The KS Series ac synchronous motors are said to double the torque of their predecessors, enabling designers to reduce the size and weight of the motor they need while improving system performance. These high-torque motors are offered in six sizes and in torque ratings from 80 to 700 oz.-in. Motor speeds are 72 rpm on a 60-Hz supply or 60 rpm on a 50-Hz supply. The motors come in NEMA 23 (60 Series) and NEMA 34 (90 Series) frame sizes and operate from single-phase power at either 120 vac or 240 vac. A phase-shifting network is used to provide smooth, quiet operation. Other features of the high-torque motors include: the ability to start, stop or reverse within 1-1/2 cycles of the applied frequency; impedance protection that enables the motors to be stalled without damaging them; and the ability to start higher inertia loads than earlier models. Options include the availability of rear shafts, CE-compliant models, and a wide range of gear motors for applications that need lower speeds and higher torque. In addition, the motors can be equipped with either 12" leads or a terminal box.