在正常工作条件下，保护层保护器的性能表现为高电阻。流过保护层保护器的电流为毫安级，不会影响电缆保护层的运行方式。当过电压侵入时，不接地端的护套或护套交叉换位互联处会有较高的冲击过电压。此时，护套保护器呈现较小的电阻，使过电压能量很容易通过保护器流入大地，同时保护器本身不应受到损坏，接地端应恢复高电阻状态。
Under normal working conditions, the performance of protective layer protector is high resistance. The current flowing through the protective layer protector is in milliampere level, which will not affect the operation mode of the cable protective layer. When the overvoltage intrudes, there will be a higher impulse overvoltage at the sheath or sheath cross-position interconnection of the ungrounded end. At this time, the sheath protector presents a smaller resistance, so that the overvoltage energy can easily flow into the earth through the protector, while the protector itself should not be damaged, and the grounding terminal should restore the high resistance state.
由非线性电阻元件即阀板组成的屏蔽保护器，对波头较陡的瞬时过电压有较好的保护效果，在额定工况下不会频繁损坏。但由于其热容量有限，在运行过程中有时会烧坏元件，因此提高阀片的通流能力是避免元件热损坏的关键。低温煅烧阀门在运行中容易受潮，导致残余压力增大，残余劳动比增大，流量减小。
The shielding protector composed of non-linear resistance elements, i.e. valve plates, has better protection effect on the instantaneous overvoltage with steeper wave head, and will not be damaged frequently under rated working conditions. However, due to its limited heat capacity, components are sometimes burnt out during operation. Therefore, improving the flow capacity of valve plates is the key to avoid thermal damage of components. Low-temperature calcined valves are easy to be damped in operation, which results in the increase of residual pressure, the increase of residual labor ratio and the decrease of flow rate.