Red Seal Industrial Electrician Practice Exam

What does the term 'phase rotation' refer to in electrical systems?

1. The speed of electrical devices

2. The order in which phases reach maximum voltage

3. The direction of current flow

4. The overall power consumption

The correct answer is: The order in which phases reach maximum voltage

Phase rotation refers to the order in which the different phases in a three-phase power system reach their maximum voltage levels. In a three-phase system, the three phases are typically labeled as A, B, and C, each separated by an electrical angle of 120 degrees. The sequence in which these phases reach their peak voltage is critical, especially for the correct operation of three-phase motors and other equipment designed to run on a specific phase rotation. When the phase rotation is correct, it ensures that motors and other three-phase equipment operate smoothly and efficiently. If the phase rotation is incorrect, motors can run in the opposite direction, which could lead to mechanical damage and safety hazards. This is why it’s essential to measure and verify phase rotation when setting up or troubleshooting three-phase systems. The other options do not directly relate to the concept of phase rotation. The speed of electrical devices, the direction of current flow, and overall power consumption deal with different aspects of electrical engineering and do not pertain to the sequencing of phase voltage peaks.