intro to controllers Flashcards
definition of process control
process control is the regulation or manipulation of the variable that influence the process.
What are control strategies?
methods used to bring the controlled variable back to the desired value
What are the three control strategies
feedback control, feed forward control and feedfoward-feedback control
purpose of a controller
- to react as quickly as possible with minimal upset when the operator changes the set point
- to hold the controlled variable (process variable as close as possible to the set point
- to react as quickly as possible and with minimal upset when the process conditions change the value of the controlled variable.
What are controllers?
A device or program which operates automatically to regulate a controlled variable
Draw a loop block diagram
Definition of error
In process instrumentation the algebraic difference between the indication and the ideal value of the measured signal
formula for error Direct acting (DA)
e = PV - SP
formula for error Reverse acting (RA)
e = SP - PV
Can error be both negative and positive?
Yes
if the controller must increase when the Pv increases then the controller must be _________.
Direct acting (DA)
if the controller must decrease when the Pv increases then the controller must be _________.
Reverse acting (RA)
What is Gain?
Amount by which the input error is multiplied to produce an output
