News Release

Headline what is Comparative Tracking Index (CTI)

CTI is used to measure the electrical breakdown (tracking) properties of an insulating material.Tracking is an electrical breakdown on the surface of an insulating material wherein an initial exposure to heat chars the material,and the char is more conductive than the original insulator, producing more current flow, more heat, and eventually complete failure.

The CTI value is used for electrical safety assessment of electrical apparatus, as for instance carried out by Underwriters Laboratory in USA and many other laboratories in the world. The minimum required creepage distances over an insulating material between electrically conducting parts in apparatus, especially between parts with a high voltage and parts that can be touched by human users, is dependent on the insulator's CTI value. Also for internal distances in an apparatus by maintaining CTI based distances, the risk of fire is reduced.

Material: XPC, FR-1 (CTI≤150) ; CEM-1, CEM-3, FR4 (CTI: 175~225)



Reference: https://en.wikipedia.org/wiki/Comparative_Tracking_Index