According to the principal of photoelectricity transform,the authors developed a k ind of photoelectricity leak detector for blast furance dust collection system of bag type.

This paper introduces a new Kind of Ultrasonic leak detector as well as itsworking principles, properties, Characteristics,experimental results and application prospects.

This paper makes a deep comparison between new and old standard instrument used to calibrate DC high-voltageand high-resistance box and reachs a conclusion that the new equipment (digital type high resistance calibrator) operation issimple and convenient , rapid , efficient , without the artificial regulation balancing of by hand, of working safely and reliable,considerably advanced and novel.