Control Systems: Comprehensive Control
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Regulation systems are becoming more advanced and fast-paced development offers a variety of new solutions. These articles present a few of the control and monitoring systems for the most common types of compressors. In this article we talk about comprehensive control in a compressor installation.
Why is there a need for a comprehensive control system?
Compressors that are a part of a system composed of several machines should have coordinated compressor operations. There are many factors that make a comprehensive control system advantageous. The division of operating times between machines reduces the risk of unexpected stoppages. Compressor servicing is also easier to plan. Standby machines can be connected if something should occur during operations. The simplest and most common form of master control system is the commonly used and tested start sequence selector.
What is a start sequence selector?
This selector equally divides the operating times and starts among the connected compressors. The start sequence can be switched on manually or automatically, following a time schedule. This basic selector uses an on/off pressure transducer, with one transducer per compressor, as a simple and practical solution. The disadvantage is that there are relatively large steps between the different compressor's loading and off-loading levels. This results in relatively broad pressure bands (the span between maximum and minimum levels) for the installation. This type of selector should therefore not be used to control more than 2–3 compressors. A more advanced type of start sequence selector has the same type of sequence control, but with only one, centrally-positioned, analogue pressure transducer. This manages to keep the installation's total pressure band within a few tenths of a bar and, as a result, can control 2–7 machines. A start sequence selector of this type, which selects the machines in fixed sequences, does not take the capacity of the compressors into account. The connected compressors should thus all be approximately the same size.