What is the value of Starting Torque of a Wound Rotor Motor when using full resistance in the rotor circuit?

The value of starting torque for a wound rotor motor when using full resistance in the rotor circuit is indeed maximum torque. This is because the inclusion of resistance in the rotor circuit significantly influences the initial torque produced by the motor when it starts.

When the resistance is at its highest, it allows for optimal slip during startup. The presence of resistance in the rotor windings increases the voltage drop across the rotor, which maximizes the effective current passing through the rotor. This is essential for generating a high starting torque, as torque is directly proportional to the rotor current. Therefore, using full resistance in the rotor circuit facilitates maximum current flow under starting conditions, leading to the highest possible starting torque.

This concept is central to the operation of wound rotor motors, especially in applications requiring high torque at startup, such as in cranes or heavy machinery. In contrast, when resistance is reduced or not present, the starting torque would be lower, providing less immediate power for overcoming initial inertial loads.