Generally, DGA results alert to possible arcing/sparking or low/high temperature overheating. So typically, the problem is current related.
However, an increase in hydrogen in the oil may point to corona discharge which may be related to the higher voltage.
In this case the insulation of the...
PDS68,
I am no expert but certainly, there are no quick answers to this question.
A proper analysis must first be done on the root cause of the motor failure/s. (Root cause and contributory cause to clearly established). Insulation punch through will indicate problems with voltage spikes...