🔍 Key Concepts

• Relationship between prime mover speed (engine or turbine) and AC frequency • Difference between measuring instruments (indicate frequency or phase) and control devices (actually change speed/load/voltage) • How the ship’s main engine/generator governor affects generator output characteristics

💭 Think About

• Which component on a main switchboard is used to actually CHANGE the alternator’s output frequency, not just display it? • What variable must be changed to alter AC frequency: voltage, speed, or phase angle? Which device controls that variable? • On a generator panel, which control is adjusted when matching frequency before paralleling two generators?

✅ Before You Answer

• Identify which options are indicating instruments only versus true control mechanisms • Recall that AC frequency is directly tied to rotational speed and number of poles, and only one of these options can change speed in normal operation • Think about which control you physically move when bringing another generator on the board and matching its frequency