High-altitude　electromagnetic　pulse　(HEMP)　can　produce　Electromagnetic　interference　(EMI)　on　the　generator　system.　Without　a　precise　machine　model,　over-voltage　on　the　stator　winding　of　generator　cannot　be　accurately　evaluated,　and　this　is　a　new　challenge　for　the　design　of　nuclear　power　plant　generator　system.　Therefore,　the　paper　establishes　the　motor　model　by　considering　multi-conductor　transmission　line,　and　employs　this　model　to　design　a　set　of　precautions.　At　first,　the　expression　of　HEMP　and　coupling　channel　of　HEMP　are　performed　to　analyze　magnitude　and　waveform　of　over-voltage　caused　by　HEMP.　Then,　a　novel　stator　winding　model　is　developed　which　bases　on　the　analysis　for　multi-conductor　transmission　line.　This　model　is　computationally　efficient　and　the　voltage　of　winding　per　turn　under　HEMP　can　be　calculated　fast　and　accurately　via　it.　The　proposed　approach　can　be　validated　through　a　three-dimensional　electromagnetic　simulation　software.　Finally,　couple　of　precautions　are　derived　based　on　the　existing　lightning　protection　measures　and　the　above　analysis.　©　2020　IEEE.