JPH039692B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a new connection method that prevents deterioration of the electrical properties of insulating oil when connecting OF cables using the lead method. BACKGROUND ART A typical example of an OF cable connection structure is as shown in Fig. 1, in which a reinforcing insulating paper layer 1 is provided around the outer periphery of the connection part of the cable conductor, and a metal sheath 3 is provided at the two ends of the cable.
A semi-stop 5 is applied over the shielding layer 4, and then the end of the copper pipe 6 covering the cable connection part is covered with a lead wire 7 into a cable sheath, and the inside is filled with insulating oil 8. Problems to be solved by the invention It was discovered that the electrical properties of the insulating oil sampled after the cable connection were unexpectedly lowered at the connection part of the OF cable as described above, and the cause was investigated. Upon further investigation, it was discovered that the effect of heat during lead work was involved. In OF cables, the metal sheath of the cable is usually lead-sheathed or aluminum-sheathed, but in particular, in the case of aluminum sheathing, high-temperature lead sheathing is likely to occur, causing many of the above problems. Since the work is generally similar to manual work, it was found that the controlled temperature during lead work is likely to be the cause of variations, and the degree of deterioration of electrical characteristics also varies. The inventors of the present invention further investigated the cause of the deterioration of electrical characteristics at the OF cable connection section, and as a result, trace amounts of dissolved metal were detected in the insulating oil whose electrical characteristics had deteriorated after lead work. It was found that there is a correlation between the degree of molten metal and the amount of dissolved metal. The detected molten metals are consistent with the materials of metal parts inside the connections used near the lead work, especially copper,
It was found that lead and zinc have a large negative effect on electrical properties. Means for Solving the Problems The present invention has been made in order to solve the above problems, and includes applying anti-corrosion treatment to the metal parts inside the connection parts that are exposed to heat from the lead metal when connecting OF cables. More specifically, parts made of metals such as copper, lead, and zinc are treated with benzotriazole, tolyltriazole, or their derivatives to prevent lead. This method prevents the metal from dissolving into the insulating oil during construction and prevents the electrical properties from deteriorating. According to studies conducted by the present inventors, the mechanism by which metal dissolves in insulating oil and deteriorates the electrical properties of the insulating oil cannot be clarified, but it is presumed as follows. Hydrocarbon-based insulating oils such as mineral oil and alkylbenzene are mainly used as insulating oils for OF cables, but if this type of insulating oil is attached to metal and subjected to heat treatment such as when working with lead, the oil will oxidize. It deteriorates to produce an organic acid, and this organic acid dissolves the metal into the oil as an organic acid salt, degrading the electrical properties. As a result of various studies from this standpoint, the present invention has been developed to prevent deterioration of the electrical properties of insulating oil after lead work by pre-corrosion-preventing treatment of metal parts as described above. Ta. The rust inhibitors used in the present invention include benzotriazole (BTA) and tolyltriazole (TTA).
or its derivatives, or heterocyclic compounds such as pyrrole rings, pyrazole rings, thiazole rings, imidazole rings, mercapto groups, and thioureas, which have little adverse effect on insulating oils and are effective. As a method for rust prevention treatment of metal material parts, for example, a rust preventive agent is dissolved in a volatile solvent such as alcohol or triethane to a predetermined concentration, the metal material parts are treated with this solution, and then the solvent is dried. Just let it happen. As mentioned above, the anti-corrosion treatment was particularly effective for metal parts containing copper, lead, and zinc. Embodiments Embodiment 1 When performing the connection method of the OF cable having the structure shown in Fig. 1, the following metal material parts are used near the lead work. Shielding layer using copper, junction box, brass semi-stop, lead spacer, tinned copper wire and lead tape. The metal material parts were previously washed with alcohol and then dried. Cleaning alcohol solution is 2.0%
The one containing BTA was used. The plumber is directly under the plumber.

[Table] Effects of the Invention As described above, the present invention suppresses metal elution into oil due to heat from lead work by pre-corrosion-preventing treatment of metal parts inside connecting parts used near lead work parts. This prevents deterioration of the electrical properties of the insulating oil at the connection portion.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a typical structural example of an OF cable connection part. 1... Reinforced insulating paper, 2... Cable, 3... Metal sheath, 4... Shielding layer, 5... Semi-stop,
6... Copper pipe, 7... Lead work, 8... Insulating oil.

Claims (1)

[Claims] 1. When connecting OF cables including lead work,
A connection method characterized by pre-corrosion-preventing treatment of the metal material parts inside the connection part that are exposed to lead metal heat. 2. The method for connecting an OF cable according to claim 1, wherein the metal material component is a component containing copper, lead, and zinc. 3. The OF cable connection method according to claim 1, wherein the rust prevention treatment is performed using benzotriazole, tolyltriazole, or a derivative thereof.