JPS63175404A - Lead wire leading structure for resin-molded electric apparatus - Google Patents

Abstract

PURPOSE:To improve water resistance performance and to use a lead wire having fluorine resin or vinyl chloride insulating coating and excellent weather resistance by providing a specific protect tube and burying the longitudinal part of the tube in an injection molding resin layer. CONSTITUTION:A protect tube 7 made of a fluorine polymer material in which its surface is activated is provided at the lead of lead wirings 6, the tube 7 is connected with a pressure sensitive adhesive 13 to the wirings 6, and the activated surface of the tube 7 is rigidly secured to a resin molding layer 5. Accordingly, an outdoor resin-molded electric device having a lead wire leading structure in which water resistance performance and insulating performance can be stably maintained for a long period can be obtained. The structure is improved to utilize the excellent weather resistance of the fluorine or vinyl insulator-coated lead wirings.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lead-out structure for a lead wire in an induction electric appliance such as a resin-molded transformer or transformer that is installed outdoors.

[Conventional technology]

Epoxy resin molded electrical appliances are being widely used in the field of outdoor equipment, as epoxy resins have been praised for their excellent heat resistance, weather resistance, and form stability. For example, when installed on a utility pole together with a pole transformer, leakage due to poor insulation of the pole transformer or its load circuit1! A zero-phase current transformer that detects current is being considered. In this type of current transformer, the entire so-called iron-core secondary winding, in which the secondary winding is wound around a ring-shaped iron core, is molded in epoxy resin, and the lead wire conductively connected to the secondary winding is molded with a layer of molded resin. Usually, a structure is adopted in which the pipe is drawn directly from the pipe. When adopting such a lead wire lead-out structure, the insulation coating of the lead wire has excellent weather resistance, and even if exposed to direct sunlight or rain dew for many years, it will be firmly fixed without causing deterioration such as cracks, and the tension applied to the lead wire will be reduced. It is required to be able to withstand bending, screwing, etc., and maintain adhesion for a long period of time to prevent moisture from penetrating from the drawer. Therefore, in conventional outdoor resin molded electric appliances, polymer materials such as polytetrafluoroethylene and vinyl chloride are used for the insulation coating, with emphasis placed on the weather resistance of the lead wire. Each has a material composition that can stably withstand long-term outdoor use.

[Problem that the invention seeks to solve]

In conventional resin-molded electrical appliances formed as described above, the insulation coating of the loosely exposed wires, which emphasizes weather resistance, has adhesion (also called adhesiveness) with epoxy resins such as polytetrafluoroethylene and vinyl chloride. Because of this, the interface between the insulating coating of the lead wire and the epoxy resin mold layer tends to peel off at the lead-out part of the lead wire, and the heat applied due to changes in ambient temperature during long-term use is likely to occur. The peeling will expand due to stress or mechanical stress applied through the lead wire, and moisture will penetrate into the iron core secondary winding through this gap, resulting in a decrease in the insulation resistance of the winding and leakage. Increase in current.

There was a problem in that damage such as corrosion of the iron core and winding conductor and breakage of the winding conductor was likely to occur.

In particular, in the case of a zero-sequence current transformer installed on a utility pole, it is necessary to detect the zero-sequence current (leakage current) generated in the load circuit as a minute current on the order of several mA on the secondary winding side. ,
The secondary winding conductor is extremely thin and its insulation coating is also thin. Therefore, even a small amount of water intrusion may cause a decrease in insulation resistance or corrosion of the winding conductor.

The purpose of this invention is to improve the water resistance by strengthening the adhesion with the resin mold layer and mechanical reinforcement at the lead wire lead-out part, and to use a lead wire having a fluororesin-based or vinyl chloride-based insulation coating. There are things you can do to make it possible.

[Means for solving problems]

In order to solve the above-mentioned problems, (1) according to the present invention, an induction electric appliance main body including an iron core and a winding wire wound around the iron core, and a lead-out portion of a lead-out wire conductively connected to the winding are molded in cast resin. In the molded product, the lead wire is fixed with a pressure sensitive adhesive so as to cover the outer peripheral surface of the lead part of the lead wire,
A protective tube made of a polymeric material whose outer surface has been activated is provided, and a portion of the protective tube in the length direction is embedded in the casting resin mold layer.

