24v dc voltage drop calculations
- Thread starter mileson
- Start date
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H
holmslaw
..
Why? If this is a wind turbine, you're probably doubling the cost of it by having it so far away.
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H
holmslaw
..
25mm^2 SWA has a mV/A/m rating of 1.85
The figures above are for 120mm^2 SWA!
The figures above are for 120mm^2 SWA!
You need to do exactly what the national grid does, get the voltage stepped up much higher for the transmission lines.
If you can get 24v ac out of the thing then chuck that into a transformer and pull it up to 240v, then things get much much more sensible.
If you can get 24v ac out of the thing then chuck that into a transformer and pull it up to 240v, then things get much much more sensible.
H
holmslaw
..
Chivers asked if your numbers were for a 25mm^2 cable.
25mm^2 SWA has a mV/A/m rating of 1.85, whereas your numbers are done with an mV/A/m value of 0.39 which would suggest your numbers are based on a 120mm^2 cable....
Its not that hard to grasp unless i've missed something.
25mm^2 SWA has a mV/A/m rating of 1.85, whereas your numbers are done with an mV/A/m value of 0.39 which would suggest your numbers are based on a 120mm^2 cable....
Its not that hard to grasp unless i've missed something.
0.39 whats? 0.39 mV/A/m that's what. Parameter concerned is the voltage drop rating and the units are mV/A/m. The parameter is NOT called the "mV/A/m rating" , "mV drop" or anything else like that and is not quoted as a simple number.
Check by DIMENSIONS (a technique taught in year 8 maths when I was at school):
mV/A/m x A X m = mV Which is the correct unit for the calculated voltage drop
mV X A X m = milliVoltAmpmetres which is not the unit of voltage drop
Stepping up the voltage before transmission is definately a good idea, even allowing for losses in the transformers the improvement over a hundred metres is worth it.
But it isn't just that simple when you (apparently) have a fixed load of 800 watts and a very variable source of power from zero watts to what ever the generator's maximum safe output is.
If wind energy into generator is below 800 watts then do you shut down the load. If the wind energy is greater than 800 then what do you do with excess output if the generator cannot be regulated.
Do you regulate voltage at the generator output as 24 plus twice known voltage drop along cable ( load sees 24 volts ) or do you measure voltage at the load and send that back to the generator regulator.
But it isn't just that simple when you (apparently) have a fixed load of 800 watts and a very variable source of power from zero watts to what ever the generator's maximum safe output is.
If wind energy into generator is below 800 watts then do you shut down the load. If the wind energy is greater than 800 then what do you do with excess output if the generator cannot be regulated.
Do you regulate voltage at the generator output as 24 plus twice known voltage drop along cable ( load sees 24 volts ) or do you measure voltage at the load and send that back to the generator regulator.
H
holmslaw
..
H
holmslaw
..
FFS.
I was pointing out to chivers that 25mm had a loss figure 5 times higher than your original working, and that your original numbers were on 120mm cable.
I was pointing out to chivers that 25mm had a loss figure 5 times higher than your original working, and that your original numbers were on 120mm cable.
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