In physics, the term dielectric strength has the following meanings:
- Of an insulating material, the maximum electric field strength that it can withstand intrinsically without breaking down, i. Physics (Greek Physis - φύσις in everyday terms is the Science of Matter and its motion. In Physics, the field strength of a field is the magnitude of its vector value e. , without experiencing failure of its insulating properties. Failure ( fail, phail or flop) in general refers to the state or Condition of not meeting a desirable or intended objective
- For a given configuration of dielectric material and electrodes, the minimum electric field that produces breakdown. In Physics, the space surrounding an Electric charge or in the presence of a time-varying Magnetic field has a property called an electric field (that can
The theoretical dielectric strength of a material is an intrinsic property of the bulk material and is dependent on the configuration of the material or the electrodes with which the field is applied. A dielectric is a nonconducting substance ie an insulator. The term was coined by William Whewell in response to a request from Michael Faraday. At breakdown, the electric field frees bound electrons. If the applied electric field is sufficiently high, free electrons may become accelerated to velocities that can liberate additional electrons during collisions with neutral atoms or molecules in a process called avalanche breakdown. Avalanche breakdown is a phenomenon that can occur in both insulating and semiconducting materials Breakdown occurs quite abruptly (typically in nanoseconds). The second ( SI symbol s) sometimes abbreviated sec, is the name of a unit of Time, and is the International System of Units , resulting in the formation of an electrically conductive path and a disruptive discharge through the material. The term electrical breakdown has several similar but distinctly different meanings For solid materials, a breakdown event severely degrades, or even destroys, its insulating capability.
Breakdown field strength
The field strength at which breakdown occurs in a given case is dependent on the respective geometries of the dielectric (insulator) and the electrodes with which the electric field is applied, as well as the rate of increase at which the electric field is applied. In Physics, the space surrounding an Electric charge or in the presence of a time-varying Magnetic field has a property called an electric field (that can Because dielectric materials usually contain minute defects, the practical dielectric strength will be a fraction of the intrinsic dielectric strength seen for ideal, defect free, material. Dielectric films tend to exhibit greater dielectric strength than thicker samples of the same material. For instance, dielectric strength of silicon dioxide films of a few hundred nm to a few micrometres thick is approximately 10 MV/cm. Multiple layers of thin dielectric films are used where maximum practical dielectric strength is required, such as high voltage capacitors and pulse transformers. A capacitor is a passive electrical component that can store Energy in the Electric field between a pair of conductors A transformer is a device that transfers Electrical energy from one circuit to another through inductively coupled Electrical conductors
Dielectric strength (MV/m) of various common materials:
| Substance | Dielectric Strength (MV/m) |
|---|---|
| Air | 3 |
| Quartz | 8 |
| Strontium titanate | 8 |
| Neoprene rubber | 12 |
| Nylon | 14 |
| Pyrex glass | 14 |
| Silicone oil | 15 |
| Paper | 16 |
| Bakelite | 24 |
| Polystyrene | 24 |
| Teflon | 60 |
See also
External links
- Dielectric Strength and Insulation Materials of Mineral Insulated Cable
- Article "The maximum dielectric strength of thin silicon oxide films" from IEEE Transactions on Electron Devices
- Properties of silicon dioxide and silicon nitride, from semiconductorglossary.com
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