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The rotor resistance per phase of a 4 pole 50 Hz 3 phase induction motor are 0.024 ohm and.12 ohm respectively. Find the speed at maximum torque.also find the value of additional rotor resistance per phase required to develope 80 percentage of maximum torque at starting.?
Most Upvoted Answer
The rotor resistance per phase of a 4 pole 50 Hz 3 phase induction mot...
Calculation of Speed at Maximum Torque:
Calculation of Additional Rotor Resistance:
Explanation:
- Given, rotor resistance per phase (Rr1) = 0.024 ohm and (Rr2) = 0.12 ohm
- Number of poles (p) = 4
- Frequency (f) = 50 Hz
- Maximum torque occurs at slip (s) = 0.20
- Formula for speed at maximum torque is,
Ns = (1 - s) x (f/p) x 60
where, Ns is synchronous speed - Substituting the given values, we get
Ns = (1 - 0.20) x (50/4) x 60 = 900 rpm
Calculation of Additional Rotor Resistance:
- Given, rotor resistance per phase (Rr1) = 0.024 ohm and (Rr2) = 0.12 ohm
- Percentage of maximum torque (T) required at starting = 80%
- Formula for percentage of maximum torque is,
T = (1 - s)² / (1 + sRr)²
where, Rr is total rotor resistance per phase - At starting, slip (s) = 1
Substituting the given values,
0.8 = (1 - 1)² / (1 + 1Rr)²
Simplifying the equation, we get
Rr = 0.6 ohm (approx.) - Additional rotor resistance required (Radd) = Rr - Rr1
Substituting the values, we get
Radd = 0.576 ohm (approx.)
Explanation:
- The speed at maximum torque is calculated using the formula Ns = (1 - s) x (f/p) x 60, where Ns is synchronous speed, s is slip, f is frequency and p is number of poles.
- The additional rotor resistance required to develop 80% of maximum torque at starting is calculated using the formula T = (1 - s)² / (1 + sRr)², where T is percentage of maximum torque and Rr is total rotor resistance per phase.
- By solving the above equations, we get the required values of speed and additional rotor resistance.
Community Answer
The rotor resistance per phase of a 4 pole 50 Hz 3 phase induction mot...
Answer 1
S=R2/X2
gives Sm=0.2
speed = Synchronous speed*Slip
N=300rpm
Tst/Tm=2R2*X2/(R2^2+X2^2)
0.8= 2a/(1+(a)^2)
where a=X2/R2
gives Rext= 0.156Ohm
S=R2/X2
gives Sm=0.2
speed = Synchronous speed*Slip
N=300rpm
Tst/Tm=2R2*X2/(R2^2+X2^2)
0.8= 2a/(1+(a)^2)
where a=X2/R2
gives Rext= 0.156Ohm
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The rotor resistance per phase of a 4 pole 50 Hz 3 phase induction motor are 0.024 ohm and.12 ohm respectively. Find the speed at maximum torque.also find the value of additional rotor resistance per phase required to develope 80 percentage of maximum torque at starting.?
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The rotor resistance per phase of a 4 pole 50 Hz 3 phase induction motor are 0.024 ohm and.12 ohm respectively. Find the speed at maximum torque.also find the value of additional rotor resistance per phase required to develope 80 percentage of maximum torque at starting.? 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 The rotor resistance per phase of a 4 pole 50 Hz 3 phase induction motor are 0.024 ohm and.12 ohm respectively. Find the speed at maximum torque.also find the value of additional rotor resistance per phase required to develope 80 percentage of maximum torque at starting.? covers all topics & solutions for Electrical Engineering (EE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for The rotor resistance per phase of a 4 pole 50 Hz 3 phase induction motor are 0.024 ohm and.12 ohm respectively. Find the speed at maximum torque.also find the value of additional rotor resistance per phase required to develope 80 percentage of maximum torque at starting.?.
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