JPH0325911B2 - - Google Patents

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]

This type of motor is used under water under constant water pressure, and the connection between the outlet cable end and the power cable end is also often submerged in water, so insulation at the connection part is required. The coating is required to have high water impermeability.

FIG. 1 is a schematic side sectional view of essential parts of an example of a motor used in a submerged state. In the figure, 1
is the yoke of the motor which is formed airtight to withstand water pressure, 2 is the stator core, 3 is the stator coil, and 4 is the stator coil.
5 is a rotor, 5 is an output cable, 6 is an internal connection between the output cable and the coil conductor, and 7 is a connection between the output cable 5 and the power cable 8. Further, in the example shown in the figure, a hollow portion 10 that encloses the stator core 2, stator coil 3, and internal connection portion 6 is formed by a partition wall 9 made of a non-magnetic material that is airtightly bonded to the inner wall surface of the yoke 1. Insulating oil 1 is placed in the hollow part 10.
1 is filled with the thermosetting resin composition to prevent water from entering the hollow part 10 and to maintain a good insulation state. By resin molding, it is configured to prevent insulating oil from penetrating into the conductor of the lead-out cable made of stranded copper wire. However, due to thermal stress or mechanical vibrations applied to the internal connection part 6 due to temperature changes due to changes in motor load or startup/stop, cracks may occur in the mold insulation layer of the internal connection part 6, or cracks may occur between the lead cable 5 and the mold insulation layer. If separation occurs between the layers, the insulating oil will penetrate into the void in the twisted copper wire of the lead cable based on the differential pressure between the internal pressure caused by the insulating oil 11 and the water pressure applied to the motor, causing the lead cable 5 and the connection to A problem arises in that internal pressure is generated in the portion 7.

FIG. 4 is a cross-sectional view showing the conventional structure of the connecting portion between the lead cable and the power cable. While being conductively connected, 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 is coated on the outside and both ends are fixed to the insulation coatings 5A and 8B of the cable. layer 14
It is designed to prevent water from entering.
In this way, the connection portion 7 covered with a water-shielding insulating layer consisting of the cable insulation coatings 5B, 8B having elasticity such as polyethylene or rubber and the insulating layer 14 having elasticity is protected against water pressure from the outside. Although it is strong against internal pressure, it is weak against internal pressure. Therefore, repeated changes in hydraulic pressure due to temperature changes etc. can occur through cracks or peeling surfaces in the internal connection part 6, causing the insulation coatings 5B and 8B to Adhesive surface 15 with mold layer 13 and insulation coating 5
The adhesive surface 16 between B, 8B and 14 gradually peels off and the insulating oil 11 leaks into the water, and at the time when the electric motor stops and the oil pressure decreases, the peeled part and the center conductor 5A of the lead-out cable 5 Sky =
Water will enter the hollow part 10 through the
This not only corrodes the stator core 2 and degrades the insulation performance of the stator coil 3, but also poses a risk of causing an unexpected accident such as dielectric breakdown of the connecting portion 7 when the motor is started.

[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 water-resistant treatment method for a cable connection part that can prevent water from entering even under conditions where internal pressure is applied to the connection part and has high insulation reliability.

[Key points of the invention]

The present invention cuts off 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. A predetermined range in the length direction including the ends of the sheathing is airtightly covered with a filler layer made of a synthetic resin composition and a water barrier layer made of a heat-shrinkable tube, and a predetermined length region including the outside and the cable insulation sheath is covered airtightly. The mechanical reinforcing layer is constructed to be airtightly covered with a waterproof mechanical reinforcing layer consisting of a resin molded insulating layer and a resin-impregnated binding tape layer, so even when internal pressure is applied to the connection part, the mechanical reinforcing layer provides This prevents the water-shielding layer from expanding and prevents separation between the water-shielding layer and the cable insulation coating.

