13.8 kV selective high-resistance grounding system for a geothermal generating plant — A case study

13.8 kV selective high resistance grounding systems for bus connected generators are non-existent due to two reasons: One, the stray capacitance current of the system can be high, (>10–12A); second the sensitivity and selectivity of the ground fault devices to detect low-levels of ground fault currents is required. The paper describes the relay types, sensors, settings on protective relays, flow of currents for various fault locations in a 13.8 kV system and demonstrates how a selective HRG has been implemented. To the author's knowledge, there is no HRG selective system at 13.8 kV.