• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar

How Engineering Works

  • Home
  • MCQ
    • Electrical MCQ
    • Civil MCQ
    • Mechanical MCQ
  • Interview Questions
  • About Us
  • Privacy Policy
  • Disclaimer
  • Contact Us

Why is DC excitation used in a synchronous alternator instead of AC excitation?

July 10, 2018 by

DWQA Questions › Category: Alternator & Synchronous Motor › Why is DC excitation used in a synchronous alternator instead of AC excitation?
0 Vote Up Vote Down
admin Staff asked 5 years ago
2 Answers
0 Vote Up Vote Down
admin Staff answered 5 years ago

Synchronous machines work on the principle of “magnetic locking”. For magnetic locking the rotor must rotate at synchronous speed and if we give ac to the rotor then polarity of the field in the rotor changes continuously and it fails to synchronize with the stator rmf and hence there is no magnetic locking and the rotor field produces sinusoidal flux distribution with respect to space angle. To keep it short we can conclude that to get steady state torque and to synchronize the rotor we use dc excitation.

You can also Read :
Interview Questions
MCQ or objective

0 Vote Up Vote Down
admin Staff answered 5 years ago

If you use AC excitation, flux will be alternating. Then what you need is a static coil to induce voltage. This is nothing but a transfomer based on statically induced emf.

For dynamically induced emf, you need a constant flux (provided by DC excitation) and a rotating coil. This is the basic principle of DC/AC generator. The voltage induced is AC in both generators. In DC generators voltage is rectified using a commutator.

You are welcome to read more Important Interview Questions and MCQs.

Primary Sidebar

Related Questions

  • What are Turbo alternators? asked by admin
  • Why Generator & Alternator rated in kVA. Not in kW? asked by
  • What is the difference between an alternator and a generator? asked by admin
  • What is the working principle of alternator? asked by admin

INTERVIEW QUESTIONS

MCQ or Objective


Recommended Post

Electrical Engineering Interview Questions

MCQs on Electrical Devices

MCQs on Induction Motor

MCQs on Transformer

MCQ on Electrical Unit – 1

Categories



Join Our Whatsapp Group


About Us | Privacy Policy | Disclaimer


Copyright@ Since-2017