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How to Evaluate Dielectric Strength Under Vibration

Dielectric material stores electrical energy. Two parallel metal plates, for example, when they̵7;re connected to a battery, will store electrical charge ̵2; storing electrical energy. Take those same metal plates, and put a dielectric material between them, and the amount of energy stored between the plates goes up. The energy goes up because the atoms within the dielectric are distorted, distorted in a reversible way that can release energy. But if the electric field gets too strong, the atoms get so distorted they ̶0;break down,̶1; letting sparks cross between the plates. The electric field at which they break down is called the dielectric strength.

Things You'll Need

Parallel metal plates
Dielectric material to fit between the plates
Charging circuit
Ammeter
Vibration fixture
Vibration table

Instructions

- 1
  Measure the dielectric thickness. Insert the dielectric material between the parallel plates. Make sure the plates are held right against the dielectric.
- 2
  Connect the parallel plates to the charging circuit and ammeter. Monitor the current as the voltage is increased. The current will increase linearly as the voltage increases, until breakdown is reached, when the current will spike as a spark jumps the gap between the plates.
- 3
  Calculate the dielectric strength with the equation: breakdown voltage / dielectric thickness.
- 4
  Remove the dielectric from between the plates, and replace it with another identical dielectric. Measure the thickness and ensure the plates are held against the dielectric.
- 5
  Mount the parallel plates in a vibration fixture and attach the vibration fixture to the vibration table. The vibration fixture will hold the capacitor so that the vibration gets transmitted to the parallel plates without letting them come apart.
- 6
  Repeat Steps 2 and 3 at a specific level of vibration.
- 7
  Repeat Step 6 as many times as desired to characterize the changes in dielectric strength as the vibration level increases.

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