L
Leesparkykent
Quick smoke packet calculation if the Ze is 0.05 and the manufacturer gives a max Zs of 0.09 at 100% your design max Zs is 0.075ohms at 80% to allow for conductor operating temp. Over a distance of 80meters a 185mm CPC would bring you just in under this value by a gnats cock. 120mm 4 core SWA based on 250A and 80 meter run will give you a volt drop of approximately 6.6V.
Using 35mm SWA from this panel board for the 30 meter 100A supply to the 3phase DB will give you a calculated volt drop of around 8.8V added to the 6.6V that's 15.4V In reality the total volt drop is going to be under this as it wont be pulling full load current and at 250A the cable isn't at its maximum CCC so wont be at maximum conductor temp at which the figures are based. With a 25mm CPC that would give you a calculated Zs/Zdb of around 0.12ohms which should be under the max permitted for a 100A OCPD.
The above is rough and vague but should hopefully point you in the right direction for your own calcs.
Using 35mm SWA from this panel board for the 30 meter 100A supply to the 3phase DB will give you a calculated volt drop of around 8.8V added to the 6.6V that's 15.4V In reality the total volt drop is going to be under this as it wont be pulling full load current and at 250A the cable isn't at its maximum CCC so wont be at maximum conductor temp at which the figures are based. With a 25mm CPC that would give you a calculated Zs/Zdb of around 0.12ohms which should be under the max permitted for a 100A OCPD.
The above is rough and vague but should hopefully point you in the right direction for your own calcs.
