继电保护原理与应用(第三版)3.1-3.5(26)

Typical polarity indications for three commonly used directional-sensing units are shown in Figure 3.7. This uses the custom of showing several loops for voltage coils and a single loop for current coils, of placing the reference circuit or voltage circuit above the current circuit, and of placing the polarity markings diagonally, all as shown on the relay schematics in Figure 3.7.
三种常用方向感测装置的典型极性指示如图3.7所示。这使用了显示电压线圈的多个回路和电流线圈的单个回路的习惯，将参考电路或电压电路置于电流电路上方，并将极性标记对角放置，所有这些都如图3.7中继电器示意图所示。

FIGURE 3.7 Typical directional relay characteristics.
图3.7典型方向继电器特性。
The reference quantity is commonly called the ‘‘polarizing’’ quantity, especially for ground-fault relaying, where either current polarizing or voltage polarizing is used, or both. The polarity marks (Figure 3.7) are small plus symbols () placed, as illustrated, above one end of each coil, diagonally as shown, or on the opposite diagonal. As shown in Figure 3.5, relay operation is not affected whether the polarity marks are on one diagonal or the other.