A 1895, Jamus Overtone ya samar da farko a duniyaDC lantarki rawar soja.An yi harsashi da baƙin ƙarfe na siminti kuma yana iya haƙa ramukan 4mm a cikin farantin karfe.Daga baya, mitar wutar lantarki mai hawa uku (50Hz) ta bayyana, amma saurin motar ya kasa wuce 3000r/min.A cikin 1914, kayan aikin lantarki waɗanda ke tafiyar da injunan jeri guda ɗaya sun bayyana, kuma saurin motar ya kai fiye da 10000r/min.A cikin 1927, kayan aikin lantarki na tsaka-tsaki tare da mitar wutar lantarki na 150 zuwa 200 Hz ya bayyana.Ba wai kawai yana da fa'idar babban saurin saurin jerin motoci guda-ɗaya ba, har ma yana da fa'idodin injin mitar wutar lantarki mai sauƙi da aminci mai ƙarfi uku.Koyaya, yana buƙatar kawota tare da mitar halin yanzu., An iyakance amfani.