Reliability of relay protection and automatics algorithms for intermittent ground faults in 6–35 kV networks

Intermittent arc faults make about 60% out of all earth faults in 6–35 kV grids [1]. Modern relay-protection and automatics devices not always able to process properly current, voltage signals, and to ensure reliable operation in all possible situations (inadequate reaction of protection algorithms, errors in their functioning) due to specific features of this fault, such as: short period of existence, about dozens of milliseconds [1], high-frequency transient processes, nonconstant equivalent resistance.