Integrated Transformer Health Estimation Methodology Based on Markov Chains and Evidential Reasoning

Table 4

The evaluation grades for solid insulation.

Dielectric losses	Insulation state	Hn
tgδ ≤ 1%	Good condition	3
1% < tgδ ≤ 1.5%	Moderately good	2
1.5% < tgδ ≤ 2%	Moderately bad	1
tgδ > 2%	Poor	0