Regarding A.C generator

[sankar_mariner]

Please explain why the usual arrangement is to have stationary A.C windings and rotating poles ? ( for reasons other than high maintenance of slip ring and lower power to weight ratio )

Thanks.

[Big Pete]

Smaller current through the rotating Poles to produce the magnetic field, much larger current through the stationary windings, therefore it reduces the problem of commutating i.e. slip rings/ commutators to connect the rotating shaft to a power supply and reduces the rotating mass, hence smaller cheaper bearings, less inertia to overcome during start up / stopping, therfore less force on the couplings.
Perfectly possible to make an Alternator or DC Dyanamo the other way round, but it works better in the standard configuration.

BP.