🔍 Key Concepts

• Trace how the frequency meter (F) is wired to both generators on the EL-0003 diagram. • Remember that in a three‑phase alternator, all three legs have the same system frequency under normal operation. • Notice there is only one frequency meter but two generators — think about how the switch must function in that context.

💭 Think About

• Follow the wiring from each generator stator up toward Panel 2 and see where it passes through the devices marked F SW/FM Sel. Sw. before reaching the frequency meter. • Ask yourself: is the switch changing something about the three individual phase legs, or is it choosing which source is connected to the single meter? • Look at the other selector switches (for ammeter and voltmeter). Do they measure differences between phases, or do they simply select which generator or line is being monitored?

✅ Before You Answer

• Verify that there is only one frequency meter (F) on the entire board, but there are two generators feeding it. • Confirm whether any wiring from the F SW goes separately to each phase leg, or instead ties into a potential transformer or common point for each generator. • Before choosing, eliminate any options that require the switch to compare or average multiple phase frequencies, and focus on what a simple selector switch on a shipboard switchboard normally does.