Table 1.

Composition of two used transformer oil samples from different substations of the Italian Transmission System Operator.

Chemical Agent	Method	Unit	CT.134	CT.729
Total gas concentration	IEC 60567	μL/L	78,579	65,611
Furfural (2-FAL)	IEC 61189	ppm	0.112	0.114
Σ furan derivatives		ppm	<0.010	<0.010
Methanol		ppm	0.567	0.408
Ethanol		ppm	0.306	0.250