One major drawback of the vibrating points regulator?

• A. Higher efficiency
• B. Less reliability due to moving parts and wear
• C. No maintenance required
• D. Increased reliability

Answer: (B)

The key idea here is that a vibrating points regulator relies on moving electrical contacts that continually vibrate to control the generator’s field. That mechanical motion introduces wear and arcing at the contact surfaces, so the contacts degrade over time. As the contacts wear, the regulation becomes less stable, and the regulator can fail to hold the proper voltage. Because of this, reliability drops and maintenance is often required to clean, adjust, or replace the points.

So the major drawback isn’t about efficiency or the needlessness of maintenance or overall reliability improvements. It’s specifically the wear and potential failure due to the moving parts. The other options don’t fit because higher efficiency isn’t the main issue, maintenance is indeed needed, and reliability isn’t increased.