That 160 MVA unit has located far of consumer center (100 km) and one long overhead transmission line transferred produced power to test loads. In starting stage, they run up generator and connected it to no load bus. They want to study the generator behavior against load variation from zero to full load in many steps. But in first stage, while they closed generator circuit breaker for supplying of first load step, they front of generator trip due to related reverse power relay operation.
How can you explain the reason of that protection system mal-operation?