Cable Sizing Formula — No Ads

[ I_req = 84.9 / 0.87 \approx 97.6 \text A ]

Voltage drop (use R=0.87 О©/km, X=0.08 О©/km for 25 mmВІ): [ V_d = \sqrt3 \times 0.1 \times 84.9 \times (0.87\times0.85 + 0.08\times0.526) \approx 11.8 \text V ] % drop = ( 11.8 / 400 \times 100 = 2.95% ) в†’ OK (<5%).

[ V_d = \sqrt3 \times L \times I \times (R_ac \cos\phi + X \sin\phi) ]

But for sizing, we use the formula: