JEF-300 jerin electromagnetic flowmeter ya ƙunshi firikwensin da mai canzawa.Ya dogara ne akan dokar Faraday na shigar da wutar lantarki, wanda ake amfani da shi don auna ƙarar kwararar ruwa mai ɗaukar nauyi tare da haɓakawa fiye da 5μs/cm.Mita ce ta inductive don auna ma'aunin ƙarar matsakaicin gudanarwa.