FH series auxiliary switch is one of the auxiliary components of high voltage equipment, taking into account the characteristics of auxiliary switch and transfer switch. Compared with traditional auxiliary switches, the contact Angle control of FH series auxiliary switches is more flexible, and customers can achieve more diversified control needs through different combinations. Compared with manually operated transfer switches, FH series auxiliary switches are more convenient to connect with the actual operating mechanism, which is convenient for mechanical transmission control. It is suitable for controlling the closing, opening, interlocking and signal loop of various high-voltage switch operating mechanisms, and can also be used as a conversion or combination switch.