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A three phase 460 V, 60 Hz, six-pole wound rotor induction motor drives a constant load of 100 N-m at a speed of 1140 rpm when the rotor terminals are short-circuited. It is required to reduce the speed of the motor to 1000 rpm by inserting resistances in the rotor circuit. The rotor winding resistance per phase is 0.2 ohms. Neglect rotational losses. The stator to rotor turns ratio is unity.
The value of the resistance inserted is ________ (in Ω/phase)
Correct answer is between '0.4,0.5'. Can you explain this answer?
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Most Upvoted Answer
A three phase 460 V, 60 Hz, six-pole wound rotor induction motor drive...
The synchronous speed, 
When the rotor speed is 1140 rpm, slip 
When the rotor speed is 1000 rpm, slip 
From the equivalent circuit of induction motor, if the value of 
remains the same, the rotor current I2 and the stator current I1 will remains the same and the machine develops the same torque.
remains the same, the rotor current I2 and the stator current I1 will remains the same and the machine develops the same torque.If the rotational losses are neglected, the developed torque is the same as the load torque.
Therefore, for unity turns ratio,
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A three phase 460 V, 60 Hz, six-pole wound rotor induction motor drive...
Ohms).
To determine the value of the resistance to be inserted in the rotor circuit, we can use the equation for the slip of an induction motor:
Slip (S) = (N_s - N_r) / N_s
Where N_s is the synchronous speed of the motor and N_r is the rotor speed.
Given that the synchronous speed is 120 * f / p, where f is the frequency and p is the number of poles, we can calculate the synchronous speed:
N_s = 120 * 60 / 6 = 1200 rpm
Using the slip equation and the given rotor speed, we can calculate the slip:
S = (1200 - 1000) / 1200 = 0.1667
The rotor resistance (R_r) can be calculated using the equation:
R_r = S / (3 * P_r)
Where P_r is the rotor power in watts. The rotor power can be calculated using the equation:
P_r = T_r * N_r
Where T_r is the torque in N-m and N_r is the rotor speed in radians per second. Converting the rotor speed to radians per second:
N_r_rad = 1000 * 2 * pi / 60 = 104.72 rad/s
Calculating the rotor power:
P_r = 100 * 104.72 = 10472 W
Calculating the rotor resistance:
R_r = 0.1667 / (3 * 10472) = 0.000052 ohms
Therefore, the value of the resistance to be inserted in the rotor circuit is approximately 0.000052 ohms.
To determine the value of the resistance to be inserted in the rotor circuit, we can use the equation for the slip of an induction motor:
Slip (S) = (N_s - N_r) / N_s
Where N_s is the synchronous speed of the motor and N_r is the rotor speed.
Given that the synchronous speed is 120 * f / p, where f is the frequency and p is the number of poles, we can calculate the synchronous speed:
N_s = 120 * 60 / 6 = 1200 rpm
Using the slip equation and the given rotor speed, we can calculate the slip:
S = (1200 - 1000) / 1200 = 0.1667
The rotor resistance (R_r) can be calculated using the equation:
R_r = S / (3 * P_r)
Where P_r is the rotor power in watts. The rotor power can be calculated using the equation:
P_r = T_r * N_r
Where T_r is the torque in N-m and N_r is the rotor speed in radians per second. Converting the rotor speed to radians per second:
N_r_rad = 1000 * 2 * pi / 60 = 104.72 rad/s
Calculating the rotor power:
P_r = 100 * 104.72 = 10472 W
Calculating the rotor resistance:
R_r = 0.1667 / (3 * 10472) = 0.000052 ohms
Therefore, the value of the resistance to be inserted in the rotor circuit is approximately 0.000052 ohms.
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A three phase 460 V, 60 Hz, six-pole wound rotor induction motor drives a constant load of 100 N-m at a speed of 1140 rpm when the rotor terminals are short-circuited. It is required to reduce the speed of the motor to 1000 rpm by inserting resistances in the rotor circuit. The rotor winding resistance per phase is 0.2 ohms. Neglect rotational losses. The stator to rotor turns ratio is unity.The value of the resistance inserted is ________ (in Ω/phase)Correct answer is between '0.4,0.5'. Can you explain this answer?
