If a three-phase motor controlled by the...

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Question 1 of 2066636eed28f7522a1c51dc65

If a three-phase motor controlled by the control circuit illustrated in figure "B" of the illustration is running in the forward direction, which of the following sequences must occur before the motor will reverse rotation assuming that the stop button is depressed first? Illustration EL-0011

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Question 1 of 20

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🔍 Key Concepts

• Forward/reverse three-phase motor starter control circuits • How normally open (NO) and normally closed (NC) auxiliary contacts change state when a coil is energized or de‑energized • Electrical interlocking that prevents both forward and reverse contactors from being energized at the same time

💭 Think About

• When the motor is running forward, what is the state of the F auxiliary contacts (both NO and NC) in figure B? After you hit the stop button and de‑energize F, how do those same contacts change? • Look at the path that must be completed to energize the reverse (R) coil. Which F contact is in that path, and does it have to be closed or open for R to pick up? • In what order must these events happen: F coil drops out, its auxiliary contact(s) change state, and the reverse start button is pressed, so that forward and reverse contactors are never energized together?

✅ Before You Answer

• Identify exactly which F contact (NO or NC) is wired in series with the reverse coil R in figure B – this is critical. • Confirm from the drawing what the F contact’s normal state is (NO or NC) and what its state is while F is energized vs de‑energized – do not rely on memory, trace it on the diagram. • Make sure your chosen sequence never allows a condition where both F and R coils could be energized at the same time – that would defeat the interlock.

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