Hi I just want some ideas on transfer a control signal (just on off)
the thing is it have to be safe voltage its a level switch in a water tank the distance is 300+ meter and i will have a voltage drop that will effect the working of the contacters and relais
normaly i work with 24V control voltage and have big problems to work with 220V control voltage (did it only one time under protest on demand of acustomer and no responsability paper from him)
the aplication is in laos so radio transmitting is not Alowed by law
my idea is to step up the voltage on one side of the line just for the transportation and step it down on the other side also to keep cable to a minimum size (see drawing)
relay impendance is 80hm: so +/- 0.3 Amp will be the current
the distance is 300 meter so total wire lengt is 600m
i calculated with gauge nr23 (I am not familiar with this type of writing the wire size) 0.5 sqr mm
that comes down on a resistance of +/- 40hm: (according online tables)
so if i have a output from 36V than it should work
i still keep it optional to put a resistor (Value unknown yet 5 Watt) in series to fine tune the whole thing on site situation as the lenkt of the cable could vary a bit