3 Phase Unbalanced Load
An unbalanced load in a three-phase system occurs when the current or voltage in each phase of a three-phase power supply system is unequal. This is the case if the loads connected to each phase have different power ratings, different power factors or faults occur in the system, e.g. in case of a phase loss.
3 phase unbalanced star connection
3 phase unbalanced star connection
If the resistors R1, R2 and R3 do not have the same value, the phase currents are different. As a result, the neutral carries current, which we can determine by the vector diagram of the currents.
The vectors are added mathematically by adding the XY-values of the polar coordinates:
Calculation Unbalanced load
Example: The resistors R1 = 100 Ω, R2 = 80 Ω and R3 = 50 Ω are connected to a star with neutral wire (3-Phase 4 Wire). Calculate the current INeutral and the total power and sketch the current vectors.
