The pop-up screen "ISP CONTROLS" below allows the operator to view all the pertinent system data and to control the intermediate service pumps. This display is selected by clicking on the level it controls or the pumps that control the level. Each pump has a "Pump Control Module" in the machine level Steeplechase Visual Logic Controller. This Module is represented in the Citect Graphical User Interface, providing H (Hand), O (Off) and A (Auto) control of the pump. In Automatic mode the output of the system responds to a Required signal coming from the Pump Matrix. This matrix allows the selection of which pump is called for each of five steps of requirement. The speed of two Variable Frequency Drive pumps (ISP-2 & ISP-3) are controlled by a PID control loop, trying to maintain a constant level in the intermediate pump pit. When the VFD system is not able to maintain the Desired Level, the Add or Subtract Pump setpoint is overcome by the Pit Level and after the Pump Delay, the next step is added or the last step is subtracted accordingly. A Close button is provided for each pop-up or "child" window.
The pop-up screen "SLUDGE BATCH CONTROLS" below allows the operator to view all the pertinent system data and to control the Clarifier sludge draw down process. In this system the operator monitors the sludge blanket level and decides which Clarifier, When, How Much and at what Rate to draw off the sludge. During the process the words "BATCH IN PROGRESS" appear and flash red. When the batch is completed, the Control Valve is closed, "BATCH IN PROGRESS" replaced with the words "BATCH COMPLETED" in black. The Operator selects Start, Stop, Reset, Gallons to draw off, desired valve position during draw off and Manual control of each valve.
Each process in the system is operated entirely within the Steeplechase VLC, making it immune from Windows environment issues. Control parameters are sent to the Steeplechase from the Citect User Interface. Should the Windows environment fail for any reason, the Steeplechase continues to operate local and remote telemetry as well as all mission critical tasks, without the need for a separate and proprietary PLC subsystem.