Explain how to use a pump panel to switch between manual and governor-controlled operation if available.

• A. In automatic governor mode you set a fixed RPM; in manual you let the engine adjust RPM.
• B. In manual mode the engine automatically maintains target discharge pressure; in governor mode you set a fixed RPM.
• C. In governor mode, the engine adjusts RPM to hit PDP; in manual mode you set a fixed RPM; toggle the switch and verify governor engagement.
• D. The panel cannot switch between modes.

Answer: (C)

Switching between manual and governor control on a pump panel changes who governs the engine speed. In governor mode, the governor automatically adjusts engine RPM to hit the target pump discharge pressure (PDP). As demand changes, the governor nudges RPM up or down to keep PDP where you set it. In manual mode, you set a fixed RPM and the governor is not actively controlling the speed, so discharge pressure will vary with flow and load.

To switch if the panel supports it, flip the mode selector to governor control to engage automatic pressure-based speed control, and set the target PDP as required. Start or run the pump and verify the governor is working by watching that the RPM responds to PDP changes and that the PDP trends toward the target. Then flip back to manual mode to lock in a fixed RPM, and confirm the governor engagement indicator shows disengagement and the RPM remains at the set value.