JPS61179081A - Water resisting treatment for cable connection - 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 [Technical Field to Which the Invention Pertains] The present invention relates to a method for waterproofing a connecting portion between an outlet cable end portion drawn out from a submersible pump motor, an undersea work motor, etc. and a power cable end portion.

[Prior art and its problems]

The electric motors in this building are used under water and under constant water pressure, and the connection between the outlet cable terminal and the power cable terminal is also often submerged in water, so the connections must be insulated. The coating is required to have high water impermeability.

FIG. 1 is a schematic side sectional view of the main parts of a stone chamber mower used in a submerged state. In the figure, 1 is the yoke of the motor that is airtight to withstand water pressure, 2 is the stator core, 3 is the stator coil, 4 is the rotor, 5 is the outlet cable, and 6 is the internal connection between the outlet cable and the coil conductor. A portion 7 is a connection portion between the outlet cable 5 and the power cable 8.

In the example shown in the figure, a partition wall 9 made of a non-magnetic material and airtightly bonded to the inner wall surface of the yoke 1 is connected to a stator core 2, a stator coil 3. A hollow part 10 is formed that encloses the internal connection part 6, and the hollow part 10 is filled with insulating oil 11 to prevent water from entering the hollow part 10 and to maintain a good insulation state. The internal connection part 6 immersed in the insulating oil 11 is resin-molded with a thermosetting resin composition so that the insulating oil does not enter into the conductor of the lead-out cable made of stranded m-wires. has been done. However, due to thermal stress or mechanical vibrations applied to the internal connection part 6 due to temperature changes due to changes in the load of the motor or startup and stoppage, cracks may occur in the mold insulation layer of the internal connection part B, or cracks may occur. If peeling occurs between the cable 5 and the molded insulating layer, the insulating oil 1
Based on the pressure difference between the internal pressure in step 1 and the water pressure applied to the motor, the insulating oil penetrates into the voids in the copper wire of the lead cable.
A problem arises in that internal pressure is generated in the outlet cable 5 and the connecting portion 7.

FIG. 4 is a sectional view showing the conventional structure of the connecting portion between the outlet cable and the power cable, in which the center conductors 5A and 8 made of stranded copper wire of the outlet cable 5 and the power cable 8 are shown.
The end of A is conductively connected by a silver solder 12 or the like, and is connected to the center conductor 5A.

A resin mold layer 13 is formed on the exposed part of the cable 8A to maintain the electrical and mechanical strength of the connection part, and an elastic insulation layer 13 is coated on the outside and both ends are fixed to the insulation coatings 5A and 8B of the cable. The layer 14 is formed to prevent water from entering.

In this way, the connection part 7 covered with a water-shielding insulating layer consisting of the cable's insulating coatings 5B and 8B having elasticity such as polyethylene or rubber and the insulating layer 14 also having elasticity is protected against external damage. Although it is strong against water pressure, it is weak against internal pressure, so if the pressure changes due to temperature changes etc. are applied repeatedly through cracks or peeling surfaces that occur in the internal connection part B, the insulation coating 5B will be damaged. , 8
B and the adhesive surface 15 of the resin mold layer 13 and the insulation coating 5B.

The adhesive surface 16 between 8B and 14 gradually peels off and the insulating oil 11
leaks into the water, the electric motor stops, and the oil pressure decreases.
If water enters the hollow part 10 through the gap in the center conductor 5A, it will corrode the stator core 2, degrade the insulation performance of the stator coil 3, and cause the motor to start. In some cases, there is a risk that an unexpected accident may occur, such as dielectric breakdown of the connecting portion 7.

[Purpose of the invention]

The present invention was made in view of the above-mentioned situation, and it is an object of the present invention to provide a method for waterproofing a cable connection part that can prevent water from entering even under conditions where internal pressure is applied to the connection part, and therefore has high insulation reliability. .

[Key points of the invention]

The present invention blocks the flow of liquid between the two conductors by inserting the ends of the conductors made of stranded copper wires of a pair of cables into the recesses of the connecting fittings and brazing them. Then, a predetermined range in the length direction including the ends of the insulation coating is airtightly covered with a filler layer made of a synthetic resin composition and a water-blocking layer made of heat-shrinkable material. By covering the predetermined length area airtightly with a waterproof mechanical reinforcing layer consisting of a resin-molded insulating layer and a resin-impregnated bonding tape layer, the machine can be protected even when internal pressure is applied to the connection part. The water barrier layer is prevented from expanding by the reinforcement layer, and peeling between the water barrier layer and the cable insulation coating can be prevented.

[Embodiments of the invention]

The present invention will be explained below based on examples.

FIG. 1 is a side sectional view of a cable connection section showing an embodiment of the present invention. In the figure, the insulating coatings 5B of the outlet cable 5 and the power cable 8 are shown.

The center conductor 5A is exposed by peeling off the end of 8B.

The end of 8A is inserted into the recess of the rod-shaped connecting fitting 21, conductively connected with solder or silver solder, and filled with an epoxy resin composition that hardens at room temperature or at a relatively low temperature of 50 to 80'C. After applying the agent, heat shrink the outside of the filler so that it can be covered with a heat shrinkable tube made of ethylene propylene rubber, polyethylene, polyester, silicone rubber, fluororesin, etc. so that no voids remain between it and the filler. Insulation coating 5B, 8
A water-blocking layer 25 is formed from the BX-7 layer z4.

