INSTRUMENTATION CONTROLS TECHNICIAN INTERVIEW
MOCK QUESTIONS AND ANSWERS UPDATED 2026 – 2027 .
Difference between 4-20mA signal and a 0-10v signal? - correct Answers -Both are analog signals. 4-
20mA is preferred because it has a live zero that can be referenced against a true zero. Its also less
susceptible to electrical noise.
0-10v is easier to implement but more prone to interference and voltage drop. Typically used for short
runs.
Describe the process you take to calibrate an instrument. - correct Answers --Gather tools and materials
needed.
-Gather documentation.
-Inspect instrument for damage, loose connections, or other issues.
-Follow manufacturer's or company guidelines for calibration process.
-Documentation once calibration is complete.
-Verify calibration was correct.
Describe calibration procedure. - correct Answers -Follow the company's or manufacturer's calibration
procedures. I then compare the instrument's output against a known reference standard. I then will
adjust input values and record the output values. Once complete, I will adjust the zero and span screws
and repeat the process. I will stop once the instrument is within tolerance.
What safety precautions do you take when working with equipment? - correct Answers --Wear
appropriate PPE.
-Lockout/Tagout.
-Verify power is off using a multi-meter.
-Communicate with team members.
1
, What is HART communication? - correct Answers -Its a communication protocol that allows transmission
of analog and digital signals between field devices and control systems. Allows users to access diagnostic
information from field devices and configure information.
What are common issues that occur with pressure transmitters? - correct Answers --They can drift
overtime from the original calibration due to temperature, vibration, or aging components.
-Small orifices can become clogged and lead to inaccurate readings.
Explain what loop checking is. - correct Answers -The process of checking that a loop functions correctly.
The means verifying the proper function of all sensors, transmitters, controllers, and final control
elements such as valves or actuators.
How do you ensure proper documentation of instrument calibration? - correct Answers -Follow an
approach that includes maintaining detailed records of procedures done. This means any information
about the devices loop number, location, calibration date, and any maintenance preformed. I will then
communicate with supervisors and team members if any significant concerns arise.
What is the role of an instrument tech ensuring plant safety? - correct Answers -Our role in plant safety
would be maintaining, calibrating, and repair of instruments and control systems. These instruments
and vital to the operation of the plant which directly affect the safety of the plant.
Explain the importance of grounding for instrument systems. - correct Answers -It provides a stable
reference point for electrical signals by minimizing noise interference. It also provides protective
measures for electrical faults and equipment damage. This also means it protects personnel from
electric shocks.
What is a thermocouple? - correct Answers -A device for measuring temperature. It has 2 wires with
different metals connected at one point. This will develop a voltage based off of temperature at the
junction.
What is a RTD? - correct Answers -A device that measures temperature. A wire that changes resistance
due to temperature. It will then read the resistance and calculate the temperature.
2
MOCK QUESTIONS AND ANSWERS UPDATED 2026 – 2027 .
Difference between 4-20mA signal and a 0-10v signal? - correct Answers -Both are analog signals. 4-
20mA is preferred because it has a live zero that can be referenced against a true zero. Its also less
susceptible to electrical noise.
0-10v is easier to implement but more prone to interference and voltage drop. Typically used for short
runs.
Describe the process you take to calibrate an instrument. - correct Answers --Gather tools and materials
needed.
-Gather documentation.
-Inspect instrument for damage, loose connections, or other issues.
-Follow manufacturer's or company guidelines for calibration process.
-Documentation once calibration is complete.
-Verify calibration was correct.
Describe calibration procedure. - correct Answers -Follow the company's or manufacturer's calibration
procedures. I then compare the instrument's output against a known reference standard. I then will
adjust input values and record the output values. Once complete, I will adjust the zero and span screws
and repeat the process. I will stop once the instrument is within tolerance.
What safety precautions do you take when working with equipment? - correct Answers --Wear
appropriate PPE.
-Lockout/Tagout.
-Verify power is off using a multi-meter.
-Communicate with team members.
1
, What is HART communication? - correct Answers -Its a communication protocol that allows transmission
of analog and digital signals between field devices and control systems. Allows users to access diagnostic
information from field devices and configure information.
What are common issues that occur with pressure transmitters? - correct Answers --They can drift
overtime from the original calibration due to temperature, vibration, or aging components.
-Small orifices can become clogged and lead to inaccurate readings.
Explain what loop checking is. - correct Answers -The process of checking that a loop functions correctly.
The means verifying the proper function of all sensors, transmitters, controllers, and final control
elements such as valves or actuators.
How do you ensure proper documentation of instrument calibration? - correct Answers -Follow an
approach that includes maintaining detailed records of procedures done. This means any information
about the devices loop number, location, calibration date, and any maintenance preformed. I will then
communicate with supervisors and team members if any significant concerns arise.
What is the role of an instrument tech ensuring plant safety? - correct Answers -Our role in plant safety
would be maintaining, calibrating, and repair of instruments and control systems. These instruments
and vital to the operation of the plant which directly affect the safety of the plant.
Explain the importance of grounding for instrument systems. - correct Answers -It provides a stable
reference point for electrical signals by minimizing noise interference. It also provides protective
measures for electrical faults and equipment damage. This also means it protects personnel from
electric shocks.
What is a thermocouple? - correct Answers -A device for measuring temperature. It has 2 wires with
different metals connected at one point. This will develop a voltage based off of temperature at the
junction.
What is a RTD? - correct Answers -A device that measures temperature. A wire that changes resistance
due to temperature. It will then read the resistance and calculate the temperature.
2
