These units are powered by a low-speed engine for extra-quiet operation, allowing you to be a “good-neighbor” during routine testing of our gensets. QUIETER, GREENER, MORE POWERFUL. Engineered to run at only 1500 rpm for substantially quieter performance, the low-speed, liquid-cooled engine on the Protector QS Series packs more power into a smaller footprint than air-cooled models. Enjoy reduced fuel consumption, and long engine and alternator life. EVOLUTION™ CONTROLLER. A cutting-edge, intuitive control. The Evolution controller features a multilingual, two-line LCD text display with color-coded, backlit buttons. It has received upgrades, including USB flash capability, smart battery charging, voltage adjustment, and backlit membrane pad style buttons.