Abstract : This paper details the design scheme and implementation method of replacing the thyristor-controlled AC electronic switch cabinet with an inverter in the rolling line of a 2800 mm middle plate reheat furnace. The focus is on the excellent application effect of this modification in meeting production requirements and the application characteristics of PLC control for speed regulation. Keywords : Inverter; Speed ​​regulation Keywords : inverter controlling, rotation speed 1 Introduction With increasing competition in the international and domestic plate markets, the product specifications, varieties, and quality of Angang's 2800MM medium and heavy plate rolling mill must meet market demands. To adapt to these demands, Angang's Second Rolling Mill systematically upgraded the electrical equipment of the original heating furnace, particularly the equipment affecting large billet rolling and new product development. This was to meet the production needs of large billets, avoid frequent roller trips, and thus improve equipment operating rates. 2. Conditions Before Modification Hardware Structure: The heating furnace charging roller conveyor consisted of 7 YZR280M-8 55KW motors, centrally driven in 7 groups. The furnace exit roller conveyor was composed of 40 YGA200L2-10 8.5KW AC motors connected to suspended reducers for single-roller transmission. The original roller conveyor control system used a JDK series thyristor AC electronic drawer-type switch cabinet, a type of AC electronic switchgear that uses low power to control high power. Its main working principle relies on the forward and reverse triggering of bidirectional thyristors to control the forward and reverse rotation of the AC motor. For the motor, this is a direct full-voltage start, resulting in a particularly large impact on the mechanical equipment during production. Although the JDK series thyristor AC electronic switchgear has an energy-saving braking circuit that can adjust the energy consumption time and current as needed, its braking circuit is extremely unstable. Circuit board connectors frequently fail, preventing the roller conveyor from braking quickly and failing to meet the process requirements for steel loading on the furnace front roller conveyor. [b][align=center]For details, please click: Frequency Conversion Retrofit of 2800ram Medium Plate Heating Furnace Roller Conveyor[/align][/b]