Tag: controllers
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Basic Features of Modern PID Controllers
Most modern PID controllers have the following features: Manual versus automatic modeOutput trackingSetpoint trackingAlarm capabilitiesProcess variable (PV) characterization and dampingSetpoint limitsOutput limitsPID tuning security Manual and Automatic Modes When the controller manually calculates … Read more
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Direct Digital Control (DDC)
In direct digital control (DDC) a single computer is able to carry out PID control for multiple loops at the same time make that loop data accessible between loops for purposes of cascade control, feedforward control, ratio control… Read more
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Digital PID Controllers
Digital PID controllers have replaced most pneumatic and electronic analog controllers in industrial control applications. Digital PID controllers are preferred over the analog types because they employ microprocessors which can execute multiple functions at ago hence they bring with them … Read more
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Benefits of Cascade Control
We know very well that closed loop control provides increased performance over open loop control. So it would be rational to expect benefits from adding inner control loop around plant items that have degrading overall performance. The Figure (a) below … Read more
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Proportional plus Derivative (PD) Control System
Proportional plus derivative (rate) control is a control mode in which a derivative section is added to the proportional controller. This derivative section responds to the rate of change of the error signal, not the amplitude as with the integral … Read more
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Proportional Plus Integral (PI) Control System
This type of control is combination of two control modes, proportional and integral (reset). The Combining of the two modes results in gaining the advantages and compensating for the disadvantages of the two individual control modes. The main advantage … Read more
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Two Position Controller
A Two position controller is a device that has two operating conditions: Completely ON or completely OFF. The input to output relationship in two position controller. From the figure above, we can see the characteristic waveform for a two position … Read more
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What is the Controller?
A controller is a device that generates an output signal based on the input signal it receives. The input signal is actually an error signal, which is the difference between the measured variable, and the desired value, or setpoint. The … Read more