根据IEC 61226规定，在正常电源运行和关机期间，测试执行A类、B类和C类功能的仪控系统的原则，以检查功能可用性，尤其是在检测可能妨碍安全重要功能正常运行的故障方面。涵盖短时间间隔测试或连续监测的可能性，以及更长时间间隔的定期测试。它还为测试设备及其与安全重要系统的接口的设计和应用建立了基本规则。与前一版相比，主要变化包括将范围扩大到对安全重要的所有系统，以及对执行a类、B类和C类功能的系统和设备的要求分级。

Lays down principles for testing I&C systems performing category A, B and C functions, per IEC 61226, during normal power operation and shutdown, so as to check the functional availability especially with regard to the detection of faults that could prevent the proper operation of the functions important to safety. Covers the possibility of testing at short intervals or continuous surveillance, as well as periodic testing at longer intervals. It also establishes basic rules for the design and application of the test equipment and its interface with the systems important to safety. The main change with respect to the previous edition includes an extension of the scope to cover all systems important to safety, and a requirement gradation for systems and equipment performing category A, B and C functions.