In physics, the glow and audible event occurring when an insulator is exposed to excessive voltages is called a corona. It may also be known in the electric industry as “corona discharge,” “plume discharge,” “brush discharge” or “glow discharge.”
Toughened glass bell insulators are easily identified through the application of color bands on the caps, signifying the most common strength class products.
When designing a high voltage transmission line utilizing toughened glass bell insulators, engineers must consider whether or not to specify a zinc sleeve to accompany the insulator pins. Although the upfront cost is slightly more than the forged steel pin, those who are new to the use of toughened glass bells may ask what justifies a slightly higher expense for the addition of this feature.