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A control loop is the fundamental building block of control systems in general and industrial control systems in particular. It consists of the process sensor, the controller function, and the final control element (FCE) which controls the process necessary to automatically adjust the value of a measured process variable (PV) to equal the value of a desired set-point (SP).
Note that a 4-wire instrument has a power-supply input separate from the current loop. Panel mount displays and chart recorders are commonly termed "indicator devices" or "process monitors". Several passive indicator devices may be connected in series, but a loop must have only one transmitter device and only one power source (active device).
There were no allied vessels in the harbour so the indicator loops on the minefields were activated. Two hours later, at 23:32, current was detected in an indicator loop laid in a remotely controlled minefield, induced by the submarine as it passed over the cable. Activation of the loop detonated mines in the field, sinking the submarine. [10]
RAMP Simulation Software for Modelling Reliability, Availability and Maintainability (RAM) is a computer software application developed by WS Atkins specifically for the assessment of the reliability, availability, maintainability and productivity characteristics of complex systems that would otherwise prove too difficult, cost too much or take too long to study analytically.
Pressure vessels and tanks are fitted with local pressure indicators (PI). In the petrochemical industry pressure is controlled by maintaining a constant pressure in the upper gas space of a vessel. [1] [9] [4] A pressure controller (PIC) adjusts the setting on a pressure control valve (PCV) that feeds gas forward to the next stage of the ...
Its name comes from the information path in the system: process inputs (e.g., voltage applied to an electric motor) have an effect on the process outputs (e.g., speed or torque of the motor), which is measured with sensors and processed by the controller; the result (the control signal) is "fed back" as input to the process, closing the loop. [1]
Within modern distributed control systems and programmable logic controllers, it is much easier to prevent integral windup by either limiting the controller output, limiting the integral to produce feasible output, [5] or by using external reset feedback, which is a means of feeding back the selected output to the integral circuit of all ...
Neither open loop control nor teleoperator systems require the sophistication of a mathematical model of the physical system or plant being controlled. Control based on operator input without integral processing and interpretation through a mathematical model of the system is a teleoperator system and is not considered feedforward control.