©　2017　IEEE.　The　objective　of　this　paper　is　to　determine　minimum　arcing　interruption　performance　of　a　126　kV　single-break　vacuum　circuit　breaker　with　3/4　coil-type　axial　magnetic　field　(AMF)　contacts.　The　full　contact　gap　was　50　mm.　A　spring　type　mechanism　was　used　to　provide　an　average　opening　velocity　of　3.0　m/s　within　20　mm　after　contacts　separation.　Test　duty　T100s　experiment　with　a　rated　short　circuit　current　of　40　kA　rms　was　carried　out　by　using　current　injection　synthetic　test　method.　The　experiment　results　showed　that　the　minimum　arcing　time　was　determined　as　4.8　ms.　The　corresponding　minimum　arcing　contact　gap　was　determined　as　14.4　mm.　Further　analyses　indicated　that　with　increasing　of　contact　gap　from　11.7　to　25.8　mm　in　the　experiment,　phase　shift　time　decreased　from　0.84　to　0.63　ms.　While　residual　axial　magnetic　flux　density　at　current　zero　decreased　from　153.25　to　89.97　mT.　Phase　shift　time　and　residual　axial　magnetic　field　of　126　kV　single-break　vacuum　circuit　breaker　at　minimum　arcing　contact　gap　were　0.77　ms　and　136.22　mT,　respectively.