Correct AnswerD. All of the above.
Quick Explanation
A smoothing reactor is inserted in series with the DC line to reduce current ripple, limit the rate and magnitude of fault current, and help prevent current discontinuity/commutation disturbances. The collection of functions given in option D is therefore correct.
Detailed Explanation
Correct Answer
D — All of the above.
Concept and Reasoning
A smoothing reactor is inserted in series with the DC line to reduce current ripple, limit the rate and magnitude of fault current, and help prevent current discontinuity/commutation disturbances. The collection of functions given in option D is therefore correct.
Calculation / Key Relation
vL=L di/dt → large L opposes rapid DC-current change
Exam Takeaway
Smoothing reactor means smoother DC current plus fault-current restraint.
Common Mistake
It does not serve as the main AC harmonic filter; those filters are connected separately.
