The DU Series are designed for DC Circuits (with AC Coils) and DC Motor Control. The S-U Series are compact horsepower rated units used in compressors, blowers, fans and pump motors. The S-N Series Compact 3-Pole units, S-N18, S-N38 and S-N48, were designed for machine control panels with limited space available. The DC Interface Contactors and Modules were specially designed to be directly driven by the transistor output of a Programmable Logic Controller.