Question

A three-phase induction motor has 6 poles and the following Y-connected per phase equivalent circuit parameters: R₁ = 3.5Ω, X₁ = 5.2Ω, R₂ = 3.1Ω, X₂ = 5.5Ω, R_C = 2200Ω,X_M = 1350Ω. The rotational and stray losses are negligible. The motor is connected to a 3300 V, 50 Hz, three-phase source. The motor’s rated speed is 965rpm. Answer the following questions when it is operating at rated speed;

Question 11

Find the motor’s slip.

0.028

0.014

0.035

0.053

0.046

0.041

Question 12

Find the motor’s armature current

21.39/_-10.06 A

18.94/_-8.73 A

27.51/_-11.24 A

14.25/_-15.33 A

24.14/_-10.52 A

8.67/_-9.91 A

Question 13

Find the motor’s output power in kW.

98.64

120.56

131.45

96.94

75.63

107.22

Question 14

Find the motor’s output torque in Nm.

1253

845

1061

797

936

1311

Question 15

Find the percentage efficiency of the motor.

92

95

97

83

89

86

Question 16

Find the starting current (amperes) drawn by the motor if the motor is connected to an infinite bus of 3300V.

136.83/_-35.71 A

151.97/_-58.32 A

184.14/_-41.57 A

146.23/_-69.12 A

105.81/_-47.86 A

214.87/_-29.18 A

Answer 1