Q3. The following data are taken to obtain the magnetization curve of a 15-kw, 150-V, 6-pole de machine at its mated speed of 1200 rpm. Ir in A 0.5 1.5 2 2.5 3 3.5 4. Eo in V 6. 70 112 130 140 145 149 152 155 158 Sketch the magnetization curves for speeds of 1200 rpm and 800 rpm.

Stray losses represent: O A. Resistive losses in the windings of the machine O B. Losses due to friction of the moving parts O C. Losses due to magnetization and demagnetization of the core O D. Windage losses O E. None of the other choices are correct

× 4:03 K s.eng.ruh.ac.lk □ Û 8. Figure 4 shows the core of a simple dc motor. The magnetization curve for the metal in this core is given by Figure 5 and Figure 6. Assume that the cross-sectional area of each air gap is 18 cm² and that the width of each air gap is 0.05 cm. The effective diameter of the rotor core is 4 cm. L It is desired to build a machine with as great a flux density as possible while avoiding excessive saturation in the core. What would be a reasonable maximum flux density for this core? ii. What would be the total flux in the core at the flux density of part (i)? iii. The maximum possible field current for this machine is I A. Select a reasonable number of turns of wire to provide the desired flux density while not exceeding the maximum available current. Flux Density, B (T) 2.8 སྤྲ ཤཱ ཀ ཀཱ བྷ ཀ ཡཱཾ བ ་ 1.2 1.0 0.4 0.2 4-48cm Figure 4 0 10 20 30 40 50 100 → Depth 4 cm -0.05 cm 200 300 500 1000 2000 Magnetizing Intensity, H (A.turns/m) Figure 5 Magnetization curve…