Why do some AC motors have 12 leads?

Some AC motors have 12 leads primarily to allow for the external switching between Wye and Delta configurations. This capability is significant because Wye (Y) and Delta (Δ) configurations affect the motor's operational characteristics, such as starting torque and overall performance.

When configured as a Wye, the motor will typically have a higher starting torque and can be used at lower voltage levels, making it advantageous for specific applications. Conversely, a Delta configuration can provide higher torque at rated speed, which is beneficial for different operational needs.

By having multiple leads, the motor can be adaptable to different electrical supply conditions or variations in load requirements. This flexibility allows the motor to be more versatile and enhances its applicability across various scenarios. In sum, the design of these motors facilitates efficient operation and adaptability, which is why having 12 leads serves an important functional purpose.