3.4 An example of a milestone schedule for a typical control system design for a WRRF.
2.2 Automation Design Implementation Documents
In addition to the documents listed in Section 2.1, the drawings described in this section are typically part of the implementation of a complete automation design package. Implementation is typically carried out by a contractor, system integrator, end user, packaged equipment supplier by water process original equipment manufacturer, or a combination of these.
2.2.1 Loop Diagrams
ISA Standard S5.4 details the content and format standards for loop diagrams. Each diagram traces the complete route of a control loop’s wiring. They are useful during installation and critical for system maintenance. Loop diagrams cannot be prepared during the design phase because they involve actual vendor shop drawings and documentation. Instead, they are created during the shop-drawing phase by the design engineer or the contractor’s system integrator.
In general, it is better to have the design engineer prepare loop diagrams, although it depends on whether the owner is willing to pay for this service as part of the design fee or as part of construction costs. Some owners may not require these drawings and simply rely on other documents already produced instead. Whether a loop diagram is used or not depends on maintenance practices at specific facilities.
2.2.2 Interconnecting Wiring Diagrams
Interconnecting wiring diagrams are also known as point-to-point wiring diagrams and, as the name implies, provide wiring connections for the complete control system in addition to wiring connections for equipment power and all other wiring needed for a complete facility design. Interconnecting wiring diagrams include all external wiring for each piece of equipment, control panel, instrument field devices, local control station, motor control centers, VSDs, automated control valves, lighting, and power panels. These diagrams are typically prepared by installing contractors, although, in some instances, design engineers can prepare them if they are included in the electrical design contract. Items to be included are
• Numbered terminal block identification for each wire termination;
• Identification of the assigned wire numbers and color coding for all interconnections;
• Identification of all wiring by the conduit, cable tray, wireway, and tag with, which the cable is installed;
• Terminal, junction boxes, and pull boxes in which the wire or cable is installed;
• Identification of equipment with functional name and contract tag number to which wiring is to be connected; all numbering must match the other contract documents including P&IDs; and
• Fiber optic patch panels with all fibers labeled and terminated, including spares.
2.2.3 Control Panel Design Drawings
Control panel design drawings are a basic component of control system engineering implementation. The design engineer should develop panel sizes conservatively as part of his or her design to allocate enough space in the facility for the panels. In addition, design guidelines should be included in the panel specifications to allow the system integrator to create detailed panel layout and construction drawings for the panel shop. Every effort should be made to solicit facility maintenance personnel input on panel sizing if possible. The panel supplier should provide the following:
• Panel detailed layout drawings with exterior views of the panels that illustrate doors and hinges, lock mechanism, disconnects, and lifting lugs;
• Interior panel layouts of all components, along with naming and numbering standards;
• Panel electrical schematic diagrams;
• Panel bill of material keyed to panel components; and
• Manufacturer data sheets for all panel components.
2.2.4 Programmable Logic Controller Program
Complete program logic documentation should be provided by the system integrator or engineer performing this function. Chapter 14 contains information on different formats of program documentation.
2.2.5 Distributed Control System Configuration
Distributed control system configuration should include logic diagrams in the vendor’s specific format, including controller configuration with all parameters defined.
2.2.6 Instrument Data Sheets
To present information in a uniform standardized format, data sheets should comply with ISA requirements ISA-TR20.00.01 and ISA-20. The ISA data sheets should not replace the vendor catalog and annotated manufacturer technical data sheets that have all model numbers and options clearly delineated.
2.2.7 Detailed Process Control Narratives
The system integrator should be required to submit detailed PCNs that will ensure that his or her interpretation of the PCNs prepared by the design engineer is correct. In addition, PCNs prepared by the system integrator should include more details on how the control functions are implemented.
2.2.8 Logic Diagrams and Detailed Process Control Sequence Flow Charts
The system integrator should be required to provide logic diagrams and detailed process control sequence flow charts as part of the implementation package. When submitted early, flow charts help flush out the details of PCNs in a simple graphic format using flow chart symbols.
2.3 Sources of Technical Design Information
2.3.1 Technical Societies
Several technical societies offer a wealth of information (e.g., compact discs, conferences, online forums, periodicals, standards, textbooks, videos, workshops, etc.) on instrumentation and control system design. Of these organizations, Water Environment Federation (WEF) and the Instrumentation Testing Association (ITA) tailor their information to WRRFs, and ITA even provides test reports on instrumentation used at WRRFs. For more information on technical societies, see the “Suggested Readings” section at the end of this chapter.
2.3.2 Vendors
Because control systems must be built using commercially available products and services, vendors represent an important source of information. Design engineers should keep up to date on vendor information to ensure that their control systems make use of the best technologies available. Sources of vendor information include brochures, catalogs, compact discs, Web sites, and so on. After a preliminary review using these sources, design engineers still need to contact vendors directly for more project-specific information. Design engineers can also request a meeting with the vendor (or vendor’s representative) for a more in-depth presentation.
Water Environment Federation’s Annual Technical Exhibition and Conference, the largest water and wastewater treatment conference in North America, offers an excellent opportunity for design engineers to meet vendors and to compare products. Other important conferences include the ISA Expo and American Water Works Association’s Annual Conference and Exposition and State Water Environment Association.
2.3.2.1 Selecting Vendors and Technologies
Design engineers should thoroughly review product literature, specifications, references, and detailed manuals