In a balanced three-phase circuit, you can calculate the line current (also known as the line-to-line current) from the phase current using the following relationship:
Line Current (IL) = Phase Current (IP)
For a balanced three-phase system, the line current is the same as the phase current. This is true for both the magnitude and phase angle of the currents.
It's important to note that this relationship holds true only for a balanced system where all three phases have equal magnitudes and are 120 degrees apart in phase. In real-world scenarios, three-phase systems are often designed and operated to be balanced to ensure that the line currents are equal to the phase currents. However, in cases where the system is not balanced, the relationship between phase currents and line currents becomes more complex, and additional calculations are required to determine the line currents accurately.