JPH0259575B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method of manufacturing an OF cable,
It relates to a drying/impregnating process that is particularly suitable for long cables.

Background and purpose The so-called radial flow drying and impregnating method described below has been proposed (Japanese Patent Application Laid-Open No.
No. 67893).

"Fig. 1" is a schematic explanatory diagram thereof, and numeral 10 indicates a drying pot. For example, dehumidified and degassed high-temperature insulating oil 16 is fed under pressure into the internal oil passage 14 of the undried cable core 12 placed therein, and the inside of the insulating paper layer 18 is radially moved from the inside to the outside. flow in the direction. The insulating paper is then dried and impregnated by dissolving and absorbing the moisture in the insulating paper in the oil.

However, the above method cannot be used with long cables (submarine OF
When applied to cables, etc.), as shown in the middle row of Figure 1, the pressure P ₀ at the center becomes much smaller than at both ends due to the pressure loss within the oil passage 14. Since the drying/impregnation time is determined by this P ₀ , the required time becomes very long. Also, as shown in the lower part of the figure, the radial flow rate in the shaded area is wasted.

In order to solve this problem, the following method has been proposed (Japanese Patent Application No. 57-64590).

That is, as shown in FIG. 2, a long plastic tube 26 with a large number of small holes 24 provided only in a certain range in the length direction is inserted into the oil passage 14, and the dehumidifying oil is fed through the plastic tube 26. The degassed oil enters the insulating paper layer 18 through the small holes 24 and flows in the radial direction as described above, drying and impregnating only that part (the area where the small holes 24 are provided). Once that section is completed, the tube 26 is moved lengthwise and the adjacent section is dried and impregnated in the same manner as described above, and this process is repeated over the entire length.

Note that 20 is an oil dehumidification/degassing device, 22 is a pressure pump, 28 is a seal, 30 is a vacuum suction device for the drying pot 10, and 32 is a heater. However, the oil dehumidification/degassing device 20 can be omitted.

However, the above method has a problem in that it is difficult to move the tube 26.

This invention solves the above problems and makes it possible to easily apply the so-called radial flow method to long cables.

Structure of the invention (Figure 3) (1) The above-mentioned so-called radial flow drying method
(2) reducing the radius of oil within the insulating paper layer 18 by forming an oil barrier layer 36 on the cable core 12, leaving only a certain area 34 along the length of the cable; (3) The fixed range 34 is sequentially moved from one end of the cable core 12 to the other end. do.

DESCRIPTION OF CONSTRUCTION The barrier layer 36 is formed, for example, by wrapping a plastic tape or a metal tape, each alone or in combination, over the cable.

The oil barrier layer 36 is formed leaving only a certain area 34 where drying and impregnation are performed as described above. Then, only the certain area 34 is put into the drying pot 10. At that time, only the part of the above-mentioned certain range 34 is wrapped around the bread, and the drying pot 1, which is commonly used in the past, is used.
0 (cylindrical shape with the center axis in the vertical direction), and the part on which the barrier layer 36 is formed may be placed outside, but if a horizontally elongated pipe-shaped piece is used as the drying pot 10, Cable core 1 in it
2, the cable core can be easily moved.

The dehumidified and degassed high-temperature oil that is press-fitted from both ends of the internal oil passage 14 is hardly able to flow in the radial direction within the insulating paper layer 18 in the portion where the barrier layer 36 is formed. No certain range 34
The water flows through the insulating paper layer 18 only in that area, and only that part is dried and impregnated. At the same time, drying pot 1
The inside of the cable is evacuated by the vacuum suction device 30, and the cable is dried and the oil is dehumidified and degassed.

Therefore, as in the case of "Figure 2", less oil is needed for drying and impregnation. Moreover, the oil pressure loss at both ends of the oil passage 14 is also small (pressure loss is proportional to the square of the flow rate).

After drying and impregnating the certain area 34, the cable core 12 is moved, for example, to the right.

At that time, for example, as shown in "Figure 4", drying pot 1
The cable core 12 coming out from the cable core 12 is sequentially wrapped with plastic tape 36a to form a blocking layer 36. Further, the plastic tape 36a and the like are peeled off from the cable core 12 entering the drying oven 10, and the barrier layer 36 is sequentially removed. In addition, the flyer 38 and the stripping side part holder 40
is rotated by a suitable power source, but illustration is omitted.

Then, dry and impregnate the area adjacent to the area that has been dried and impregnated first.

Then, the same process is repeated from one end of the cable core 12 to the other end to dry and impregnate the entire cable core.

Thereafter, coating with a metal sheath (the blocking layer 36 is removed before that) is performed in the same manner as in the prior art.

Effects of the invention (1) As in the case of the conventional method shown in FIG. Although the scale can be reduced, the present invention is easier to work with than moving the plastic tube 26.

(2) A barrier layer 36 serves to protect the cable core 12 during the drying and impregnating process.

[Brief explanation of the drawing]

Figure 1 shows the conventional drying method (radial flow method)
Figure 2 is an explanatory diagram of another conventional technique, and Figure 3 is an explanatory diagram of the present invention. FIG. 4 is an explanatory diagram of one of the steps. 10: drying pot, 12: cable core, 14: internal oil passage, 18: insulating paper layer, 34: certain area where no oil barrier layer is provided, 36: oil barrier layer.

Claims (1)

[Claims] 1. Dehumidification and
An OF cable manufacturing method that includes a step of drying and impregnating the insulating paper layer by feeding degassed high-temperature insulating oil under pressure and flowing the insulating paper layer in a radial direction from the inside to the outside. By forming an oil barrier layer on the cable core, leaving only a certain range in the horizontal direction, oil flow within the insulating paper layer occurs only in the area where the oil barrier layer is not formed. A method for manufacturing an OF cable, characterized in that the range in which the oil does not form an oil barrier layer is sequentially moved from one end of the cable core to the other end.