Which component is used to achieve operation of the regulator by automatic or manual control?

The component that allows for the operation of a regulator through either automatic or manual control is the control selector. This device provides the user with options to choose the method by which the regulator will operate. In manual mode, the control selector enables the operator to set the output level directly. In automatic mode, it allows the system to adjust the regulation based on the feedback it receives from other components, ensuring that the output remains stable within predetermined parameters.

The control selector is critical because it facilitates the transition between these two modes of operation, allowing for flexibility depending on the situation or specific operational needs. This versatility is essential in maintaining optimal performance of the electrical system the regulator is controlling.

In contrast, while the power switch is necessary to activate the regulator, it does not influence how the regulation is controlled. The voltage meter provides crucial monitoring of the output voltage but does not directly impact the mechanism of control. The feedback loop is integral to the automatic regulation process but relies on the control selector to operate effectively in conjunction with the chosen mode, either manual or automatic.