The City of Arvada, Denver, upgraded its hardwired dedicated control system with a computer based system using a successful mix of technologies and equipment. By using standard programmable logic controllers (PLCs), personal computers, and off-the-shelf plant monitoring software, a economically feasible system that allows sophisticated plant control for a medium sized system was created. A team was used to define significant project requirements and the planning and implementation processes. A clearly defined filter control strategy had to be adopted to ensure proper plant influent and filter effluent control; the revised control scheme used the principle of operating filters at or near a steady-state flow by choosing the filter effluent flow rate as the single point of flow control. The city's desire for many levels of redundancy required that automatic controllers be provided for use during a PLC failure. Another more complex control problem was in the plant influent flow control. Controllers were tuned during the first phase of the project; this succeeded with specific tuning parameters at fixed flow ranges. During implementation, a maximum flow rate limiter was installed. Filter control was an important component, along with automated backwash and chemical feed system control. The transmission and distribution system controls mixed the best of the old and new control systems. Plant alarm capabilities took an integrated alarm approach.
| File Size : | 1
file |
| ISBN(s) : | 0898675812 |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 14 |
| Published : | 01/01/1991 |
