Question

The field winding of a dc shunt machine has
1. current excitation
2. voltage excitation
3. Both (1) and (2)
4. separate excitation

Answer 1

Correct Answer - Option 2 : voltage excitation

DC shunt machine:

• The field winding, which produces the constant magnetic field in the stator, is wired in parallel, or in shunt, with the armature windings in shunt DC motors.
• The same power supply is therefore used to power both the armature and the field windings, and the total current is split into two parallel paths.
• The filed winding has voltage excitation.
• The field winding in shunt DC motors is made of many windings of thin wire, to both increase the magnetic field’s strength and limit the current through the coil.
• The current is reduced through the field coil and thus increases in the armature.
• The larger current in the armature produces a phenomenon known as back EMF – an electromotive force produced by the armature’s magnetic field rotating through the stator field – and the back EMF serves to reduce the current through the armature winding.