Installation cable gland Precautions
1. The conductor connection requires low resistance and sufficient mechanical strength, and no sharp corners should appear at the connection. The commonly used connection of medium and low voltage cable conductors is crimping, and the crimping should be noted:
Choose a conductor connecting pipe with appropriate conductivity and mechanical strength;
The fit gap between the inner diameter of the crimping tube and the outer diameter of the connected core is 0.8～1.4mm;
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;
Before crimping, coat the outer surface of the conductor and the inner surface of the connecting pipe with conductive glue, and use a wire brush to destroy the oxide film;
Use a file or sandpaper to smooth the sharp corners and burrs on the connecting tube and the core conductor.
2. Internal semiconductor shielding treatment.
Where the cable body has an inner shielding layer, the inner shielding layer of the conductor part of the crimping tube must be restored when the joint is made. A part of the inner semiconductor shielding of the cable must be reserved so that the inner shielding of the connector on the connecting tube can communicate with each other. Ensure the continuity of the internal semiconductor, so that the field strength at the junction is evenly distributed.
3. Treatment of external semiconductor shielding.
The outer semiconductor shield is a semi-conductive material that functions as a uniform electric field outside the insulation of the cable and the cable joint. Like the inner semiconductor shield, it plays a very important role in the cable and the joint. The outer semiconductor ports must be neat and uniform, and smooth transition with insulation is required, and a semiconductor tape is added to the cable joint to connect with the semiconductor shield outside the cable body.
4. Treatment of cable reaction force cone.
During construction, the reaction force cone with the exact shape and size has the same potential distribution on the entire cone surface. When making the cross-linked cable reaction cone, special cutting tools are generally used, or it can be slightly heated with a slight fire and carried out with a sharp knife. After cutting and basic forming, use 2mm thick glass to scrape, and finally use sandpaper to polish from coarse to fine until smooth.
5. Metal shielding and grounding treatment.
The role of metal shielding in cables and connectors is mainly to conduct cable fault short-circuit current and to shield electromagnetic interference from electromagnetic fields to adjacent communication equipment. In operation, the metal shield is at zero potential under a good grounding state. When the cable fails , It has the ability to conduct short-circuit current in a very short time. The grounding wire should be reliably welded, the metal shields and armor tapes on the cable body of the two ends should be firmly welded, 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 to ensure the safe and reliable operation of the joint. It is necessary to prevent the penetration of moisture and moisture into the cable joint. In addition, a joint protection groove or cement protection box shall be installed at the joint position.