🔍 Key Concepts

• Autotransformer reduced-voltage starting – how the circuit uses different contactors for START vs RUN • Roles of contactors KM1, KM2, KM3 in the power circuit portion of EL-0080 • Difference between feeding the motor through the autotransformer versus across the line (full voltage)

💭 Think About

• When the starter is in the START position, trace the path from L1–L2–L3 to the motor terminals U–V–W. Through which contacts does current actually pass? • In the RUN condition, which contactor(s) must be picked up or dropped out so the motor is no longer connected to the autotransformer windings? • Looking only at the left (power) side of the diagram, what changes for the motor terminals when KM3 changes state compared with when only KM1 and KM2 are energized?

✅ Before You Answer

• Verify which contactor directly bridges the motor leads (U, V, W) to the line side (L1, L2, L3) without going through the transformer windings. • Confirm from the dashed outlines which contacts belong to KM3 and whether they are in series with the autotransformer or bypass it. • Be sure you can state for each contactor: "KM1 does ___ in START, KM2 does ___ in START, KM3 does ___ in RUN" before choosing your option.