Electric breakdown, also known as electrical breakdown or dielectric breakdown, refers to the phenomenon where an insulating material that is normally unable to conduct electricity suddenly becomes conductive due to the presence of a strong electric field. This breakdown can occur in various contexts, such as in gases, liquids, and solid materials. It typically involves the sudden and rapid increase in the flow of electric current through the material, leading to the breakdown of its insulating properties.
The electric breakdown can occur in different mediums as follows:
Gas Breakdown: In a gas, such as air, under normal conditions, the atoms and molecules are electrically neutral. However, when a sufficiently high electric field is applied across the gas, it can ionize the gas particles, creating positively charged ions (cations) and negatively charged ions (anions). This creates a conductive path through the gas, allowing electric current to flow. This is the principle behind phenomena like sparks, lightning, and corona discharges.
Liquid Breakdown: Similar to gases, liquids can also experience breakdown when subjected to high electric fields. In liquids, the breakdown usually involves the dissociation of molecules or the creation of ions, enabling the liquid to conduct electricity. This is seen in phenomena like electrical arcing in water or other liquids.
Solid Breakdown: In solids, breakdown can occur due to the accumulation of charge carriers, such as electrons or holes, in localized areas. These carriers can lead to the creation of conductive paths through the material, effectively reducing its insulating properties. This can happen in materials like insulating plastics or polymers when exposed to high electric fields.
The electric breakdown voltage, also known as the dielectric strength, is the minimum electric field required to initiate breakdown in a given material. This voltage depends on the nature of the material, its thickness, and the surrounding environment (such as pressure and temperature).
Electric breakdown is a significant consideration in electrical engineering, as it can lead to equipment failure, fires, and other hazards. Engineers design systems and components to withstand potential breakdown scenarios by selecting appropriate insulating materials, designing insulation structures, and ensuring that operating conditions remain within safe limits to prevent breakdown.