Plant Operator Selection System Test Process Control and Instrumentation 3

Question 1

The term 'turndown ratio' for a flow meter describes:

Accepted Answer

The ratio of the maximum to minimum measurable flow with acceptable accuracy

Answer

The maximum pressure the meter can withstand

Answer

How quickly the meter responds to flow changes

Answer

The angle at which the meter must be installed

Question 2

In a heat exchanger control scheme, the coolant flow is increased when the process outlet temperature rises above setpoint. This is an example of:

Accepted Answer

Feedback control

Answer

Feedforward control

Answer

Ratio control

Answer

Split-range control

Question 3

What is the purpose of an interlock in a process plant?

Accepted Answer

To automatically prevent or stop an operation when an unsafe condition is detected

Answer

To synchronize production rates across multiple units

Answer

To lock valves open during normal operations

Answer

To record production data in the historian

Question 4

A pressure transmitter has a range of 0-100 psig and a 4-20 mA output. What current signal corresponds to 50 psig?

Accepted Answer

12 mA

Answer

8 mA

Answer

10 mA

Answer

14 mA

Question 5

Control valve hysteresis is best described as:

Accepted Answer

The difference in valve position between increasing and decreasing signal strokes

Answer

The valve response lag when switching from heating to cooling service

Answer

The maximum allowable leak rate through a closed valve

Answer

The travel time from fully open to fully closed

Question 6

When calibrating a pressure transmitter, the technician applies a known input pressure and adjusts the output to match the expected 4-20 mA value. The two adjustments made are:

Accepted Answer

Zero and span

Answer

Gain and offset

Answer

Range and damping

Answer

Bias and proportional band