Normally the neutral of the 120/240 leg is grounded.
A ground fault detection system is not used with a solidly grounded system.
If you use a high resistance ground on the neutral, you must use a ground detector which can accept 120 volts, 120 volts and 208 volts as normal inputs, or monitor the grounding resistor voltage or current.
If the neutral is not used, a delta type ground detector may be used.
The code may require the neutral point to be solidly grounded.
respectfully
