The principle of wire and cable selection

Update:18 Sep 2017
Summary:

   ⒈ wire and cable model selection When using wire and […]

   wire and cable model selection When using wire and cable, to consider the use, laying conditions and safety; for example, depending on the use of different power cables, overhead insulated cables, control cables, etc .; depending on the laying of different conditions, Plastic insulated cable, steel armored cable, steel wire armored cable, anti-corrosion cable, etc .; according to safety requirements, can use non-flame retardant cable, flame retardant cable, halogen-free flame retardant cable, fire-resistant cable.
   ⒉ wire and cable specifications to determine the use of wire and cable specifications (conductor cross-section), the general should consider the heat, voltage loss, economic current density, mechanical strength and other selection conditions.
According to experience, low-voltage power line because of its large load current, it is generally the first choice according to heat conditions cross-section, and then check the voltage loss and mechanical strength; low-voltage lighting line because of its higher voltage level requirements, Select the cross-section, and then check the heat conditions and mechanical strength; for high-voltage lines, the first by the economic current density selection section, and then check the heat conditions and allow the voltage loss; and high-voltage overhead lines, but also check its mechanical strength. If the user has no experience, should consult the relevant professional units or people's views. General wire and cable specifications are selected in the table below:
Wire and cable specifications selection reference conductor cross-section copper core PVC insulated cable ambient temperature 25 ℃ overhead laying copper core PVC insulated power cable ambient temperature 25 ℃ direct burial steel core aluminum stranded wire ambient temperature 30 ℃ overhead laying instructions:
  
A. The same specifications of the aluminum core conductor current is about 0.7 times the copper core, the choice of aluminum core wire can be larger than a copper conductor specifications, cross-linked polyethylene insulation can choose a small file size, fire wire and cable should choose a larger size The
   B. The calculated capacity of this table is based on three-phase 380V, Cosφ = 0.85, if the single-phase 220V, Cosφ = 0.85, the capacity should be × 1/3.
   3. When the ambient temperature is higher or the use of Ming Fu, etc., its safe carrying capacity will decline, this time should use a larger size; when used for frequent start of the motor, should use large 2 to 3 specifications.
   4. PVC insulated wire according to a single overhead laying way to calculate, if the pipe or multiple laying, you should use a large 2 to 3 specifications.
   5 The above data is for reference only, the final design and determine the cable model and specifications should refer to the relevant professional information or electrical manual.

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