JPH0419768B2 - - Google Patents

Description

[Detailed description of the invention]

(a) Industrial application field The present invention relates to a method for assembling an OF cable connection part,
In particular, the present invention relates to an assembly method for reducing moisture absorption during wrapping of reinforcing insulating oil-impregnated paper. (b) Prior Art An insulating reinforcing layer of oil-impregnated paper as shown in FIG. 1 is usually formed at the connecting portion of an OF cable. That is, after the conductors 2 and 2 of the cable 1 and 1 are connected using the conductor sleeve 3, a reinforcing insulating layer 5 is formed on the core 4 by wrapping oil-impregnated paper, and then the outer periphery of the layer 5 is After that, a connecting copper tube is placed between the metal sheaths 6, 6, and the inside of the tube is evacuated and degassed, and then insulating oil is injected to complete the assembly of the connecting portion. (c) Problems to be solved by the invention By the way, in the connection part as described above, as in the connection part of a general cable, the part A near the end face of the metal sheath 6 is the weakest in terms of electrical insulation. . Therefore, it is desirable to minimize the moisture absorption of the cable insulating paper 7 in this part and the insulating oil-impregnated paper 5a wrapped directly above the core. This is because when the insulating paper absorbs moisture, its insulating strength decreases significantly, reducing the reliability of the connection. However, in the past, the reinforcing insulating oil-impregnated paper was wrapped in the atmosphere;
Forming the reinforcing insulating layer 5 consisting of a and 5b takes a long time, especially in the case of OF cables with a nominal voltage of 275XV or more because the connection part is large, and during this time the connection part is exposed to the atmosphere, so The cable insulating paper 7 and the reinforcing insulating oil-impregnated paper 5a directly above the core, which are in contact for a long time, absorb moisture, reducing the insulation performance of the connection part. (d) Means for Solving the Problems The present invention was made for the purpose of obtaining a connecting part for OF cables with excellent insulation performance, and it consists of a reinforcing insulating oil-impregnated paper wrapped around the cable core and directly above the cable. The tapered part is covered with an oil pan, and insulating oil is injected into the inside of the taper.While maintaining this state, the remaining (upper layer) reinforcing insulating oil-impregnated paper is rolled up.Then, the oil pan is removed and the shielding layer is covered. Formation/Installation of connecting copper pipes/
This is a method for assembling a connection part, which is characterized by performing vacuuming and insulating oil injection. According to this method, at least the insulating oil-impregnated paper located at the electrically insulating weak point is sealed with oil from immediately after the oil-impregnated paper immediately above the core is wrapped until the reinforcing insulating layer is completed, so that its moisture absorption is small. This prevents the insulation strength of oil-impregnated paper from decreasing. For large connections, it may take longer to wrap the reinforcing insulating oil-impregnated paper around the outer periphery of the conductor than at the conductor connection area. Since there is a risk that the insulating paper on the core side may absorb moisture, the insulating paper on the cable core exposed by stripping off the metal sheath should be soaked in insulating oil until just before the work begins to wrap the reinforcing insulating oil-impregnated paper directly above the cable core. It is preferable to cover it with an oil pan to be injected. This method is shown in FIG. 2. As shown in the figure, after the metal sheath is removed, an oil container such as a plastic tube 9 is sealed at both ends with taping 8 on the outer periphery of the insulating paper 7 of the cable 1. Install it and inject insulating oil 10 inside it.
The work of connecting the conductors 2, 2 by compressing the conductor sleeve 3 and the work of wrapping the reinforcing insulating oil-impregnated paper 5 on top thereof are performed. When the above work is completed, remove the tube 9, or if the time required to complete the wrapping with the oil-impregnated paper 5 is shortened, the above-mentioned core oil sealing work can be omitted and the core 4 can be removed as shown in FIG. A wrapped layer of oil-impregnated paper 5a is formed directly above, and then the exposed core-side insulating paper 7 and the tapered part of the reinforcing oil-impregnated paper 5a, which are essential in the present invention, are covered with an oil receiver such as a plastic tube 9 as described above ( When carrying out the work shown in Fig. 2, it is sufficient to pull one end of the tube on the core and fix it to the tapered part of the layer 5a), and then inject insulating oil 10 into the inside of the tube and maintain this state as shown in Fig. 1. Perform the wrapping work shown in section 5b. If you do this,
The contact time of the cable insulating paper and the reinforcing insulating oil-impregnated paper with the atmosphere can be greatly reduced, and the amount of moisture absorbed can be suppressed accordingly. For example, the results of a moisture absorption experiment on oil-impregnated paper, in which a 125-μ thick insulating oil-impregnated paper was wrapped around a cable core and left in an atmosphere with a humidity of 70 to 85% for 3 hours, showed that from the outermost layer to the second layer, The oil-impregnated paper absorbed 1% or more of moisture, and the moisture absorption rate was 1% or more from the end surface of the paper to about 1.5 to 2 mm in the length direction, and the insulation strength of the moisture-absorbing oil-impregnated paper was as shown in Attached Table 1. However, it has been confirmed through experiments that the cable connection part assembled by the method of the present invention absorbs almost no moisture and maintains almost the same insulation properties as normal oil-impregnated paper.

[Table] Note that if the oil pan used to seal the insulating paper is the above-mentioned plastic tube, it will be easier to attach and detach, and there will be less economical burden even if it is disposable. In addition, when using a half-split sleeve, it can be used repeatedly. (e) Effects As explained above, according to the method of the present invention, it is possible to reduce moisture absorption of cable insulating paper and reinforcing insulating oil-impregnated paper during connection work, and to create highly reliable connections with excellent insulation performance. is obtained.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway front view showing a state in which a conventional OF cable connection part is being assembled, and FIGS. 2 and 3 are front views showing the assembling method of the present invention. DESCRIPTION OF SYMBOLS 1... Cable, 2... Conductor, 3... Conductor sleeve, 4... Cable core, 5... Reinforcement insulation layer,
6...Metal sheath, 7...Cable insulation paper, 8...
...Taping, 9...Plastic sleeve, 1
0...Insulating oil.

Claims (1)

[Claims] 1. Covering the tapered part of the cable core and the reinforcing insulating oil-impregnated paper wrapped directly above the cable core with an oil pan,
Then, insulating oil is injected into the inside, and while maintaining this state, the remaining (upper layer) reinforcing insulating oil-impregnated paper is wrapped up, and then the oil pan is removed and a shielding layer is formed.
A method for assembling an OF cable connection, which is characterized by attaching a connecting copper pipe, drawing a vacuum, and injecting insulating oil. 2. Just before starting the work of wrapping reinforcing insulating oil-impregnated paper directly above the cable core, cover the insulating paper of the cable core exposed by peeling off the metal sheath with an oil pan into which insulating oil will be injected. A method for assembling an OF cable connection portion according to claim 1.