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AC Motor Redesign

Publication date: 
February 2014
Type of media: 

EASA’s AC Motor Redesign manual explains how to make all possible changes in the ratings of AC electric motors, within design limitations. Besides mathematical formulas, it provides guidelines on the limitations for each type of redesign. These are useful in determining whether a desired new rating is possible before the motor is stripped. Terms are expressed in both English and metric units. Each chapter contains at least one example to guide you through your own redesigns.

This book is available to EASA members as a FREE download or printed copies can be purchased.

Chapters in this book include:

  • Wire size change
  • Voltage change
  • Horsepower or kilowatt change
  • Frequency change
  • Phase change
  • Circuit change
  • Span or chord factor change
  • Winding connection change
  • The master formula
  • Converting concentric windings to lap windings
  • Converting lap windings to concentric windings
  • Notes on pole changing
  • Decreasing speed by increasing poles
  • Increasing speed by decreasing poles
  • Single-speed to two-speed, one winding
  • Single-speed to two-speed, two winding
  • Developing a winding for a bare core
  • Strengthening or weakening a motor - short method
  • Determining the proper connection
  • Single-phase redesign
  • Calculation of secondary voltage
  • Determining three-phase coil grouping 
AC motors
Winding connections