Voltage drop happen during long way travel of power from supplier to load. The standard allowable voltage drop is between 3-5%. Normally variable that affect voltage drop is cable length(internal resistance), load resistance & impedance. Basiclly we can calculate this voltage drop from online voltage drop calculator.

The question is....

Is it any voltage drop occur during transferring signal that take 1km long (i.e from transmitter to PLC). From my understanding, I believe voltage drop will occur due to length of cable(internal resistance). But since transmitter and PLC is provided with external power supply and since transmitter can be consider as power supply while PLC can be consider as load, is it PLC will affect the voltage drop.

How the calculation and parameter affect the voltage drop?

Any reference i.e books, notes can be used as reference?