When a dielectric is applied with electrical field strength, it surpasses a critical value, and a large current flows through it. The dielectric loses its insulating property and starts conducting. This is called dielectric breakdown. Basically, it’s an insulating material’s failure to prevent the flow of current under applied electrical stress. The breakdown voltage is the point at which this failure takes place. The electrical field strength at which the dielectric breakdown happens is called dielectric strength.The types of breakdown mechanisms are intrinsic breakdown, chemical, and electrochemical breakdown, defect breakdown, discharge break down, thermal breakdown, and avalanche breakdown.