DC 24V - Cabling Sizing -

[dimcha]

Dear all,

I need to supply DC 24V power to long distance. The required power is low up to 9W. What is the maximum allowable voltage drop?

 

[malcolmsanford]

The volt drop calcs used in the electrical contracting industry is for low voltage installations and so not really relevant for extra low voltage.

What is it your supplying, how long is the run and are there any manufacterers guidelines to work to

 

[telectrix]

in the absence of anything i can find, as you load is so small, less than 0.5A, just depends on the run. alarm cable with 2 cores paired will carry that for 50-60m, no sweat. what cable type are you considering?

 

[Chr!s]

Dear all,

I need to supply DC 24V power to long distance. The required power is low up to 9W. What is the maximum allowable voltage drop?

If its power only, then work to 5%, so a Volt drop of 1.2 volts Max.

 

[pmac10]

panel mounted 24vdc power supplies sometimes have an adjustment pot. on the front, you may be able to adjust it up to 28vdc, Schnieder Electric make these

 

[dimcha]

Indeed.... the current is very low 350mA. The distance is quite long.. up to 175meters. If I keep the voltage drop to 4% or 5%, than everything is fine because the cable is going to be 2.5mm2 which is the maximum allowable cable cross section of the controller board. What kind of cable is that? two core cable or two conductors of single core?

If I have to decrease the voltage drop, then the acceptable cable length is more than 10mm2. I am not sure buti n that case, I need to drop an AC cable, and then converted to DC.

 

[aptsys]

You'd be better off putting the transformer at the other end of the run! Is this not an option?

 

[dimcha]

You'd be better off putting the transformer at the other end of the run! Is this not an option?

Unfortunately, it's not an option.

 

[telectrix]

Indeed.... the current is very low 350mA. The distance is quite long.. up to 175meters. If I keep the voltage drop to 4% or 5%, than everything is fine because the cable is going to be 2.5mm2 which is the maximum allowable cable cross section of the controller board. What kind of cable is that? two core cable or two conductors of single core?

If I have to decrease the voltage drop, then the acceptable cable length is more than 10mm2. I am not sure buti n that case, I need to drop an AC cable, and then converted to DC.

you can only run single core single insulated if it's in containment. depending on the risk factor as regards mechanical damage, you could use T/E or SWA.

 

[vaughant]

Most 24V control circuits I`ve worked on have been 2.5mm stranded and as said above,conduit or armoured.

 

[dimcha]

you can only run single core single insulated if it's in containment. depending on the risk factor as regards mechanical damage, you could use T/E or SWA.

If the cable is 2.5mm2, can't be a conductor with two cores?

All the cables are going to be buried underground, so SWA is necessary.

 

[72-van]

Could you not use a 24v battery instead?

 

[dimcha]

Its a PV Farm installation. It needs a permanent solution for a long time...