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In a constant V/f control of induction motor, the ratio V/f is maintained constant from 0 to base frequency, where V is the voltage applied to the motor at fundamental frequency f. Which of the following statements relating to low frequency operation of the motor is TRUE?
- a)At low frequency, the stator flux increases from its rated value.
- b)At low frequency, the stator flux decreases from its rated value.
- c)At low frequency, the motor saturates.
- d)At low frequency, the stator flux remains unchanged at its rated value.
Correct answer is option 'B'. Can you explain this answer?
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Verified Answer
In a constant V/f control of induction motor, the ratio V/f is maintai...
During constant V/f control, at low frequency, the voltage also applied to the induction motor is low. Hence the stator flux also decreases from its rated value.
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In a constant V/f control of induction motor, the ratio V/f is maintai...
Statement: At low frequency, the stator flux decreases from its rated value.
Explanation:
Constant V/f control:
In a constant V/f control of an induction motor, the ratio V/f is maintained constant from 0 to the base frequency. This means that the voltage applied to the motor (V) is directly proportional to the frequency (f) of the power supply.
Stator Flux:
The stator flux in an induction motor is the magnetic field generated by the stator windings. It is responsible for producing the rotor current and the resulting torque in the motor. The stator flux is directly proportional to the stator voltage and inversely proportional to the stator frequency.
Effect of low frequency:
At low frequency, the stator flux decreases from its rated value. This can be explained as follows:
1. According to the constant V/f control, the voltage applied to the motor decreases proportionally with the decrease in frequency. Since the stator flux is directly proportional to the stator voltage, it also decreases.
2. At low frequency, the motor operates at a reduced speed. The slip (difference between synchronous speed and rotor speed) of the motor increases, leading to a decrease in rotor current and torque. This results in a decrease in the stator flux.
Effect on motor performance:
The decrease in stator flux at low frequency can have several effects on the motor performance:
1. Reduced torque: As the stator flux decreases, the torque produced by the motor also decreases. This limits the motor's ability to deliver high torque at low speeds.
2. Increased slip: With the decrease in stator flux, the slip of the motor increases. This leads to increased rotor losses and decreased motor efficiency.
3. Saturation: It is important to note that saturation (option C) does not occur at low frequency. Saturation refers to the phenomenon where the magnetic core of the motor reaches its maximum magnetic flux density and cannot further increase its magnetic field strength. Saturation typically occurs at high voltages and frequencies, not at low frequencies.
Therefore, the correct statement is option B: At low frequency, the stator flux decreases from its rated value.
Explanation:
Constant V/f control:
In a constant V/f control of an induction motor, the ratio V/f is maintained constant from 0 to the base frequency. This means that the voltage applied to the motor (V) is directly proportional to the frequency (f) of the power supply.
Stator Flux:
The stator flux in an induction motor is the magnetic field generated by the stator windings. It is responsible for producing the rotor current and the resulting torque in the motor. The stator flux is directly proportional to the stator voltage and inversely proportional to the stator frequency.
Effect of low frequency:
At low frequency, the stator flux decreases from its rated value. This can be explained as follows:
1. According to the constant V/f control, the voltage applied to the motor decreases proportionally with the decrease in frequency. Since the stator flux is directly proportional to the stator voltage, it also decreases.
2. At low frequency, the motor operates at a reduced speed. The slip (difference between synchronous speed and rotor speed) of the motor increases, leading to a decrease in rotor current and torque. This results in a decrease in the stator flux.
Effect on motor performance:
The decrease in stator flux at low frequency can have several effects on the motor performance:
1. Reduced torque: As the stator flux decreases, the torque produced by the motor also decreases. This limits the motor's ability to deliver high torque at low speeds.
2. Increased slip: With the decrease in stator flux, the slip of the motor increases. This leads to increased rotor losses and decreased motor efficiency.
3. Saturation: It is important to note that saturation (option C) does not occur at low frequency. Saturation refers to the phenomenon where the magnetic core of the motor reaches its maximum magnetic flux density and cannot further increase its magnetic field strength. Saturation typically occurs at high voltages and frequencies, not at low frequencies.
Therefore, the correct statement is option B: At low frequency, the stator flux decreases from its rated value.
