Circle Diagram in Three Phase Induction Motor - MCQs with Answers

Circle Diagram in Three Phase Induction Motor - MCQs with Answers

Q1. The Y-axis and X-axis in a circle diagram represents

a. Voltage and current
b. Current and power
c. Power and voltage
d. Current and voltage

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Q2. The circle diagram can be used to

a. Predict the performance of an induction motor under various load condition
b. Find losses in an induction motor
c. Efficiency of an induction motor
d. All of these

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Q3. For plotting circle diagram no load power factor is required. The value of no load power factor will be

a. Lesser than 0.5
b. Greater than 0.5
c. Equal to 0.5
d. 1

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Q4. For conducting no load test on an induction motor two wattmeter’s are required. Readings of the meters

a. Both will be positive
b. One will be positive and other will be negative
c. Both will be negative
d. None of these

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Q5. If I_c is the active component and I_m is the magnetizing component of no load current (I_o) obtained in the no load test of an induction motor. Then the no load branch resistance and no load branch reactance is

a. V_o / I_c , V_o / I_m
b. V_o / I_m , V_o / I_c
c. V_o / I_o , V_o / I_c
d. V_o / I_c , V_o / I_o

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Q6. While drawing the graph of no load losses versus voltage, the voltage is extrapolated to V = 0. The extrapolated region shows

a. Copper losses
b. Core losses
c. Friction and windage losses
d. None of these

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Q7. In the blocked rotor tests, slip is equal to

a. 0
b. 1
c. 0.5
d. 0.707

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