Jos steel rolling mill plant direct current machine speed control using silicon control rectifier speed control is presented. Jos steel rolling mill is one of the three inland rolling mills established by the Federal government of Nigeria to enhance the development of steel sub-sector. As part of the ongoing efforts to revive the nation’s steel industry so that the country can commence steel production. No nation can really develop without the development of its steel industry. The pivot to this development of the steel industry is through research that calls for this research in the steel industry. Rolling mills are types of metal forming machinery that process various metals through sets of roll to reduce thickness, create uniform thickness, imprint a design or compact loose material. Three types of rolling mills are two high pulls over mill that has two rolls with a constant direction of rotation around a horizontal axis, two high reversing mill that allow you to see the productivity improvement when using the two-high reversing mill and three-high rolling mill. Stress on Jos Steel Rolling Mill plant systems is increasing day by day, due to faults and sudden load change that constitutes negative threat to Jos Steel rolling mill stability. To maintained mill quality services, Study was carried out to examine the capacity and transient stability of the Jos Steel Rolling Mill. The direct current (DC) machines are electro-mechanical energy converters in which the electrical energy is exchanged with the supply load in the form of direct currents and voltages. Closed-loop silicon-controlled rectifier (SCR) which allows electricity to flow in one direction is used in a high-power control and has 3 terminal and 4 solid state layer semiconductor current controlling device, but with the added ability to be able to turn it on and off. The laboratory experiment was conducted which shows that as the rheostat ‘R’ was varied until armature voltage’ = 175Vdc. Jos steel rolling mill speed of DC machine was control by changing supply voltage or the field current. The separated excited machine, the field was changed by a rheostat by power electronic means using close- loop Silicon Control Rectifiers Speed Control. While the shunt machine a variable resistor was introduced in the shunt circuit. The field was weakening and the speed increased for smooth Jos steel rolling mill operation. The effect upon the dc machine speed and the armature voltage’ shows that at low DC machine speed, the armature conduct late. The highest speed obtained was 3540 rev/min before the DC machine turned ‘OFF’. To provide filtration for the smooth operation of the DC machine in Jos Steel Rolling Mill, Silicon control rectifier (SCR) reactance ‘’’ filter choke was incorporated and connected to terminal 3 and 10 of the SCR to provide filtration for the smooth operation of the DC machine in the Jos Steel Rolling Mill to prevent heavy armature transient surge current. A Silicon control rectifier capacitor ‘’’ the electrolytic filtering capacitor was connected across the dc machine and the armature winding was connected to terminal 8 and 1. This is because, the capacitor have to discharge through armature winding when the SCR is not conducting and for the smooth running of the DC machine, the terminal 8 and 11 was used for the smooth operation of the dc machine instead of terminal 8 and 1. The capacitor absorbs the current peak during each cycle rather than the armature and the dc machine vibrate cooler than before. Experiment on the drives performances and Jos Steel Rolling Mill dc machine run-up characteristics using silicon control rectifier speed control for various results was presented graphically for dynamic study and This is recommendation for machines designers, engineers and operators of Jos Steel rolling mill industries
