Back to questionChoose “Save as PDF” in the print window.

SarkariResultOutBMS · 2024

Previous Year Question

In HVDC systems, the smoothing reactors are used to
  1. Reduce the incidence of commutation failure in inverters caused by dips in the AC voltage at the converter bus.
  2. Avoid discontinuous current at light loads.
  3. Reduce DC harmonics in line.
  4. All of the above.

Correct answer: D

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.

Formula

vL=L di/dt → large L opposes rapid DC-current change

Step-by-step solution

Purpose of Smoothing Reactor explanatory diagram

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.

Common mistake

It does not serve as the main AC harmonic filter; those filters are connected separately.

Exam tip

Smoothing reactor means smoother DC current plus fault-current restraint.

Quick method

Smoothing reactor means smoother DC current plus fault-current restraint.