We have a 2.5MW DG in parallel with a 20MVA trafo. While paralleling the DG to the transformer, sometimes the DG is tripping on reverse power. The DG is located in a separate DG house located around 300m from the switchboard to which both the DG & the transformer are connected. The relay which synchronises the DG to the grid is located in the DG House. According to the commissioning engineer this is happening because of the time gap in the breaker closing - gap between the command and the actual breaker closing due to the distance. Is this possible? Will not the command issued by the relay(potential free)act instantaneously on the breaker closing coil.

 

First of all reverse power protection should be time delayed so time delay on close command may be not reason for tripping. Dg set should be came to spinning reserve load after syn. please check this.