Testing result

Aging state

Next detection time

tanδ ≤ 1.2 × 10−3

No aging

5 years later

1.2 × 10−3 ≤ tanδ ≤ 2.2 × 10−3

Slightly aging

1 year later

2.2 × 10−3 ≤ tanδ

Severly aging

Normally