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:
- η = power out / power in
- η = 1 – overall losses / power in
The losses in an induction motor are distributed as follows:
- Stator winding loss Pcu1 – approximately 40-45%
- Rotor winding loss – Pcu2 – approximately 15%
- Friction loss Pfric – approximately 10-15%
- Iron loss Pfe – approximately20%
- Stray loss Pstray – approximately 10%
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 .
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|
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