Problem a. (i) Sketch the ideal power curve of the turbine with the following characteristics: • rated speed is 14 m/s ⚫rated power is 1.25 MW ⚫ cut-in speed is 5 m/s ⚫furling or cut-out speed is 20 m/s (ii) Given part (i), calculate the energy produced in one day if the wind blows continuously between 15 and 20 m/s all day (iii) Can the energy produced in one year be determined if you are told that the average wind speed is 14 m/s? Explain why.

A 6 pole wave wound d.c. shunt generator has 500 conductors. A generator delivers 50 kW of power at 250 voltage at full load. The resistance of the field circuit is 125 2. Actual brush shift is 10°. Then find the demagnetizing and cross magnetizing ampere turns per pole and how many additional turns must be wound on each pole to eliminate the demagnetizing effect.

× 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…

3.17. A 200-turn coil is rotating at a speed of 3600 rpm in a 4-pole generator. The flux per pole is 2 mWb. Determine (a) the frequency of the induced emf, (b) the maximum value of the induced emf, (c) the rms value of the induced emf in an ac generator, and (d) the average value of the induced emf in a dc generator.