Arrester Aging

There are two types of aging that can occur in arresters. Both are forms of long term degradation.

• Disk Aging: This is a slow change in the electrical characteristic of the ZnO varistor due to electrical stress over time. If this does occur, the loss's of the disk and arrester may increase to a point where the arrester could fail due to excess heating and thermal runaway of the disks.
• Shed Aging: This is a slow change in the physical characteristics of the weather sheds that can lead to external flashover or puncture. If puncture occurs the arrester may fail internally due to ingress of moisture of contamination.