Title: Calculation & Selection of Cable Cross-Section for Capacitor Powering & Voltage Drop

I came across a pattern in the network that allows me to determine the required cable cross-section directly so as to maintain the permissible voltage drop (p. 21, pattern 19):

Selection of leads

I don't know if I fully understand it correctly. I would like to use it to determine the voltage drop of the cable for powering the capacitor. Assuming that the capacitor has something cos fi = 0, the formulas show that the voltage drop is 0, which conflicts with my intuition and in total probably right, because it should not only take into account the resistance of the cable but also the reactance (which in the mentioned study is written on the next page in determination of voltage drop, e.g. at engine start-up).

Only that it is some inconsistent - for the formula to be applied I should probably put on a real capacitor (which has some resistance) and determine the actual cos fi (which will not come out completely 0, and a little more) and then also take into account the reactance of the cable. But why the contractual treatment in the document on page 15 of a capacitor as an element with cos fi = 0? Is it about simplifying the calculation?

In that formula on the 15th page the power is given in vars which is normal for capacitor banks because the capacitor bank takes capacitive reactive power.
In short, you substitute what power in vars for the current formula in the capacitor. Then, depending on the calculated current, you look at what cross-section fits. Then you count the voltage drop. And depending on the cross-section you have two simplified formulas (probably up to 25mm2) and taking into account the resistance and reactance of the wire.

Okay, you count from the formula the cross-section because of the voltage drop but what something to substitute for? 0? Then 0 mm2 cross section will come out ...

Merki wrote:

I came across a pattern in the network that allows me to determine the required cable cross-section directly so as to maintain the permissible voltage drop (p. 21, pattern 19):

It is better to use these:

Voltage drop - selection of the cable cross-section in single-phase AC networks

Voltage drop - selection of the cable cross-section in three-phase AC networks

Power and current calculator in three-phase systems