DC Motor.docx

- **Introduction to DC MOTORS.** - **Principle.** - **Construction.** - **Working.** - **Types.** - **Applications.** DC MOTOR ============================== - A DC motor or Direct Current Motor converts electrical energy into mechanical energy. - A...

- **Introduction to DC MOTORS.** - **Principle.** - **Construction.** - **Working.** - **Types.** - **Applications.** DC MOTOR ============================== - A DC motor or Direct Current Motor converts electrical energy into mechanical energy. - A direct current (DC) motor is a fairly simple electric motor that uses electricity and a magnetic field to produce torque, which turns the rotor and hence give mechanical work. PRINCIPLE OF DC MOTORS ====================== - In any electric motor, operation is based on simple electromagnetism. - When a current-carrying conductor is placed in an external magnetic field, it will experience a force i.e. Lorentz force. - Due to this force torque is produced which rotates the rotor of motor and hence a motor runs. CONSTRUCTION ================================= - DC motor consist of 2 windings... 1. Field winding. 2. Armature winding. - Field winding is stationary and armature winding can rotate freely. - Field windings when given DC supply, magnetic field is produced. - Armature winding when connected to DC source, shaft connected to it rotates due to Lorentz force. WORKING OF DC MOTORS ========================================== - ### DC motor are of 3 types they are..... 1. **DC SHUNT MOTOR** 2. ### DC SERIES MOTOR 3. **DC COMPOUND MOTOR** 1. **DC SHUNT MOTOR** - The parallel combination of two windings is connected across a common dc power supply. - The resistance of shunt field winding (Rsh) is always higher than that is armature winding. - This is because the number of turns for the field winding is more than that of armature winding. - The cross-sectional area of the wire used for field winding is smaller than that of the wire used for armature winding. 2. DC SERIES MOTOR -------------------------------------- - The field winding is connected in series with the armature. - The current passing through the series winding is same as the armature current. - Therefore the series field winding has fewer turns of thick wire than the shunt field winding. - Also therefore the field winding will posses a low resistance then the armature winding. 3. DC COMPOUND MOTOR ----------------- I. ### LONG SHUNT COMPOUND MOTOR - In this the series winding is connected in series with the armature winding and the shunt winding is connected in parallel with the armature connection. II. ### SHORT SHUNT COMPUND MOTOR - In short shunt compound motor the series winding is connected in series to the parallel combination of armature and the shunt winding - This is done to get good starting torque and constant speed characteristics. a. ### CUMULATIVE COMPOUND DC MOTORS - If the two field windings i.e. series and shunt are wounded in such a way that the fluxes produced by them add or assist each other b. ### DIFFERENTIAL COMPOUND DC MOTORS - If the two field winding i.e. series and shunt are wounded in such a way that the fluxes produced by them always try to oppose and try to cancel each other. -- -- -- -- BIBLIOGRAPHY ============ - [www.google.com](http://www.google.com/) - en.wikipedia.org - Electrical technology