JPS6014450B2 - Preheating method for coated cable conductor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of heating a coated cable conductor in an atmosphere of an inert gas such as N2 gas.

Continuous cross-linking devices equipped with so-called conductor child heating devices include catenary type, vertical type, etc., and the catenary type continuous cross-linking device has a configuration as shown in the schematic diagram of FIG. 1.

That is, the conductor A supplied from the supply drum 1 is guided by the supply cap stan 2, and the conductor A is guided through the conductor child heating device 3.
The material is introduced into a tube and heated, then an insulating coating is applied by an extruder 4, and then introduced into a crosslinked tube 5 for crosslinking and cooling, and then wound on a drum 6. By the way, if the conductor is preheated by the conductor preheating device in an air atmosphere, the conductor will immediately change color.

To prevent this, the conductor is usually preheated in an atmosphere filled with an inert gas such as N2 gas. Further, an electromagnetic induction method is generally adopted for preheating the conductor. The size of the induction heating power source is appropriately determined depending on the wire diameter of the conductor. A very large induction heating power source is required for the heating of large conductors such as cross-linked polyethylene power cables. By the way, in such a large current conductor preheating device, the structure itself generates heat due to eddy current loss due to the large current, and the lubrication of the bearing of the thief that guides the movement of the conductor deteriorates, which often causes failures. In a continuous cross-linking device with a conductor heating device, it is important to stabilize the heating temperature of the conductor. If the heating temperature is unstable, the physical properties of the insulation coating applied to the outside after crosslinking may deteriorate. A problem arises. However, in a large conductor heating device like the one mentioned above,
There is a disadvantage that the temperature of the inert gas also rises due to heat generation due to eddy current loss, making the conductor temperature unstable. Therefore, this invention
The purpose is to prevent the structure of the conductor heating device and the inert gas-filled cover from generating heat due to frequent eddy current heating. The method according to the present invention is a preheating method for heating a covered cable conductor in an inert gas atmosphere such as N2 gas, in which the inert gas in the gas-filled cover is cooled by heat exchange with a cooling medium. be. Here, air, water, etc. can be used as the cooling medium.

Such a cooling medium is preferably forced to flow through the heat exchanger. Examples of the present invention will be described below.

As shown in FIG.
0 includes a short-circuiting sheave 11 and an insulating sheave 12, and each of these sheaves 11 and 12 is covered with a cover 13 filled with an inert gas such as N2 gas.

The coated cable conductor A introduced into the cover 13 is stretched between the short-circuit sheave 11 and the insulating sheave 12, and is pulled out from the upper part of the outer circumference of the short-circuit sheave 11 in the tangential direction, and moves between the two sheaves 11 and 12. It is heated by electromagnetic induction method using a ring transformer.

The cover 13 includes an upper cover part 14 that covers the short-circuit sheave 11 and a lower cover part 15 that covers the insulating sheave 12. Lotus is suitable.

A blower 17 and a heat exchanger 18 are attached to the circulation passage 16, and when the blower 17 is driven, the inert gas in the upper cover part 14 flows through the circulation passage 16 and the heat exchanger 18. It is cooled and flows into the lower cover part 16.

In addition, the inert gas that has flowed into the lower cover part 16 after heat exchange flows through the conductor guide path 19 that passes between the lower cover part 15 and the upper cover part 14, and flows into the upper cover part I4. Then, it circulates between the upper cover part 14 and the lower cover part 15. Therefore, the cooled inert gas can cool a structure that generates heat due to eddy current loss. In addition,
By forming a cooling medium supply path 20 in the heat exchanger 18 and forcing the cooling medium to flow through the blower 21 attached to the two supply paths, a great effect can be achieved in cooling the inert gas. .

The heat exchanger 18 as described above can be installed at any position, and as shown in FIG. 3, it can also be installed inside the upper cover part 14 and the lower cover part 15.

As described above, according to the present invention, since the inert gas sealed in the cover for preventing discoloration of the conductor is cooled by contact with the cooling medium, the structure of the conductor heating device is It is possible to eliminate problems such as malfunctions caused by the temperature of the inert gas-filled cover rising above the allowable limit, and it is also possible to form an insulating coating with excellent physical properties because the conductor temperature can be stabilized. .

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a catenary type continuous cross-linking device, FIG. 2 is a cross-sectional view showing an example of a conductor child heating device used for carrying out the method according to the present invention, and FIG. It is a sectional view showing an example. 13...Gas filling cover, 18...Heat exchanger. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] 1. A method for preheating a coated cable conductor in an inert gas atmosphere, wherein the inert gas in the gas-filled cover is cooled by heat exchange with a cooling medium.