• A disconnection of the field circuit in the shunt excited mo-
tor leads to a rapid increase in speed if the motor is run-
ning at no load.
• The rated current value of the DC motor is greater than
the starting current.
• In separately excited DC motor, To reverse the rotation
direction of the motor you need to change both : the po-
larity of the supply voltage of the armature and the sup-
ply voltage of the field winding.
• In separately excited DC motor, The field circuit must be
connected before the armature circuit.
• In DC shunt excited motor, if the armature current decrease
the speed n increase
• In a serial DC motor, if the torque is very less the speed in-
creases to dangerously high value.
• In DC shunt excited motor, if the torque decrease the speed
n increase
Tor F
• In separately excited DC motor, If the armature current
Ia increase the speed n increase.
• A serial DC motor is considered as a fixed speed drive mo-
tor
• In separately excited DC motor, if the field current If in-
creases, the speed n decreases.
• In DC shunt excited motor, if the supply voltage decrease
the speed n increase
• In DC shunt excited motor, "Ra. Ia" is small
• In DC shunt excited motor, the field current is quasi con-
stant
• A series DC motor is often used for traction