Exam Question

### (a) Explanation of Single Phasing (6 Marks)
Single phasing is a fault condition in a three-phase electrical system where one of the three supply lines (or phases) to a polyphase induction motor is lost or disconnected. A three-phase AC supply is essential for creating a rotating magnetic field (RMF) of constant magnitude within the motor's stator, which is necessary for self-starting and smooth operation.
**Mechanism and Effects:**
1. **Loss of Rotating Magnetic Field (RMF):** When one phase is lost, the balanced three-phase system degenerates into a single-phase supply across the remaining two lines. This configuration can no longer produce a true RMF. Instead, it generates a *pulsating* or *oscillating* magnetic field.