An Intelligent Line Selection Instrument Of Single Phase To Ground In Small Current Neutral Grounding System

This paper studies with an emphasis on " S Injection Method and relative detection" , a principle for selection and position of faulty line, by which the single-phase to ground fault on the overhead line system with small current neutral grounding and CT on two phases can be detected. The paper also introduces the study on the general purposed device for single-phase to ground fault line selection and positioning protection on a small current neutral grounding system based on this principle. This device is a Distributed Controlled System composed with MCS-51 serial micro-controller and RS-485 communication standard, It has system clock and E2PROM, and it also has very kind user interface. This device can run automatic with high reliability. It has made the CT on two phases system more perfect which has been used more than 40 years.