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  3. 1 write the equation for the armature current and developed...

Question: 1 write the equation for the armature current and developed...

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1. Write the equation for the armature current and developed torque in a DC motor and answer the following questions by using these equations:
a. Why should not a DC motor be directly started from its rated voltage?
b. What is the best value for the field current of a DC motor during start?
c. How to maintain the speed of a DC motor shown in Figure 1.
2. Write the equation for the induced emf in a synchronous generator.
3. Suppose a synchronous generator is driven by a DC motor at its rated speed n, and it is generating its rated voltage V, at rated frequency f. The generator is assumed to be at no-load.
a. How will V and f be affected if the speed of the synchronous machine is increased by 10%?
b. How will V and f be affected if the air-gap flux of the synchronous machine is increased by 10%?
c. How will V and f be affected if the field current of the synchronous machine is increased by 10%?
4. What is your expected shape of no-load characteristics (saturation curve) of a synchronous generator?
5. What is meant by voltage regulation of a synchronous generator?
6. What is meant by synchronous speed?
7. What is meant by the phase sequence? How to change the phase-sequence of a synchronous generator?

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