CPT Process Control & Automation 3

Question 1

What is the primary purpose of a distributed control system (DCS) compared to a standalone controller?

Accepted Answer

To distribute control across multiple processors while providing centralized monitoring

Answer

A DCS distributes control functions across multiple controllers while allowing operators to monitor and manage the entire plant from centralized operator stations.

Question 2

In a programmable logic controller (PLC), what is a 'scan cycle'?

Accepted Answer

The sequential process of reading inputs, executing logic, and updating outputs

Answer

A PLC scan cycle consists of reading all input states, executing the control program logic, and then writing the results to all outputs, repeated continuously.

Question 3

What does 'split-range control' involve?

Accepted Answer

Sending a single controller output to two or more final control elements that operate in sequence

Answer

Split-range control sends one controller output signal to multiple valves that each operate over a different portion of the output range (e.g., 0–50% and 50–100%).

Question 4

Which term describes the change in process variable per unit change in controller output, expressed as a ratio?

Accepted Answer

Process gain

Answer

Process gain is the ratio of the change in the controlled variable to the change in the manipulated variable, characterizing how sensitive the process is to control action.

Question 5

A thermocouple produces a signal based on which principle?

Accepted Answer

Voltage generated at the junction of two dissimilar metals

Answer

Thermocouples operate on the Seebeck effect, where a voltage is produced at the junction of two dissimilar metals proportional to the temperature difference.

(CPT) Certified Process Technician Practice Test

(CPT) Certified Process Technician Practice Test

CPT Process Control & Automation 3