[Effect]

By immersing the fluorine thread resin in a metal sodium 17um alcohol solution with a predetermined concentration and activating the surface, the adhesion (adhesiveness) with the mold resin can be improved by the mechanical breaking strength Kl of the fluororesin. Based on the experimental study results, a protective chip made of an activated fluororesin-based polymer material was applied in advance to cover the lead-out part of the lead wire using a pressure-sensitive adhesive, and then attached to the iron-core secondary winding. After making the conductive connection, the protective tube is resin-molded together with the iron core secondary winding so that a portion of the length in the length direction is buried in the molded resin layer, so that the lead-out portion of the lead wire is embedded in the resin molded layer through the protective tube. In addition to being firmly fixed, the lead-out part of the lead wire is reinforced with a protective tube, and the mechanical stress applied to the lead-out part of the lead wire is alleviated. By using the lead wire with excellent weather resistance, it is possible to obtain an outdoor resin molded electric appliance with excellent water immersion resistance at the lead part.

〔Example〕

The present invention will be explained below based on examples.

Figure 1 is a side view showing the embodiment device, and Figure 2 is A of Figure 1.
-A partially fragmented side sectional view including the A cross section, both of which show the overall structure of the embodiment device.

In the figure, 1 is a cored secondary winding which is the main body of the current transformer, and consists of a secondary winding 4 wound around an annular iron core 2 with an insulating layer 3 in between, and both ends of the secondary winding 40. The part is conductively connected to the lead wire 6 and drawn out to the outside of the resin mold layer 5 made of an epoxy resin composition, and the protection tube 7 whose lengthwise part is embedded in the resin mold layer 5 is connected to the lead wire 6. is attached to the outer periphery of the lead wire 6 using a pressure-sensitive adhesive (not shown). In addition, a through hole 8 is formed in a portion of the resin mold layer 5 that corresponds to the hollow portion of the iron core secondary winding 1. It is formed so that the reciprocating conductors 9A and 9B (three conductors in the case of three phases) can penetrate therethrough. In the zero-phase current transformer formed in this way, when load currents of equal magnitude and opposite directions flow through the reciprocating conductors 9A and 9B, the current magnetic fields generated by both conductors cancel each other out and become zero. , no voltage (current) is induced in the iron core secondary winding 1, but when an unbalanced current such as a leakage current to the ground side occurs, the current magnetic field due to this unbalanced current circulates through the iron core 2,
As a voltage (current) is induced in the secondary winding 4 by this magnetic flux, it is possible to detect the occurrence of an unbalanced TL current (zero-sequence current). This is an enlarged cross-sectional view showing the detailed structure of the lead line drawing part. In the figure, inside the resin mold layer 5 that encloses the iron-core secondary winding 1, one terminal of the winding conductor 4A of the secondary winding 4 and one terminal of the conductor 6A of the lead wire O are connected by soldering, for example. 10 etc., and on both sides where the lead wire 6 intersects the surface 5A of the resin mold layer 5, that is, the lead-out portion of the lead wire, an insulating coating 6B of the lead wire is applied with a pressure-sensitive adhesive 13. The protective tube t1 is activated in advance to form an activated surface 17, and a part 7A of the protective tube 7 is covered with a resin mold layer. 5, the activated surface 17 and the resin mold layer 5 are firmly fixed without any gaps, and the remaining part 7B is exposed to the atmosphere, and the lead line 6 forms an acute angle at the surface 5A of the resin mold layer 5. Make sure not to bend it.

It is also formed to act as a protective tube that relieves stress so that large stress is not applied to the drawer section.

In the example device, for the lead wire B, a lead m with excellent weather resistance such as a fluororesin insulated lead wire with an insulating coating material such as polytetrafluoroethylene or polytrifluoroethylene or a vinyl chloride insulated lead wire is used. , as the protective tube 7,
Polytetrafluoroethylene.

Fluorine fiber resin cubes such as polytrifluoroethylene, polyvinyl fluoride, polyvinylidene butylene, polyhexafluoropropylene, etc. are immersed in an alcohol solution containing several percent of metallic sodium for about 1 minute to activate the surface. After surface activation treatment of the tube 7, adhesive pressure-sensitive adhesive is applied to the position corresponding to the lead-out part of the lead line B. By thermally softening the adhesive, it is possible to form an adhesive layer 13 with high adhesion between the lead wire and the protective tube, and moisture can penetrate through the adhesive surface after resin molding. You can completely prevent it from happening.

