Soken tester - is a portable single yoke instrument for assessing the power loss in electrical steel laminations.
It has been developed for quick assessment of power loss in electrical steel sheet without the need for cutting and annealing, as it is the case for standardised methods like Epstein frame.
Both these signals are detected from the magnetising yoke, which is contained in an aluminium head (55 mm in diameter as shown in the photo).
The measurement is based on similar principle as employed in the standardised single sheet tester.
The manufacturers of the instrument claim that its measurement uncertainty is lower than 5% (as referred to results from Epstein frame).