🔍 Key Concepts

• Across-the-line vs reduced-voltage starting – what extra components are usually needed for reduced-voltage starting (autotransformer, resistors, multiple contactors, star-delta, timer, etc.)? • Control transformer and secondary voltage – what does it mean if the control circuit is fed from the secondary of a transformer instead of directly from L1, L2, L3? • Single-phase vs three-phase motor symbols – how many power leads go to the motor, and what does the "3~" marking at the motor symbol indicate?

💭 Think About

• Count how many main contactors (KM) are in the power circuit feeding the motor. Would reduced-voltage starting normally use more than one contactor? • Trace the control circuit from the pushbuttons back to its power source. Does it tie straight into the line, or does it go through a transformer first? • Look closely at the motor symbol and its terminals (U, V, W). Does this look like a single‑phase or a three‑phase connection?

✅ Before You Answer

• Verify whether there is only one main contactor in the power circuit, or several used in a sequence (which would suggest reduced‑voltage starting). • Verify whether the control devices (pushbuttons and KM1 coil) are fed from the secondary of a control transformer (X1–X2) or directly from L1–L2–L3 (which would mean full line control voltage). • Verify whether the motor symbol shows three supply lines (three-phase) and a "3~" marking, or only two lines (single-phase).