CLASSIFICATION OF DC MACHINES part2

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PROBLEMS

1. The armature of a 4 pole wave wound DC shunt generator has 144 slots and 3 conductors per slot. If armature is rotated with a speed of 1200 rpm in a field of 0.025 wb/pole, calculate the EMF generated.

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2. An 8 pole DC generator has 960 conductors and a flux/pole of 20 m wb. Calculate the EMF generated when running at 500 rpm for (i) A lap connected armature winding and (ii) A wave connected armature winding.

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3. An 8 pole DC shunt generator with 778 conductors wave connected and running at 500 rpm supplies a load of 12.5 .0 resistance at terminal voltage of 250 V, the armature resistance is 0.24.0 and the field resistance is 250 .0. Find the armature current, induced emf and <l/pole.

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4. A 4 pole long shunt lap wound generator supplies 25 kW at a terminal voltage of 500 V. The armature resistance is 0.03 .0. Series field resistance is 0.04.0 and shunt field resistance is 200 .0. The brush drop may be taken as 1.0 V. Determine the emf generated. Calculate also the number of conductors if the speed is 1200 rpm and <l/pole is 0.02 wb. Neglect armature reaction.

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