TECHNICAL INTERVIEW AND EXAMINATION QUESTION FOR INSTRUMENTATION ENGINEER :

Updated: Jan 26

In this article, we will look at some most common question asked in the interview. Even for some competitive exam, it may be helpful.

We all know that instrumentation is a vast field. For every different discipline, you confront different types of question.

Here, in this question and answer series, I will cover question and answer based on the instrumentation and automation field.

Due to the number of questions is higher, I will write down in several parts.

1) What is Instrumentation?

Ans - Instrumentation means measurement. As an instrumentation engineer, you deal with different types of measurement and they can be like pressure, temperature, flow, level, analytical and vibration, etc.

2) What is a sensor?

Ans - Sensor is a device which measures process variable and converts that process variable to a low level of an electrical signal.

3) What is a transmitter?

Ans - Transmitter, as a name suggest, is used to transmit a signal to a long distance without losing data. The main function of the transmitter is to convert the signal to 4-20 mA and maintain that value of current to transmit it over a long distance.

4) What is the Transducer?

Ans - Transducer is a device which is used to convert one form of a signal to another form. For example, diaphragm which converts the mechanical displacement to pressure.

5) A unit of low pressure is?

Ans - Torr

6) psi stands for?

Ans - Pounds Per Square Inch.

7) Where Pirani gauge is used?

Ans - In Low-Pressure Measurement.

8) What HP and LP indicate of differential pressure transmitter?

Ans - HP stands for High Pressure and LP stands for Low Pressure.

9) Why we use 4-20 mA signal instead 0-20 mA?

Ans - In 0-20 mA signal, if a wire gets cut you can not identify whether a signal is coming due to wire break or due to actual process value. To prevent this confusion 4-20 mA is preferred.

The second reason is that it maintains the 1:5 ratio. It means that when 4-20 mA signal travels to Analog card then first it converts it to 1-5 Volt signal with the help of inbuilt 250-ohm resistor. Due to that conversion become much easier.

10) What MWP indicate on pressure transmitter?

Ans - MWP means Maximum Working Pressure a transmitter can handle.

11) Give the name of the pressure sensor

Ans - Diaphragm, bourdon tube, bellows, capsules, etc. used as a pressure sensor.

12) Difference between accuracy and precision.

Ans - Degree of closeness is known as accuracy.

To measure a value repeatedly over a long period of time is called precision.

13) What is a resolution?

Ans - The smallest change that can be detected by an instrument is called resolution.

14) Types of the sensor

Ans - It can be an Analog or Digital sensor.

15) Types of Transducer

Ans - It can be Active or Passive Transducer.

16) Functional elements of instruments.

Ans - 1. Primary sensing element (sensor)

2. Variable conversion element

3. Data transmission element

4. Data presentation element

17) Give the name of the process variable

Ans - Temperature, pressure, level, flow, etc. known as a process variable.

This is the basic question you may confront in an interview. I will cover other questions in my upcoming article based on electronics, electrical, instrumentation and automation field.

If you have any doubt or wants to ask some more questions then please put down there in the comment section.

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