Final answer:
The base current (IBase) is calculated to be 2.624 A, and the Y-connected base impedance (ZBaseY) is 48.4 Ohms. For 50% per unit, the actual current is 1.312 A, and the actual Y-connected impedance is 96.8 Ohms.
Step-by-step explanation:
The base current (IBase) can be calculated using the formula:
IBase = Sbase / (sqrt(3) × VLLbase)
Where Sbase is the apparent power base and VLLbase is the line-to-line voltage base.
Given Sbase = 1 MVA and VLLbase = 220 kV:
IBase = 1 MVA / (sqrt(3) × 220 kV) = 2.624 A (rounded to three decimal places).
The base Y-connected impedance (ZBaseY) is given by:
ZBaseY = VLLbase² / Sbase
ZBaseY = (220 kV)² / 1 MVA = 48.4 Ω (rounded to one decimal place).
Now, to calculate the actual values of current and Y-connected load corresponding to 50% per unit:
Actual Current = 50% of IBase = 0.5 × 2.624 A = 1.312 A
Actual Impedance = ZBaseY / 0.5 = 48.4 Ω / 0.5 = 96.8 Ω