What does “line current” and “phase current” indicate in a 3-phase electrical system?

In a 3-phase electrical system, particularly in a Y (or star) connection, the relationship between line current and phase current is a fundamental concept. In a Y-connected system, each phase of the load is connected to a neutral point, allowing for the line currents to be equal to the phase currents. This means that the current flowing through each line conductor (line current) is the same as the current flowing through each individual load (phase current).

This equality arises because the line conductors are directly carrying the current that is flowing through the corresponding phase loads. Therefore, if you measure the current on any line in a Y-connected system, it will match the current flowing through the load attached to that phase. Understanding this relationship is crucial for calculations and analysis in three-phase systems, especially when dealing with power distribution, circuit design, and addressing issues related to load balance.

In contrast, in a Delta connection, line current is indeed different from phase current, and its value is higher than the phase current. This reinforces the importance of recognizing the type of connection when analyzing a 3-phase system. Hence, the statement regarding line current being equal to phase current in a Y-connected system is accurate and reflects a key aspect of how these systems operate.