Standalone RTUs and MCC panels for three pumping stations, Al Dhafra

About this project

Parks and playgrounds across Al Dhafra needed pumping stations at Al Mirfa automated and connected to the supervisory system the municipality already runs. Three stations were in scope: two single tank stations and one twin tank station.

The word that shapes this project is existing. There was no new SCADA to design. The stations had to appear inside a stormwater supervisory system already in service, speak DNP3 to it, and present the points the operators there already expect. That makes the point list and the addressing the first engineering deliverable rather than a late formality, because everything downstream depends on it.

Al Dhafra also changes the calculation on reliability. These are not stations someone can reach in twenty minutes. A UPS, a battery charger and lead acid batteries back the PLC and RTU so that a power interruption produces a reported event rather than silence, and so that a site visit is a planned trip rather than a guess about what has failed.

Each station carries an MCC with variable frequency drives for the pumps and a separate PLC, RTU and HMI panel. Analogue signal splitters let a single field transmitter feed both the local controller and the RTU without one instrument being answerable to two masters, which is the ordinary way a level reading and a SCADA reading quietly stop agreeing.

The twin tank station is the one that carries the real logic. Two tanks means level relationships, transfer decisions and duty selection that a single tank station never has to make, and it is where most of the configuration and commissioning time went.

Deliverables included the technical submittal, the DNP3 list, shop drawings, as built drawings and the written operation philosophy. On a remote site the operation philosophy matters more than usual, because the person who eventually troubleshoots the station will not be the person who commissioned it.