Abstract:AC contactors are widely used in low voltage distribution systems. The voltage dip leads to the release of AC contactor, thus affecting the safety production of industrial enterprises. To solve this problem, there are two schemes mainly adopted: contactor restart after voltage dip and voltage dip retainment. However, these schemes do not consider the vibration and impact of AC contactor contacts in the actual implementation process. In order to solve the problem of contactor contact impact during voltage dip, this paper proposes the concept of AC contactor flexible switching and a voltage dip retainment for AC contactor closed during voltage dip based on flexible switching. This scheme can adaptively output DC voltage to ensure that AC contactors with different capacities can be stably closed during voltage dip, and can avoid the vibration and impact of contactor contacts during voltage dip and switching. The effectiveness of this scheme is verified by the actual device test.