What is the main purpose of interlocks in a star/delta starter?

The main purpose of interlocks in a star/delta starter is to prevent the star and delta contractors from closing simultaneously. This safety feature is crucial because if both contractors were to engage at the same time, it could create a short circuit condition, leading to damage to the motor and associated circuitry. The interlock ensures that the motor transitions smoothly from the star connection, which limits the voltage and starting current, to the delta connection, which allows the motor to run at full capacity. This orderly switching is vital for the efficient and safe operation of three-phase induction motors during startup and operation.

The other options, while they might pertain to aspects of motor control or efficiency, do not accurately reflect the primary function of interlocks in this context. Independent control of motor phases, increasing overall efficiency, and providing overcurrent protection are functions managed by other components in the motor control circuit but are not the specific role of the interlocks.