001-8353 A

  However, in the 275 kV to 500 kV class ultra-high voltage power cable connection part, the thickness of the cross-linked polyethylene insulator of the cable becomes as thick as about 23 to 30 mm, and the volume of the rubber block increases. Thermal expansion and contraction also increases. As a result, when a conventional method is used for heat cycles or when measuring surface pressure for a long time at a constant high temperature, the lead wire near the surface pressure sensor breaks during measurement and a high percentage of cases occur. Turned out to be.

  An object of the present invention is to provide a method for measuring a surface pressure that is less likely to be unmeasurable when measuring the surface pressure at the interface between a cable insulator and a rubber block over a long period of time.

In order to achieve the above object, the present invention provides a method for measuring a surface pressure applied to a cable insulator by a rubber block by installing a surface pressure sensor at an interface between the cable insulator and a cylindrical rubber block placed thereon.
A rigid holder having a support portion that supports a surface opposite to the pressure receiving surface of the surface pressure sensor, a frame portion that surrounds the periphery of the surface pressure sensor, and a housing portion that accommodates a lead wire of the surface pressure sensor is used. In addition, the surface pressure sensor is fitted into the concave portion formed by the support portion and the frame portion of the holder to hold the surface pressure sensor, and the lead wire in the vicinity of the surface pressure sensor is accommodated in the housing portion with slack. The surface pressure sensor and the holder incorporating the lead wire are fitted into a recess formed in a part of the outer peripheral surface of the cable insulator, and the rubber block is put over to measure the surface pressure at the interface between the cable insulator and the rubber block. It is characterized by doing.

  In the surface pressure measuring method according to the present invention, the surface pressure sensor is a horizontal type in which a lead wire is drawn out from a part of a peripheral edge thereof, and the holder is formed of a concave portion constituted by the support portion and a frame portion. It is preferable that a lead wire accommodating portion is provided on the side, and the accommodating portion is filled with a filler having rubber elasticity so as to embed the lead wire therein.

  Further, in the surface pressure measuring method according to the present invention, the surface pressure sensor is a vertical type in which a lead wire is drawn out from a surface opposite to the pressure receiving surface, the holder is cylindrical, and A support portion and a frame portion are formed, a space below the support portion is a lead wire accommodating portion, and a notch portion is formed at a part of the lower edge of the lead portion. The lead wire can be pulled out of the holder.

  According to the present invention, the surface opposite to the pressure receiving surface of the surface pressure sensor is supported by the support portion of the holder, and the periphery of the surface pressure sensor is surrounded by the frame portion of the holder. There is little risk of displacement or deformation due to the pressure of the rubber block, and the lead wire near the surface pressure sensor is housed in the holder housing with slack, so that the thermal expansion of the cable insulator and rubber block Even if the contraction is large or a high pressure is applied to the surface pressure sensor, the possibility that the lead wire near the surface pressure sensor is broken is reduced. Therefore, it is possible to reduce the number of cases where measurement is impossible even if the surface pressure measurement is performed for a long time while keeping the temperature constant or applying a heat cycle.

An example of the surface pressure measuring method which concerns on this invention is shown, (A) is a cable radial direction longitudinal cross-sectional view, (B) is the plane expanded view in the BB line of (A). The horizontal type surface pressure sensor used for the Example of FIG. 1 is shown, (A) is a top view, (B) is a side view. The other example of the surface pressure measuring method which concerns on this invention is shown, (A) is a cable radial direction longitudinal cross-sectional view, (B) is the plane expanded view in the BB line of (A). FIG. 4 is a side view showing a vertical type surface pressure sensor used in the embodiment of FIG. 3.

Example 1 FIG. 1 shows an example of the present invention. In the figure, 1 is a cable insulator made of cross-linked polyethylene or the like coated on the outer periphery of a conductor of a power cable, 2 is a cylindrical rubber block that covers the outer periphery of the cable insulator, and 3 is a cable insulator 1 and a rubber block. 2 is an interface, 4 is a surface pressure sensor, 5 is a lead wire of the surface pressure sensor 4, and 6 is a rigid (for example, metal) holder.

  The surface pressure sensor 4 has a disk shape as shown in FIG. 2 and is a horizontal type in which the lead wire 5 is drawn out from a part of the periphery. Reference numeral 5 a denotes a pair of insulating core wires of the lead wire 5. For example, the surface pressure sensor 4 attaches a strain gauge to the back surface of the diaphragm constituting the pressure receiving surface 4a, and detects the pressure applied to the diaphragm as a resistance change of the strain gauge due to the distortion of the diaphragm.

  Further, the holder 6 has a flat plate shape, a support portion 6 a that supports a surface opposite to the pressure receiving surface 4 a of the surface pressure sensor 4, an annular frame portion 6 b that surrounds the periphery of the surface pressure sensor 4, and the surface pressure sensor 4. And an accommodating portion 6c for accommodating a nearby lead wire 5. The surface pressure sensor 4 is fitted in a recess formed by a support portion 6a and a frame portion 6b of the holder 6, and is fixed to the holder 6 with an adhesive or the like. Further, the portion of the lead wire 5 near the surface pressure sensor 4 is accommodated in the accommodating portion 6c with a slack, and is further embedded with a filler 7 having rubber elasticity filled in the accommodating portion 6c. As the filler 7, it is preferable to use a silicone rubber-based or epoxy-silicone rubber-based filler.

