🔍 Key Concepts

• Compare the frequency and phase angle of the BUS and Incoming Machine sine waves in graph "A". • Recall how, in the sequence (three‑lamp) synchronizing method, the direction of lamp rotation indicates whether the incoming generator frequency is higher or lower than the bus. • Remember that the speed of lamp rotation is proportional to the difference in frequency between the incoming generator and the bus.

💭 Think About

• From graph "A", is the Incoming Machine waveform leading or lagging the BUS waveform? What does that tell you about whether its frequency is slightly higher or slightly lower? • In the sequence‑lamp method (circuit "B"), if the incoming generator frequency is higher than the bus, which way do the lamps appear to rotate (fast or slow direction)? What if it is lower? • Does graph "A" show a large frequency difference or only a small one? How would that affect whether the lamps revolve rapidly or slowly?

✅ Before You Answer

• Verify from graph "A" which waveform is labeled BUS and which is Incoming Machine, and which one completes a cycle first. • Confirm whether the phase difference between the BUS and Incoming Machine waves is increasing or decreasing over time, since this determines the apparent rotation direction of the lamps. • Make sure you match the observed condition (small vs large frequency error) with the correct choice of rapidly vs slowly in the answer options.