16 Loss of SCADA Network
The SCADA (Supervisory Control and Data Acquisition) network is critical to the smooth monitoring and operation of the El Estero Wastewater Treatment Plant. This SOP describes the actions to be taken in the event that plant personnel lose the SCADA network. |
SCADA can be a great tool while working in an environment where operational duties need to be monitored through electronic communication instead of locally. For example, an operator can position a valve to open or close through SCADA without leaving the control station or the computer. The SCADA system also can switch a pump or motor on or off and has the capability of putting motors on a Hand operating status, Off, or Automatic.
Remote terminal units (RTUs) connect to sensors in the process and convert sensor signals to digital data. They have telemetry hardware capable of sending digital data to the supervisory system, as well as receiving digital commands from the supervisory system.
Programmable logic controller (PLCs) connect to sensors in the process and convert sensor signals to digital data. PLCs have more sophisticated embedded control capabilities than RTUs. PLCs do not have telemetry hardware, although this functionality is typically installed alongside them. PLCs are sometimes used in place of RTUs as field devices because they are more economical, versatile, flexible, and configurable.
A human–machine interface or HMI is the apparatus or device which presents processed data to a human operator, and through this, the human operator monitors and interacts with the process.
2-way communication devices (radio, mobile phone, etc.) to communicate with Operator in Control Room.
- SCADA will notify plant staff that SCADA is not working properly.
- Immediately notify your supervisor.
- Notify the Control System Operations Specialist.
- Go through the plant and check individual SCADA stations. Confirm that SCADA reflects actual conditions in the field. Confirm field conditions in the following order: Influent Pump Station (check often and regularly); Disinfection/Dechlorination (check often and regularly); Solids Handling Building; Blower Room; Sludge Pump Room; Distribution Pump Station.
- Continue monitoring field conditions until SCADA is restored.
- Once SCADA control resumes, confirm field conditions and match against SCADA.
- Clear all alarms.
- Put all equipment back in Automatic mode.