What is the first step in systematic fault finding?

Observe the symptoms and gather information

Replace the most likely failed component immediately

Recalibrate the transmitter to its original range

Isolate and lock off the entire control loop

If a 4-20mA loop signal sits steadily at 3.8mA, what is the most likely cause?

The process value is below the bottom of the calibrated range

The process variable has exceeded the upper range value set on it

Excessive supply voltage applied across the loop terminals

Electrical noise coupled onto the signal cable in the tray

Free mock exam

Fault Finding — Instrumentation Practice

Free topic-focused mock exam: all 10 questions on Fault Finding, drawn from the wider Instrumentation bank. 35-minute timer, 70% to pass, worked explanation on every question. Use this when you've taken the full mock once and want to drill the topics you got wrong.

Questions: 10
Time limit: 35 min
Pass mark: 70% · 7/10
Question bank: 10

Free, no sign-up. Retake as many times as you like — the questions are reshuffled, with the answer order changed.

Sample questions

01What is the first step in systematic fault finding?
- AObserve the symptoms and gather information
- BIsolate and lock off the entire control loop
- CRecalibrate the transmitter to its original range
- DReplace the most likely failed component immediately
Why: Systematic troubleshooting begins with observing symptoms, gathering information, and understanding the problem before testing.
02If a 4-20mA loop signal sits steadily at 3.8mA, what is the most likely cause?
- AThe process value is below the bottom of the calibrated range
- BExcessive supply voltage applied across the loop terminals
- CElectrical noise coupled onto the signal cable in the tray
- DThe process variable has exceeded the upper range value set on it
Why: Under NAMUR NE43, 3.8–4.0 mA is a valid under-range signal: the process value is below the lower range value. Below 3.8 mA signals a failure (3.6 mA or less failed low, 3.6 to 3.8 mA failed detected low), and 21 mA or more signals failed high.
03What tool is used to simulate a transmitter output for testing?
- ADigital oscilloscope
- BDigital multimeter
- CLoop calibrator
- DPower supply
Why: A loop calibrator can source precise current signals to simulate transmitter outputs for testing purposes.

Common questions

Is the Fault Finding mock exam free?

Yes, it is free with no sign-up needed. Questions are pulled at random from a substantial bank, with a worked explanation on every question after you submit.

Can I retake the mock exam?

Yes. Every attempt picks a different random selection and reshuffles the options, so each retake gives you genuinely new questions. No limit on retakes.

Does this count as a qualification?

No. This is independent practice material and does not award a qualification, card or certificate. Where a subject has a formal qualification or card, you gain it through an approved provider.