Industrial Automation and Control Systems Interview Questions


The below lists shows the Industrial Automation and Control Systems Interview Questions, and also questions on PID, DCS, Control systems.

Industrial Automation and Control Systems

At present, what are the three levels of industrial automation ?

  1. Classical control theory

  2. Modern control theory

  3. Intelligent control theory

Give some example of intelligent control?

Typical examples of intelligent control the fuzzy logic that is considered as the automatic control systems it uses artificial intelligent and neural networks comparatively for automatic control.

Give some examples of automatic control systems?

Basically automatic control system can be divided into two types

  1. open-loop control system

  2. closed-loop control system

What are the integral components of control systems?

A control system includes a controller (PID, PI, P), sensors, transmitters, actuators, input and output interfaces. The output of the controller output sends signals to actuator which controls the required dynamics of system according to set points.

Do we use the same sensors on every control system theory?

No, different control systems requires different sensors, transmitters, actuators. For example, in a pressure control system we use pressure sensor for calculation of pressure. Electric heating control system uses temperature sensor.

What is the smart regulator function (intelligent regulator) of PID controller?

Major companies that are developing PID controllers have the feature of self-tuning of parameters this technology is called the smart regulator function or intelligent regulator. This type of PID controller adjust parameters automatically through intelligent adjustment or self-tuning adaptive algorithm to achieve optimized system dynamics.

How PID(Proportional Integral Differential controller) is linked with PLC(Programmable Logic Controller) and DCS(Distributed Control System)?

PID controller generates gain for actuator for the optimized values of pressure, temperature, flow, levels etc by its comprehensive Proportional gain, integral time and deferential time which are converted to electric signal and sent to PLC for communication of PLC, PID, Actuator, DCS(Distributed Control System) operator who just set the set points of system dynamics.

What is an open-loop control system?

Open-loop control system can be referred as the output of system has no effect on the output of the controller. In this type of control system controller gain is usually very high.

What is the closed-loop control system?

Closed-loop control systems a type of system in which output of system is sent (feed) back to controller to affect the output of the controller.

What do you mean by positive and negative feedback system?

If output of system is added to controller then we can say it is a positive feedback, if output of system is subtracted from controller then it is called negative feedback system.

Give some example of negative feedback system?

We can say a person is a closed-loop control system with negative feedback, the eye is the sensor which sends signals to the brain and brain acts as controller, what we see is sent to brain as negative feedback, the human brain system performs constant correction to finally make the correct action. If no eyes (Sensor) there will be no feedback loop, system at this stage could be assumed as an open-loop control system. Another interesting example is the automatic washing machine which continuously check the clothes are washed or not (via a sensor output) when it sees clothes are washed properly it cut off power automatically that example is also a closed-loop control system.

What is the step response of a system?

Step response is the output of system when step input (step function) is applied to the system, .

What do you mean by steady-state error (Offset error)?

The steady-state error refers as in steady state response of the system, the difference between the desired output (Set point) and the actual output (Process Value).

Define Stability of system?

A bounded input to the system generates the bounded output is referred to as stable system, that deals with the system poles, if all poles of the system lies at negative half plane then it is BIBO(Bounded Input Bounded Output System), however if some (Not all) poles of system lies at axis of plane system can be considered as marginally stable.