In a three-phase generator, how far apart are the coils?

In a three-phase generator, how far apart are the coils?

• A. 90 degrees
• B. 60 degrees
• C. 180 degrees
• D. 120 degrees

Answer: (D)

The key idea is that three-phase operation uses three windings spaced so their induced voltages are 120 electrical degrees apart. This arrangement makes the phase voltages reach their peaks one after another by 120 degrees, producing three sine waves that are evenly offset in time and creating a smooth rotating magnetic field for balanced power delivery. The electrical angle depends on the rotor’s pole count, so electrical 120 degrees corresponds to a specific mechanical spacing that varies with the number of poles. In short, the windings are placed 120 electrical degrees apart to maintain the 120-degree phase difference between the three outputs.

The key idea is that three-phase operation uses three windings spaced so their induced voltages are 120 electrical degrees apart. This arrangement makes the phase voltages reach their peaks one after another by 120 degrees, producing three sine waves that are evenly offset in time and creating a smooth rotating magnetic field for balanced power delivery. The electrical angle depends on the rotor’s pole count, so electrical 120 degrees corresponds to a specific mechanical spacing that varies with the number of poles. In short, the windings are placed 120 electrical degrees apart to maintain the 120-degree phase difference between the three outputs.