  The holder 6 in which the surface pressure sensor 4 and the lead wire 5 are incorporated as described above is fitted into a recess 1a formed in a part of the outer peripheral surface of the cable insulator 1, and is fixed by an adhesive or the like. In this state, the pressure-receiving surface 4 a of the surface pressure sensor 4 substantially coincides with the outer peripheral surface of the cable insulator 1. Therefore, when the rubber block 2 is put on the outer periphery of the cable insulator 1, the surface pressure sensor 4 causes the cable insulator 1 to be covered. The surface pressure at the interface between the rubber block 2 and the rubber block 2 can be detected. The lead wire 5 passes through the interface between the cable insulator 1 and the rubber block 2, is led out from the end of the rubber block 2, and is connected to a measuring instrument (not shown). In this state, the surface pressure at the interface between the cable insulator 1 and the rubber block 2 is measured.

  By doing so, the surface pressure sensor 4 is firmly held by the holder 6, so that the surface pressure sensor 4 is less likely to be displaced or deformed by the pressure of the rubber block 2, and the surface pressure sensor 4 is located near the surface pressure sensor 4. Since the lead wire 5 is accommodated in the accommodating portion 6c of the holder 6 with a slack and embedded with a filler 7 having rubber elasticity, even if a high pressure is applied to the surface pressure sensor 4, a cable insulator or Even if the thermal expansion and contraction of the rubber block is large, the possibility that the lead wire 5 near the surface pressure sensor is disconnected is reduced. Therefore, even if the surface pressure measurement under a constant high temperature or a heat cycle is performed for a long time, the number of cases in which measurement cannot be performed can be reduced.

  According to the conventional surface pressure measurement method and the surface pressure measurement method of this embodiment, a surface pressure measurement at a constant temperature of 100 ° C. was performed for n test pieces for 200 days. While it became impossible to measure, only 30% became impossible to measure with the surface pressure measuring method of this example.

<Embodiment 2> FIG. 3 shows another embodiment of the present invention. In FIG. 3, the same or corresponding parts as in FIG. As shown in FIG. 4, the surface pressure sensor 4 used in this embodiment is a vertical type in which a lead wire 5 is drawn from a surface opposite to the pressure receiving surface 4a.

  The holder 6 has a cylindrical shape, and an annular support portion 6 a that supports a surface opposite to the pressure receiving surface 4 a of the surface pressure sensor 4 and an annular frame portion 6 b that surrounds the surface pressure sensor 4 at the upper end thereof. The space below the support portion 6 a is a housing portion 6 c that houses the lead wire 5 near the surface pressure sensor 4. The surface pressure sensor 4 is fitted in a recess formed by a support portion 6a and a frame portion 6b of the holder 6, and is fixed to the holder 6 with an adhesive or the like. Further, the portion of the lead wire 5 in the vicinity of the surface pressure sensor 4 is accommodated in the accommodating portion 6c with a slack. A notch 6 d is formed in a part of the lower end edge of the holder 6. The lead wire 5 comes out of the holder 6 from the notch 6d, rises along the outer peripheral surface of the holder 6, passes through the interface between the cable insulator 1 and the rubber block 2, and passes from the end of the rubber block 2 to the outside. And connected to a measuring instrument (not shown).

  In such a state, even if the surface pressure measurement at the interface between the cable insulator 1 and the rubber block 2 is performed, the same effect as in the first embodiment can be obtained.

1: Cable insulator 1a: Depression 2: Rubber block 3: Interface 4: Surface pressure sensor 4a: Pressure receiving surface 5: Lead wire 5a: Insulating core wire 6: Holder 6a: Support portion 6b: Frame portion 6c: Housing portion 6d: Notch 7: Filler

Claims (3)

In the method of measuring the surface pressure applied to the cable insulator by the rubber block by installing a surface pressure sensor at the interface between the cable insulator and the cylindrical rubber block placed on the cable insulator,
A rigid holder having a support portion that supports a surface opposite to the pressure receiving surface of the surface pressure sensor, a frame portion that surrounds the periphery of the surface pressure sensor, and a housing portion that accommodates a lead wire of the surface pressure sensor is used. In addition, the surface pressure sensor is fitted into the concave portion formed by the support portion and the frame portion of the holder to hold the surface pressure sensor, and the lead wire in the vicinity of the surface pressure sensor is accommodated in the housing portion with slack. The surface pressure sensor and the holder incorporating the lead wire are fitted into a recess formed in a part of the outer peripheral surface of the cable insulator, and the rubber block is put over to measure the surface pressure at the interface between the cable insulator and the rubber block. A method for measuring the surface pressure at the interface between a cable insulator and a rubber block.   The surface pressure sensor is a horizontal type in which a lead wire is drawn out from a part of the periphery of the sensor, and the holder has a lead wire receiving portion beside a recess formed by the support portion and the frame portion. 2. The surface pressure at the interface between the cable insulator and the rubber block according to claim 1, wherein the accommodating portion is filled with a filler having rubber elasticity so as to embed a lead wire therein. Measuring method.   The surface pressure sensor is a vertical type in which a lead wire is drawn out from a surface opposite to the pressure receiving surface, the holder is cylindrical, and the support portion and the frame portion are formed at an upper end portion thereof, and the support portion The lower space is the lead wire receiving part, and a notch is formed in part of the lower edge of the lead wire, and the lead wire is drawn out of the holder from this notch. The method for measuring the surface pressure at the interface between the cable insulator and the rubber block according to claim 1.

Images