What should I pay attention to when using wire and cable?

1. Selection of wire and cable models

When using wire and cable, consider the use, laying conditions and safety; for example, depending on the purpose of use, use power cables , overhead insulated cables, control cables, etc.; depending on the laying conditions, use general plastic insulated cables, steel strips Armored cable, wire armored cable, anti-corrosion cable, etc.; according to safety requirements, non-flammable cable, flame retardant cable , halogen-free flame-retardant cable, fire-resistant cable, etc. may be used.

2. Selection of wire and cable specifications

When determining the usage specifications (conductor cross-section) of 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 large load current, so generally select the cross section first according to the heat conditions, and then check its voltage loss and mechanical strength; low voltage lighting line can first press the allowable voltage loss condition because of its higher voltage level requirements. Select the section, and then check the heating conditions and mechanical strength; for high-voltage lines, first select the section according to the economic current density, and then check its heating conditions and allowable voltage loss; and high-voltage overhead lines, should also check the mechanical strength. If the user has no experience, they should consult the relevant professional unit or person.

Explanation:

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

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

3. When the ambient temperature is higher or the surface coating method is adopted, the safe ampacity will be reduced. At this time, larger specifications should be used. When used for frequent starting of the motor, two to three specifications should be used.

4. The PVC insulated wire of this watch is calculated according to the single overhead laying method. If it is a pipe laying or multiple laying, two or three sizes shall be selected.