Abstract: Abstract: Insulation partition is an important part of high voltage switchgear. An experimental setup was developed to simulate the high-voltage arc and material ignition. Ignition experiments were carried out for SMC insulation separator with thickness of 5mm and 10 mm. The change rules of mass loss rate, residual flame time, temperature curve with arc duration were studied. The results show that under the high voltage, the two electrodes first form an inverted U-shaped clamping heating arc around the SMC vertical plate. The ablation process of SMC samples under the continuous arc can be divided into four stages: arc rising, clamping ignition, side arc falling and remaining burning. The residual flame of 10 mm sample is produced later, and need longer time to form significant self sustaining combustion and the carbonization ablation degree is lower. It illustrates that thicker SMC insulation partition is better for the integrity of partition structure and fire resistance. The surface temperature curves of different areas of the sample also indicate the heating intensity of the arc root on the surface of the sample is weaker. Namely, the temperature rise of the sample surface is affected by both of the arc column distance and the self-sustaining flame. It contains multiple mutually influencing heat process. The results can be used for the scientific selection and optimal layout of insulation diaphragms of high-voltage switchgear, and provide scientific support for improving the fire safety performance of switchgear.

Key words: Key words: high-voltage switchgear, SMC, insulating partition, electric arc, ignition mechanism