以前是S71。02-1991. 建立过程测量和控制设备电源的统一分类，为用户和制造商提供指定测量或控制系统可能连接的电力系统的电气或气动参数的方法。不打算用作安全布线实践手册。

Formerly S71.02-1991. Establishes uniform classifications of power supplied to process measurement and control equipment, providing users and manufacturers with a means of specifying the electrical or pneumatic parameters of a power system to which a specified measurement or control system may be connected. Not intended to serve as a safe wiring practices manual.