Hi I've got a question regarding volt drop.
When calculating volt drop to a 3 phase distribution board do I use 230v (11.5v) or 400v (20v)
The board I'm attempting to put a cable to is 75 meters away.
Design current 100A
From TABLE 4D4A Cable selected = 25 mm²
For 25 mm²: mV/A/m 1.75 for 230v
Voltdrop = (mV/A/m x Length x Design current) / 1000Voltdrop = ( 1.75 x 75 x 100 ) / 1000
Voltdrop = 13.13 Volts
Which is too high so:
From TABLE 4D4A Cable selected = 35 mm²
For 35 mm²: mV/A/m 1.25 for 230v
Voltdrop = (mV/A/m x Length x Design current) / 1000Voltdrop = ( 1.25 x 75 x 100 ) / 1000
Voltdrop = 9.38 Volts
Which is fine for volt drop.
But if I use the value for 400v in TABLE 4D4A Cable selected = 25 mm²
For 25 mm²: mV/A/m 1.75 for 400v
Voltdrop = (mV/A/m x Length x Design current) / 1000Voltdrop = ( 1.5 x 75 x 100 ) / 1000
Voltdrop = 11.25 Volts
which is well below the 20v limit for 400v.
Now I know it wont break the bank putting a 35mm in. I just wan to know how to do it correctly.
Hopefully I'm getting my calculation correct and my question makes sense?
When calculating volt drop to a 3 phase distribution board do I use 230v (11.5v) or 400v (20v)
The board I'm attempting to put a cable to is 75 meters away.
Design current 100A
From TABLE 4D4A Cable selected = 25 mm²
For 25 mm²: mV/A/m 1.75 for 230v
Voltdrop = (mV/A/m x Length x Design current) / 1000Voltdrop = ( 1.75 x 75 x 100 ) / 1000
Voltdrop = 13.13 Volts
Which is too high so:
From TABLE 4D4A Cable selected = 35 mm²
For 35 mm²: mV/A/m 1.25 for 230v
Voltdrop = (mV/A/m x Length x Design current) / 1000Voltdrop = ( 1.25 x 75 x 100 ) / 1000
Voltdrop = 9.38 Volts
Which is fine for volt drop.
But if I use the value for 400v in TABLE 4D4A Cable selected = 25 mm²
For 25 mm²: mV/A/m 1.75 for 400v
Voltdrop = (mV/A/m x Length x Design current) / 1000Voltdrop = ( 1.5 x 75 x 100 ) / 1000
Voltdrop = 11.25 Volts
which is well below the 20v limit for 400v.
Now I know it wont break the bank putting a 35mm in. I just wan to know how to do it correctly.
Hopefully I'm getting my calculation correct and my question makes sense?