The Comparative Tracking Index (CTI) tester is an electrical testing device used to evaluate the electrical insulation properties and resistance of solid electrical insulating materials, such as plastics and polymers. It measures the ability of these materials to withstand surface tracking and electrical breakdown caused by the presence of moisture, contaminants, and voltage stress.
The CTI value is an important parameter in assessing the safety and reliability of materials used in electrical and electronic equipment. The test involves applying a voltage to two electrodes placed on the surface of a test specimen while subjecting it to a controlled environment of elevated temperature and humidity. The test measures the time it takes for tracking and breakdown to occur on the surface of the material. A higher CTI value indicates better resistance to electrical tracking.
This testing method helps manufacturers and engineers choose appropriate materials for specific applications where electrical insulation is crucial. It ensures that materials used in electrical devices and equipment can perform reliably in conditions where exposure to moisture and contaminants is likely.