Core Loss and Exciting Current Measurement
Core loss values are determined using wattmeter meth- ods that eliminate the factor of copper loss and voltage drop in the test windings. Exciting current values are measured using a true rms reading ammeter, so excit- ing power (exciting volt-amperes) is the rms value.
This necessary annealing not only decarburizes the material, but also produces grain growth. Both of these are essential to the development of the optimum magnetic properties of semi-processed grades.
Because decarburization and grain growth are involved, proper decarburizing atmospheres must be used, and both temperature and time of annealing care- fully controlled. Temperatures generally are higher and annealing times somewhat longer than for stress-relief annealing.