Dielectric Strength - What is dielectric strength?

Answer:

A property of insulating materials, which is defined as the maximum electrical field that the material can withstand under “ideal” conditions without breaking down (i.e. without its insulating properties failing and allowing a current to pass through the material). The dielectric strength of a material is usually expressed as volts per metre (V/m), although volts per centimetre (V/cm) and megavolts per metre (MV/m) may also be used.

Dielectric strength can be influenced by the thickness of the material, the “purity” of the material (i.e. the presence of any defects or other elements within the material), and temperature (along with other factors).