1 Application HD11B and HS11B series single-changeover and double-changeover protecting knife switches are new products based on HD11 and HS11 series which were developed by our company. They are the perfect replacements of HD11, HD11F, HS11 series products. They conductive part in protection property to human body, and prevent error touch to the conductive part in operation .They are mainly used to infrequently make and break, isolate the power supply with hand in the low voltage distributing equipments. This production is in conforming to standard GB14048:3-2002. 2 Characteristic 3.1 Rated voltage isAC380V,DC220V 3.2 Rated current is100A,200A,400A