scope:

The dielectric withstanding voltage test (also called high-potential, over potential or voltage breakdown test) consists of the application of a voltage higher than rated voltage for a specific time between mutually isolated portions of a PWB or between isolated portions and ground. This is used to prove that the PWB can operate safely at its rated voltage and withstand momentary over potentials due to switching, surges, and other similar phenomena. Although this test is often called a voltage breakdown test, it is not intended that this test cause insulation breakdown or to be used for detecting corona. Rather, it serves to determine whether insulating materials and/or conductor spacings are adequate.