Testing

Advanced electric motor driven systems for pumps, fans, compressors, etc. often use today variable frequency converters to adjust the electric power demand to the required torque and speed of the application. The converter use can lead to large energy savings because the necessary electric power and the duration of its use can be reduced. On the other hand, converters as power supplies have an intrinsic electric loss in standby and in operation, plus they also cause further losses in the driven electric motor due to the non-sinusoidal voltage and current delivered from its pulse width modulation.

The electric losses and efficiency of converters for motor driven systems have not yet, in a publicly available independent study, been systematically determined, analyzed and different products com-pared. A well-defined, internationally accepted and used measuring method for converter losses that delivers accurate and repeatable results, has not existed so far.

The Round Robin program for Converter Losses (RR’C) was initiated at the end of 2017 as a joint project between 4E EMSA and IEC SC22G WG18. After the publication of the first standard for converter losses in IEC 61800-9-2, edition 1, on 3 March 2017, the necessity arose to clarify the testing program for converter losses and to verify the so far not tested reference losses in order to set the future IE-classes for edition 2.

The RR’C program is divided in two phases:

Phase 1

From November 2017 to the end of February 2019. Phase 1 serves as a pilot phase of the RR’C with a small number of laboratories and converters to elaborate a testing method.

Phase 2

From beginning of March 2019 to the end of 2021. Phase 2 tries to provide sufficient evidence of a larger number of converters to serve as a basis to define reference losses and efficiency classes.