1. General principles for the selection of Sheng brand electric wires

When selecting wires and cables, generally pay attention to the selection of wire and cable models and specifications (conductor cross-sections).

⒈The choice of wire and cable model

When selecting wires and cables, consider the use, laying conditions and safety; for example:

According to different purposes, power cables, overhead insulated cables, control cables, etc. can be selected;

According to different laying conditions, general plastic insulated cables, steel tape armored cables, steel wire armored cables, anticorrosive cables, etc. can be selected;

According to safety requirements, flame-retardant cables, halogen-free flame-retardant cables, fire-resistant cables, etc. can be selected.

⒉The choice of wire and cable specifications

When determining the use specifications (conductor cross-section) of the wire and cable, the selection conditions such as heat generation, voltage loss, economic current density, and mechanical strength should generally be considered.

According to experience, the low-voltage power line has a relatively large load current, so generally select the cross section first according to the heating conditions, and then check its voltage loss and mechanical strength; low-voltage lighting lines have higher requirements for voltage levels,

The section can be selected according to the allowable voltage loss conditions, and then the heating conditions and mechanical strength can be checked; for high-voltage lines, the cross section should be selected according to the economic current density first, and then the heating conditions and allowable voltage losses can be checked

; And for high-voltage overhead lines, their mechanical strength should also be checked. If the user has no experience, he should consult relevant professional units or persons.

1. The current carrying capacity of the aluminum core wire of the same specification is about 0.7 times that of the copper core. The aluminum core wire can be one size larger than the copper core wire. The cross-linked polyethylene insulation can be a smaller specification. The fire-resistant wire and cable should be selected.

Large specifications.

2. The calculated capacity of this table is based on three-phase 380V, Cosφ=0.85, if single-phase 220V, Cosφ=0.85, the capacity should be × 1/3.

3. When the ambient temperature is high or the open method is adopted, the safe current carrying capacity will decrease. At this time, a larger size should be selected; when it is used to frequently start the motor, 2 to 3 larger sizes should be selected.

4. The PVC insulated wires in this table are calculated according to the single overhead laying method. If they are laid through pipes or multiple wires, 2 to 3 larger specifications should be selected.

5. The above data is for reference only, and the final design and determination of cable type and specifications should refer to relevant professional materials or electrical manuals.

2. Installation and construction of wires and cables

The design and construction of wire and cable laying and installation should be carried out in accordance with GB 50217-94 "Power Engineering Cable Design Code" and other relevant regulations, and necessary cable accessories (terminals and joints) should be adopted. Power supply system operation

Quality, safety and reliability are not only related to the quality of the wires and cables themselves, but also to the construction quality of cable accessories and lines.

Through statistical analysis of line faults, the faults caused by construction, installation and connection are often much more likely than the faults caused by the defects of the wires and cables. Therefore, the high temperature resistance must be selected correctly

In addition to the design and construction of wires, wires and cables and supporting accessories, the following aspects should be noted:

⒈Cable laying and installation should be carried out by qualified professional units or professionals. Construction and installation that do not meet the requirements of relevant specifications may cause the cable system to fail to operate normally.

⒉When laying cables by manpower, command and control the rhythm in a unified manner. Every 1.5 to 3 meters, one person carries the cables on their shoulders, pulls them while laying them, and releases them slowly.

⒊When laying cables mechanically, a special cable laying machine is generally used and necessary traction tools are used. The traction force is appropriate and controlled evenly to avoid damage to the cable.

⒋Before discharging the cable, check the appearance of the cable and whether the seal is intact. Pay attention to the direction of rotation of the cable reel when disposing. Do not flatten or scratch the outer sheath of the cable. Do not hit the cable in low temperature in winter.

Straighten the cable to prevent the insulation and sheath from cracking.

⒌The bending radius of the cable should be greater than the specified value when laying. Before and after cable laying and installation, use a 1000V megohmmeter to measure whether the insulation resistance between the conductors of the cable is normal, and according to the cable type, specification and length

Correct the measurement results appropriately for the difference in ambient temperature. For cables with small specifications (solid conductors below 10mm 2 ), you should also measure whether the conductors are on or off.

⒍If cables are directly buried, pay attention to soil conditions. Generally, the buried depth of cables under buildings is not less than 0.3 meters, and the surrounding environment is relatively soft, such as cultivated land, construction sites or roads, etc.

There must be a certain burying depth (0.7~1m) to prevent accidental damage to the directly buried cables, and obvious signs should be erected when necessary.

Third, the use characteristics of wires and cables

Please refer to the specific product introduction for details of product usage characteristics.

4. Transportation and storage of Sheng brand cables

⒈It is strictly forbidden to drop the cable or the cable reel with the cable from a high place during transportation, especially at low temperature (usually around 5℃ and below). Throwing or dropping the cable may cause the insulation and sheath to crack.

⒉As far as possible, avoid storing cables in the open in a bare way, and the cable reels are not allowed to lay flat.

⒊When hoisting packages, it is strictly prohibited to hoist several trays at the same time. On vehicles, ships and other transportation tools, the cable reels should be fixed by suitable methods to prevent collision or tipping over each other to prevent mechanical damage to the cables.

⒋Cables are strictly prohibited from contacting acids, alkalis and mineral oils, and should be stored in isolation from these corrosive substances. There should be no harmful gases that damage insulation and corrode metals in the warehouse where cables are stored.

⒌The cable should be rolled regularly during the storage period (once every 3 months in summer, other seasons can be extended as appropriate). When rolling, the storage tray shall be turned down and turned upward to prevent the bottom surface from being damp and rotted. Always note when storing

Whether the cable gland is intact or not.

⒍The cable storage period is limited to the product delivery period. Generally, it should not exceed one and a half years, and the longest should not exceed two years.