Discussion
After a shunt motor is up to speed, the speed may be increased by:
Answer: A
The speed may be increased by increasing the field circuit resistance.
The speed of a DC motor is \(N \propto \frac{V - I_{a}R_{a}}{\phi}\). Adding resistance in the shunt field circuit reduces the field current and so the flux, and with less flux the motor must run faster to generate the back emf the supply requires. This field weakening is the standard way to raise a shunt motor above its normal speed.
Decreasing the field resistance strengthens the field and lowers the speed. Adding armature resistance increases the \(I_{a}R_{a}\) drop and also lowers the speed. Reducing the load raises the speed only slightly in a shunt motor and is not a method of speed control.
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