Exam Question

### **Determination of Neutral Current in an Unbalanced 4-Wire Star System**
#### **1. Fundamental Principle**
In a 3-phase, 4-wire star-connected system, the neutral wire provides a return path for current. According to Kirchhoff's Current Law, the instantaneous current in the neutral wire is the sum of the instantaneous currents in the three line conductors.
For a balanced system, the phasor sum of the three line currents is zero, resulting in zero current flow in the neutral wire. However, when the loads are unbalanced (i.e., different magnitudes or power factors), the phasor sum is non-zero. This resultant current, known as the out-of-balance current, flows through the neutral wire.