What is Dielectric breakdown: Definition and 18 Discussions

Electrical breakdown or dielectric breakdown is a process that occurs when an electrical insulating material, subjected to a high enough voltage, suddenly becomes an electrical conductor and electric current flows through it. All insulating materials undergo breakdown when the electric field caused by an applied voltage exceeds the material's dielectric strength. The voltage at which a given insulating object becomes conductive is called its breakdown voltage and depends on its size and shape. Under sufficient electrical potential, electrical breakdown can occur within solids, liquids, gases or vacuum. However, the specific breakdown mechanisms are different for each kind of dielectric medium.
Electrical breakdown may be a momentary event (as in an electrostatic discharge), or may lead to a continuous electric arc if protective devices fail to interrupt the current in a power circuit. In this case electrical breakdown can cause catastrophic failure of electrical equipment, and fire hazards.

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  1. ilovepudding

    I Dielectric breakdown voltage of air vs. Electric field in thunderstorm

    The dielectric strength of air (ie the maximum electric field that the material can withstand under ideal conditions without undergoing electrical breakdown and becoming electrically conductive) is 3 000 kV ( https://en.wikipedia.org/wiki/Dielectric_strength#Break_down_field_strength ). In...
  2. J

    Derivation of the equation for HV Gaseous Breakdown?

    Hello, I am solving a dielectric materials assignment to derive the equation for the growth of current in a gap stressed with the high electric field. The equation is as follows: The equation combines the anode, cathode and attachment process as shown below: I have derived the two equations...
  3. J

    How to Derive the Equation for HV Gaseous Breakdown?

    Hello, I am solving a dielectric materials assignment to derive the equation for the growth of current in a gap stressed with the high electric field. The equation is as follows: The equation combines the anode, cathode and attachment process as shown below: I have searched the following...
  4. Marcus95

    Power Transmitted in a Coaxial Cable

    Homework Statement A coaxial transmission line consists of an inner cylindrical conductor of radius a = 1 mm and a cylindrical outer conductor chosen to make the characteristic impedance 75 ohm. The space between the conductors is lled with a gas which can stand a maximum eld of 105 V/m without...
  5. B

    Does dielectric breakdown have a physical indication?

    I have a capacitor which I would like to know if the dielectric has undergone dielectric breakdown. Is there anyway I can tell without specialist equipment, is there physical damage to the material that I can see with the naked eye? The material is quartz. Thanks.
  6. T

    Dielectric breakdown with insulating electrodes

    Consider this stack of materials: metal - dielectric - air - dielectric - metal Assume that air has a lower breakdown field than the dielectric. As the voltage (DC) on the metal electrodes increases the field inside the air gap increases and eventually reaches breakdown causing it to become...
  7. J

    Electrostatic discharge without dielectric breakdown?

    I saw an experiment the other day, where a van de graaf generator charges up this big smooth chrome sphere. There is a "wand" with a much smaller sphere nearby that's grounded, and periodically a spark can be heard and seen when the big sphere dischrages to the wand, which corresponds to...
  8. F

    Estimate the Dielectric Breakdown of Air

    Homework Statement A capacitor is charged to V = 5 kV. A wire is then connected to one plate and is slowly connected to the other. Before actually touching the plate, a spark of length l = 1 cm shoots from the wire to the plate. Using this information, estimate the dielectric breakdown of air...
  9. N

    Strong electric field and dielectric breakdown

    Say you had two needles sticking out of an insulator in an air-filled chamber covered by an aluminum foil cup. The needles are charged to a high enough electric field to cause dielectric breakdown of air. Will a spark go from needle to needle? Or will the needles cause an induced negative charge...
  10. I

    Why is dielectric breakdown damaging?

    Dielectric break down... i understand that there is current passing through the insulator but why is this damaging to the insulator? please go as deep as you can. thankyou
  11. C

    Do magnetic fields have any effect on dielectric breakdown

    Would a magnetic field have any effect on the dielectric breakdown of insulators? For example, the dielectric breakdown of air is 3 Mega volts per meter at a gap of one meter; if you applied a magnetic field to that breakdown, would it help guide the electrons along the path and therefore reduce...
  12. jaumzaum

    Difference between Corona Discharge and Dielectric Breakdown?

    What's the difference between Corona Discharge and Dielectric Breakdown? For me both stand for the same process, but wikipedia (as many other sites) says they are different. Actually they say corona discharge occurs when the electric gradient is high but not enough to create an electrical...
  13. D

    Dielectric Breakdown and Capacitance

    If a capacitor's dielectric partially breaks down, as in some of the material has ionized and acted as a conductor, will there still be a capacitance to the component? Say its a high frequency AC signal on a capacitor with a small part of its dielectric material in a breakdown state. My...
  14. M

    Maximum Voltage without causing Dielectric Breakdown?

    1. What plate area is required if an air-filled, parallel-plate capacitor with a plate separation of 2.3 mm is to have a capacitance of 24 pF? Which I found correctly to be 6.2 x 10^-3 m^2 by using the formula C= k(8.85x10^-12)A/d What is the maximum voltage that can be applied to this...
  15. T

    Calculating Dielectric Breakdown Voltage & Effects of Electrode Material

    I have another question. Let us assume we have some dielectric oil and two electrodes (submerged into dielectric oil) connected to positive and negative of a voltage source. The system shall have some breakdown voltage , how can I calculate that? Any link available to get the formula...
  16. H

    Energy Stored leading to Dielectric breakdown

    Homework Statement A cavity can only store 1J of EM energy as it reaches dielectric breakdown at 3kV/mm. What dielectric strength would a new gas filling the cavity have if the energy stored was to be 4J. Homework Equations U=\frac{1}{2}(epsilon)E2The Attempt at a Solution I would use the...
  17. B

    Max Voltage Cylindrical Capacitor w/Dielectric

    Homework Statement Hello: I am asked to find the maximum voltage in a cylindrical capacitor. The capacitor consists of an inner wire and an outer cylindrical shell. The wire has radius r_{1} and the cylinder has inner radius r_{2}. The space between the wires is filled with a dielectric...
  18. S

    How can I simulate dielectric breakdown?

    Are there any programs around which will do this? I initially thought of Sonnet, but after some thought, I began to doubt that it would model dielectric breakdown. Any ideas at all? I've searched the web, and I can find some electrical (spice) models for it, but nothing geometric. Thanks...
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