Three Phase Traction Motor
Three Phase Traction Motor
Three Phase Traction Motor
Made Simple
11.2.2021
Historical background
• The electrical power got developed with DC
'
'
Torque Speed characteristics
Induction Motor
• The motor is a transformer with secondary
shorted
120𝑓
• The speed of the motor is Ns =
𝑃
• Torque is T =𝑠𝐸2𝑟2 ÷ ( r2)2 +(sx2)2
• The motor draws 6 to 7 times the rated
current at start
• The starting torque is about half the
maximum torque
Cont’d
• Parallel operation of two motors is not
possible unless current difference can be
tolerated.
• Wheel diameters are needed to be almost
equal
Comparison of Torques
• I2cos(θ-2π/3)*ā + I3cos(θ+2π/3)*ā2
failures
failures
FRPCPY
failures
FRPCPY
FRPCPY
No. of
No. of
No. of
Av.
Av.
Av.
Population
Population
Population
Pinion 18 324 5.6 33 336 9.8 64 354 18.1
Bearing 3 324 0.9 10 336 3.0 13 354 3.7
1 2
I M characteristics
Typical Three Phase system
Variation in voltage