Fault　arc　detection　is　an　important　technology　to　ensure　the　safe　operation　of　electrical　equipment　and　prevent　electrical　fires.　The　high-frequency　noise　of　the　arc　current　is　one　of　the　typical　arc　characteristics　of　almost　all　loads.　In　order　to　accurately　detect　arc　faults　in　a　low-voltage　alternating-current　(AC)　system,　a　novel　differential　high-frequency　current　transformer　(D-HFCT)　sensor　for　collecting　high-frequency　arc　currents　was　proposed.　The　sensitivity　and　frequency　band　of　the　designed　sensor　were　verified　to　ensure　that　the　acquisition　requirements　of　the　high-frequency　current　were　satisfied.　A　series　arc　fault　simulation　experiment　system　was　built,　and　resistive,　inductive,　and　non-linear　load　and　high-power　shielding　load　experiments　were　carried　out.　Experiments　showed　that　the　sensor　output　signal　was　close　to　zero　in　the　non-arc　state,　and　the　sensor　output　response　was　a　high-frequency　glitch　in　the　arc　state.　The　results　were　consistent　for　different　loads,　and　the　discrimination　between　normal　and　fault　states　was　obvious,　which　proved　that　the　sensor　is　suitable　for　series　arc　fault　detection.　©　2019　by　the　authors.　Licensee　MDPI,　Basel,　Switzerland.