TEST YOUR KNOWLEDGE 1. The real power absorbed by a synchronous motor can be found in the same way, and using the same f

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Test Your Knowledge 1 The Real Power Absorbed By A Synchronous Motor Can Be Found In The Same Way And Using The Same F 1 (27.92 KiB) Viewed 54 times

Test Your Knowledge 1 The Real Power Absorbed By A Synchronous Motor Can Be Found In The Same Way And Using The Same F 2 (43.83 KiB) Viewed 54 times

TEST YOUR KNOWLEDGE 1. The real power absorbed by a synchronous motor can be found in the same way, and using the same formula as with a transmission line. Explain. 2. A 2000 kW synchronous motor operates at a three-phase line-to-line voltage of 4 kV. It has a synchronous reactance of 40 per phase. Calculate: a) The nominal full load current of the machine when the excitation voltage Eo (line-to-line) is 4 kv. b) The short-circuit current when the excitation voltage Ep (line-to-line) is 4 kV.

3. a) In Question 2, if the excitation voltage Eo is equal to the terminal voltage (4 kV), what is the maximum real power which the motor can deliver without losing synchronism? b) What is the rotor pole shift in electrical degrees, corresponding to the nomi- nat load of 2000 kW? 4. The motor cannot operate in a stable manner when the rotor poles move beyond an angle of 90 electrical degrees from their no-load position. Can you explain why? 5. If the motor in Question 2 is at the end of a transmission line which has a react- ance of 82 per phase, what is the maximum power which the machine can develop, given that the sender voltage is 4 kV and the induced voltage Eo is also 4 kV (line-to-line)? How does this maximum power compare with the nominal rating of the machine? Calculate by how much the rotor poles move from their no-load position before the motor loses synchronism. Why is this angle less than 90°? Between which two voltages is the angle equal to 90% when peak power has been attained?