Question Description
A three phase 460 V, 60 Hz, six-pole wound rotor induction motor drives a constant load of 100 N-m at a speed of 1140 rpm when the rotor terminals are short-circuited. It is required to reduce the speed of the motor to 1000 rpm by inserting resistances in the rotor circuit. The rotor winding resistance per phase is 0.2 ohms. Neglect rotational losses. The stator to rotor turns ratio is unity.The value of the resistance inserted is ________ (in Ω/phase)Correct answer is between '0.4,0.5'. Can you explain this answer? for Electrical Engineering (EE) 2024 is part of Electrical Engineering (EE) preparation. The Question and answers have been prepared according to the Electrical Engineering (EE) exam syllabus. Information about A three phase 460 V, 60 Hz, six-pole wound rotor induction motor drives a constant load of 100 N-m at a speed of 1140 rpm when the rotor terminals are short-circuited. It is required to reduce the speed of the motor to 1000 rpm by inserting resistances in the rotor circuit. The rotor winding resistance per phase is 0.2 ohms. Neglect rotational losses. The stator to rotor turns ratio is unity.The value of the resistance inserted is ________ (in Ω/phase)Correct answer is between '0.4,0.5'. Can you explain this answer? covers all topics & solutions for Electrical Engineering (EE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A three phase 460 V, 60 Hz, six-pole wound rotor induction motor drives a constant load of 100 N-m at a speed of 1140 rpm when the rotor terminals are short-circuited. It is required to reduce the speed of the motor to 1000 rpm by inserting resistances in the rotor circuit. The rotor winding resistance per phase is 0.2 ohms. Neglect rotational losses. The stator to rotor turns ratio is unity.The value of the resistance inserted is ________ (in Ω/phase)Correct answer is between '0.4,0.5'. Can you explain this answer?.
A three phase 460 V, 60 Hz, six-pole wound rotor induction motor drives a constant load of 100 N-m at a speed of 1140 rpm when the rotor terminals are short-circuited. It is required to reduce the speed of the motor to 1000 rpm by inserting resistances in the rotor circuit. The rotor winding resistance per phase is 0.2 ohms. Neglect rotational losses. The stator to rotor turns ratio is unity.The value of the resistance inserted is ________ (in Ω/phase)Correct answer is between '0.4,0.5'. Can you explain this answer? for Electrical Engineering (EE) 2024 is part of Electrical Engineering (EE) preparation. The Question and answers have been prepared according to the Electrical Engineering (EE) exam syllabus. Information about A three phase 460 V, 60 Hz, six-pole wound rotor induction motor drives a constant load of 100 N-m at a speed of 1140 rpm when the rotor terminals are short-circuited. It is required to reduce the speed of the motor to 1000 rpm by inserting resistances in the rotor circuit. The rotor winding resistance per phase is 0.2 ohms. Neglect rotational losses. The stator to rotor turns ratio is unity.The value of the resistance inserted is ________ (in Ω/phase)Correct answer is between '0.4,0.5'. Can you explain this answer? covers all topics & solutions for Electrical Engineering (EE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A three phase 460 V, 60 Hz, six-pole wound rotor induction motor drives a constant load of 100 N-m at a speed of 1140 rpm when the rotor terminals are short-circuited. It is required to reduce the speed of the motor to 1000 rpm by inserting resistances in the rotor circuit. The rotor winding resistance per phase is 0.2 ohms. Neglect rotational losses. The stator to rotor turns ratio is unity.The value of the resistance inserted is ________ (in Ω/phase)Correct answer is between '0.4,0.5'. Can you explain this answer?.
Solutions for A three phase 460 V, 60 Hz, six-pole wound rotor induction motor drives a constant load of 100 N-m at a speed of 1140 rpm when the rotor terminals are short-circuited. It is required to reduce the speed of the motor to 1000 rpm by inserting resistances in the rotor circuit. The rotor winding resistance per phase is 0.2 ohms. Neglect rotational losses. The stator to rotor turns ratio is unity.The value of the resistance inserted is ________ (in Ω/phase)Correct answer is between '0.4,0.5'. Can you explain this answer? in English & in Hindi are available as part of our courses for Electrical Engineering (EE).
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