🔍 Key Concepts

• Electrical interlocks in multi-speed motor controllers prevent conflicting contactors from energizing at the same time • For contactor M3, trace the normally closed (NC) contacts in the control circuit that open when other contactors pick up • Focus on which other speeds or configurations would be unsafe if energized together with 3rd-speed (M3)

💭 Think About

• Look at the control diagram at the bottom: when M3 coil is energized, which normally closed contacts in series with other coils does it open? • Follow the dashed interlock lines and the NC contact symbols labeled with other M numbers that are in series with the M3 coil • Ask yourself: which other contactors would cause an electrical or winding conflict if they were to close while M3 is energized?

✅ Before You Answer

• Verify which contacts in series with the M3 coil are labeled with other M-designations (for example, contacts marked M1, M2, etc.) and are normally closed • Confirm that those same contact labels do not appear as NC contacts in series with coils that do not interact with M3 • Double-check that every interlocked contactor you choose is actually part of the electrical interlock chain for M3 in the control circuit, not just mechanically separated in the power circuit