D.C. Machine losses

D.C. Machine losses

As explicit  in Section twenty one.1, a generator may be a machine for changing energy into voltage and a motor may be a machine for changing voltage into energy. once such conversions crop up, sure losses occur that ar dissipated within the sort of heat.

The principal losses of machines are:

(i) Copper loss,

 Copper loss, because of I^2R heat losses within the coil and field windings.

ii) Iron (or core) loss

 Iron (or core) loss, because of physical phenomenon and eddy-current losses within the coil. This loss may be reduced by constructing the coil of element steel laminations having a high impedance and low physical phenomenon loss. At constant speed, the iron loss is assumed constant.

(iii) Friction and windage losses,

Friction and windage losses, because of bearing and brush contact friction and losses because of air resistance against moving elements (called windage). At constant speed, these losses ar assumed to be constant.

(iv) Brush contacts

 Brush contact loss between the brushes and electric switch. This loss is roughly proportional to the load current.


The total losses of a machine may be quite significant and operational efficiencies of between eightieth and ninetieth ar common.