🔍 Key Concepts
• Three-phase motor rotation and how reversing is achieved by changing phase sequence
• Role of the H (hoist) and L (lower) contactors in this control circuit
• Difference between stator leads (T1, T2, T3) and rotor leads (M1, M2, M3) on a wound-rotor induction motor
đź’ Think About
• Look at the paths from L1, L2, and L3 through the H contactor to T1, T2, and T3. Then compare those paths to the L contactor connections. Which two motor terminals swap their line sources between hoist and lower?
• Ask yourself: does reversing a three-phase motor normally involve changing the rotor connections or the stator (line) connections? How does that apply to this drawing?
• Trace just one line, for example from L1, and see where it ends up at the motor for hoist vs. lower. Then repeat for L2 and L3. From this, what change in phase sequence do you see?
âś… Before You Answer
• Verify which contactor (H or L) is energized in hoist and in lower, and follow each line from L1, L2, L3 down to T1, T2, T3.
• Confirm that the rotor circuit (M1, M2, M3 through resistors/contactors 1A–4A) remains the same in both directions and is only used for speed/torque control, not rotation reversal.
• Identify exactly which pair of stator terminals (T1, T2, T3) are swapped between hoist and lower; match that pair to the correct multiple-choice option.