Abstract: The security of frequency control system is often dependent on the transducer.Transducer has the protection function，but it is mainly to protect itself，and hard to realize the process monitoring for uncertain motors and unknown load.This paper puts forward a monitoring module which can be embodied in the system.The module uses rough set theory，establishes early warning alarm decision-making table，and has initially solved the problem of process monitoring in frequency control system.The results of the actual application demonstrate the feasibility and effectiveness of this method.

Key words: monitoring module, process monitoring, variable frequency speed adjusting technology, fault early warning

摘要： 变频调速系统的安全性往往依赖于变频器，虽然变频器具有一定的保护功能，但主要保护的是变频器本身，很难实现对不确定的马达和未知的负载实现过程监控。设计了一个可嵌入在系统中的监控模块，采用粗糙集理论，建立预警报警决策表，初步解决了变频调速系统的过程监控的问题，实际应用结果表明，该方法有一定的可行性和有效性。

关键词: 监控模块, 过程监控, 变频调速, 故障预警