Automation of the life support systems for the new aquarium at the Ushaka Island Marine Park in Durban. Operation and control of the Filter systems, including an extensive backwash sequence with many interlocks. The system has to return to normal filter mode if any alarm occurs e.g a valve position is not read, or backwashing sequence takes too long, because the exhibit could empty if a problem occurs and the water is dumped to drain without enough makeup water being added. To ensure that the canals do not appear dirty because of filter backwashing the filters are only backwashed a certain times. The filter systems are standalone and are not monitored via the SCADA system in the main control room. The Ozone Generators are new to the Aquarium staff therefore specifications on the operation and dosage rates had to be flexible and easily accessible. The Ozone Generators are all connected to PLC I/O and then the information displayed on the SCADA package. This information is vital to the scientists as they manipulate dosage rates and ozone levels in various parts of the control system. Ozone Generator dosage rates, maximum and minimum levels and switching the Generators on or off are controlled from the SCADA. All alarms and interlocks that could cause the Ozone Generator to switch off, or reduce dosage rates are displayed on the SCADA package. Certain parameters can be manipulated via password only, this is to prevent any accidental setpoint changes. Flow rates of the seawater abstraction plant as well as make up water flowrates for each exhibit are also displayed. Alarming is displayed for safety purposes and critical alarms e.g Oxygen or Ozone leak is also displayed via an audible siren and a flashing beacon outside the relevant plantroom.
Fountain controls in the childrens water park as well as on the lazy river ride are done using a PLC with a random number generator and a few timers to keep the valves open for a set time.