Which motor has high starting torque AC or DC?

DC motors typically have higher starting torque compared to AC motors. Here's a brief explanation:

DC Motors:

1. Series Wound DC Motors: These motors have a very high starting torque, which makes them suitable for applications like traction systems, cranes, and hoists where high initial torque is necessary to overcome inertia.

2. Shunt Wound DC Motors: While they don't offer as high a starting torque as series motors, they still provide a good amount of starting torque and have better speed regulation.

3. Compound DC Motors: These combine aspects of both series and shunt motors, offering a compromise with high starting torque and adjustable speed.

AC Motors:

1. Induction Motors: Standard induction motors have a lower starting torque compared to DC motors. However, they are very common due to their simplicity, reliability, and lower cost. Special designs like slip ring motors or using variable frequency drives (VFDs) can increase the starting torque.

2. Synchronous Motors: These generally do not have high starting torque when started as an induction motor (which is common practice), but when run up to speed and then synchronized, their torque characteristics are different. However, special designs or configurations like those with damper windings can improve starting torque.

For applications requiring very high starting torque, DC series motors are often preferred. However, with advancements in power electronics and motor control, AC motors can also be designed or controlled to provide higher starting torques when necessary, often through the use of VFDs or other control mechanisms. 

Remember, the choice between AC and DC for high starting torque also depends on other factors like speed control, efficiency, maintenance, environment, and the overall system design.

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