Question
Download Solution PDFWhich of the following statements is true regarding the voltage drop due to armature reaction for leading power factors in an alternator?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFThere are three causes of voltage drop in the alternator.
- Armature circuit voltage drop
- Armature reactance
- Armature reaction
The first two factors always tend to reduce the generated voltage, and the third factor may tend to increase or decrease the generated voltage. The nature of the load affects the voltage regulation of the alternator.
Effect of Load Power Factor on Armature Reaction
1.) Unity Power Factor Load: When the load has a unity power factor i.e. pure resistive load, then the armature reaction distorts the main field flux in the air gap of the machine and does not weaken it.
2.) Zero Lagging Power Factor Load: When the load power factor is zero lagging i.e. pure inductive load, then the armature reaction weakens the main field flux. Due to the reduction in the main field flux, the generated EMF is decreased.
3.) Zero Leading Power Factor Load: When the load power factor is zero leading i.e. pure capacitive load, then the armature reaction strengthens the main field flux. This causes an increase in the generated voltage.
Nature of armature reaction on alternator:
|
Power factor |
Nature |
|
Unity |
Cross-magnetizing |
|
Zero PF lagging |
Purely demagnetizing |
|
Zero PF leading |
Purely magnetizing |
|
0.8 lagging |
Partially cross-magnetising and partially demagnetizing |
|
0.8 leading |
Partially cross magnetizing and partially magnetizing |
Last updated on Jun 16, 2025
-> SSC JE Electrical 2025 Notification will be released on June 30 for the post of Junior Engineer Electrical/ Electrical & Mechanical.
-> Applicants can fill out the SSC JE application form 2025 for Electrical Engineering from June 30 to July 21.
-> SSC JE EE 2025 paper 1 exam will be conducted from October 27 to 31.
-> Candidates with a degree/diploma in engineering are eligible for this post.
-> The selection process includes Paper I and Paper II online exams, followed by document verification.
-> Prepare for the exam using SSC JE EE Previous Year Papers.