在自动化工业过程时，工程师定义过程因素压力、温度等的范围，过程在这些范围内正常运行。如果过程超出或低于限值(表明过程中存在问题)，则限位开关会触发动作，例如警报。

　　原文：

　　When automating industrial processes, engineers define ranges for the process factors pressure, temperature, etc. within which the process runs normally. If the process overruns or underruns the limit-value, which indicates a problem in the process, a limit switch triggers an action, such as an alarm.