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- How emf is built up in self-excited D.C shunt generator. Explain critical resistance and critical speed in D.C shunt generator.
- A four pole DC shunt Generator with shunt field resistance of 100 ohms and armature resistance of 1 ohm, has 378 wave connected conductor in armature. The flux per pole is 0.02 wb. If a load of 10 ohm is connected across armature terminal and generator is driven at 1000 rpm, Calculate power absorbed by load.
- A 460 V series motor runs at 500 rpm taking current of 40 A. Calculate the speed and percentage change in torque if load is reduced so that motor is taking 30 A. Total resistance of armature and field is 0.8 ohm. Assume flux is proportional to field current.
- A 220 V shunt motor has armature resistance of 0.5 ohm and takes armature current of 40 A on certain load. By how much the main flux to be reduced to raise speed by 50% if developed torque is constant. Neglect saturation and armature reaction.
- Derive E.M.F. and Torque equations of a DC machine.