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The interaction of turns and pitch: How they react affects the performance of a motor

Publication date: 
February 2012
Jim Bryan, EASA Technical Support Specialist
Type of media: 

When designing or redesigning an electric motor, there are many trade-offs. For instance, opening up the air gap to improve power factor might diminish the efficiency. For every action taken in adjusting the motor's design, there is a reaction at some other point that affects the motor's performance. One of the critical considerations involves the interaction of the turns per coil and pitch. As you shorten the pitch, it requires more turns to generate the same torque. But, as you increase the number of turns, the wire takes up more space in the slot. The way to overcome this problem is to decrease the wire size. But decreasing the wire size decreases the current density, increasing the I2R losses and operating temperature. Discussion includes:

  • Factors to consider
  • Shortcuts: Good ones and bad ones
  • Number of turns in coil