A Shunt generator running at 1000 rpm has generated emf of ___

Electrical Engineering MCQ Electrical Machines MCQ
1

A Shunt generator running at 1000 rpm has generated emf of 100 V.

If the speed increases to 1200 rpm, the generated emf will be nearly

A. 120 V
B. 140 V
C. 175 V
D. 240 V

Show Answer

Answer: A

Share your understanding of this question with the correct explanation.

2

Explanation

To determine the approximate generated emf when the speed of a shunt generator increases from 1000 rpm to 1200 rpm, we can use the formula:

Emf2 / Emf1 = (N2 / N1) * (Φ2 / Φ1)

Where:

  • Emf1 is the initial generated emf (100 V)
  • Emf2 is the final generated emf (unknown)
  • N1 is the initial speed (1000 rpm)
  • N2 is the final speed (1200 rpm)
  • Φ1 is the initial magnetic flux
  • Φ2 is the final magnetic flux

Assuming the magnetic flux remains constant, we can simplify the equation to:

Emf2 / Emf1 = N2 / N1

Plugging in the values: Emf2 / 100 = 1200 / 1000

Cross-multiplying and solving for Emf2: Emf2 = (1200 / 1000) * 100 Emf2 = 12 * 100 Emf2 = 120 V

Therefore, the generated emf will be approximately 120 V when the speed increases to 1200 rpm. Thus, the correct answer is A.