测量继电器和保护装置. 第121部分: 距离保护的功能要求

[中文适用范围]： 本部分IEC 60255规定了通常在有效接地三相电力系统的线路应用中使用的距离保护功能的功能和性能评估的最低要求，但不限于此。本标准还定义了如何记录和实施性能测试。本标准的距离保护功能是指其运行特性可以在阻抗平面上定义的功能，包括保护功能、测量特性、相位选择、方向性、启动和时间延迟特性的规范。本标准包括验证性能特性和准确性的测试方法。标准定义了影响稳态条件下准确性的影响因素以及动态条件下的性能特性。它还包含了保护功能所需的互感器要求。本标准涵盖的距离保护功能包括：相间距离保护和接地（大地）距离保护。 [外文原描述]： IEC 60255-121:2014 specifies minimum requirements for functional and performance evaluation of distance protection function typically used in, but not limited to, line applications for effectively earthed, three-phase power systems. This standard also defines how to document and publish performance tests. This standard covers distance protection function whose operating characteristic can be defined on an impedance plane and includes specification of the protection function, measurement characteristics, phase selection, directionality, starting and time delay characteristics. The test methodologies for verifying performance characteristics and accuracy are included in this standard. The standard defines the influencing factors that affect the accuracy under steady state conditions and performance characteristics during dynamic conditions. It also includes the instrument transformer requirements for the protection function. The general requirements for measuring relays and protection equipment are defined in IEC 60255-1.