Generators are classified according to the method of excitation. Seperately excited dc generators Self excited dc generators Seperately excited dc generator :- In seperately excited dc generator, field current is provided by using an independent external d.c. source. V = Eg – Ia Ra Seperately excited Generators are rarely used in practice.
There are two windings in a dc generator and a dc motor: Field winding Armature winding. The purpose of field winding is to produce magnetic field (called main flux) whereas the purpose of armature winding is to carry to armature current. Although the armature winding is not provided for the purpose of producing a magnetic field, still the current… Read More Armature Reaction in DC machines
Failure of self-exication means in Armature winding there will be generation of flux So Dc Generator will not produce any output voltage, while Rotor is rotating. There are so many reasons for failure of self-exication of Dc Generator.These are following… Absence of Resuidal Magnetism Wrong field winding connection Wrong direction of Rotation Resistance of Field-winding (Rf)… Read More Reasons for failure of self exication of DC generator
Electrical World 