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In a constant V/f control of induction motor, the ratio V/f is maintained constant from 0 to base frequency, where V is the voltage applied to the motor at fundamental frequency f. Which of the following statements relating to low frequency operation of the motor is TRUE?a)At low frequency, the stator flux increases from its rated value.b)At low frequency, the stator flux decreases from its rated value.c)At low frequency, the motor saturates.d)At low frequency, the stator flux remains unchanged at its rated value.Correct answer is option 'B'. Can you explain this answer?
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In a constant V/f control of induction motor, the ratio V/f is maintained constant from 0 to base frequency, where V is the voltage applied to the motor at fundamental frequency f. Which of the following statements relating to low frequency operation of the motor is TRUE?a)At low frequency, the stator flux increases from its rated value.b)At low frequency, the stator flux decreases from its rated value.c)At low frequency, the motor saturates.d)At low frequency, the stator flux remains unchanged at its rated value.Correct answer is option 'B'. Can you explain this answer? for GATE 2024 is part of GATE preparation. The Question and answers have been prepared according to the GATE exam syllabus. Information about In a constant V/f control of induction motor, the ratio V/f is maintained constant from 0 to base frequency, where V is the voltage applied to the motor at fundamental frequency f. Which of the following statements relating to low frequency operation of the motor is TRUE?a)At low frequency, the stator flux increases from its rated value.b)At low frequency, the stator flux decreases from its rated value.c)At low frequency, the motor saturates.d)At low frequency, the stator flux remains unchanged at its rated value.Correct answer is option 'B'. Can you explain this answer? covers all topics & solutions for GATE 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for In a constant V/f control of induction motor, the ratio V/f is maintained constant from 0 to base frequency, where V is the voltage applied to the motor at fundamental frequency f. Which of the following statements relating to low frequency operation of the motor is TRUE?a)At low frequency, the stator flux increases from its rated value.b)At low frequency, the stator flux decreases from its rated value.c)At low frequency, the motor saturates.d)At low frequency, the stator flux remains unchanged at its rated value.Correct answer is option 'B'. Can you explain this answer?.
In a constant V/f control of induction motor, the ratio V/f is maintained constant from 0 to base frequency, where V is the voltage applied to the motor at fundamental frequency f. Which of the following statements relating to low frequency operation of the motor is TRUE?a)At low frequency, the stator flux increases from its rated value.b)At low frequency, the stator flux decreases from its rated value.c)At low frequency, the motor saturates.d)At low frequency, the stator flux remains unchanged at its rated value.Correct answer is option 'B'. Can you explain this answer? for GATE 2024 is part of GATE preparation. The Question and answers have been prepared according to the GATE exam syllabus. Information about In a constant V/f control of induction motor, the ratio V/f is maintained constant from 0 to base frequency, where V is the voltage applied to the motor at fundamental frequency f. Which of the following statements relating to low frequency operation of the motor is TRUE?a)At low frequency, the stator flux increases from its rated value.b)At low frequency, the stator flux decreases from its rated value.c)At low frequency, the motor saturates.d)At low frequency, the stator flux remains unchanged at its rated value.Correct answer is option 'B'. Can you explain this answer? covers all topics & solutions for GATE 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for In a constant V/f control of induction motor, the ratio V/f is maintained constant from 0 to base frequency, where V is the voltage applied to the motor at fundamental frequency f. Which of the following statements relating to low frequency operation of the motor is TRUE?a)At low frequency, the stator flux increases from its rated value.b)At low frequency, the stator flux decreases from its rated value.c)At low frequency, the motor saturates.d)At low frequency, the stator flux remains unchanged at its rated value.Correct answer is option 'B'. Can you explain this answer?.
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ample number of questions to practice In a constant V/f control of induction motor, the ratio V/f is maintained constant from 0 to base frequency, where V is the voltage applied to the motor at fundamental frequency f. Which of the following statements relating to low frequency operation of the motor is TRUE?a)At low frequency, the stator flux increases from its rated value.b)At low frequency, the stator flux decreases from its rated value.c)At low frequency, the motor saturates.d)At low frequency, the stator flux remains unchanged at its rated value.Correct answer is option 'B'. Can you explain this answer? tests, examples and also practice GATE tests.
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