3 RESULTS
3.1 MORPHLOGY AND ELEMENTAL ANALYSIS OF
DEPOSITS ON INSULATING PAPER
Figure 2 shows the external appearance of the
insulating paper’s surfaces which were faced to the
copper strips, and the copper strips after the heating
tests. The copper strips turned black for all the heating
tests conditions. On the other hand, oxygen and DBPC
significantly influenced the black deposits formation on
the insulating papers. Especially, the effect of oxygen on
the deposits formation is clear when the oil contains
DBPC (oil B)