🔍 Key Concepts

• Brushless alternator excitation and the role of a rotating exciter armature • How a 3‑phase bridge rectifier on the rotor feeds the main field without slip rings • Which windings are stationary vs. rotating in this diagram (exciter field, main armature, main field)

💭 Think About

• Look at the current path from the automatic voltage regulator (AVR) to the exciter and then to the main field. At what point would you normally need slip rings and brushes, and how is that avoided here? • Ask yourself: if the exciter armature and the rectifier are already mounted on the rotating shaft, does any DC need to be transferred from a stationary part to a rotating part? • Compare this scheme with an older DC‑excited alternator that uses slip rings. What key component in this drawing replaces the need for brushes?

✅ Before You Answer

• Identify clearly which components are on the rotating shaft (inside the dashed ‘Rotating Elements’ box). • Confirm whether any DC circuit crosses from stationary to rotating parts without using a rectifier that is also on the rotor. • Verify if the exciter field is stationary and fed directly from the AVR, and whether the main field is supplied entirely from the rotor‑mounted rectifier.