(a) In what respect does the construction of an A.C. generator differ from that of a D.C. generator?
(b) What normally drives the alternators in a Thermal Power Station? What fuels can be used to heat water in the boiler?
(a) Construction-wise, the only difference between a D.C. generator and an A.C. generator is in the way the two ends of the generator coil are linked to the outer circuit. In a D.C. generator we connect the two ends of the coil to a commutator consisting of two half rings of copper. In an A.C. generator we connect the two ends of the coil to two full rings of copper called slip rings. There is no commutator in an A.C. generator.
(b) Generally, the alternators in a Thermal Power Station are driven by the power of high pressure steam.
To heat water in the boiler, fuels like coal or natural gas can be used.