What is a 12-lead AC motor?

What is a 12-lead AC motor?

• A. A single-voltage motor with fixed delta.
• B. A dual-voltage motor that can be reconfigured between wye and delta; four leads per phase (12 total).
• C. A motor that always uses star connection only.
• D. A 9-lead motor with extra test leads.

Answer: (B)

A 12-lead AC motor is built with two windings for each of the three phases, giving twelve terminals. This lets the motor be wired for two different line voltages and reconfigured between wye (star) and delta. For low voltage, the two windings per phase are connected in parallel so each winding sees part of the line voltage; for high voltage, they are connected in series so each winding handles a portion of the higher voltage. After choosing the winding arrangement, the three phases can be connected in either wye or delta to control starting current and torque. The four leads per phase (twelve total) come from having two windings per phase, each with its own pair of terminals. This flexibility isn’t available with a single-voltage fixed-delta motor, nor with a motor that’s locked to one connection type or with an arrangement that doesn’t match the standard two-winding-per-phase layout.

A 12-lead AC motor is built with two windings for each of the three phases, giving twelve terminals. This lets the motor be wired for two different line voltages and reconfigured between wye (star) and delta. For low voltage, the two windings per phase are connected in parallel so each winding sees part of the line voltage; for high voltage, they are connected in series so each winding handles a portion of the higher voltage. After choosing the winding arrangement, the three phases can be connected in either wye or delta to control starting current and torque. The four leads per phase (twelve total) come from having two windings per phase, each with its own pair of terminals. This flexibility isn’t available with a single-voltage fixed-delta motor, nor with a motor that’s locked to one connection type or with an arrangement that doesn’t match the standard two-winding-per-phase layout.