JPS6063826A - Oil-immersed laminated insulator - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an all-plastic oil-immersed laminated insulator with improved properties, and particularly to an oil-immersed laminated insulator useful as an oil-immersed insulator for ultra-high pressure oil-immersed cables and the like. be.

In ultra-high voltage OF cables, the dielectric loss increases, so research has been carried out to insulate the cable using a plastic film with a small dielectric constant and dielectric constant, but this has not yet been put into practical use. Not yet.

17) The reason is that when using an all-plastic film as an oil-immersed insulator, the rIJJ problem is that C1ta
Plastics with good nδ generally have (i) poor oil resistance; Swells in oil and increases in thickness and size.

(ii) When a laminated insulator is used, the 1mp withstand voltage deteriorates.

On the other hand, plastics that are excellent in terms of (i) and (ii) above generally have a bad tan δ of 6.

An object of the present invention is to overcome these conventional problems and provide an oil-immersed laminated insulator that improves oil resistance and mechanical breakdown voltage without impairing dielectric properties.

That is, polypropylene or polyethylene is generally considered as an all-plastic OF insulator, but
Such films tend to sag in oil in a short period of time, but as a countermeasure to this, it is possible to restrain the sagging by attaching a plastic film with good oil resistance to both of these polyolefin films 1111.

On the other hand, the impulse resistance of plastic film is very high when used alone, but it drops significantly when it is made into a table shape. A possible cause of this is destruction due to oil discharge in the butt gap caused by laminated tape winding.

Therefore, if the corona resistance of the plastic film used is good, the Imp withstand pressure of the laminate will also be improved. Therefore, when a plastic film with good corona resistance properties is laminated onto the surface of a polyolefin film, the impulse pressure resistance of the resulting composite film increases.

The present inventor completed the present invention as a result of intensive research based on this idea.

Specifically, in the present invention, a desired sheet of a composite film in which a plastic film with excellent oil resistance and corona resistance is laminated on both sides of a polyolefin film is laminated, and M gas insulation is provided between the film layers of this laminate. It is characterized by being impregnated with songs.

In the present invention, examples of the laminating film to be laminated to both sides of the polyolefin film include those shown in Table 1.

The following methods can be used to bond the polyolefin film shown in Table 1 to the bonding film.

(A) Wet lamination (C) Dry lamination (C) Hot melt lamination (C) Extrusion lamination (E) Co-extrusion An electrical insulating oil such as decylbenzene is used. The present invention will be further explained with reference to Examples.

Example 1 A single-sided embossed polycarbonate film having a thickness of 20 μm was laminated to each ihi of a polypropylene film having a thickness of 90 μm to form a composite film.

The bulge characteristics, ε, and tan δ of this bonded single-bonded film, polypropylene film alone, q, and electrical insulating oil were measured, respectively. Also, can you make miniature cables (insulation thickness 1 mm) using each film? was prepared and the Imp withstand voltage was measured.

The obtained results are also listed in Table 2.

As seen from the measurement results in Table 2, in this example product, ε, t
Although an δ is 1, which is a little worse than that of polypropylene alone, the oil swelling properties and Imp withstand voltage as an oil-immersed insulator are significantly improved. As can be seen from the results of the examples, the oil-immersed laminated insulator of the present invention can be used for ultra-high voltage or ultra-high voltage OF
It maintains properties that allow it to be used satisfactorily as an oil-immersed insulator for cables.

Note that the reason why one side of the polycarbonate was embossed was to improve the oil impregnation properties of the laminate and to absorb changes in thickness.

Example 2 A composite film was prepared by bonding a cellophane film embossed on one side to both sides of a biaxially stretched polypropylene film having a thickness of 90 μm via an adhesive.

The properties of this composite film and the biaxially stretched polypropylene film of Hesa 90) were measured in the same manner as in Example 1. The obtained results are shown in Table 8.Table 8 As mentioned above, the oil-immersed laminated insulator of the present invention has a dielectric constant ε and a dielectric loss tangent tan δ while retaining the advantages of an all-plastic material. It has excellent oil resistance and Imp pressure resistance, and its practical value is extremely large.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a main part of an embodiment of the present invention. l... Polycarbonate film layer (thickness 20μ) 2
...Adhesive layer (thickness: 1μ) 8: Polypropylene film Wt (8:90μ)
. Special W “Applicant Furukawa Electric Co., Ltd. Figure 1

Claims (1)

[Claims] L. Desired sheets of a composite film in which plastic films with excellent oil resistance and corona resistance are laminated on both sides of a polyolefin film are laminated, and R6 insulating oil is impregnated between the film layers of this laminate. An oil-immersed laminated insulator characterized by: