GF Current Coordination of a HRG System

[Kiribanda]

During NGR sizing we estimate the total capacitance current and we set NGR current rating slightly above the estimated system total charging current.
During feeder GF settings what is the industry practiced percentage that the feeder GF setting should have above its own feeder charging current?

 

[dpc]

If the feeder is part of an HRG system, there's generally no attempt to selectively coordinate based on current and GF settings on feeders are really only useful in the unlikely event of a resistor failure. If the feeder is part of a LRG or solidly-grounded system, I've never heard of anyone worrying about the feeder charging current since the setting are generally going to be quite a bit higher than the charging current. Sizing of the NGR to match the capacitive current is a compromise to limit the maximum overvoltage to a reasonable value of maybe 200%. Protection of HRG systems has traditionally used neutral overvoltage (59G) protection rather than current.