Then a fault occurs. You forgot to calculate the prospective short circuit current. That transformer can deliver for the first few cycles. Your 600-amp breaker sees that current and welds itself shut. The arc sustains. The fire starts.
( Z_cable, actual = 0.0025 + j0.0035 \Omega ). ( Z_base, ohms = V_base^2 / S_base = 480^2 / 10^7 = 0.02304 \Omega ). ( Z_cable, pu = (0.0025 + j0.0035) / 0.02304 = 0.1085 + j0.152 ).
Q: What is the per unit system? A: The per unit system is a method of representing power system quantities, such as voltage, current, and impedance, as dimensionless values.
Short Circuit Current — Calculation
Then a fault occurs. You forgot to calculate the prospective short circuit current. That transformer can deliver for the first few cycles. Your 600-amp breaker sees that current and welds itself shut. The arc sustains. The fire starts.
( Z_cable, actual = 0.0025 + j0.0035 \Omega ). ( Z_base, ohms = V_base^2 / S_base = 480^2 / 10^7 = 0.02304 \Omega ). ( Z_cable, pu = (0.0025 + j0.0035) / 0.02304 = 0.1085 + j0.152 ). short circuit current calculation
Q: What is the per unit system? A: The per unit system is a method of representing power system quantities, such as voltage, current, and impedance, as dimensionless values. Then a fault occurs