继电保护原理与应用(第三版)3.1-3.5(27)

参考量通常称为“极化”量，特别是对于接地故障继电器，其中使用电流极化或电压极化，或两者兼有。极性标记（图3.7）为小加号（），如图所示，位于每个线圈一端上方，如图所示为对角线，或位于相反的对角线上。如图3.5所示，无论极性标记在一条对角线上还是在另一条对角线上，继电器的运行都不受影响。
The meaning of the polarity for a specific relay must be stated clearly in words or by a diagram, such as the one shown in Figure 3.7. These show the basic design characteristics of an individual relay, independent of any connection or association with the power system. The terms maximum-torque line and zero-torque line come from the electromechanical designs long used and still common in the industry. With solid-state designs, these would be the operating lines or thresholds, but the well-established terminology no doubt will continue for many years for all types of designs.
必须用文字或图表（如图3.7所示）明确说明特定继电器极性的含义。这些显示了独立于电力系统的任何连接或关联的单个继电器的基本设计特征。最大转矩线和零转矩线这两个术语来源于机电设计，这两个设计在工业中已经使用了很长时间，并且仍然很常见。对于固态设计，这些将是操作线或阈值，但对于所有类型的设计，公认的术语无疑将持续多年。
The interpretation ofrelay polarity isillustrated in Figure 3.7 for three typical electromechanical units. Solid-state units can have adjustments for (1) the maximum-torque angle and (2) the angle limits of the operate zone, but the application and operation is the same for both types. In Figure 3.7a, the maximum-operating torque or energy occurs when the current flows from polarity to nonpolarity (Ipq) and leads by 308 the voltage drop from polarity to nonpolarity (Vrs). The minimum pickup of the directional unit is specified as the maximum-torque or operating condition. As seen, the unit will operate for currents from almost 608 lagging the reference voltage Vrs to almost 1208 leading. The operate (trip, contact close) zone or area is represented by the half plane, bordered on one side by the zero-torque (nonoperating) line and extending in the direction that contains both the reference (polarizing) and operating quantities. Higher-current values will be required when Ipq deviates from the maximum-torque line. The solid-state relays can adjust this torque line for increased sensitivity by adjusting it to the fault line. The operating torque at any angle is a function of the cosine of the angle between the current (Ipq) and the maximum-torque line, as well as the magnitudes of the operating quantities.