Calculation of conductor cross-sectional area and current carrying capacity;
First, the general copper wire current carrying capacity The safe current carrying capacity of the wire is determined according to the maximum allowable temperature, cooling conditions and laying conditions of the wire core. Generally, the safe current carrying capacity of copper conductor is 5~8A/mm2, and that of aluminum conductor is 3~5A/mm2. < key point > for example, the recommended safe current carrying capacity of 2.5 mm2 BVV copper conductor is 2.5×8A/mm2=20A 4 mm2 BVV copper conductor is 4×8A/mm2=32A.
2. Calculate the cross-sectional area of copper conductor. The recommended safe current carrying capacity of copper conductor is 5~8A/mm2, and the upper and lower limits of the cross-sectional area of copper conductor are calculated: s =
Third, power calculation general load (can also become electrical appliances, such as lighting, refrigerators, etc. ) is divided into two types, one is resistive load and the other is inductive load. Calculation formula of resistive load: P=UI fluorescent lamp load calculation formula: p = UI COS where the fluorescent lamp load power factor COSф= 0.5. Different inductive loads have different power factors, so the power factor cosф Ф can be 0.8 when calculating household appliances uniformly.
The total input power of four or eight air conditioners (rated) is 8*736=5888W.
The maximum current is I = p/u = 5888/220 = 26.76a.
26.76A/8=3.345
Five, according to the calculation requirements, it is enough to configure eight air conditioning 4mm2 copper core wires. If auxiliary heating is considered, 6mm2 copper core wires are the main ones. There is still a margin, which can protect the line system.