Process control systems use two different types of instruments: field instruments and panel instruments. While there are some similarities between these 2 types of instruments, there are also many significant distinctions.
The position of field instruments and panel instruments is the primary distinction between them. Instruments used in the field are often stationed out in the field, in close proximity to the process that is being monitored or controlled. In comparison, panel instruments are often found at a console or control panel, far from the process being monitored or controlled.
The kind of signal that these two different types of instruments receive is a significant additional distinction. Temperature, pressure, flow rate, and level are only a few examples of the process variables that can be measured and transmitted by field instruments. They often have sensors built into them that convert physical parameters into electrical signals that may be sent to the control room. Depending on the type of equipment, the signal may be digital or analogue.
Field instrument is required to employ the following signal types: 2 wire, 4–20 mA analogue input/output. Using digital input:Potential Free contact. . 24 VDC digital output. The platform control system must supply power for signals between control systems and other panels. Proximity switches with a NAMUR interface are in position. 0.2 to 1.0 barg are the pneumatic signals. Digital communication via instrument field buses is an option if the concept shows cost savings and satisfies the needs for quick responses.
While panel instruments are intended to show and/or regulate process variables, they also receive signals from the field instruments. The signal could take the form of a voltage, current, or digital signal. Indicators, recorders, controllers, and displays are all examples of panel instruments.
The level of sophistication of these two different types of instruments is a significant distinction. Since they must be capable of withstanding extreme environmental conditions and deliver accurate and consistent data, field instruments are frequently more advanced than panel devices. They are frequently made to function in dangerous locations, corrosive conditions, or high temperatures. Temperature sensors, pressure transmitters, flow meters, and level sensors are a few types of field instruments.
Panel instruments, on the other hand, do not need to function in challenging situations, hence they are often less sophisticated than field equipment. They are frequently used to display process variables in an easy-to-understand way and are often built for user-friendliness. Digital displays, analogue gauges, controllers, and indicators are some types of panel instruments.
Their degree of integration with the process control system is a key distinction between these two categories of instruments. Field instruments are frequently used to offer real-time feedback to the process control system and are immediately incorporated into the system. On the other hand, panel instruments may be standalone devices that are employed to monitor or control specific elements of the process.
The cost of these two categories of instruments can likewise vary greatly. Since field instruments must be more sophisticated and able to resist extreme climatic conditions, they are frequently more expensive than panel equipment. Since panel instruments are less complex and frequently employed for straightforward monitoring and control tasks, they are typically less expensive.
In summary, there are two different kinds of instruments utilized in process control systems: field instruments and panel instruments. While these two types of instruments have certain similarities, there are also many key variations between them, including their location, the signal type they receive, their complexity level, how well they are integrated into the process control system, and their cost. When choosing and utilizing these instruments in process control applications, it’s important to understand these distinctions.