JPS634283B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to oil-immersed electrical equipment using a novel electrical insulating oil. Polyolefin has excellent electrical insulation properties, so electrical insulation paper, which is made by laminating a polyolefin film such as polyethylene or polypropylene to fiber paper such as kraft paper, has been developed and is used as an insulation layer for power cables and capacitors. ing. Such an insulating layer is constructed by winding these laminated papers onto a conductor and impregnating the wound layer with a synthetic insulating oil such as dodecylbenzene. However, polyethylene and polypropylene have a slight swelling and solubility in dodecylbenzene, which has the disadvantage of adversely affecting the cable's bending properties and oil flow resistance properties, for example in the case of power cables. . In order to address this issue, the present inventors investigated the effects of various electrically insulating liquid substances on polyolefins, and found that the solubility and swelling properties of triisopropyltoluene and triisopropylbutylbenzene on polyolefins were extremely low. I found it. The present invention has been made based on this knowledge, and includes an insulating layer formed by impregnating an electrically insulating oil into a wrapped layer of an electrically insulating film or fiber paper on the outer periphery of a conductor. The object of the present invention is to provide an oil-immersed electrical device characterized in that the film or fiber paper is made of polyolefin, and the electrical insulating oil consists of triisopropyltoluene and/or triisopropylisobutylbenzene. The insulating film used in the present invention can be made in the form of a normal film or non-woven fabric, as well as a laminate of a film and a non-woven fabric, or a non-woven fabric that is immersed in a polyolefin solution and then made into a non-woven fabric. There are those in which polyolefin is attached in the form of fine fibers in a solvent, and those in which polyolefin is dried as is without being immersed in a non-solvent. Polyolefins that can be used include polyethylene, polypropylene, or those crosslinked by crosslinking peroxide, electron beam irradiation, etc., silyl-modified polyethylene that is hydrolyzed and cross-linked by grafting vinyltrimethoxysilane, etc., and silyl-modified polypropylene. etc. In the present invention, in addition to films and fiber papers formed from these polyolefins alone, films and fiber papers made of materials other than polyolefins, such as polyester films, kraft paper, and polyester cloth, are laminated. Film or fiber paper can also be used. Triisopropyltoluene and triisopropylisobutylbenzene used in the present invention have the properties shown in Table 1, and as shown in the table, they have a higher solubility in polyolefins than other electrical insulating oils. Very low swelling.

[Table] The oil absorption and dissolution amounts of the film in the table are calculated by placing 20g of film and 250c.c. of sample oil in a beaker and heating it to 100℃.
This is after heating for 96 hours. Next, examples of the present invention will be described. Example The silyl-modified polyethylene and catalyst masterbatch used in the tests shown in Table 1 were fed into an extruder and extruded into a film, and while it was in a softened state, 50μ thick kraft paper was pressed on both sides, and then The silyl-modified film was crosslinked in a high humidity atmosphere to produce a laminated insulating paper of kraft paper/silyl-modified polyethylene film/kraft paper = 50μ/50μ/50μ. Next, a 275KVOF cable with the following configuration was manufactured using this laminated insulating paper. Combustion wire conductor 1 x 2000mm ² Insulator Laminated insulating paper (17.5mm thick) Shielding material Carbon paper + metal chemical paper Aluminum sheath PVC anti-corrosion Impregnation oil: triisopropyltoluene (Example 1) and triisopropylisobutylbenzene (Example 2) The change in core diameter after heating at 100°C was measured for each of the samples using the following methods. The measurement results are shown in Table 2.

[Table] *Dodecylbenzene (hard) impregnation Next, both ends of the cable core of each of the above examples were sealed, a hydraulic pressure of 1 kg/cm ² was applied to the oil passage, and the amount of oil flowing out from the outer periphery of the core was measured for a certain period of time. The oil flow resistance R was determined from the following formula. △P=QηR/2π・logd ₂ /d ₁ △P: Differential pressure between the oil passage and the outer surface of the core Q: Amount of oil flowing out per unit length of cable and unit time η: Oil viscosity d ₁ : Conductor Diameter d ₂ : Core diameter The measurement results are shown in the drawing. As is clear from the above examples, according to the present invention, swelling and dissolution of polyolefin in the oil-immersed insulator are small, so oil flow resistance increases and bending properties decrease due to swelling and dissolution of polyolefin. can be avoided.

[Brief explanation of the drawing]

The drawing is a graph showing oil flow resistance of an embodiment of the present invention.

Claims (1)

[Scope of Claims] 1. A conductor in which an insulating layer is provided around the outer periphery of a conductor, the insulating layer being a wrapped layer of an electrically insulating film or fiber paper impregnated with electrically insulating oil, wherein the insulating film or fiber paper is made of polyolefin. 1. An oil-immersed electrical device, characterized in that the electrical insulating oil consists of triisopropyltoluene and/or triisopropylisobutylbenzene. 2. The oil-immersed electrical device according to claim 1, wherein the polyolefin is made of silyl-modified polyethylene.