Test 1 Flashcards
Process Variable
Dependent variable this is to be controlled in a control system.
Control Variable
Independent variable in a process.
Controller
Controls control variable in a process.
Primary Element
Detects process variable. (thermal couple)
Final Element
Receives signal from controller and regulates the amount of material or energy in a process.
Self Regulation
Tank filling and depleting at the same time.
Exothermic
Gives off heat.
Endothermic
Takes in heat.
Process Dynamics
Gain, Dead time, and lag.
Load Changes
Changing the process variable, and having to compensate by changing control variable.
Gain
Ratio of the change in output to the change in input of a process. (Linear)
Dead Time
First change made into first measured.
Lag
First measured to complete.
Types of Gain
Linear, Nonlinear
What causes lag.
Capacitance and Resistance
Capacitance
The ability of a process to store material or energy.
Resistance
An opposition to the potential that moves material or energy in or out of a process.
Feedback
(closed loop) The controller monitors the results of its actions.
Feedforward
(open loop) Sends a control signal to a final element but does not verify the results of the control.
Control Loop
Primary element -> Controller -> Final Element ->
Control Action
Direct Control, Reverse Control.
Bumpless Transfer
A controller function that eliminates any sudden change in output when switching from automatic to manual.
Control Strategies
On/Off, Proportional, Integral, Derivative.
On/Off
Two position control strategy, options being on and off.
Proportional
Changes output of a controller in proportion to the error.
Integral
Changes output in proportion to error and the duration of the error. (Faster)
Derivative
Changes output in proportion to the rate of change of the PV. (Slower)
Adaptive Gain Control
Nonlinear gain can be applied to a nonlinear process.
Cascade Control
Multiple loop control system where the primary variable is changed by changed the setpoint of a secondary controller.
Ratio Control
Control system in which the rate of one flow is controlled proportional to the rate of another.
Neural Networks
computer program that receives multiple inputs and human input to arrive at and educated output.
