Discussion
A dc series motor must never be run at no load because
Answer: D
Correct answer: its speed rises dangerously as the flux collapses
In a series machine the field carries the armature current, so at no load that current is small and the flux with it. From
\[ N \propto \frac{V - I_aR_a}{\Phi} \]a vanishing flux means a runaway speed, and the machine can destroy itself by centrifugal force. This is why a series motor is always coupled directly to its load by gearing or a shaft, never by a belt that could break, and why it is never started uncoupled.
No comment is present. Be the first to comment.
Loading…
Post your comment
Please log in or register to post a comment.
Examination Categories
- SSC Exams
- Banking Exams
- Teaching Exams
- Civil Services Exams
- Railways Exams
- Engineering Recruitment Exams
- Defence Exams
- State Government Exams
- Police Exams
- Insurance Exams
- Nursing Exams
- Other Government Exams
- NRA CET
- PG Entrance Exams
- Campus Placement
- MBA Entrance Exams
- CUET and UG Entrance
- Judiciary Exams
- Regulatory Body Exams
- Software Development