Answer / varun devulapalli

for any machine whether it may be rotating or stationary, the common losses are the iron losses and the copper losses. But in additional for the rotating machines there are mechanical losses. Iron losses comprise of two losses i.e., hysterisis loss and eddy current loss. Hysterisis loss depends on the type of the material used and its B-H curve. Eddy current loss is due to the induction of eddy currents in the armature material. these eddy currents are not useful but they create heat in the machine. so to reduce eddy current losses we use thin laminations in the core with a very thin insulation like paper in between each lamination.
Copper losses are divided into field copper loss and the armature loss. copper losses are the ohmic losses which arrive due to the resistance in the winding. square of the current multiplied by the resistance gives the copper losses.
Mechanical losses comprise of frictional and windage losses. frictional losses arive due to the ageing of the bearings. windage losses are due to the wind that oppose the rotation of the machine in a direction.
less losses leads to maximum efficiency.

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