Importance of rotational iron loss data for accurate prediction of rotating machine core losses

Rotational flux in the plane of machine laminations causes iron losses which far exceed those caused by alternating flux. Machine designers use Epstein test loss values to predict core losses in rotating machines under the assumption of alternating flux in the core. This may lead to core loss predictions that are too small. This paper describes some constructional details for an apparatus which may be used to measure rotational iron losses in steel samples. The error which is inherent in the current method of predicting iron losses in rotating machines is discussed. A consensus on a standard test for predicting rotational losses in electrical steels is imperative in order promote further investigation in this area