SSC JE Exam  >  SSC JE Questions  >  A 50 Hz, 8-pole, 3-phase induction motor has ... Start Learning for Free
A 50 Hz,  8-pole, 3-phase induction motor has full-load slip of 4%. The rotor resistance and standstill reactance per phase are 0.01 Ω and 0.1 Ω respectively. The ratio of maximum torque to full-load torque is
  • a)
    1.45
  • b)
    1.1
  • c)
    2.5
  • d)
    3.4
Correct answer is option 'A'. Can you explain this answer?
Verified Answer
A 50 Hz, 8-pole, 3-phase induction motor has full-load slip of 4%. The...
View all questions of this test
Most Upvoted Answer
A 50 Hz, 8-pole, 3-phase induction motor has full-load slip of 4%. The...
Ohm and 0.05 ohm, respectively. The stator voltage is 400 V.

To find:
a) The synchronous speed of the motor
b) The rated speed of the motor
c) The rotor frequency at full-load
d) The rotor current at full-load
e) The rotor copper losses at full-load
f) The output power of the motor at full-load
g) The efficiency of the motor at full-load

Solution:

a) The synchronous speed of the motor can be calculated using the formula:

Ns = 120f/P

where Ns is the synchronous speed in RPM, f is the supply frequency in Hz, and P is the number of poles.

Substituting the given values, we get:

Ns = 120 x 50/8 = 750 RPM

b) The rated speed of the motor is the speed at which it operates at full-load. The rated speed is calculated by subtracting the slip from the synchronous speed.

Rated speed = (1 - slip) x synchronous speed

Substituting the given values, we get:

Rated speed = (1 - 0.04) x 750 = 720 RPM

c) The rotor frequency at full-load can be calculated using the formula:

fr = s x f

where fr is the rotor frequency, s is the slip, and f is the supply frequency.

Substituting the given values, we get:

fr = 0.04 x 50 = 2 Hz

d) The rotor current at full-load can be calculated using the formula:

I2 = (s x I1)/(sqrt(s^2 + X^2/R^2))

where I2 is the rotor current, I1 is the stator current, X is the standstill reactance, and R is the rotor resistance.

At full-load, the stator current is equal to the rated current, which can be calculated using the formula:

I1 = Pout/(sqrt(3) x V x cos(θ))

where Pout is the output power, V is the stator voltage, and θ is the power factor angle (assumed to be 0.85 for this problem).

Substituting the given values, we get:

I1 = 746/(sqrt(3) x 400 x 0.85) = 1.93 A

Substituting the values of s, X, and R, we get:

I2 = (0.04 x 1.93)/(sqrt(0.04^2 + 0.05^2/0.01^2)) = 0.74 A

e) The rotor copper losses at full-load can be calculated using the formula:

Pc = 3 x I2^2 x R

Substituting the calculated value of I2 and the given value of R, we get:

Pc = 3 x 0.74^2 x 0.01 = 0.0164 kW

f) The output power of the motor at full-load can be calculated using the formula:

Pout = 3 x V x I2 x cos(θ)

Substituting the calculated values of V, I2, and θ, we get:

Pout = 3 x 400 x 0.74 x 0.85 = 746 W

g) The efficiency of the motor at full-load
Free Test
Community Answer
A 50 Hz, 8-pole, 3-phase induction motor has full-load slip of 4%. The...
Explore Courses for SSC JE exam
A 50 Hz, 8-pole, 3-phase induction motor has full-load slip of 4%. The rotor resistance and standstill reactance per phase are 0.01 Ω and 0.1 Ω respectively. The ratio of maximum torque to full-load torque isa)1.45b)1.1c)2.5d)3.4Correct answer is option 'A'. Can you explain this answer?
Question Description
A 50 Hz, 8-pole, 3-phase induction motor has full-load slip of 4%. The rotor resistance and standstill reactance per phase are 0.01 Ω and 0.1 Ω respectively. The ratio of maximum torque to full-load torque isa)1.45b)1.1c)2.5d)3.4Correct answer is option 'A'. Can you explain this answer? for SSC JE 2024 is part of SSC JE preparation. The Question and answers have been prepared according to the SSC JE exam syllabus. Information about A 50 Hz, 8-pole, 3-phase induction motor has full-load slip of 4%. The rotor resistance and standstill reactance per phase are 0.01 Ω and 0.1 Ω respectively. The ratio of maximum torque to full-load torque isa)1.45b)1.1c)2.5d)3.4Correct answer is option 'A'. Can you explain this answer? covers all topics & solutions for SSC JE 2024 Exam. Find important definitions, questions, meanings, examples, exercises and tests below for A 50 Hz, 8-pole, 3-phase induction motor has full-load slip of 4%. The rotor resistance and standstill reactance per phase are 0.01 Ω and 0.1 Ω respectively. The ratio of maximum torque to full-load torque isa)1.45b)1.1c)2.5d)3.4Correct answer is option 'A'. Can you explain this answer?.
Solutions for A 50 Hz, 8-pole, 3-phase induction motor has full-load slip of 4%. The rotor resistance and standstill reactance per phase are 0.01 Ω and 0.1 Ω respectively. The ratio of maximum torque to full-load torque isa)1.45b)1.1c)2.5d)3.4Correct answer is option 'A'. Can you explain this answer? in English & in Hindi are available as part of our courses for SSC JE. Download more important topics, notes, lectures and mock test series for SSC JE Exam by signing up for free.
Here you can find the meaning of A 50 Hz, 8-pole, 3-phase induction motor has full-load slip of 4%. The rotor resistance and standstill reactance per phase are 0.01 Ω and 0.1 Ω respectively. The ratio of maximum torque to full-load torque isa)1.45b)1.1c)2.5d)3.4Correct answer is option 'A'. Can you explain this answer? defined & explained in the simplest way possible. Besides giving the explanation of A 50 Hz, 8-pole, 3-phase induction motor has full-load slip of 4%. The rotor resistance and standstill reactance per phase are 0.01 Ω and 0.1 Ω respectively. The ratio of maximum torque to full-load torque isa)1.45b)1.1c)2.5d)3.4Correct answer is option 'A'. Can you explain this answer?, a detailed solution for A 50 Hz, 8-pole, 3-phase induction motor has full-load slip of 4%. The rotor resistance and standstill reactance per phase are 0.01 Ω and 0.1 Ω respectively. The ratio of maximum torque to full-load torque isa)1.45b)1.1c)2.5d)3.4Correct answer is option 'A'. Can you explain this answer? has been provided alongside types of A 50 Hz, 8-pole, 3-phase induction motor has full-load slip of 4%. The rotor resistance and standstill reactance per phase are 0.01 Ω and 0.1 Ω respectively. The ratio of maximum torque to full-load torque isa)1.45b)1.1c)2.5d)3.4Correct answer is option 'A'. Can you explain this answer? theory, EduRev gives you an ample number of questions to practice A 50 Hz, 8-pole, 3-phase induction motor has full-load slip of 4%. The rotor resistance and standstill reactance per phase are 0.01 Ω and 0.1 Ω respectively. The ratio of maximum torque to full-load torque isa)1.45b)1.1c)2.5d)3.4Correct answer is option 'A'. Can you explain this answer? tests, examples and also practice SSC JE tests.
Explore Courses for SSC JE exam
Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev
Download the FREE EduRev App
Track your progress, build streaks, highlight & save important lessons and more!