ensure that device calibrations are per factory settings. Some instruments will need to be calibrated in the field. As an example, magnetic flow meters are subject to wet calibration under controlled factory environments; however, a thorough check of magnetic flow meter parameters should be conducted on-site using built-in tools at the transmitter or specialized test devices furnished by the magnetic-flow supplier. In all instances, calibration documentation (e.g., certificates) should be produced by the contractor or system integrator and these should be witnessed and signed off on by site inspectors.
3.2.3 Field Tests
Field tests (site acceptance tests) as described further in this manual should be conducted after the new control system has been installed and wired and each instrument has been verified and calibrated. The ISA publishes a useful guide to testing requirements that includes site acceptance testing (SAT), system integration testing (SIT), and factory acceptance testing of automation systems in the process industry (ISA, 2011).
3.2.4 Wiring Tests
Before scheduling I&C testing (e.g., loop testing) of a control system, a thorough test of field wiring should be performed by the installing electrician. This test should include complete wire insulation testing (“meggering”) and continuity testing. It should also comprise testing for the presence of grounds, shorts, and correct terminations at the designated devices and panels in accordance with approved interconnecting wiring diagrams.
Testing for fiber cables should also be performed using an optical loss test set (OLTS). The OLTS consists of a light source and an optical power meter. The main function of this equipment is to measure the optical power or loss. Testing should be conducted according to Telecommunications Industry Association (TIA) guidelines (TIA TSB-140; http://www.instrument.org). This document provides guidelines for the field-testing length loss, and polarity of a completed fiber optic link.
3.2.5 Loop Testing
Loop testing confirms that each “control loop” in the system functions as designed. A control loop is a combination of one or more interconnected instruments that are arranged to measure or control a process variable (ISA-67.02.01-1999 and ANSI/ISA-5.1-1984).
All loop testing should be overseen and approved by the site engineer. Resulting loop sign-off sheets should be kept as test records. Consideration should be given to combining loop testing with I/O testing, especially if the integrator is also the instrument supplier. This could represent a significant reduction in costs for a project.
3.2.6 Integrated System Testing
After each control loop has been tested, the construction management team should test the entire control system, including signals to and from controlled field equipment (e.g., motors, sensors, transmitters, valves, and VSDs). Before the test begins, the system integrator should write up the entire test procedure and submit it to the design engineer for approval. It should include a list of items to be checked, such as a database listing grouped by I/O for each area of the WRRF. The database listing should include all wired I/O points, virtual (nonphysical) points, and derived points. Sorting the database I/O listing by process area helps make system checking easier.
During the integrated systems test, the control system must operate for a specified period of time without failures. If the factory acceptance test was well executed and all control system equipment from the factory was tested properly, then the integrated systems test should only be limited by field wiring issues.
The integrated system test should be overseen and approved by both the engineer and the owner. A log of all testing activities, with the initials of the system integrator, engineer, and owner next to each functioning item, should be kept as test records. The integrated system test is also referred to as SIT (ISA, 2011).
3.2.7 Commissioning and Final Acceptance
Final acceptance is also referred to as SAT (see Automated Systems in the Process Industry—Factory Acceptance Test [FAT], Site Acceptance Test [SAT], and Site Integration Test [SIT] [ISA, 2011] for a comprehensive standard on the subject). The new control system should not be formally turned over to the owner until all startup and commissioning activities are complete. The contractor should also be required to meet the following two conditions before the utility formally accepts and pays for the system:
• All as-built drawings and O&M manuals must be approved and delivered to the owner and
• All user training must be completed (see Chapter 16 for a detailed discussion of training requirements).
These prerequisites ensure that the owner ends up with a fully documented system that staff is comfortable using.
3.2.8 As-Built Drawings and Final Control System Documentation
As-built drawings and final control system documents should be provided in electronic format to the end user or owner and the design engineer of record. Adobe Acrobat portable document format is a common, universally accepted format that uses free readers to read any file submitted. Other formats can be used for drawings and/or other text-based documents based on previously agreed upon formats or as outlined in contract specifications.
4.0 REFERENCES
Blevins, T.; McMillan, G.; Wheatley, R. (2000) The Benefits of Combining High Fidelity Process and Control System Simulation. Proceedings of the International Society for Measurement and Control EXPO 2000; New Orleans, Louisiana, Aug 21–24; Instrumentation, Systems, and Automation Society: Research Triangle Park, North Carolina.
Dougall, D. J. (1997) Applications and Benefits of Real-Time I/O Simulation for PLC and PC Control Systems. ISA Transactions, 4, 305–311.
Hendrickson, C.; Au, T. (1989) Project Management for Construction. Fundamental Concepts for Owners, Engineers, Architects and Builders; Prentice Hall: Upper Saddle River, New Jersey.
International Society of Automation (2011) Automated Systems in the Process Industry—Factory Acceptance Test (FAT), Site Acceptance Test (SAT), and Site Integration Test (SIT); ANSI/ISA 62381-2011; International Society of Automation: Research Triangle Park, North Carolina.
Jekielek, J. P. (2003) Notes on Planning and Controlling I&C Projects; International Society for Measurement and Control Process Control Conference; June 5–6, King of Prussia, Pennsylvania; http://www.isa.org
Johnson, B. L.; Bailey, K. (2000) Leveraging Innovative Technology Delivers Benefits in Start Up and Daily Operations. Proceedings of the International Society for Measurement and Control EXPO 2000; New Orleans, Louisiana, Aug 21–24; http://www.isa.org (accessed March 2012)
Koons, D.; Conley, G. (2004) How to Select a Control System Integrator without a Dart Board. Control, June 2004.
Meier, F. A.; Meier, C. A. (2011) Instrumentation and Control Systems Documentation, 2nd ed.; Instrumentation, Systems, and Automation Society: Research Triangle Park, North Carolina.
Metcalf and Eddy, Inc. (2003) Wastewater Engineering Treatment and Reuse, 4th ed.; McGraw-Hill: New York.
Raven,
