Skin Effect: tendency of the current to crowd near the conductor surface.
Skin effect is proportional to frequency, conductor diameter and permiability. Skin effect increases effective resistance of conductor. In DC, no skin effect.
all day efficiency is ratio of energy output to the energy input taken over 24 hour period. design distribution transformer for max. efficiency occurring at the avarage output power. performance of distribution transformer represent by all day efficiency.
under steay state: P= (E V sinδ)/ X change in load on motor, δ adjust to new value rotor oscillate about its final equilibrium load angle called hunting. cause: sudden change in load fault in supply system sudden change in field current remedies: using flywheel using damper bar