Tracy J. Coates
Industrial control projects are not always large with hundreds of data points with extensive control action and display requirements. Many applications exist where the number of input and output (I/O) signals is small and only few display graphics are required. These smaller applications can be standalone systems or be part of a larger process that needs to be isolated from the primary control ...
The vast majority of control systems in use today are electrical. Not only do they require electricity to operate but they also use electrical circuits to affect control over associated operations or processes. Taken for granted, dependency on electrical power is often accompanied by the assumption that if the system is "powered up" all is well.
When implementing chemical process control systems, the control engineer must thoroughly understand the flow of materials through the process equipment. Flow is not always apparent as chemical species change through reaction operations. These changes can create different behaviors through various separation operations in the process sequence.
Control system electronic components have temperature limits that must not be exceeded if proper system operation is to be maintained. Ensuring proper operation of electronic components requires that the temperature inside their enclosures be controlled within operational temperature limits of these devices.
Configuration of programmable logic controllers is a common task in the controls industry because PLCs serve as the workhorse of automation in many industry segments from component manufacturing and assembly to chemical process automation. In each industry-specific requirements exist for each application, as well as individual preferences for programming methods.
Most automation projects use some form of logic control that is typically implemented in a programmable logic controller (PLC). Actual form of the PLC varies from dedicated hardware to PC applications, available from a variety of vendors. Regardless logic type, the ultimate goal is monitoring of input variables and then responding with output signals based upon a user-determined algorithm.
When working on the design of batch processes, a major factor controlling success of the completed facility is process equipment scheduling. Inadequate attention to moving materials through the process can reduce production capacity and increase capital costs, limiting the margins available for a profitable facility.
Maintenance of a control system after commissioning requires routine scheduled calibration of component parts including sensors, transmitters, and gauges. Scheduled calibration is a major quality assurance requirement for facilities operating under ISO9000 or QS9000 guidelines and a regulatory mandate for pharmaceutical processes governed by the U.
In developing or assessing the performance of control systems there are instances where complex mathematical operations must be performed. In many cases, these operations include calculus and Laplace or Fourier transforms not routinely used by many control engineers. In these cases, users must dust off old textbooks and review how to perform these operations and then execute what can be l...
In developing a control system, there are many functions that need to be considered for inclusion. The most important in almost all applications is the nature of the graphical interface, that is, how the operator will interface with the process/operation over which the control system is functioning.