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Electrical motors, how they work

Welcome! This motor book will provide you with a wealth of information about electrical motors, how they work, what they can be used for, and so on. But before we delve into detailed explanations of the world of electrical motors, we should perhaps spare a brief thought for the purpose of these motors.

The motor book
The motor book (on photo: Single phase magnetic Induction motor with exposed rotor and coil)

After all, motors are always designed to carry out specific tasks. As this is a Grundfos publication, it is only natural that we should pay special attention to motors used for pumps โ€“ although much of the information contained within these pages will benefit all those with an interest in electrical motors.


Standards for AC motors

IEC 60034-2 Efficiency standards

Several standards for testing electric machinery exist on a worldwide basis. For induction motors, the three most important ones are IEEE Standard 112, JEC 37 (Japan) and IEC 60034-2. The efficiency value obtained from the different testing standards can differ by several percent.

This seems in contradiction with the theoretical definition of the efficiency:

  • ฮท = power out / power in
  • ฮทย = 1 – overall losses / power in

The losses in an induction motor are distributed as follows:

  1. Stator winding loss Pcu1 – approximately 40-45%
  2. Rotor winding loss – Pcu2 – approximately 15%
  3. Friction loss Pfric – approximately 10-15%
  4. Iron loss Pfe – approximately20%
  5. Stray loss Pstray – approximately 10%
Loss distribution in an induction motor
Loss distribution in an induction motor

The main difference between the standards is the way in which the fifth loss component stray loss (Pstray), the additional load losses, is treated.


Standards for the testing of motors

The testing of standard motors is described in IEC 60034-2. In the following paragraphs two different methods of testing motors are presented: The direct method and the indirect one .

The difference between these two methods is the way in which the motor efficiency is established.

IEC 60034 covers the so-called industrial motors . Requirements of domestic appliances are listed in IEC 60335, which specifies somewhat different (stricter) requirements of the motors . In addition to the tests of standard motors our laboratory also undertakes to test products integrating motor and pump .

In principle the thermal tests are the same, but the tests are carried out according to other standards . Small circulator pumps are for instance tested according to IEC 60335-2-51.

Title:Motor Book – Grundfos
Format:PDF
Size:16.57 MB
Pages:252
Download:Right here | Video Courses | Membership | Download Updates
Motor Book - Grundfos
Motor Book – Grundfos

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16 Comments


  1. Ojiambo A.H
    Feb 11, 2022

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  2. Salem H. Khanfasi
    Aug 02, 2021

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  3. BV Ramesh
    Oct 19, 2020

    Thanks for giving such a detaled technical information on Motors.


  4. GOITOM ADHANA
    Jan 03, 2020

    i want to learn more detile about electrical part of grandiose pump


  5. Atodo Musa jacob
    Sep 15, 2019

    What a special people you are EEP, I hail you


  6. Sparky Ohohkaboom
    Apr 12, 2018

    Love the pretty colors. As a result I pulled my broken well pump out of the ground and replaced it with a shiny new Grundfos. Not only did I learn about motors, I now have hot water and a flushable toilet. At work they started calling me “Bear” because I was squatting down and leaning against a tree in the woods to poop. Thank you EEP and Grundfos!


  7. Mustafa
    Nov 17, 2017

    Thank you verymuch Sir,
    I want to know that how an induction motor can be rewinded with approprite wire guage (SWG) and how it create megnetic field to run a motor smoothly with its max. capacity load. If we change wire swg , the motor runs on wrong load. How can we decide approprite wire swg according to its stater and rotor?


  8. sandeep
    Jun 01, 2017

    Thank you for EEP,


  9. katakwar
    Aug 20, 2015

    Thank you very much EEP.


  10. Mark E
    Jun 29, 2015

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  11. mohammad mahdi share pasand
    Jun 28, 2015

    Dear authors
    I would like to thank you for this useful portal and its helpful contents. wish you good luck. hope you go on.


  12. Andy Walsh
    Jun 09, 2014

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    Regards,


  13. tawfik ben mussa
    Jun 09, 2014

    excellent informations , useful for students and professional engineers, i only feel sorry for not having these e books earlier, it could save me a lot of time an efforts. Thanks and keep the good work


  14. WANCLIK TADE
    Jun 08, 2014

    I COMPILE ALSO DATA ABOUT APPLICATIONS IN THE ENGINEERING


    • Lucas sonoko
      Sep 15, 2019

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  15. Ehsan Daryabeigi
    Jun 08, 2014

    Dear Mrs/Mr
    I would like to download a book entitled “Motor Book โ€“ Grundfos” from your site. However, it is not possible for me to do that for even others.

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