Next, a mold formed so that a predetermined gap is maintained and both ends fit into the cables 5 and 8 is attached to the outside of the water-blocking layer 25, and a mold made of an epoxy resin composition that hardens at room temperature is degassed in advance. Inject the cast resin. Furthermore, when this casting resin is in a semi-hardened state, the mold is released, and 100 parts by weight of a urethane resin (manufactured by Jiryuka Kogyo, Adeka Resin UP-309, etc.) is added to a glass cloth tape on the outside. A resin-impregnated tape impregnated with a resin composition containing 45 parts by weight of 126 (manufactured by Jiryuka Kogyo) is wound,
By heating and curing for several hours at room temperature and for several hours in an atmosphere of about 65° C., a mechanical reinforcing layer 28 having water-blocking properties is formed, which is composed of the resin mold insulating layer 26 and the binding tape layer 27. Additionally, aggregate or filler such as fibrous or inorganic powder may be added to the resin mold insulating layer 26, and the filler 7i! For 23, a synthetic resin composition having good adhesion to the cable insulation coating and heat-shrinkable tube layer, such as urethane resin, polyester resin, or silicone resin, may be selected.

FIG. 2 is a side sectional view showing a different embodiment of the present invention;
This embodiment differs from the previous embodiment in that the shape of the water-blocking layer 35 is changed so that the outer diameter of the filler layer 36 is approximately uniform and the heat shrinkage rate of the heat-shrinkable tube layer 34 is approximately uniform in each part. In addition, when formed in this way, the gap between the filler layer 63 and the heat-shrinkable tube layer 34 can be more reliably eliminated. Note that the resin composition used for the filler layer is preferably defoamed in advance.

In order to verify the performance of the connection made by the water-resistant treatment method shown in each of the above-mentioned examples, the cut end of the lead-out cable was inserted into a pressure vessel, and the vessel was heated to a helium gas pressure of 5⁄/cm.
– Internal pressure test to detect gas leakage from the cable connection 2 Place the cable connection in a pressure water tank and
A pressure test in which water pressure of #/- was applied from the outside of the connection part, and a pressure cycle test in which water pressure was repeatedly applied between 200 #/i and O/- five times were conducted. As a result, no gas leakage due to internal pressure or water intrusion due to external water pressure was observed in any of the cable connections formed as shown in Figures 1 and 2, and there were no cracks in the water drainage layer or mechanical reinforcement layer.
No abnormalities such as peeling were observed, and no abnormalities were observed in electrical performance such as withstand voltage or insulation resistance. In addition, in the test results of the conventional cable connection model shown in Fig. 4 conducted for comparison, water intrusion was observed in the pressure test, indicating that the water resistance treatment method of the present invention can significantly improve the water resistance performance. It was revealed.

Note that similar performance can be expected even when the method of the present invention is applied to the connection portion of a cable pulled out from a switchboard or the like and stored in an outdoor U-shaped groove or the like.

〔Effect of the invention〕

As described above, in the present invention, liquid such as insulating oil that has entered the stain source cable due to an abnormality in the internal connection part on the electrical equipment side is prevented from flowing into the stain source cable side by the rod-shaped connecting fitting. The internal pressure caused by oil is strongly suppressed by the mechanical reinforcing layer, preventing the expansion of the water-shielding layer including the end of the cable insulation coating, thereby preventing the water-shielding layer from peeling off. It is possible to provide a water-resistant treatment method that prevents leakage of insulating oil due to internal pressure and the formation of a water-infiltrated path resulting from the problem, and that can form a cable connection part that has excellent water-resistant performance even under conditions where internal pressure is applied. In addition, against external water pressure at the cable connection part, the cable is covered with four plastic insulating layers each having water-shielding properties, and a mechanical reinforcement layer maintains a high degree of morphological stability. By arranging the ends of the four plastic insulation layers in series in the creeping direction and binding them in the radial direction with the binding tape layer, a water ingress path is created at the interface between the cable insulation coating and the four plastic insulation layers. Therefore, by applying the water resistance treatment method of the present invention, it is possible to contribute to providing a cable connection part that can maintain water resistance performance even under water pressure as high as 200#/i.

[Brief explanation of drawings]

Fig. 1 is a side sectional view of a cable connection part showing an embodiment of the present invention, Fig. 2 is a side sectional view showing different embodiments of the invention, and Fig. 6 is an example of an electric motor used underwater. FIG. 4 is a side sectional view showing an example of a conventional cable connection section. DESCRIPTION OF SYMBOLS 1...Yoke, 3...Stator coil, 5...Output cable, 6...Internal connection part, 10...Hollow part,
11... Insulating oil, 7... Cable connection part, 8...
Power cable, 5A, 8A...center conductor, 5B
, 8B... Insulating coating, 21... Connection fitting, 12.
22... Conductive connection portion, 23° 36... Filler layer, 2
4.34...Heat-shrinkable chain layer, 25.35...Water-blocking layer, 26.12...Resin mold-free hlNI, 27
...Bondage tape layer, 28...Mechanical reinforcement (Mori Jinmori, 2nd grade Yamaguchi Shima') Fig. 1 Seishi Fig. 2

Claims (1)

[Claims] 1) At the mutual connection between the terminal ends of a pair of cables consisting of an outlet cable and a power cable of an electrical device, the conductor ends of the pair of cables are conductively connected via a cylindrical connecting fitting having recesses at both ends, A water-shielding layer consisting of a filler layer made of a synthetic resin composition and a heat-shrinkable tube layer formed to closely cover the conductive connection parts including the insulated ends of a pair of cables, and a water-shielding layer consisting of a heat-shrinkable tube layer covering the water-shielding layer and both ends. A cable characterized in that a resin-molded insulating layer whose part is in close contact with the insulating sheath of a pair of cables and a water-blocking mechanical reinforcing layer made of a resin-impregnated binding tape layer are formed in layers based on the above-mentioned order. Waterproof treatment method for connections.