How does current flow to the ground in Delta connection (Ungrounded) in an Earth Fault?
In normal configurations a single fault on a delta system will not cause any significant earth fault current. This is useful because the distribution system can tolerate a single fault without interruption to the consumers.
This benefit is of little use if the system does not detect the first fault and fix it. As a result, earth fault detection relays will monitor the phase-earth voltage on each line. (This will create a very weak star (wye) point on the system.) When an earth fault is detected on one phase then that phase is deliberately shorted to earth. This can help make fallen wires less likely to electrocute someone. A contact of the relay will signal the fault which can then be investigated, cleared and reset.
If the first fault is not cleared then a second fault will result in high earth current and trip out the system.