Due to limited ability of arc extinction of parallel gaps have very

steady power frequency following current can arise easily when parallel gaps are broken down by lightning

which will increase lightning trip-out rate and limit parallel gaps’ application. Clearly

it is of great significance to improve the arc-quenching ability of parallel gaps. Multi-segment microhole structure has excellent arc-quenching performance. It is widely believed that applying the structure to parallel gaps can significantly improve the arc-quenching ability of parallel gaps. Hence

a two-dimensional magneto-hydrodynamics（MHD） model of arc in multi-segment microhole structure is established in the COMSOL Multiphysics software. Also

the arc movement characteristics of arc extinguishing structure and arcing mechanism are simulated. Simulation results indicate that the arc MHD model can well describe the arc movement in arc extinguishing structure. When the amplitudes of short circuit arc current are 1 k A

2 k A

and 5 k A

the amplitude of airflow velocity through the micromoles can reach 520 m/s

813 m/s and 1 027 m/s

respectively. That is

the higher the current is

the more significant the air’s heated effect will be. Therefore

the speed of airflow after air’s heat expansion becomes faster. The speed of airflow in multi-segment microhole structure

which is needed to extinguish the arc

can be reached within 1 ms.