Insulators are one of the few components in power systems that find themselves continually exposed to a full spectrum of possible service stresses that together or even individually can cause failure. These stresses include: high electric field, pollution, wetting events, corona, temperature variation, mechanical shock, interaction with birds and other wildlife, wind, solar radiation, oil leaks, lightning and switching impulses, biological growth, vibration and vandalism. If you factor in the risk that the insulator becomes defective during manufacture, has been damaged during handling or installation or was improperly specified for its service environment, today’s low failure rate for insulators is truly an accomplishment. Indeed, the reliability and durability of modern insulators speaks to how well engineered and manufactured most of them now are.
Still, a lot can go wrong and, given their huge population on power networks, even low failure rate is no guarantee that there will not be serious problems. And, whenever something bad happens to an insulator, there will invariably be reliability and cost consequences.
Keeping words to a minimum, these images depict examples of what can go wrong with insulators and why they are so deserving of careful selection and scrutiny.