Motor Starting Devices/ Characteristics

Start Winding

• A winding that is placed in the stator closer to the rotor than the main (run) winding
  
  
• Connected in parallel with the run winding
  
  
• Placement in the stator is such that the start winding is physically 90 degree away from the run winding
  
  
• The start winding is constructed of smaller wire and may more turns than the run winding
  
  
• The start winding has a high resistance and a high inductance than the run winding
  
  
• Which results in a phase shift between the winding
  
  
• The resulting phase shift cause a rotating magnetic field to be setup in the stator and rotor, which starts the motor
  
  

Start Capacitor:

• Is connected in series with a start winding to increase the phase shift created by the start winding

Shading Coil

• A copper strap is used to separate a small portion of the run winding