SCADA

SCADA (Supervisory Control and Data Acquisition) is software that lets you see and supervise how an installation is running. On a computer screen in the control room, the operator sees a diagram of the installation: tanks with their current levels, pipes, pumps, valves, and live temperature and pressure readings. Colours and symbols show what is running, what is stopped and what is reporting a fault.

The main functions of SCADA are:

• visualisation, meaning a real-time view of the installation’s status,
• control, such as starting a process, changing a setpoint or starting a cleaning cycle,
• alarms, meaning notifications when parameters are exceeded or a failure occurs,
• data archiving, meaning a record of measurement history,
• reports and trend charts.

SCADA does not control the installation directly. That is done by controllers (PLCs). SCADA is the layer above them that gives people visibility and control. Smaller workstations are operated from simpler operator panels (HMIs) mounted next to the machine.

Example: An operator in a cosmetics plant sees a diagram of six cream production reactors on the monitor. For each one, the current temperature, agitator speed and process stage are displayed. Suddenly, reactor no. 4 turns red and the system displays an alarm: the oil phase temperature is not rising. From the screen, the operator checks that the steam valve has not opened and calls the maintenance team.

Example of using the archive: A customer complains about a batch of lotion because it is too runny. The process technologist opens the batch’s trend chart in SCADA and sees that cooling after emulsification took half as long as usual. The cause of the problem is found within minutes.