June 28, 1998
June 28, 1998
July 1, 1998
3.394.1 - 3.394.9
Low Cost Process Control Trainers
James A. Rehg Penn State Altoona
Process control laboratories in most colleges and universities include process trainers for control exercises in temperature, level, flow, and pressure. Schools are usually limited to a single trainer for each process variable because of system size and cost. The use of single systems makes it difficult to use small laboratory teams without reducing the enrollment limit placed on the laboratory section. Ideally, the process laboratory should have multiple trainers in each of the four process variables to learn the basics of process control. Then the students could move to the larger more robust system to study control of a large industrial process. This paper describes the results of a National Science Foundation (NSF) Instructional Laboratory Instrumentation (ILI) grant that supported the design of a low-cost process control trainer for temperature that introduces students to basic control concepts. Construction cost of the system is less than $500, and all of the components are available off-the-shelf from a number of industrial sources. The systems can be controlled by any single-loop process controller, a programmable logic controller, or a microcomputer using a control software product, such as LabView. In addition, the trainers work well in linear electronics laboratories to teach the use of operational amplifiers in instrumentation systems. The systems have been tested at several colleges and universities with excellent results. This paper describes the system design, construction requirements, example laboratory exercises, and test results. A web site that includes a complete set of drawings for the trainer and other supporting information is available. Send e-mail to James Rehg firstname.lastname@example.org for the URL.
The cost of process control has dropped as a result of the drop in solid state control devices. Manufacturers interested in improved quality have increased the number of closed loop controls in a broad product area using continuous, repetitive, and line type-production systems. As a result, engineering technology programs at the two- and four-year level have added control courses and laboratories to prepare the graduates for the systems awaiting them in industry. Building a controls laboratory that uses standard industrial control elements is costly and demands allocation of a large laboratory area. Traditionally, process control laboratories in schools used large system trainers to teach the control of material level, flow, temperature, and pressure. While the performance of these systems is satisfactory, problems occur when these large systems are used in introductory control theory laboratories. The problems include:
• The high trainer cost prohibits the purchase of multiple student stations. • The small number of student stations requires large student teams if standard laboratory section sizes and traditional laboratory scheduling practices are followed.
Rehg, J. (1998, June), Low Cost Process Control Trainers Paper presented at 1998 Annual Conference, Seattle, Washington. https://peer.asee.org/7266
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