“Are your cables the national standard?” We will ask this question when we buy wires and cables. In fact, many kinds of wires and cables in our country have already formulated standards, but there is no national standard for photovoltaic wire PV1-F now. The current The production standards refer to foreign standards such as TUV, UL, and IEC, so how do we judge whether the photovoltaic line PV1-F is good or bad?
1. Nominal section
It can be judged by the nominal cross section, which can be calculated by the formula, the formula is: single wire radius * 3.14 * number of wires = nominal cross section, for example: a photovoltaic wire has 84 wires with a diameter of 0.3mm Its nominal section=0.3/2*3.14*84=5.935≈6mm
2. Conductor resistance
The higher the resistance of the conductor, the higher the current loss and the smaller the current carrying capacity, so the resistance of the conductor is very important. The calculation formula of conductor resistance is: R=ρ*L/S, where ρ is the resistivity (copper core cable ρ=0.01740, aluminum core cable ρ=0.0283), L is the cable length, and S is the nominal cross section of the cable. The resistivity of copper conductors is different at different temperatures, please refer to the following table:
|Temperature℃||Copper Conductor Resistivity|
3. Cable length
The cables produced by regular manufacturers will have the length printed on the outer sheath, so how should we judge whether the length we purchased matches the actual length given by the manufacturer? We can also calculate this by formula (we have introduced it in “Wire and Cable Acceptance Inspection Steps”).
Formula: A number * B number * C length * 3.14.
A number: the number of horizontal wires
Number of B: the number of vertical cables
C length: the length from any side to the inner plate
Post time: Dec-12-2022