Cross phase is defined as which of the following?

Cross phase is defined as which of the following?

• A. A meter probe
• B. A dial indicator
• C. A protective relay
• D. Reconnecting the phases improperly causing a rotation change

Answer: (D)

Understanding phase sequence and its effect on rotation is being tested here. When you cross or swap the wiring of the three phases, you change the order in which the phases lead each other. Reversing two leads flips the phase sequence, which in a three-phase system makes the rotating magnetic field go in the opposite direction. That change in direction is exactly what is described by cross phase, so it’s the best answer. The other options are tools or devices (meter probe, dial indicator, protective relay) and don’t define what cross phase means.

Understanding phase sequence and its effect on rotation is being tested here. When you cross or swap the wiring of the three phases, you change the order in which the phases lead each other. Reversing two leads flips the phase sequence, which in a three-phase system makes the rotating magnetic field go in the opposite direction. That change in direction is exactly what is described by cross phase, so it’s the best answer. The other options are tools or devices (meter probe, dial indicator, protective relay) and don’t define what cross phase means.