Abstract : This paper introduces the key technical issues in the selection of motors and frequency converters during the electrical system renovation of the 200t 4-50t bridge crane at the Changhu Power Plant in Guangdong Province. Practical operation shows that the system is stable and reliable. Keywords : Bridge crane, Frequency converter , Electrical system 1 Introduction With the continuous progress of science and the transformation of modern enterprise management models, traditional relay contact control technology is difficult to meet the control requirements of crane machinery. In today's rapidly developing electronic technology, the integration of crane machinery and electronic technology is becoming increasingly close. Replacing the old relay logic control with PLC and replacing the traditional motor rotor series resistance speed regulation method with AC frequency conversion speed regulation devices is an inevitable trend. The generator floor of the underground plant of Guangdong Yue Dian Changhu Power Generation Co., Ltd. originally housed a 200t+30t bridge crane, designed and manufactured by Taiyuan Crane Factory. Installed and in use since the plant's initial construction in the early 1970s, it has been in operation for decades. While the mechanical equipment is well-maintained, the electrical equipment is severely aged, many components are no longer available, leading to frequent malfunctions and extremely difficult maintenance. Therefore, a renovation is necessary. The main requirements are: adopting PLC control and variable frequency speed control; replacing the original wound-rotor motor with a squirrel-cage motor; and increasing the auxiliary hook capacity from 30t to 50t. This article details the motor and frequency converter configuration during the system renovation process, related key technical issues, and introduces successful experiences in PLC-controlled frequency converters. [b][align=center]For more details, please click: Electrical System Renovation of the 200t+50t Bridge Crane at Changhu Power Plant[/align][/b]