🔍 Key Concepts

• Phase relationship between two AC signals in a two‑phase induction servomotor • How a 90° phase shift looks on a sine wave diagram versus other shifts • The physical angle between the reference signal axis and the control signal axis shown in Part B of the illustration

💭 Think About

• Look at the sine waves in Part A: at time t1, how many electrical degrees separate the peak (or zero crossing) of the reference signal from that of the control signal? • In Part B, imagine placing a protractor at the rotor center: what angular separation is drawn between the reference signal magnetic axis and the control signal magnetic axis? • Compare what you see in the time (waveform) diagram with what is drawn in the physical motor diagram—do they represent the same electrical phase angle?

✅ Before You Answer

• Verify the horizontal degree scale under the sine waves and note how far one wave is shifted relative to the other. • Confirm the labeled axes in Part B: the reference axis is horizontal, the control axis is vertical—estimate the angle between them. • Ensure your chosen answer matches both the waveform phase shift and the mechanical axis separation in the stator diagram.