This paper discusses the ability of avoiding maximal power flow of quadrilateral impedance relay and round impedance relay in detail and puts forward the setting principle and setting method of load limiting resistor of backup distance protection 本文对四边形和方向圆特性阻抗继电器躲线路最大潮流的能力进行了详细分析，提出了距离保护负荷限制电阻的整定原则和整定方法。
