Question

A 2300-V, 400-hp, 60-Hz, 1200rpm, Y-connected synchronous motor has a rated power factor of 0.8 leading. The efficiency of the motor is 90 % at full load. The armature resistance is 0.3 Ω, and the synchronous reactance is 3.55 Ω. Answer the following questions when it is operating at full load;

Question 1

What is the number of poles in this motor?

2

4

6

8

10

12

Question 2

Find the output torque in Nm.(Assume 1hp=745.7W)

1985.7

2373.6

2011.9

2674.7

1453.2

2204.3

Question 3

Find the total complex power drawn by the motor.

313.60-j235.21 kVA

370.40-j277.80 kVA

266.41-j199.83 kVA

369.38-j342.67 kVA

402.40-j301.80 kVA

331.42-j248.57 kVA

Question 4

Find the armature current. (Use phase a-to-neutral voltage as the reference)

93/_25.84 A

104/_36.87 A

87/_36.87 A

112/_25.84 A

93/_-25.84 A

104/_-36.87 A

Question 5

Find the induced internal voltage E_A per phase as a phasor.

1556.5/_-11.64 V

1428.3/_-9.28 V

1503.9/_-13.02 V

1601.4/_-10.26 V

1489.3/_-10.39 V

1511.3/_-7.62 V

Answer 1