Abstract: Based on the field experience,and the operation principle of the said speed control device,the reasons for and generation mechanism of Fault F030 of the Siemens 6RA70 DC speed control device are analyzed in detail,involving such aspects as the hardware,the software,and the system optimization,etc. And relevant solutions are also in-deep discussed. Accordingly pinpointed solution method for Fault F030 is determined,providing applicable technical guide for the on-the-site troubleshooting personal so as to ensure consistent operation of the equipment.