介电耐压试验（也称为高电位、过电位、电压击穿或介电强度试验）包括在部件的相互绝缘部分之间或绝缘部分与接地之间的特定时间内施加高于额定电压的电压。这用于证明部件能够在其额定电压下安全运行，并能承受由于开关、浪涌和其他类似现象而产生的瞬时过电位。尽管该试验通常被称为电压击穿或介电强度试验，但其目的不是使该试验引起绝缘击穿或用于检测电晕，而是用于确定部件中的绝缘材料和间距是否足够。 当部件在这些方面出现故障时，施加试验电压将导致破坏性放电或劣化。破坏性放电表现为闪络（表面放电）、火花放电（空气放电）或击穿（击穿放电）。泄漏电流过大导致的劣化可能会改变电气参数或物理特性。

The dielectric withstanding voltage test (also called high-potential, over potential, voltage-breakdown, or dielectric-strength test) consists of the application of a voltage higher than rated voltage for a specific time between mutually insulated portions of a component part or between insulated portions and ground. This is used to prove that the component part can operate safely at its rated voltage and withstand momentary overpotentials due to switching, surges, and other similar phenomena. Although this test is often called a voltage breakdown or dielectric-strength test, it is not intended that this test cause insulation breakdown or that it be used for detecting corona, rather, it serves to determine whether insulating materials and spacing in the component part are adequate. When a component part is faulty in these respects, application of the test voltage will result in either disruptive discharge or deterioration. Disruptive discharge is evidenced by flashover (surface discharge), sparkover (air discharge), or breakdown (puncture discharge). Deterioration due to excessive leakage currents may change electrical parameters or physical characteristics.