A suppression method of electrical sectioning over-voltage is proposed by constructing a potential circuit model because the over-voltage causes insulation breakdown when an electric locomotive goes through articulated electrical sectioning. A chain-type equivalent circuit model of electrical sectioning structure is established

the transition process of a locomotive going through electrical phase is analyzed

and the balance wiring and the influence of AT power supply on potential over-voltage are discussed. The induction voltage and the over-voltage are simulated by using the united simulation model of locomotive-electrical traction-network. The results show that installing a suppression circuit on electrical sectioning neutral wires can reduce the maximum over-voltage from 108.0 kV to 64.8 kV to weaken the impact of over-voltage on the insulation of traction power network and locomotives.