Q. Explain about Synchronous machines?

Large ac power networks operating at a constant frequency of 60 Hz in the United States (50 Hz in Europe) rely almost exclusively on synchronous generators to generate electric energy. They can also have synchronous compensators or condensers at key points for reactive power control. Generators are the largest single-unit electric machines in production, having power ratings in the range of 1500 MVA, and we can expect machines of several thousand MVA to come into use in future decades. Private, standby, and peak-load plants with diesel or gas-turbine prime movers also have alternators. Non-land-based synchronous plants can be found on oil rigs, on large aircraft with hydraulically driven alternators operating at 400 Hz, and on ships for variable frequency supply to synchronous propeller motors. Synchronous motors provide constant speed industrial drives with the possibility of power factor correction, although they are not often built in small ratings, for which the induction motor is cheaper.