Recently, I read that starting torque of series motors are much higher than shunt motors.
I try to find out what is reason behind it and I get to know that this is because in DC series motor torque is proportional to square of armature current (and hence we get maximum torque at starting because armature current is maximum at that instant) because field current is same as armature current.
While in DC shunt motor torque is proportional to field and armature current but in this case value of field current is very less (because we take resistance of field winding very high) hence we can say that starting torque is proportional to armature current only.
But there are few points which I still don't understand. Hope someone can help me!
Why we keep high resistance of field winding in shunt DC motor, isn't low resistance of field winding in shunt DC motor can provide same benefits as of series like high starting torque?
Why we don't consider inductances of field winding for starting torque calculation (while I think inductance value must be high as it is wrapped on a ferromagnetic material) for starting torque calculation?
And isn't starting torque should be zero in case of series and shunt motor as Inductances of field winding doesn't allow current and hence starting torque is zero?