FK series auxiliary switch is one of the auxiliary components of high voltage equipment. It is a new type of auxiliary switch developed for the use of auxiliary switches in the current power industry. Compared with the commonly used auxiliary switches such as F6 and F9, its Angle control is more flexible, and it can realize various special switching. Compared with the F10 auxiliary switch contact capacity has more than doubled, which can better meet the high current needs of the high voltage switch industry. It is more widely used to control the closing, opening, interlocking, signal loop of various high-voltage switch operating mechanisms, and can also be used as a conversion or combination switch.