Question
Download Solution PDFArmature reaction of an unsaturated DC machine results in _______ effect.
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFArmature reaction:
The effect of armature flux (ϕa) on main field flux (ϕm) is called armature reaction.
The armature reaction mmf produces two undesirable effects on the main field flux and these are
(1) Net reduction in the main field flux per pole
(2) Distortion of the main field flux wave along the air gap periphery.
The armature mmf in a dc machine is stationary with respect to field poles but rotating with respect to armature.
- Armature reaction of unsaturated DC machine results in cross – magnetizing effect.
- Armature reaction distorts the main flux, hence the position of M.N.A. gets shifted (M.N.A. is perpendicular to the flux lines of main field flux).
- Brushes should be placed on the M.N.A., otherwise, it will lead to sparking at the surface of brushes. So, due to the armature reaction, it is hard to determine the exact position of the MNA.
- For a loaded dc generator, MNA will be shifted in the direction of the rotation.
- While for a loaded dc motor, MNA will be shifted in the direction opposite to that of the rotation.
Last updated on Jun 11, 2025
-> The RRB NTPC Admit Card 2025 has been released on 1st June 2025 on the official website.
-> The UPSC Prelims Result 2025 and UPSC IFS Result 2025 has been released @upsc.gov.in
-> Railway Recruitment Board activated the RRB ALP application form 2025 correction link, candidates can make the correction in the application form till 31st May 2025.
-> The Railway Recruitment Board (RRB) has released the official RRB ALP Notification 2025 to fill 9,970 Assistant Loco Pilot posts.
-> The Railway Recruitment Board (RRB) has released the official RRB ALP Notification 2025 to fill 9,970 Assistant Loco Pilot posts.
-> The official RRB ALP Recruitment 2025 provides an overview of the vacancy, exam date, selection process, eligibility criteria and many more.
->The candidates must have passed 10th with ITI or Diploma to be eligible for this post.
->The RRB Assistant Loco Pilot selection process comprises CBT I, CBT II, Computer Based Aptitude Test (CBAT), Document Verification, and Medical Examination.
-> This year, lakhs of aspiring candidates will take part in the recruitment process for this opportunity in Indian Railways.
-> Serious aspirants should prepare for the exam with RRB ALP Previous Year Papers.
-> Attempt RRB ALP GK & Reasoning Free Mock Tests and RRB ALP Current Affairs Free Mock Tests here