SCADA systems allow facilities spread over a wide area to be monitored from a single centre using devices such as computers, mobile phones or tablets; fundamentally it is software. It can be used from a single device, or control and monitoring can be performed from multiple computers and portable devices over network connections.
Principal features of SCADA systems
- Graphical interface
- Monitoring system
- Alarm system
- Data acquisition, analysis and reporting systems
SCADA consists of three fundamental parts
Remote Terminal Unit (RTU)
The unit that collects data from field equipment, sensors and metering devices and transmits it to the centre.
Communication System
The data transport infrastructure between the RTU and the control centre: OPGW/SDH, leased line, power line carrier, Ethernet.
Control Centre (MTU)
The Master Terminal Unit — the centre where data is collected and processed and commands are generated.
Communication protocols
Many devices used in industrial applications use the EIA standards RS-232, RS-422 and RS-485 to connect to computers or to each other.
Control units
The main PLC, auxiliary PLCs, electronic protection and interlocking systems and motor control units are the principal control components. The main PLC — the most important part — keeps the entire system under control and should have the following capabilities:
- Able to talk to multiple master stations simultaneously over separate communication channels.
- Able to communicate with multiple protocols at the RS-232 and RS-485 physical layer, over copper and fiber optic media.
- Easily expandable, configurable and maintainable.
- Able to run self-tests and to raise resulting faults both locally and at the SCADA centre.
- Hardware architecture that does not require power to be cut when replacing a faulty module.
Widely used SCADA software packages include WinCC, Citect, ICONICS, iFIX, InduSoft and Entivity Studio. Using ABB Micro SCADA we provide switchyard SCADA with management and control from a single centre.
Areas where SCADA is used
- Nuclear facilities
- Electrical facilities
- Water collection, treatment and distribution
- Traffic control systems
- Automotive industry
- Natural gas facilities
- Food industry
Benefits of SCADA
- The system can be monitored at any moment
- Savings in time and labour
- Production data can be recorded and analysed
- Energy monitoring and savings
- Prevention of penalty conditions (compensation, etc.)
- Awareness of field conditions and immediate response
- Interventions on the system are logged
- Areas at risk of failure can be identified
- Immediate information about system operation (breaker status, etc.)
Although initial costs may appear high, these benefits allow the system to pay for itself in a short time. At power plant substations there is both a switchyard SCADA and a turbine SCADA. The switchyard SCADA is installed to visualise the system at the switchyard and can be configured for visualisation only or for both visualisation and control.