What is a SCADA System?
SCADA is a term that is frequently tossed about with little or no explanation. SCADA is a mnemonic for Supervisory Control and Data Acquisition. The key word in the term is supervisory. This indicates that decisions are not directly made by the system. Instead, the system executes control decisions based on control parameters entered by the agency staff. The system monitors the health of the process and generates alarm notifications when conditions are out of tolerance. It is also tasked with placing the process in a safe mode. It waits for user inputs to correct problems. The supervisory mode is designed to operate the system in a manner that avoids out of tolerance conditions. In a water / wastewater process, pumps are started and stopped by the system according to limits assigned by operations. As long as the system responds correctly to the control commands, the system remains in control. Supervisory mode also provides operations staff the capability to override control decisions.
