General purpose AC electrical motors vary in design and power source. Also called induction motors, the most common AC electrical motors are three-phase motors and single-phase motors. Three-phase motors are simpler in design and more energy efficient than single-phase motors, but require a three-phase power source to operate. Single-phase motors can be capacitor start or split phase. Capacitor start motors produce higher starting torque than split phase, which allows them to start under load. Applications include compressors, elevators, conveyors, and augers. Split phase motors are commonly used on easy-starting loads, such as air conditioners, exhaust fans, and blowers.