Ultrasonic Inspection: Electrical

Types of Electrical Problems

• Tracking - Strong electric fields can induce a breakdown of surface material. The degradation of the surface material is called tracking. It is caused by dust, moisture, or other contaminants in the air, which produce areas of differing resistivities.
• Corona Discharge - When corona tracking is not found and corrected, it can lead to a buildup of leakage paths that may result in a line-to-line or line-to-ground flashover called corona discharge. Corona is luminous and sometimes audible. The electric discharge is caused by the ionization of molecules surrounding high-voltage conductors. Ozone and nitrogen oxides are produced, which then cause deterioration of the organic materials used in insulation. It can also cause radio and communication interference.
• Arcing - A form of tracking, arcing is caused by an electric field and a conductive path from one point to another. Discharges between the points can cause erosion of the circuits, undesirable welding of components, and even fires (From 1991 to 1995 commercial properties incurred over $249 million in direct damage resulting from electrical fires¹). The difference between arcing and corona is that arcing starts at one voltage and stops when the voltage reaches 50%. Corona starts at one voltage and stops at the same voltage.

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