What is the effect of turning the voltage adjustment down on a voltage regulator?

Turning the voltage adjustment down on a voltage regulator results in a change to the reference voltage. This adjustment effectively lowers the voltage level that the regulator uses as a baseline for its operation. As the reference voltage decreases, the voltage regulator senses this change and responds accordingly by reducing the output voltage to maintain the desired operating conditions within the system.

This feedback mechanism is integral to the function of voltage regulators, which aim to maintain a stable output despite variations in load or input conditions. By adjusting the reference voltage, the system can effectively respond to the new requirements, ensuring that equipment operates safely and efficiently.

The other options do not align with the operational principles of a voltage regulator. For instance, decreasing the voltage adjustment would not cause the output voltage to increase or lead to the shutdown of the generator; nor would it result in excess current generation from the exciter. Each of these scenarios does not accurately reflect the regulatory process and balance that is maintained when adjustments are made.