JP5924468B2 - Prefab joint for DC CV cable - Google Patents

Description

  The present invention relates to a prefabricated joint for DC CV cable in which a stress cone is installed between an epoxy unit and a cable insulator.

  FIG. 3 shows a conventional prefabricated joint for CV cables (Patent Document 1). In the figure, 1 and 1 are CV cables (cross-linked polyethylene insulated power cables) to be connected, 2 is an epoxy unit, and 3 is a stress cone.

  The end portion of the CV cable 1 is stripped to expose the cable conductor 1a, the cable insulator 1b, and the outer semiconductive layer 1c. The cable conductors 1 a and 1 a are connected by a conductor connecting pipe 4. The epoxy unit 2 includes a reinforcing insulator 2a made of epoxy resin, a buried electrode 2b, and a shielding electrode 2c. The embedded electrode 2b is in contact with the conductor connecting tube 4 and has the same potential as the cable conductor 1a. The stress cone 3 includes an insulating portion 3a and a conductive portion 3b, and is pushed between the epoxy unit 2 and the cable insulator 1b by a pressing device (not shown). The stress cone conductive portion 3b comes into contact with the outer semiconductive layer 1c of the CV cable 1 and becomes a ground potential.

  A ring-shaped stopper 5 is installed between the tip surface of the stress cone insulating portion 3a and the stepped portion of the embedded electrode 2b. The stopper 5 is provided to prevent the tip of the stress cone insulating part 3a from approaching the embedded electrode 2b too much by a pressing force, but may be omitted.

JP 2003-259542 A

  FIG. 4A shows the distribution of equipotential lines in the prefabricated joint when alternating current is applied to the cable conductor 1a. In this case, no problem arises because all equipotential lines pass through the stress cone insulating portion 3a. However, when a direct current is applied to the cable conductor 1a, the distribution of equipotential lines in the prefab joint is as shown in FIG. That is, the equipotential line is shifted to the high voltage side and enters the air layer (space) S ahead of the tip of the stress cone insulating portion 3a. In such a state, there is a concern that a micro discharge may occur due to the concentration of the electric field or a temperature increase may occur, causing a problem in the cable connection portion.

  Even when the ring-shaped stopper 5 is installed between the distal end surface of the stress cone insulating portion 3a and the embedded electrode 2b as shown in FIG. 3, the air layer S remains on the inner peripheral side or the outer peripheral side of the stopper 5. The electric field concentrates there and the same problem occurs.

  In view of the above problems, an object of the present invention is to eliminate the electric field concentration near the tip of the stress cone insulating portion in the DC CV cable prefab joint, and to improve the insulating performance.

In order to achieve the above object, the present invention provides a conductor connection pipe for connecting the cable conductors in two DC CV cables having end portions stripped and exposing a cable conductor, a cable insulator, and an external semiconductive layer. And an epoxy unit having at least a reinforcing insulator made of epoxy resin, an embedded electrode in contact with the conductor connecting pipe, an insulating portion and a conductive portion, and between the epoxy unit and the cable insulator Stress cones that are pushed into
In a prefabricated joint for a direct current CV cable comprising the conductor connecting tube, the embedded electrode, the cable conductor, the cable insulator, and an air layer confined by a tip surface of the insulating portion of the stress cone .
The said portion in contact with the air layer of the front end surface of said insulating portion in the stress-relief cone, membrane DC Division photoelectrically suppressing conductive coating from the equipotential line enters into the air layer when the said cable conductor It is characterized by being formed .

  According to the present invention, by applying a conductive paint to the distal end surface of the insulating portion of the stress cone, it is possible to suppress the equipotential lines from entering the air layer existing on the distal end side (high pressure side) of the stress cone insulating portion. Therefore, generation | occurrence | production of the micro discharge in the same air layer can be suppressed, and insulation performance can be improved.

Sectional drawing which shows one Example of the prefab joint for direct-current CV cables which concerns on this invention. Explanatory drawing which shows distribution of an equipotential line at the time of direct-current charging to the prefab joint of FIG. Sectional drawing which shows an example of the conventional prefabricated joint for CV cables. FIGS. 4A and 4B are explanatory diagrams showing equipotential distributions when the AC power is applied to the prefabricated joint of FIG. 3 and FIG.

  FIG. 1 shows an embodiment of the present invention. This DC CV cable prefab joint is different from the conventional prefab joint shown in FIG. 3 in that the conductive paint 6 is applied to the front end surface of the stress cone insulating portion 3a. As the conductive paint 6, a conductive paste can be used. Specifically, Dotite (trade name) manufactured by Fujikura Kasei Co., Ltd., Super Coroheite (trade name) manufactured by Nippon Graphite Industry Co., Ltd. can be used. Since the configuration other than the above is the same as that of the conventional prefab joint shown in FIG. 3, the same parts are denoted by the same reference numerals and the description thereof is omitted.

  When the conductive paint 6 is applied as described above, the equipotential lines enter the air layer S existing on the distal end side (high voltage side) of the stress cone insulating portion 3a when the direct current is applied to the cable conductor 1a. Can be suppressed.

  FIG. 2 shows the distribution of equipotential lines in the prefabricated joint when DC power is applied to the prefabricated joint of FIG. In this case, since the conductive paint 6 is applied to the tip surface of the stress cone insulating part 3a, the equipotential lines do not enter the air layer S existing on the tip side of the stress cone insulating part 3a. For this reason, generation | occurrence | production of the micro discharge in the air layer S can be suppressed, and insulation performance can be improved.

1: CV cable 1a: cable conductor 1b: cable insulator 1c: outer semiconductive layer 2: epoxy unit 2a: reinforcing insulator 2b: buried electrode 2c: shielding electrode 3: stress cone 3a: insulating part 3b: conductive part 4 : Conductor connecting pipe 5: Stopper 6: Conductive paint S: Air layer

Claims (1)

A conductor connecting pipe for connecting the cable conductors to each other and a reinforcing insulator made of at least an epoxy resin in two DC CV cables whose ends are stepped and the cable conductor, the cable insulator, and the external semiconductive layer are exposed And an epoxy unit having an embedded electrode in contact with the conductor connecting pipe, an insulating portion and a conductive portion, a stress cone pushed between the epoxy unit and the cable insulator, and the conductor connection In a DC CV cable prefab joint comprising a tube, the embedded electrode, the cable conductor, the cable insulator, and an air layer confined by a tip surface of the insulating portion of the stress cone ,
The said portion in contact with the air layer of the front end surface of said insulating portion in the stress-relief cone, membrane DC Division photoelectrically suppressing conductive coating from the equipotential line enters into the air layer when the said cable conductor A prefabricated joint for DC CV cable, characterized by being formed .

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