SCADA or Supervisory Control and Data Acquisition is a computer system used in industrial automation for gathering and analyzing real-time data.
As the name indicates, it is not a full control system but rather focuses on the supervisory level. It is a software package positioned on top of hardware to which it is interfaced via Programmable Logic Controllers (PLCs) or other commercial hardware modules.
SCADA systems are vital components of most critical infrastructures. They monitor and control pipelines, water and transportation systems, utilities, refineries, chemical plants, various manufacturing operations, industrial processes like steel making, power generation (conventional and nuclear), distribution, chemistry, etc.
The key components of SCADA are as follows:
- Remote Terminal Unit (RTU): RTU is a device that collects data from a remote location, codes it into a transmittable format, and sends it back to a central station or master. An RTU also collects data from the master device and executes processes as directed by the master.
- Master Terminal Unit (MTU): It refers to the servers and software that communicate with field equipment (RTUs, PLCs, and so on), as well as the HMI software that runs on workstations in the control room and elsewhere.
- Field Instrumentation: It refers to the devices connected to the equipment or machines that the SCADA system controls and monitors. Sensors monitor certain parameters, and actuators control specific system modules.
- Communication Network: The communication network refers to the equipment used to send and receive data from various locations to the central station. Cable or telephone can be used as the medium. Telephone lines usually do not have access to remote controls. The use of a radio is a cost-effective option. Remote sites are connected to the host via modems.
A user interface, known as a Human Machine Interface (HMI), is also part of a SCADA system. A SCADA system’s HMI is where data is processed and presented for human operators to view and monitor. This interface typically includes a control panel that allows the user to interact with the SCADA system.
Advantages of SCADA
- It provides the facility to store a large amount of data displayed in various formats per user requirements. Many data types can be gathered from RTUs (Remote Terminal Units) connected with the master unit.
- It provides an interface to connect thousands of sensors across wide regions for various monitoring and controlling operations. Data can be monitored from anywhere, not just from local sites, thanks to advanced protocols and application software.
- With the help of operators, real data simulations can be obtained.
- It is quick to receive a response. It’s scalable and adaptable when it comes to adding more resources.
- The SCADA system incorporates unit redundancy to provide a backup in faults or failures. This makes the system more robust.
Disadvantages of SCADA
- When it comes to hardware units and dependent modules, a PLC-based SCADA system is extremely complex. The complexity necessitates highly trained operators, analysts, and programmers.
- SCADA provides data concentration and remote switching, but it does not provide complete information concentration.
- Installation costs are very high. Hardware component replacement is an expensive and unappealing option for the customer.
- In older technologies, the typical SCADA system has a lot of wires, which causes electrical noise and interference.
- It raises the unemployment rate.
- The system supports restricted software and hardware equipment.
- A successful SCADA installation relies on tried-and-true technology and adequate and thorough training of all personnel involved in the system’s operation.
- Using a web browser to control remote sites can raise security concerns. SCADA systems are vulnerable to a variety of threats.
- Failure of SCADA systems can lead to direct loss of life or indirect losses due to critical infrastructure or equipment failure.
