🔍 Key Concepts

• Role of the AVR (Automatic Voltage Regulator) in controlling generator output voltage • How a thyristor / SCR (silicon-controlled rectifier) behaves compared with an ordinary diode • What the diagram in figure "A" shows about the path from AC exciter output to DC field current

💭 Think About

• Look at the symbol drawn for the thyristor control: does it look more like a diode, a transistor, or a temperature sensor, and how many terminals does it have? • Trace the path from the AC supply from the exciter through the thyristor control to the DC field winding—what has to happen to that AC before it can feed a DC field? • Ask yourself whether main generator field windings are normally supplied with AC or DC, and whether their current needs to be varied smoothly for voltage regulation.

✅ Before You Answer

• Verify whether the field winding in the diagram is labeled DC field current or AC current. • Check if the thyristor symbol shows a gate (G) lead in addition to anode (A) and cathode (K), indicating controllable conduction rather than simple rectification. • Confirm that any temperature-sensing device (like a thermistor) would normally be shown physically attached to the field or labeled with temperature rather than placed directly in the power conversion path.