3. In DC Motors, the direction of rotation of rotor can be determined by Fleming’s left hand rule.According to this rule when thumb, fourth finger and middle finger of the left hand are stretched in such a way that all are mutually perpendicular to each other and if the fourth finger represent the direction of magnetic field, middle finger indicates the direction of current then thumb represents the direction of force.
4. DC Motors are generally of three types
– DC shunt Motors
– DC series Motors
– DC compound motors
In DC shunt motor, the field winding is connected in parallel to the armature winding. In DC series motor, the field winding is connected in series to the armature winding and the DC compound motor is the combination of the series motor and the shunt motor.
5. Current flow through the winding of a DC motor is not direct current, its an alternating current.No doubt The input current to DC motor is DC current but it is further converted into AC so that it can do useful work.
6. The device which is used to convert DC into AC in DC motor is called commutator. Actually it is the most important part of DC motor. It is responsible to produce the unidirectional torque in DC motor.
7. Construction of DC motor is similar to DC generator. Same machine can be used as DC motor as well as DC generator. It consists of two important parts one is rotating part and another is stator part. The stator part of DC motor produce the main field flux and known as magnetic field system. The rotating part of DC motor is called armature.