D.C Series motor never operated on

D.C series motor both armature and feild connected in series at noload condition current drawn by the motor is zero Ia=0 flux also zero. but very small amount of flux avalible because of residual magnetism

in series motor speed  =  N ? Eb/? Eb almost conistant

                                 =    N ? 1/?

At no load condition d.c series can be run as dangerously very high so d.c series motor
operated at load condition only