To be clear about the use of terms, a "ground fault" is a connection between a hot conductor and planet Earth. If you didn't have one before you paralleled the generators, then you didn't have one afterwards either. Something else is happening. What are the symptoms? Does the alarm system report a ground fault? Do the breakers simply trip? I gather that this has caused some equipment or component failures, but I do not know what components you are talking about. Can you explain?
Is it possible that there is something going wrong in the paralleling equipment? Perhaps an out-of-synchronization closure? Are the generators wired the same way (no differences in phase rotation, grounding, connections)? Is the oncoming generator properly prepared for the paralleling operation (i.e., running at a very slightly higher speed and with a slightly higher voltage than the on-line machine)?
