What part of a three-phase motor is connected to the supply voltage?

In a three-phase motor, the part that is connected to the supply voltage is the stator. The stator consists of windings that are arranged in a specific configuration to create a rotating magnetic field when three-phase AC voltage is supplied. This rotating field is essential for initiating and maintaining the motor's operation by inducing current in the rotor and producing torque.

The other components of the motor serve different functions; for instance, the rotor is the part that rotates and is driven by the magnetic field created by the stator. The centrifugal switch is typically used in certain types of single-phase motors for starting and stopping the motor but is not relevant in the context of the three-phase motor's connection to voltage. The base supports the motor and provides stability but does not play a role in the electrical connections.

Thus, the stator is the correct answer because it is the component responsible for connecting to the electrical power supply and generating the necessary magnetic field for the motor's operation.