Cable joints produced by Hengyuan Technology Company
The cable intermediate joint is both a cable joint and a cable head. After the cable is laid, in order to make it a continuous line, the segments must be connected as a whole. These connection points are called cable joints. The cable joints in the middle of the cable line are called intermediate joints, and the cable joints at both ends of the line are called terminal heads. Cable joints are used to lock and fix incoming and outgoing cables, and are waterproof, dustproof and vibration-proof.
Classification:
According to the installation location, it can be divided into two types: indoor type and outdoor type.
According to the production and installation materials, it can be divided into heat shrink type (the most commonly used one), dry package type, epoxy resin casting type and cold shrink type.
According to the core material, it can be divided into copper core power cable heads and aluminum core power cable heads.
According to the connector material, it is divided into plastic cable connector and metal cable connector. Metal cable joints are further divided into porous metal cable waterproof joints, anti-bending metal cable joints, double-locking metal cable waterproof joints, plastic hose cable joints, metal hose cable joints, etc.
effect:
Its main function is to make the lines unobstructed, keep the cables sealed, and ensure the insulation level of the cable joints so that they can operate safely and reliably. If the sealing is poor, not only will oil leak out and cause the oil-impregnated paper to dry up, but moisture will also invade the inside of the cable, reducing its insulation performance.
Main questions:
Causes of hot joints
Some electrical installation workers often do not pay attention to the installation quality when laying wires: they do not install casings where insulating casings should be used; they do not install junction boxes where junction boxes should be used; they even use illegal hook-shaped connection methods instead of splicing at wire joints. The contact resistance of this hook-shaped connection method is very high, and it will continue to generate heat when powered on, which will gradually dry out and carbonize the nearby wooden boards, and finally burn, causing a fire.
Heating of wire joints will not only cause a large amount of electrical energy loss, but also seriously affect the normal operation of electrical equipment. At the least, the operating current in the line will increase, and the life of electrical equipment will be shortened. At worst, ongoing production, scientific research, medical operations and other activities will be suddenly interrupted. It will also cause fires and electric shock accidents, etc., causing immeasurable losses.
Installation notes:
1. Conductor connection The conductor connection requires low resistance and sufficient mechanical strength, and there should be no sharp corners at the connection. Crimping is commonly used to connect medium and low-voltage cable conductors. When crimping, attention should be paid to:
(1) Select conductor connecting tubes with appropriate conductivity and mechanical strength;
(2) The matching gap between the inner diameter of the crimping tube and the outer diameter of the connected wire core is 0.8~1.4mm;
(3) The resistance value of the joint after crimping should not be greater than 1.2 times that of the conductor of equal cross-section, and the tensile strength of the copper conductor joint should not be less than 60N/mm2;
(4) Before crimping, apply conductive glue on the outer surface of the conductor and the inner surface of the connecting tube, and use a wire brush to destroy the oxide film;
(5) Polish the sharp corners, burrs, etc. on the connecting tubes and core conductors with a file or sandpaper.
2. Internal semiconductor shielding treatment.
If the cable body has an inner shielding layer, the inner shielding layer of the joint of the conductor part of the crimping tube must be restored when making the joint. A part of the inner semiconductor shielding of the cable must be left out so that the inner shielding of the connecting head on the connecting tube can be connected to each other to ensure the continuity of the inner semiconductor, so that the field strength at the joint joint is evenly distributed.
3. Treatment of external semiconductor shielding.
The outer semiconductor shield is a semiconductive material that acts as a uniform electric field outside the insulation of cables and cable joints. Like the inner semiconductor shield, it plays a very important role in cables and joints. The external semiconductor port must be neat and uniform and must have a smooth transition with the insulation, and a semiconductor tape must be added to the cable joint to connect with the external semiconductor shield of the cable body.
4. Treatment of cable reaction force cone.
During construction, the reaction force cone with accurate shape and dimensions will have the same potential distribution on the entire cone surface. When making the cross-linked cable reaction cone, special cutting tools are generally used. You can also use a slight fire to heat it and cut it with a sharp knife. After it is basically formed, use 2mm thick glass to scrape it, and finally use sandpaper to polish it from coarse to fine until it is smooth.
5. Metal shielding and grounding treatment.
The role of metal shielding in cables and connectors is mainly to conduct short-circuit currents due to cable faults and to shield electromagnetic fields from electromagnetic interference to adjacent communication equipment. During operation, the metal shielding is at zero potential in a well-grounded state. When a cable fails, it has the ability to conduct short-circuit current in a very short period of time. The grounding wire should be reliably welded, the metal shields and armor tapes on the cable body at both end boxes should be welded firmly, and the grounding of the terminal head should be reliable.
6. Sealing and mechanical protection of joints.
The sealing and mechanical protection of the joint are the guarantee for safe and reliable operation of the joint. Water and moisture should be prevented from seeping into the cable joints. In addition, joint protection grooves or cement protection boxes should be installed at the joint locations.