[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 insulation coating 5 of each of the outlet cable 5 and the power cable 8 is
The ends of the center conductors 5A, 8A exposed by peeling off the ends of the center conductors 5A, 8B are inserted into the recesses of the rod-shaped connecting fittings 21, and are conductively connected by solder or silver solder, for example, by room temperature curing or 50~80°C. After applying a filler made of an epoxy resin composition that hardens at a relatively low temperature of ℃, the outside is coated with ethylene propylene rubber, polyethylene, polyester, etc.
Insulating coatings 5B and 8 are heat-shrinked to cover silicone rubber-based, fluoroplastic-based, etc. heat-shrinkable tubes so that no voids remain between them and the filler.
A water-blocking layer 25 consisting of a filler layer 23 and a heat-shrinkable tube layer 24 is formed at the connection portion including the end portion of B. Next, a mold is attached to the outside of the water-shielding layer 25, which is formed so that the cables 5 and 8 can be fitted at both ends while holding a gap for a predetermined distance. Inject the cast resin. Furthermore, when this casting resin becomes semi-hardened, the mold is released, and 100 parts by weight of urethane resin (manufactured by Asahi Denka Kogyo, Adeka Resin UP-309, etc.) is added to a glass cloth tape on the outside with the trade name Adeka Hardener CA-126. (manufactured by Asahi Denka Kogyo Co., Ltd.) A resin mixture tape impregnated with 45 parts by weight of a resin composition is wound and cured by heating at room temperature for several hours and in an atmosphere of about 65°C, thereby forming a resin mold insulation layer. 2
6 and the binding tape layer 27, a mechanical reinforcing layer 28 having water-blocking properties is formed. The resin mold insulation layer 26 may contain aggregate or filler such as fibrous or inorganic powder, and the filler layer 23 may contain cable insulation coating and heat shrinkable material such as urethane resin, polyester resin, or silicone resin. A synthetic resin composition having good adhesion to the tube layer may be selected and used.

FIG. 2 is a side cross-sectional view showing a different embodiment of the present invention, in which the filler layer 33 is formed to have a substantially uniform outer shape and is shielded so that the heat shrinkage rate of the heat-shrinkable tube layer 34 is substantially uniform in each part. This embodiment differs from the previous embodiment in that the shape of the water layer 35 is changed, and by forming it in this way, the gap between the filler layer 33 and the heat-shrinkable tube layer 34 can be more reliably eliminated. can. 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 examples, the cut end of the outlet cable was inserted into the pressure vessel, and a helium gas pressure of 5 kg/cm ² was applied to the vessel to connect the cable. An internal pressure test to detect gas leakage from the cable connection part, a pressurization test in which the cable connection part is set in a pressure water tank and a water pressure of 200 kg/ ^cm2 is applied from the outside of the connection part, and a pressure test to detect gas leakage from the outside of the connection part.
A pressure cycle test was conducted in which pressure was applied repeatedly between 200 Kg/cm ² and 0 Kg/cm ² five times. As a result, the cable connections formed as shown in Figures 1 and 2 showed no gas leakage due to internal pressure or water intrusion due to external water pressure, and no cracks or peeling in the water-blocking layer and mechanical reinforcement layer. No abnormalities 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 Figure 4, which were conducted for comparison, water intrusion was observed in the pressure test, and it is clear that the water resistance treatment method of the present invention can significantly improve the water resistance performance. It became.

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 outlet cable due to an abnormality in the internal connection on the electrical equipment side is prevented from flowing into the power cable side by the rod-shaped connecting fitting, and the internal pressure due to the insulating oil is reduced. The strong mechanical reinforcing layer prevents the expansion of the water-shielding layer, including the ends of the cable insulation sheath, and prevents the water-shielding layer from peeling off. It is possible to provide a water-resistant treatment method that prevents leakage of insulating oil and the formation of a water-infiltrated path resulting from the leakage, and that can form a cable connection portion 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 reinforcing layer maintains a high degree of morphological stability. In addition, the ends of the four plastic insulation layers are arranged in series and bound in the radial direction by the binding tape layer, so that peeling that becomes a water ingress path at the interface between the cable insulation coating and the four plastic insulation layers is prevented. 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 kg/cm ² .

[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 a different embodiment of the invention, and Fig. 3 is a schematic diagram showing 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...Outgoing cable, 6...Internal connection part, 10...Hollow part, 11...Insulating oil, 7...Cable connection part, 8
... Power cable, 5A, 8A ... Center conductor, 5
B, 8B...Insulation coating, 21...Connection fittings, 1
2, 22... Conductive connection portion, 23, 33... Filler layer, 24, 34... Heat shrink tube layer, 25, 3
5... Water-blocking layer, 26, 12... Resin mold insulating layer, 27... Bondage tape layer, 28... Mechanical reinforcing layer.

Claims (1)

[Claims] 1. At the connection point 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 part including the insulated end of the cable, and a water-shielding layer consisting of a heat-shrinkable tube layer covering the water-shielding layer and both ends. A cable connection characterized in that a resin-molded insulating layer that is in close contact with the insulating coating of a pair of cables and a water-blocking mechanical reinforcing layer that is made of a resin-impregnated binding tape layer are formed in layers based on the above-mentioned order. Water resistance treatment method.