Free C-274 Practice Questions

Question 1

A flow loop repeatedly overshoots its setpoint. A synchronized trend shows the controller current and pressure at the actuator changing smoothly, but the actual valve stem remains stationary and then jumps. The same stick-and-jump motion occurs in both travel directions. Instrument-air pressure remains adequate throughout. Which fault best explains this pattern?

Accepted Answer

Excessive static friction in the valve assembly

Answer

Excessive integral action in the controller

Answer

Insufficient I/P air-supply pressure

Answer

Excessive damping applied to the measured flow signal

Question 2

After a series-connected indicator is added, a two-wire level transmitter reads correctly near the bottom of its range but cannot deliver the required high-end current. The supply holds at 24 V DC, and the transmitter requires at least 12 V at its terminals. The receiver, new indicator, and wiring contribute 250 ohms each; there are no other voltage drops. At the required 20 mA, which voltage-budget assessment is correct?

Accepted Answer

9 V would remain; excessive loading leaves insufficient transmitter voltage.

Answer

15 V would remain; the transmitter has adequate operating voltage.

Answer

19 V would remain; the transmitter has adequate operating voltage.

Answer

12 V would remain; the minimum terminal-voltage requirement would still be met.

Question 3

An operator reports that a fill pump has failed because it is off while the tank is below the upper level setting. The two-point control starts filling at 30% and stops at 70%. The pump stopped at 70%, and normal withdrawal has since lowered the level to 50%. All permissives are healthy, and the level is within the permitted operating band. What response is warranted?

Accepted Answer

Leave automatic control active; the next start is due at 30%.

Answer

Start the pump manually because the level is below the stop setting.

Answer

Isolate the fill system and troubleshoot a failed low-level switch.

Answer

Raise the start setting above 50% to end the off period.

Question 4

Before opening a transmitter's process connection, a technician locks out the identified pressure source and releases trapped liquid through the designated drain. The gauge reaches zero. After the drain is closed, pressure begins to build again; no process fitting has yet been loosened. Under the hazardous-energy procedure, what must happen before the connection is opened?

Accepted Answer

Identify and control the source of renewed pressure, then verify isolation remains effective before opening.

Answer

Repeat the drain step and loosen the connection immediately after the gauge returns to zero.

Answer

Have another technician watch the gauge while the connection is loosened slowly.

Answer

Hold the controller at zero output and use the existing lockout as proof of isolation.

Question 5

During verification of an orifice flow-measurement loop, the specified 4-20 mA output must be linear in flow over 0-200 L/min. At a reference flow of 120 L/min, the transmitter indicates 120 L/min and delivers 13.6 mA to the receiver, but the receiver displays 154.9 L/min. Both instruments agree at zero and full-scale flow. Which correction addresses the midrange mismatch without disturbing those endpoints?

Accepted Answer

Remove the extra square-root extraction at the receiving instrument.

Answer

Change the receiver's electrical input range from 4-20 mA to 0-20 mA.

Answer

Reduce the receiver's upper engineering-range value while retaining its conversion function.

Answer

Shift the transmitter's zero downward while retaining the receiver's present configuration.

Question 6

Commissioning checks confirm that increasing controller current raises I/P pressure and closes an air-to-close tank inlet valve. In automatic operation, however, a rise in measured level above setpoint causes current to fall, opening the inlet farther and accelerating the level rise. The measurement is accurate. Which controller change corrects the feedback direction while retaining the specified valve and I/P arrangement?

Accepted Answer

Change control action so output current increases when measured level rises.

Answer

Reduce proportional gain to soften the valve response.

Answer

Lengthen the integral time so the inlet valve makes slower corrective movements.

Answer

Increase PV damping to delay responses to level changes.

Question 7

A level indication has stopped responding to actual tank changes. With the process secured for testing, the technician disconnects the transmitter at its field terminals and connects a loop calibrator in simulate mode using the existing loop supply. The receiver correctly displays the configured low, middle, and high values when 4, 12, and 20 mA are simulated. What has this test actually demonstrated?

Accepted Answer

The wiring and receiver pass these signal checks; pressure sensing is still untested.

Answer

The complete level loop is calibrated, including its pressure connection.

Answer

The transmitter's pressure calibration agrees with all three current test points.

Answer

The impulse line must be blocked, since successful simulation rules out the transmitter electronics.

Question 8

A recipe change replaces a liquid of density 1,000 kg/m³ with one of density 800 kg/m³. A vented tank's hydrostatic transmitter still converts pressure to level using 1,000 kg/m³. Its pressure measurement is accurate, there is no mounting offset, and the liquid has uniform density. Automatic inlet control settles at an indicated setpoint of 1.20 m. The maximum permitted actual level is 1.40 m. How should the apparent zero control error be interpreted?

Accepted Answer

Actual level is 1.50 m; the indicated setpoint conceals an inventory above the operating limit.

Answer

Actual level is 0.96 m; the lower density has reduced the tank's controlled height.

Answer

Actual level is 1.20 m; integral control has compensated for the changed liquid density.

Answer

Actual level is 1.44 m; adding 20% to the height places the tank above its limit.

Question 9

With the process isolated for a full-stroke test, a direct-acting I/P specified for 4-20 mA to 3-15 psig produces 3 psig at 4 mA and 9 psig at 12 mA, but only 10.5 psig at 20 mA. Actual input current is verified. The installation calls for a 20 psig air supply: the header remains at 20 psig, but pressure at the I/P supply port falls to 11 psig during the upper-end test. The appropriate first correction is to:

Accepted Answer

Restore the specified air supply at the I/P under demand.

Answer

Increase the I/P span adjustment until its output reaches 15 psig.

Answer

Raise the I/P zero adjustment to recover the missing upper-end pressure.

Answer

Replace the controller output card to eliminate high-end current clipping.

Question 10

An electromagnetic meter on a conductive rinse-water line becomes erratic after the piping is rerouted over a high point. Independent flow remains steady. An inspection confirms that an air pocket leaves the meter's tube partly empty, while grounding and analog-signal checks pass. Which intervention addresses the measurement fault rather than concealing its symptoms?

Accepted Answer

Restore a fully liquid-filled measuring tube and repeat the flow check.

Answer

Raise the low-flow cutoff to suppress the fluctuations.

Answer

Perform a zero adjustment with the meter left in its partly empty condition.

Answer

Increase input filtering to smooth the indicated flow.

Free C-274 Practice Questions

Domain 1: apply process control troubleshooting safety procedures

Question 1

Domain 2: troubleshoot pressure-type liquid level sensors

Question 2

Domain 3: troubleshoot analog flow sensors

Question 3

Question 4

Domain 4: troubleshoot pneumatic proportional valves and I/P converters

Question 5

Question 6

Domain 5: troubleshoot loop controllers

Question 7

Domain 6: identify systems-level process control troubleshooting methods

Question 8

Domain 7: troubleshoot a closed-loop liquid level control system

Question 9

Domain 9: troubleshoot an on/off liquid level control system

Question 10

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