For a large starting torque, which DC motor type is most suitable?

A series DC motor is the most suitable choice for applications requiring a large starting torque. This is primarily because of its unique construction where the field windings are connected in series with the armature windings. In a series motor, when the motor starts and the armature current is low, the magnetic field generated is also weak; however, as the motor begins to accelerate, the armature current increases. This results in a stronger magnetic field, which in turn leads to an increase in torque.

The characteristic behavior of series DC motors allows them to deliver high starting torque, making them ideal for applications like cranes, lifts, and electric traction systems where substantial torque is necessary at startup. The torque produced is proportional to the product of the armature current and the field current. Since both the field and armature currents are the same in a series motor, higher loads that require more current will also produce a stronger field and therefore a greater torque, especially beneficial during startup conditions.

In contrast, shunt DC motors have a constant field current, providing a more stable speed but relatively lower starting torque. Compound DC motors can also provide higher starting torque than shunt motors, but not to the extent of series motors. Universal motors, while capable of providing high torque