Switching-on holding and switching-off tripping system

The invention discloses a switching-on holding and switching-off tripping system which comprises a rotating shaft A and a rotating shaft B. The peripheral surface of a third cam on the rotating shaft B is provided with a step protrusion, the peripheral surface of a fifth cam is provided with an arc section, and the rotating shaft B is sleeved with a torsional spring. The switching-on holding and switching-off tripping system also comprises an action spring, a crank arm and a switching-off spring. In a switching-on state, the switching-off spring applies the clockwise rotation force to the crank arm, and an upper rotating wheel of the crank arm is in contact with the arc section of the fifth cam; the rotating shaft B and the third cam only bear the torque from the anticlockwise rotation of the torsion spring; an iron core is located at the step side of the step protrusion, and the anticlockwise rotation of the third cam can be limited. According to the system, in a switching-on state, the rotating shaft B and