D.C motor are mostly used now present days. This types of motor are used, where the speed are used slow or down. Other words we says that these motors are used where load have not continuity. There are different method used to control speed of d.c shunt motor. But now we discuss only three method to control speed (up or down) of d.c shunt motor.
1:- Changing the field resistance
2:- Changing the armature terminal voltage
3:- Changing the armature resistance
These three method which are very helpful to speed up or down of d.c shunt motor.
1» changing the field resistance:-
When the field resistance of d.c shunt motor increase the field current decrease. Then the flux also decrease and armature e.m.f decrease. When (Ea) decrease armature current increase. Because the armature current (Ia) is the difference of terminal voltage and armature voltage.
When armature current (Ia) increase in case the torque also increase.
and in this case the speed of motor are increase. So we say that the field resistance increase the speed of motor also increase and if we decrease the field resistance the speed of motor also decrease.
The first part of this blog is finished. Second and last part of this blog is soon.