KPO namely control protective swirching device is a new style profucts in low-voltage electric apparatus, developed in China, fill the blank in 1990s, as a new product kinds, complies with standards of IEC60947-6-2 "Low-voltage switchgear and controlgears Part Ⅵ Multifunctional electric apparatus Section 2:Control and protective switching device" Edition 1, August, 1992;GB14048.9-1998 "Low-voltage switchgear and controlgears Multifunctional electric apparatus Section 2:Control and protective switching device" (Eqv.IEC60947-6-2). Electric design code/symbol as IEC and national standard as right drawing.