Inverter-duty gearmotors (and motors) feature variable speed, AC three-phase motor windings that are designed with a special winding insulation system to protect them from potential voltage spikes or corona damage caused by the AC "inverter" PWM speed control (Variable Frequency Drive / VFD). The special inverter-duty windings meet NEMA motor standard MG 1, Section IV, Part 31. In general, AC three-phase gearmotors and motors are more efficient than their AC single-phase counterparts, they are more compact, and provide higher output torques in the same size package. In addition, these variable-speed AC gearmotors and motors don’t require brush replacement or brush maintenance. Typical Applications are conveyor systems, food processing equipment, factory automation, pumps, lifts and packaging equipment.