Time: 20:00
Important one liner (Construction and Working Principle of DC Motor)
- A DC motor converts electrical energy into mechanical energy.
- It operates on the principle of Fleming's left-hand rule.
- The armature winding carries current and interacts with magnetic field.
- Stationary magnetic field is produced by field winding or permanent magnets.
- Commutator reverses current direction to maintain unidirectional torque.
- Brushes provide sliding contact between supply and rotating armature.
- Back EMF opposes applied voltage and limits armature current.
- Torque is proportional to armature current and flux.
- Shunt motors offer nearly constant speed under varying loads.
- Series motors provide high starting torque but variable speed.
- Compound motors combine series and shunt characteristics.
- Armature cores are laminated to reduce eddy current losses.
- Interpoles improve commutation and counteract armature reaction.
- Speed control by varying field current or armature voltage.
- Copper losses occur in armature and field windings due to resistance.
- Mechanical losses include friction and windage losses.
- Stray losses arise from leakage flux and harmonics.
- Bearings support the shaft and reduce friction.
- Voltage equation: V = E + I_a R_a.
- Armature reaction distorts the main flux under load.
- Commutation quality affects brush sparking and performance.
- DC motors require regular maintenance of brushes and commutator.
- Applications include traction, fans, lathes, and household devices.
Keywords: construction of DC motor, working principle of DC motor, Fleming's left-hand rule, commutator function, armature reaction, DC motor torque, back EMF in DC motor, DC motor speed control, shunt motor characteristics, series motor characteristics, compound DC motor, DC motor applications, DC motor parts quiz