How is line current calculated for a 3-phase system with 120 A per phase?

In a 3-phase system, the line current can be calculated using the relationship between line current and phase current, specifically when considering a balanced load. When phase current is measured at 120 A, the relationship between line and phase currents can be expressed as follows for a star (Y) connection: the line current is equal to the phase current.

However, when analyzing other configurations such as delta (Δ) connections, the calculation becomes different. In a delta configuration, the line current is related to the phase current by the factor of √3 (approximately 1.732). This is where the multiplication by 1.732 fits into the context.

For a balanced 3-phase system, if each phase is supplying 120 A, and you need to find the line current as per the scenario of delta connection, the calculated line current would increase because it involves combining the currents from multiple phases. Hence, when you multiply the phase current by √3, it reflects the total current consumed by the loads in the system, which explains why this choice is appropriate for calculating line current in a delta configuration. Understanding this relationship is essential for anyone dealing with 3-phase electrical systems.