Electrical breakdown or dielectric breakdown is when current flows through an electrical insulator when the voltage applied across it exceeds the breakdown voltage. This results in the insulator becoming electrically conductive.


What happens at breakdown voltage? The maximum reverse bias voltage that can be applied to a p-n diode is limited by breakdown. Breakdown is characterized by the rapid increase of the current under reverse bias. The corresponding applied voltage is referred to as the breakdown voltage. The breakdown voltage is a key parameter of power devices.

what is the meaning of breakdown voltage?

The breakdown voltage of an insulator is the minimum voltage that causes a portion of an insulator to become electrically conductive. For diodes, the breakdown voltage is the minimum reverse voltage that makes the diode conduct appreciably in reverse. Some devices (such as TRIACs) also have a forward breakdown voltage.

What is Zener breakdown voltage? A normal p-n junction diode allows electric current only in forward biased condition. This sudden rise in electric current causes a junction breakdown called zener or avalanche breakdown. The voltage at which zener breakdown occurs is called zener voltage and the sudden increase in current is called zener current.

how do you calculate breakdown voltage?

Measuring breakdown voltage is done by applying an increasing reverse voltage to the device until a certain test current is reached that indicates that the device is in breakdown.

How does Zener breakdown occur? The Zener effect is a type of electrical breakdown that occurs in a reverse-biased PN junction when the electric field enables tunnelling of electrons from the valence to the conduction band of a semiconductor, leading to a large number of free minority carriers which suddenly increase the reverse current.

at what voltage does air break down?

30 kV/m

What is the cause of reverse breakdown voltage? Zener breakdown If reverse voltage is applied on the narrow depletion p-n junction diode, the immobile ions in the depletion region gains energy from the external voltage. Hence, the electric field of the immobile ions increases. At this point, a small increase in reverse voltage causes sudden rise in reverse current.

What is breakdown voltage in pn junction?

Breakdown voltage of a PN junction is the maximum reverse Bias Voltage that can be applied to eat after which there is no change in the voltage.

What is reverse voltage? The reverse voltage is the voltage drop across the diode if the voltage at the cathode is more positive than the voltage at the anode (if you connect + to the cathode). This is usually much higher than the forward voltage. As with forward voltage, a current will flow if the connected voltage exceeds this value.

Is water a good dielectric?

Pure water is a non polar dielectric. But they are not at rest and can't induce charges to produce electric field like a solid dielectric. The motion of water molecules varies the capacity of a capacitance constantly. Therefore water can't be used as dielectric in a capacitor.

How many volts does it take to Arc 1 inch?

Short answer: it takes about 30,000 volts per centimeter, or about 75,000 volts per inch, to jump a clear air gap. Once the gap is ionized, the sustaining voltage is less. That's in normal air, at normal temperature, humidity and air pressure, with nothing else near the gap.

What is meant by avalanche breakdown?

Avalanche breakdown is a phenomenon that can occur in both insulating and semiconducting materials. It is a form of electric current multiplication that can allow very large currents within materials which are otherwise good insulators. It is a type of electron avalanche.

What is breakdown and its types?

Zener Breakdown and Avalanche Breakdown. The Avalanche Breakdown and Zener Breakdown are two different mechanisms by which a PN junction breaks. The avalanche breakdown occurs because of the ionisation of electrons and hole pairs whereas the Zener diode occurs because of heavy doping.

What is the breakdown voltage of silicon?

There actually are simple Silicon diodes have a forward biased voltage of approximately 0.7 volts. The maximum reverse-bias voltage that a diode can withstand without “breaking down” is called the Peak Inverse Voltage, or PIV rating.

Is glass a dielectric?

In practice, most dielectric materials are solid. Examples include porcelain (ceramic), mica, glass, plastics, and the oxides of various metals. Some liquids and gases can serve as good dielectric materials. Dry air is an excellent dielectric, and is used in variable capacitors and some types of transmission lines.

Which material has highest dielectric strength?

So what material has the highest Dielectric Strength? It might surprise you to know that a perfect vacuum is actually the best electrical insulator. A perfect vacuum has the highest dielectric strength, rated at 1×1012 MV/m.

What is the value of dielectric strength for air?

The dielectric strength of air is approximately 3 kV/mm. Its exact value varies with the shape and size of the electrodes and increases with the pressure of the air.

Is air an insulating medium?

Conditions for Dielectric or Insulation Failure For example, Table AI of IEC 664 gives voltage withstand values for various distances through air (an insulating medium). We find that air has an electric strength of about 1000 volts/mm for distances up to about 1 mm, decreasing to about 500 volts/mm at 10 mm.