Coupling
Coupling
Under normal circumstances, the capacitance to ground of transformers and wire will attempt to keep the phase voltages relatively the same in reference to ground/earth. It would be normal to use 5kV conductors on this system so that an unintentional ground will not exceed the conductor rating. However, ungrounded systems of this type are subject to arcing faults because of the leakage current through system capacitance. Such arcing faults, if the current is high enough, will lead to cable damage and fires. It is good practice, to provide some kind of ground detection (not the same as ground fault). There are many commercially available systems that monitor the resistance to ground of the conductors and set alarms if resistance is low, indicating an insulation failure. There is no requirement to ground these systems using corner (IEEE recommends against) or impedance (grounding transformer) systems. Also, if there are surge arresters on the 2500V system, make sure they are rated to handle the line-line voltage continuously.