Know how to match the rated power and open the wiring

That's mainly up to your planning, so that you can wiring It's not okay to imagine it out of thin air, calculate the capacity first, and then check the manual to see what wire diameter to use.

The current of the single-phase circuit (household electricity 220V) = load power The use voltage is 3000W, and the working current when fully open = 3000 220 = or so.

Three-phase circuit (industrial electricity 380V) current = power voltage voltage voltage phase angle load power factor such as a motor, power factor, current = 7500 380, the normal working current is about about about after knowing the current, according to the maximum current carrying capacity of the copper core wire, you can choose the appropriate wire diameter, but it is necessary to consider that the wire does not heat up for a long time to work safely, and there is a margin, and the choice of empty opening is the same, and there is a margin for it.

The operating current is calculated from the power.

Then according to the working current plus the safety factor, select the appropriate wire and air opening.

The current of the single-phase circuit (household electricity 220V) = load power The use voltage is 3000W, and the working current when fully open = 3000 220 = or so.

Three-phase circuit (industrial electricity 380V) current = power voltage voltage voltage phase angle load power factor such as a motor, power factor, current = 7500 380, the normal working current is about about about after knowing the current, according to the maximum current carrying capacity of the copper core wire, you can choose the appropriate wire diameter, but it is necessary to consider that the wire does not heat up for a long time to work safely, and there is a margin, and the choice of empty opening is the same, and there is a margin for it.

70kw, assuming the voltage is 380v, power factor.

The current is 70000 380, with, if the allowable voltage drop of 5%, within 300 meters can meet the requirements;

The air opening needs to be matched according to the nature of the load.

If the load is a motor, the air opening is configured according to 2-3 times of the working current, that is, if the air opening is 300A-400A, the setting current is 133A;

For non-motor loads, the air opening is configured according to the multiple of the working current, that is, if the air is equipped with 160A-200, the setting current is 133A;

In the case of three phases, the power factor is not counted: it is about 110 amps. It is possible to use 16 square millimeters of copper wire or 25 square millimeters of aluminum wire. Air opening can be 150-200 amperes.