Interview Questions and Answers - Control Loop
What is a Primary element ?
Primary element is the measuring element that quantitatively converts the measured variable energy into a form suitable for measurement.
What is a transmitter ?
A transmitter is device which converts a non standard signal into a standard signal. 3-15 psi,4-20 ma etc.
What is meant by controlled variable?
A controlled variable is the value which is sensed to originate a feedback signal. Controlled variable is also known as process variable.
What is a controller?
A controller is a device which operates automatically to regulate a controlled variable.
What is Controller algorithm?
Controller algorithm is a mathematical representation of the control action to be performed.
What is set point?
Set point is an input variable which sets the desired value of the controlled variable.
Question - Draw a closed control loop?
what is error in a closed loop ?
The algebraic difference between the real value and ideal value of the measured signal.
What is manipulated variable?
A quantity or condition which is varied as a function of the algebraic error signal so as to cause a change to the value of the directly controlled variable.
What is feedback control?
Control action in which a measured variable is compared to its desired value to produce an actuating error signal which is acted upon in such a way as to reduce the magnitude of the error.
What Cascade control ?
Control in which the output of one controller is introduced as the set point for another controller.