Heat Shrinkable Pipe And Other Insulating Body Treatment Cable Intermediate Connector

- Dec 27, 2018-

Installation steps for cable intermediate connectors 

1, the pretreatment of the cable 

2, conductor connection 

Peel the wire do not damage the wire, the joint staggered to prevent short circuit, with hydraulic clamp pressure good.

3, internal semi-conductive layer recovery 

4, Insulation layer recovery 

Organic silicone + self-adhesive Waterproof Tape-"Heat shrinkable tube-" insulation tape (can enhance insulation treatment). 

5, recovery of the outer semi-conductive layer 

6. Recovery of metal shielding layer 

7, restoration of the armored layer 

8, recovery of the protective sleeve 

Waterproof treatment steps for low voltage wire and cable silicone wire intermediate joint 

1) After the terminal is pressed, wrap the waterproof filling glue around the terminal. Shrink the heat shrinkable tube.

2) If it is generally slightly moist environment, at both ends of the cable winding on the waterproof filler tape, shrinkage casing (the two ends of the casing must be glued) can be. 

3) If the environment is relatively bad, you must use self-adhesive waterproof tape to enhance waterproof (can also use hot shrinkage waterproof tape, we generally use self-adhesive tape, heat shrinkable tape is used for cable breakage repair). The method is: A, after filling the waterproof filler glue, in the filling glue outer layer with self-adhesive waterproof tape winding a layer or stretching self-adhesive waterproof tape Winding multi-layer, but the thickness is not too thick, so as not too large to cause insulation pipe cover not to go in. B, shrink the heat shrinkable tube sleeve at the glue. C, wrap the waterproof tape at both ends of the heat shrinkable tube, then wrap a layer of self-adhesive waterproof tape, wrap the waterproof tape and self-adhesive tape at both ends of the cable insulating sheath, and then heat the casing to shrink to complete.

The intermediate joint usually refers to the cable connector, that is, the cable joint in the middle of the cable line. The intermediate joint is a cable accessory for the intermediate connection of a cross-linked cable or oil-immersed cable for various voltage grades. The main function is to make the line smooth, keep the cable sealed, and ensure the insulation level at the cable joint, so that it runs safely and reliably.


Manufacture of intermediate connectors.

1. If you can buy a good quality heat shrinkable tube locally, you can put the heat shrinkable pipe on a certain cable first. Note: the diameter of the heat shrinkable tube is at least 1.5 times times the diameter of the original cable

2. Dig the cable well (manhole) where the cable is ready to connect, facilitate construction and maintenance, check whether the cable head is damp before the connector, and cut off the damp part. 

3, two cables are laid in place, and the cables at the joints are placed straight and overlapping in order to cut off the end part. (because the conductor of the fracture may not be round, can not wear into the takeover)

4. Mark (center) at the position where the connector is prepared, and cut off the excess cable at the 3-5cm before this mark. (Because each phase is twisted and together, the length after separation will be different, to be finally positioned as needed)

5, according to the need for joints, from the cable fracture began to peel off the outer sheath, armored layer. Note: Do not break the insulation when peeling the armored layer.

6, the each phase is separated, peeled off the insulating layer, the stripping length is: Take over the length of the/2+3~5mm. Note: Do not hurt the conductor when peeling insulation.

7. Clean the conductor; press and connect. The number of crimping, crimping order and spacing refer to the GB14315 of the rules.

8, wipe away the excess antioxidants. 

9, the use of 3M insulation tape (23#) to restore the insulation layer, tape thickness of the original insulation thickness of twice times. Note: The tape usage method is followed by instructions and wraps back and forth.

10, cover the insulating belt with PVC tape, wrap a back and forth. 

11. Restore the electrical connection of the armored layer. If there is a 3M armor belt, the armor strap can be used. It is recommended to use tin-plated copper braided wire crossover, both ends with copper filament gang. If there is a condition for solder.

12,A, if there is a heat shrinkable tube, pull the heat shrinkable pipe to the joint, heat shrinkage, the two ends of the mouth with waterproof belt around 2 laps, PVC belt around the bag 2 laps cover. B, if there is no heat shrinkable tube, the 3 m waterproof belt (2228#) wrap around the joint, covering the original sheath fracture 10cm, around the bag 2 back and forth. Cover one back and forth with an insulating strap, and finally cover a back and forth with a PVC strap.


Precautions related to intermediate connectors.

1. When purchasing intermediate joints, pay special attention to the quantity and quality of J-30 insulating glue and semi-conductive tape,

Try to choose the use of large contact area, through tin or galvanized process treatment of the standard intermediate joint. In the case of good process control, cold shrinkage cable accessory seal waterproof should be better than hot shrinkage cable accessories, you can give priority to the full cold shrinkage intermediate connector

2, in the outdoor production of high-pressure intermediate joints, air relative humidity should be 70[%] below, humidity can improve the ambient temperature or heating cable. 100KV or more of the intermediate joint construction should be built temporary shed, the ambient humidity is strictly controlled, the temperature should be 10~30℃, to prevent dust, debris fall into. Construction in fog or rain is strictly prohibited

3, the design should consider the cable length requirements, as far as possible to avoid the use of intermediate connectors, must use intermediate joints, should be on both sides of the cable connector and adjacent cable 2~3m long section of the application of fireproof paint or fireproof tape. 

4, the cable intermediate joint must have high insulation strength and large enough mechanical strength, in order to resist all kinds of mechanical stress and short-circuit current impact electric power, the joint at the long-term environmental moisture impact, should be reliable sealing.


Seal 

Sealing includes two layers of meaning: one to moisture-proof, two to try to avoid the existence of Air gap. 

(1) The water content of crosslinked polyethylene insulated cable is a subject which has been paid more attention in the international and domestic countries in recent years. The water contained in the insulation will cause the water branches to form in the insulator, resulting in insulation damage. Water branches are discharge pathways consisting of many microscopic water-filled voids less than a few microns in diameter, and the combined action of electric fields and water forms water trees. Therefore, the power cable in the installation, operation process, not allowed in the conductor, insulation layer in the presence of water, air or other impurities. These impurities are prone to ionization under the action of high-strength electric field, charged particles under the action of alternating electric field, so that the cable insulation layer in the course of operation gradually aging leading to breakdown, resulting in cable failure, so sealing work-must be done well. Each phase composite pipe at both ends and inside and outside the casing should be sealed to fill the sealant, to achieve effective moisture-proof. When the hot shrinkage pipe is coated with sealed metal parts such as connecting tubes and metal sheath, the metal parts should be heated to 60-70 degrees Celsius in order to obtain a good sealing effect.

(2) In order to reduce the existence of air gap, we can do the following: ① the insulating end into a cone to ensure that the winding filler and insulating end can be well bonded; ② evenly coated with a layer of silicon fat paste on the main insulating surface to enhance the sealing function; ③ composite pipe at both ends to wrap around the sealant; ④ to backfill the filler before installing the internal and external sheath, Fill the SAG, so that the whole joint presents a neat appearance, with PVC tape winding tight; ⑤ internal and external sheath installation to wrap at both ends of the sealant.

The above several problems in the field work are complementary, each process is connected to each other, mutual influence, we have to take them as a continuous whole to see.

The basic structure of 10,000 KV crosslinked polyethylene cable is certain, the cable intermediate head is made with reference to the installation instructions, to achieve the process specification and in accordance with the construction process construction, then the quality of the cable intermediate joint can meet the requirements of long-term safe operation.