Question

What would happen if the field of a D.C. shunt motor is opened?

Answer 1

when their is a suddern loss in the field connection of DC shunt machine,the flux will decrease exponentially as the current in the field winding is decreased.but as the coil is made of Soft iron,there will a small amount of flux will remain in the field coil,within the machine thereafter the decreasing reach the zero value,as we know,t his is called "residual flux". this will be at a value of 2-10% of the main flux..