The repeatability of IEEE standard 112B induction motor efficiency tests

The IEEE standard 112B is widely used as the method for determining induction motor efficiency. However, there is sparse work about the repeatability of this measurement method. This paper presents an analysis of a set of measurements of motor efficiency using the IEEE 112B standard in order to assess the repeatability of the method. The measurements were repeatedly performed on four different motors of varying sizes over a number of years. The conditions of the tests and variations in measurements of efficiency of the motors are presented in this paper and the repeatability coefficient is discussed. The accuracy of the IEEE 112B method is also discussed and causes of the variations are highlighted for future revisions of the standard. This work is important for comparison of the standard with other standards and for interpreting induction motor efficiency measurements.