What are the alternatives to the use of overload releases?

Direct protection against overheating or burning-out of motor windings may be built into the motor. Built-in protectors may take the form of thermostats or thermistors embedded in the end windings of the stator while the motor is under construction. These devices are sensitive to the winding temperatures and are arranged in a suitable circuit so as to cause the motor to be switched off if the windings heat up excessively.