Investigation on 110kV composite material pole: Effects of grounding methods on insulation of conductor-pole gaps

110kV Composite Material Pole has many advantages over traditional steel towers and concrete poles to enhance the operation reliability of power system. The grounding methods has obvious effect on the phase-ground insulation performance of composite materials pole of 110 kV transmission line. Four grounding methods of 110 kV composite materials pole were investigated in this paper, which including switching impulse test and lightning impulse test of phase-ground air gaps, and pollution test of phase-ground. The test results showed that the insulating level of composite materials pole satisfied the transmission line operation requirements by adopting proper grounding method. And when the grounding wire was overhanging lead to ground, the insulating level of composite materials pole was vastly improved, whose lightning impulse voltage was increased by over 60 %, and creepage distance was increased by over 40 %. The application of insulation of composite materials poles in transmission lines is favorable for reducing the fault of transmission lines, such as windage yaw, pollution, icing flashover.