The total core loss of a specimen of silicon steel is found to be 1500 W at 50 Hz. Keeping the flux density constant the loss becomes 3000 W when the frequency is raised to 75 Hz. Calculate separately the hysteresis and eddy current loss at each of those frequencies.
Chapter 2
Q. 2.9
Step-by-Step
Verified Solution
From Eqs. (2.36)
P_{h} =K_{h} fB^{n}_{m} W/ m^{3}and (2.37)
P_{e} =K_{e} f^{2} B^{2} W/ m^{3}for constant flux density, total core loss can be expressed as
P=Af+Bf^{2} or P/ f=A+Bf
1500/ 50=A+50B or 30=A+50B (i)
3000/ 75=A+75B or 40=A+75B (ii)
Solving Eqs. (i) and (ii), we get A=10,B=2/ 5
Therefore P=10f+2/ 5f^{2} =P_{h} +P_{e} (iii)
At 50 Hz P_{h}=10\times 50=500 W
P_{e}=2/ 5\times 2500=1000 W
At 75 Hz P_{h}=10\times 75=750W
P_{e}=2/ 5\times \left(75\right) ^{2} =2250 W