FUNCTION

 

SCADA (Supervisory Control and Data Acquisition) is a general term

for a type of  computerised industrial control systems. These systems

are usually characterised by a large number of remote sites/assets

that can be great distances from the centralised server. A Telemetry

System refers to the subset of a SCADA system that relies on long-

distance communications to remote sites. For example, a major water

treatment plant may have a SCADA system in place for onsite controls, and a telemetry system connection in place for collecting data from the distribution system, e.g. storage tank levels. 

 

 

A SCADA or telemetry system usually consists of the following elements:

 

• A central supervisory computer running specialised SCADA software, primarily acting as a data collection device, database and data server to various applications. The solution could be located on a utility’s premises or be cloud-based. 

• Operator Interfaces:

  • Operator graphical displays (HMI –Human Machine Interface)

  • Alarm management displays, report generators etc

• Communications infrastructure:

  • Local area using either proprietary technology or more commonly Ethernet

  • Wide Area such as Radio, fibre, POTS (dial-up modems), leased direct circuits etc.

• Communication Interfaces – using both proprietary and open standards (e.g. DNP3, IEC60870-5-104, OPC DA): 

  • Remote Terminal Units (RTUs)

  • Programmable Logic Controllers (PLCs)

• Sensors/instrumentation and controlled elements

 

 

SCADA/telemetry functions include:

 

• Support for a wide range of private and public wide-area communications  media/services, (e.g. PSTN, ADSL, GSM/GPRS, private radio, LEO and GEO satellite)

• Real-time database, with the option to include a data historian

• Real-time display/visualisation (e.g. plant schematics, alarm lists, trend displays, etc.)

• Alarm management (e.g alarm suppression, dynamic alarming, generation of metrics/ KPIs for alarm system performance monitoring, operator decision support and business process support for managing responses to alarms)

• Report generation

• Open standard data interfaces for third parties (e.g. ODBC, OPC, DNP3, IEC60870-5-104)

• API for bi-directional exchange of data and controls with external applications (e.g. pump scheduling optimisation, network modelling and leakage management)

• Configuration tools and data management for the SCADA itself

• System management tools, including multi-site and multi-user operation (e.g. restricting authenticated users to separate areas of interest)

 

 

BENEFITS

 

Today’s water utilities are confronted with an array of challenges unprecedented in their scale and scope. SCADA/telemetry has long been an essential tool for managing large numbers of geographically distributed assets and the complex business processes, organisation, and people needed to support those assets. SCADA will play an increasingly important role in improving service delivery, asset management, and customer experience going forward.

 

The use of SCADA in providing real-time visibility and remote control of assets enables:

 

• Single site to aggregate information and present to skilled operators

• Reduced leakage through advanced leak/burst detection and localisation

• Improved customer service by increasing operational capability to respond proactively (e.g. through use of real-time analytics, real-time models, and decision support tools)

• Improved asset management through improved understanding of asset performance and condition (e.g. using data mining and predictive analytics)

• Reduced energy and chemical cost (e.g. through automated water resource and pump scheduling optimisation)

• Provision of data necessary for more effective, fact-based decision-making for business planning

 

 

SYSTEM REQUIREMENTS

 

To implement a SCADA system, the following are necessary:

 

• Meters and sensors in the field connected to RTUs

• PRVs, pumps, and valves with controls from the RTUs

• Wide-area communications system in place

• Centralised control room and skilled staff