CPAT Process Control Systems & Automation 2

Question 1

What is the primary function of a Distributed Control System (DCS) in a process plant?

Accepted Answer

Distribute control functions across multiple controllers while providing centralized operator monitoring

Answer

Perform only safety shutdown functions independent of process control

Answer

Centralize all I/O signals into a single processor for faster scanning

Answer

Replace all field transmitters with digital communication only

Question 2

What primarily distinguishes a Programmable Logic Controller (PLC) from a Distributed Control System (DCS) in industrial applications?

Accepted Answer

PLCs are typically optimized for discrete logic and sequential control; DCS is optimized for continuous process control

Answer

PLCs can only handle analog signals; DCS handles only digital signals

Answer

PLCs require field bus communication; DCS uses hardwired I/O only

Answer

PLCs operate at higher voltages than DCS systems

Question 3

What does the acronym SCADA stand for in industrial automation?

Accepted Answer

Supervisory Control And Data Acquisition

Answer

Sequential Control And Data Analysis

Answer

System Control And Device Automation

Answer

Supervisory Configuration And Device Architecture

Question 4

In process control, what is the standard signal range used by a 4–20 mA current loop transmitter to represent 0–100% of the measured variable?

Accepted Answer

4 mA = 0%, 20 mA = 100%

Answer

4 mA = 100%, 20 mA = 0%

Answer

0 mA = 0%, 20 mA = 100%

Answer

4 mA = 50%, 20 mA = 100%

Question 5

What is the purpose of a process interlock in an automated control system?

Accepted Answer

Automatically take a corrective or protective action when a process variable exceeds a defined limit

Answer

Fine-tune PID controller parameters during operation

Answer

Calibrate field instruments during normal operation

Answer

Synchronize the clocks of multiple PLCs on a network

Question 6

What is the function of a 'loop sheet' (or loop diagram) in an instrumentation and control project?

Accepted Answer

Detail the wiring, signal types, terminal connections, and instrument tags for a single control loop

Answer

Show the physical layout of all instruments in the field

Answer

Provide the process flow and major equipment arrangement

Answer

List all spare parts required for each instrument loop

Question 7

In a process control context, what is a 'setpoint'?

Accepted Answer

The desired target value that the controller attempts to maintain for the process variable

Answer

The current value being measured by the sensor in the field

Answer

The difference between the measured value and the desired value

Answer

The maximum allowable operating limit before a safety shutdown