Which configuration provides more starting torque to a three-phase motor?

Which configuration provides more starting torque to a three-phase motor?

• A. Run capacitor
• B. Wye connected motor
• C. Delta connected motor
• D. Start capacitor

Answer: (C)

The configuration that provides more starting torque to a three-phase motor is the delta connected motor. In a delta configuration, each winding of the motor is connected across two phases of the supply, which allows for higher line currents to flow. This results in a greater starting torque because the effective voltage across each winding is maximized due to the phase-to-phase connections. This increased voltage leads to a higher current and therefore more torque at startup. In contrast, other configurations do not provide the same level of starting torque. For instance, a run capacitor is primarily used for improving running efficiency and power factor in single-phase motors, rather than increasing starting torque. Wye connected motors typically have less starting torque compared to delta models as the winding connections operate at a lower phase voltage, resulting in less starting current and torque. A start capacitor can temporarily boost starting torque when used in single-phase motors, but it does not apply to three-phase motors in the same manner, as three-phase motors inherently provide different starting characteristics based on their winding configurations.

The configuration that provides more starting torque to a three-phase motor is the delta connected motor. In a delta configuration, each winding of the motor is connected across two phases of the supply, which allows for higher line currents to flow. This results in a greater starting torque because the effective voltage across each winding is maximized due to the phase-to-phase connections. This increased voltage leads to a higher current and therefore more torque at startup.

In contrast, other configurations do not provide the same level of starting torque. For instance, a run capacitor is primarily used for improving running efficiency and power factor in single-phase motors, rather than increasing starting torque. Wye connected motors typically have less starting torque compared to delta models as the winding connections operate at a lower phase voltage, resulting in less starting current and torque. A start capacitor can temporarily boost starting torque when used in single-phase motors, but it does not apply to three-phase motors in the same manner, as three-phase motors inherently provide different starting characteristics based on their winding configurations.