Figure 4 shows adhesive strength test data showing the activation treatment effect in Example. After immersing a polytetrafluoroethylene tube in an alcohol solution containing 5% metallic sodium for 1 minute, it was thoroughly washed with water and dried. An epoxy resin mold model simulating the lead line part shown in Fig. 6 was created using a mold that did not undergo this treatment and a mold that did not undergo this treatment.
The drawings show the results of measuring the pull-out adhesive strength with and without heat sealing treatment performed at 00°C for t-5 cycles. In the figure, for those without activation treatment, 887 cyd before heat shock treatment and 6 #/cyd after heat shock treatment.
6687 and the protective tube easily pulls out at the interface with the epoxy resin.
It was found that the adhesive strength was as high as ad, the protective tube was tensile sheared before the adhesive surface peeled off, and the adhesive strength was only slightly reduced by heat-shrinking treatment. It became clear that the effect of surface activation treatment was extremely large.

Fig. 5 is a characteristic table showing the results of the underwater immersion test after heat shock treatment of the current transformer of the example.
, weight 0.3# zero phase current transformer t--20℃→100℃5
This figure shows the results of immersion in water after cyclic heat shock treatment. In the example current transformer in which the protective tube was activated, the insulation resistance of 2000 MΩ or more was maintained even after being immersed in water for 500 to 5000 hours, and no change in appearance was observed in the lead-out wire part. . On the other hand, in the comparative current transformer, which is a conventional technology that does not use a protective tube, the insulation resistance was 50 MΩ after being immersed in water for 1,000 hours, and after 2,000 hours, the insulation resistance decreased to almost zero, and slight peeling was observed. It was found that moisture infiltration occurs through interfacial peeling between the lead wire and the epoxy resin mold layer, demonstrating the superiority of the lead wire lead-out structure using a fluororesin protective tube that has been subjected to blow activation treatment. It was also revealed that by adhering the protective chain 1 to the lead wire using a pressure-sensitive adhesive, the mechanical strength and water resistance of this part could be maintained sufficiently.

〔Effect of the invention〕

As mentioned above, this invention provides a protective tube made of a fluorine thread polymer material whose surface has been activated, for the lead wire lead-out portion of an outdoor resin molded electric appliance using a fluorine-based or vinyl chloride-based insulated lead wire. , and glue the protective tube to the lead wire using pressure-sensitive adhesive.
The activated surface of the protective tube was configured to be firmly fixed to the resin mold layer. As a result, the problem of conventional technology in which poor adhesion between the lead wire and the resin mold layer causes the interface between the two to peel, allowing moisture to penetrate and reducing insulation performance has been eliminated, and the lead wire can be removed at the lead-out portion. For outdoor use, it has a lead wire structure that is firmly fixed to the resin mold layer, is mechanically strong, and does not easily peel off due to thermal stress, and therefore can stably maintain excellent water resistance and insulation performance over a long period of time. We can provide resin molded electrical appliances. In addition, by improving the opening structure,
The advantage is that the excellent weather resistance of the fluorine-based or vinyl-based insulated lead wire can be utilized.

[Brief explanation of the drawing]

Fig. 1 is a side view of a zero-phase current transformer showing an embodiment, Fig. 2 is a partially fragmented side sectional view showing the A-A cross section of Fig. 1, and Fig. 3 is an enlarged view of the main part showing an embodiment. A cross-sectional view, FIG. 4 shows adhesive strength test data showing the activation treatment effect in Examples, and FIG. 5 shows underwater immersion test data in Examples. DESCRIPTION OF SYMBOLS 1... Iron core secondary winding, 2... Iron core, 3... Insulating layer, 4... Secondary winding, 5... Resin mold layer, 6...
... Lead wire, 6A ... Conductor, 6B ... Insulation coating,
7...Protection tube, 8...Through hole, 9, 9A, 9
B... - next conductor, 10... solder connection, 16...
Pressure sensitive adhesive, 17... Activated surface, 7A... Embedded part of protective tube, 7B... Exposed part of protective tube. 3rd (2)

Claims (1)

[Scope of Claims] 1) An induction electric appliance body including an iron core and a winding wound around the iron core, and a lead part of a lead wire conductively connected to the winding, which are molded with a cast resin, A protective tube made of a polymeric material whose outer surface is activated is fixed with a pressure-sensitive adhesive so as to cover the outer peripheral surface of the outlet portion of the outlet wire, and a portion in the length direction of the protective tube is fixed to the outer peripheral surface of the outlet portion of the outlet wire. A lead wire lead-out structure for a resin-molded electric appliance, characterized in that it is embedded in a cast resin mold layer. 2) The resin-molded electric appliance according to claim 1, characterized in that the protective tube is made of a fluororesin-based polymer material and has been activated with a metal sodium alcohol solution. Output line extraction part structure. 3) A lead wire lead-out structure for a resin-molded electric appliance as claimed in claim 1 or 2, wherein the protective tube has heat-shrinkable properties.