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A 208-V, 7.5KW, four pole, 60 Hz, Y-connected induction motor has a full-load slip of 5 % 1)What is the synchronous speed of this motor? 2)What is the rotor speed of this motor at rated load? 3)What is the rotor frequency of this motor at rated load? 4) What is the shaft torque of this motor at rated load?
Most Upvoted Answer
A 208-V, 7.5KW, four pole, 60 Hz, Y-connected induction motor has a fu...
Solution:
1) Synchronous Speed:
Synchronous speed can be calculated using the formula given below:
Synchronous speed = (120*f)/p where f is the frequency and p is the number of poles.
Given, f = 60 Hz and p = 4
Synchronous speed = (120*60)/4 = 1800 RPM
2) Rotor Speed:
Rotor speed can be calculated using the formula given below:
Rotor speed = (1 - s)*Synchronous speed where s is the slip.
Given, s = 5% = 0.05
Rotor speed = (1 - 0.05)*1800 = 1710 RPM
3) Rotor Frequency:
Rotor frequency can be calculated using the formula given below:
Rotor frequency = (s*f)/p
Given, s = 5% = 0.05, f = 60 Hz and p = 4
Rotor frequency = (0.05*60)/4 = 0.75 Hz
4) Shaft Torque:
The shaft torque can be calculated using the formula given below:
Shaft torque = (p*power)/(2*pi*n) where power is the rated power, n is the rotor speed and p is the number of poles.
Given, power = 7.5 kW, n = 1710 RPM and p = 4
Shaft torque = (4*7500)/(2*pi*1710) = 25.56 Nm
Explanation:
- The synchronous speed is the speed of the rotating magnetic field in the stator.
- The rotor speed is the speed of the rotor with respect to the stator.
- The rotor frequency is the frequency of the current induced in the rotor due to the slip.
- The shaft torque is the torque developed by the rotor which is transferred to the load. It depends on the power, rotor speed and number of poles of the motor.
1) Synchronous Speed:
Synchronous speed can be calculated using the formula given below:
Synchronous speed = (120*f)/p where f is the frequency and p is the number of poles.
Given, f = 60 Hz and p = 4
Synchronous speed = (120*60)/4 = 1800 RPM
2) Rotor Speed:
Rotor speed can be calculated using the formula given below:
Rotor speed = (1 - s)*Synchronous speed where s is the slip.
Given, s = 5% = 0.05
Rotor speed = (1 - 0.05)*1800 = 1710 RPM
3) Rotor Frequency:
Rotor frequency can be calculated using the formula given below:
Rotor frequency = (s*f)/p
Given, s = 5% = 0.05, f = 60 Hz and p = 4
Rotor frequency = (0.05*60)/4 = 0.75 Hz
4) Shaft Torque:
The shaft torque can be calculated using the formula given below:
Shaft torque = (p*power)/(2*pi*n) where power is the rated power, n is the rotor speed and p is the number of poles.
Given, power = 7.5 kW, n = 1710 RPM and p = 4
Shaft torque = (4*7500)/(2*pi*1710) = 25.56 Nm
Explanation:
- The synchronous speed is the speed of the rotating magnetic field in the stator.
- The rotor speed is the speed of the rotor with respect to the stator.
- The rotor frequency is the frequency of the current induced in the rotor due to the slip.
- The shaft torque is the torque developed by the rotor which is transferred to the load. It depends on the power, rotor speed and number of poles of the motor.
Community Answer
A 208-V, 7.5KW, four pole, 60 Hz, Y-connected induction motor has a fu...
Sync speed N---- 120f/p 120*60/4=1800
Full load slip 5% =1/20
Rotor speed N =[1-s]*Ns
(1-1/20)*1800=1710
Rotor freq.(Ns-Nr)*P/120
(1800-1710)*4/120=3hz
P=7.5kw=7.5*746=5595
Shaft torque=p/wm
60*P/2πN.
9.55*5595/1710=31.24Nm
Full load slip 5% =1/20
Rotor speed N =[1-s]*Ns
(1-1/20)*1800=1710
Rotor freq.(Ns-Nr)*P/120
(1800-1710)*4/120=3hz
P=7.5kw=7.5*746=5595
Shaft torque=p/wm
60*P/2πN.
9.55*5595/1710=31.24Nm
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A 208-V, 7.5KW, four pole, 60 Hz, Y-connected induction motor has a full-load slip of 5 % 1)What is the synchronous speed of this motor? 2)What is the rotor speed of this motor at rated load? 3)What is the rotor frequency of this motor at rated load? 4) What is the shaft torque of this motor at rated load?
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A 208-V, 7.5KW, four pole, 60 Hz, Y-connected induction motor has a full-load slip of 5 % 1)What is the synchronous speed of this motor? 2)What is the rotor speed of this motor at rated load? 3)What is the rotor frequency of this motor at rated load? 4) What is the shaft torque of this motor at rated load? 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 208-V, 7.5KW, four pole, 60 Hz, Y-connected induction motor has a full-load slip of 5 % 1)What is the synchronous speed of this motor? 2)What is the rotor speed of this motor at rated load? 3)What is the rotor frequency of this motor at rated load? 4) What is the shaft torque of this motor at rated load? covers all topics & solutions for Electrical Engineering (EE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A 208-V, 7.5KW, four pole, 60 Hz, Y-connected induction motor has a full-load slip of 5 % 1)What is the synchronous speed of this motor? 2)What is the rotor speed of this motor at rated load? 3)What is the rotor frequency of this motor at rated load? 4) What is the shaft torque of this motor at rated load?.
A 208-V, 7.5KW, four pole, 60 Hz, Y-connected induction motor has a full-load slip of 5 % 1)What is the synchronous speed of this motor? 2)What is the rotor speed of this motor at rated load? 3)What is the rotor frequency of this motor at rated load? 4) What is the shaft torque of this motor at rated load? 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 208-V, 7.5KW, four pole, 60 Hz, Y-connected induction motor has a full-load slip of 5 % 1)What is the synchronous speed of this motor? 2)What is the rotor speed of this motor at rated load? 3)What is the rotor frequency of this motor at rated load? 4) What is the shaft torque of this motor at rated load? covers all topics & solutions for Electrical Engineering (EE) 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A 208-V, 7.5KW, four pole, 60 Hz, Y-connected induction motor has a full-load slip of 5 % 1)What is the synchronous speed of this motor? 2)What is the rotor speed of this motor at rated load? 3)What is the rotor frequency of this motor at rated load? 4) What is the shaft torque of this motor at rated load?.
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