2. Over view
• Electric motors
• Types of electric motors
• Losses in induction machines
• Motor efficiency
• Energy efficient motor
2
3. ELECTRIC MOTORS
• Convert electric energy to mechanical energy
• Operate by the interaction between magnetic field and winding
current
• Operate in both motoring and braking mode
• Use in industrial fans ,pumps, machine tools etc..
3
7. 7
DC MOTOR
• Permanent magnet DC motor
• Separately excited DC motor
• Series field wound DC motor
• Shunt field wound DC motor
• Compound motor
8. 8
Losses in induction machines
• Electrical losses due to heat produced in the stator and
rotor winding (copper losses)
• Magnetic loss in the iron due to hysteresis and eddy
current
• Mechanical loss due to friction in the bearing and
ventilation
• Stray load losses
12. 12
Mechanical losses
• Due to friction in the bearing and ventilation
• This losses vary slightly with load and speed
• This variation are considered to be negligible
14. Motor Efficiency
• Ratio between the shaft power out put to
the electrical input
• Ƞ = P out/P in
• Ƞm = (Pout )(746)/Pin
when Pout in hP
14
15. Energy Efficient motors
• 2 to 8 percentage more efficiency than the standard
motor
• Same out put by consuming lesser amount of power
• Achieved by
1. More copper in the winding
2. Reduced fan loss
3. Higher quality thinner steel lamination
4. Optimal air gap between rotor and stator
5. Greater length high quality aluminum used
in the rotor frame 15