My Interview Questions And Answers [Electronics,Electrical and Instrumentation]

How Does a Battery Work?

2009-08-05T13:31:00.001-07:00

Interview Question:How Does a Battery Work?

and How does a battery charge?

Answer:

Battery has got two leads,one positive and other negative.Electrons gather at the negative terminal of the battery and if you connect a wire across negative to positive,then the electrons from negative end will quickly flow through the wire to the positive terminal.Normally you will have a load connected in the wire which reduces the flow of electrons like a bulb or motor.

Working

Inside the battery itself, a chemical reaction produces the electrons. The speed of electron production by this chemical reaction (the battery's internal resistance) controls how many electrons can flow between the terminals. Electrons flow from the battery into a wire, and must travel from the negative to the positive terminal for the chemical reaction to take place.

Difference between megger and earth tester?

2009-07-24T09:41:00.001-07:00

Interview Question: Difference between megger and earth tester?

Answer:

Megger is an instrument which in addition to measurement of high resistance can be used to test the quality of the insulation at or above its operating voltage. whereas earth tester is used to measure low earth resistance.

Megger is used for measuring an insulation resistance of motor winding of cable etc. which is measured in megaohm. While earth tester has earth electrodes which are used to measure eathpit resistance & it is measured in ohm.

HR Interview Questions For Electronics/Instrumentation Engineers

2009-07-16T08:18:00.001-07:00

HR Interview Questions For Electronics /Communication /Instrumentation Engineers

1.) How much salary you’re Expecting?
Answer : I would expect a salary which reflects the experience and qualifications that I bring to the role.

Alternate Answer : Based on the information I have about the position, a salary in the range 15,000 - 18,000 would reflect the experience and expertise that I would bring to the role.

2)Why did you take Instrumentation as your branch in Engineering?

Answer:After having passed my class 12th examination,I actually didn’t have any idea about what was involved in Instrumentation.But I wanted to built my career around something from where we could control and monitor a whole industry.

3.) What kind of person would you refuse to work with?
Well, I am a person, who can work with all kinds of people. However, I feel bit uncomfortable to work with persons of selfish and ingratitude in nature.

4.) What have you done to improve your knowledge in the last year?
Every should learn from his mistake. I always try to consult my mistakes with my kith and kin especially with elderly and experienced person.

5.) What is more important to you: the money or the work?
Money and work both are like siblings. But I believe when you work hard; money will flow to you. So work is more important than money. Only hard work can help you put another feather in your success cap.

6.) Why do you want to join in industry?
industry is a place where the graduates have the opportunity to apply their skills n knowledge which they learn from their respective institutions. so feel industry is a best way for a person to applying their practical knowledge.

7.) Are you a team player?
while answering this question, try to keep yourself on both sides. For example, if the interviewer asks if you prefer to work alone or on a team, he may be trying to get you to say you are one way or the other. But you don't have to play this game. The reality is that most jobs require us to work both independently and in teams. Your response to this question should show that you have been successful in both situations or (In case you don’t find yourself comfy with team work say this) - I believe in individual work recognition [this would not put your weakness in front of others that strongly, Remember people who take interviews are super masters, do not fool them]

8)What is your greatest strength?

My greatest strength includes my analytical approach, my strong logics and my patience

Difference between electrical and electronics?

2009-07-15T09:10:00.001-07:00

Interview Question:

What is the main difference between electrical& electronics? Define them.

Answer:

In Electronics, as we study about the motion of electrons in the semi conducting materials, the currents and voltages are of very negligible values. With the less amounts of current and voltages we are able to perform many tasks using Electronics.

Where as in electrical, it is the study of motion of electrons in metals.So, usually the conductivity is more for metals, so more voltage of order 230v and more currents of higher order amps are used.

Job Inspirational Quotes

2009-07-15T01:30:00.001-07:00

"You cannot be successful in any business without believing that it is the greatest business in the world. You have to put your heart in the business and the business in your heart"

How to Calibrate Control Valve? Which Instrument is Used?

2009-07-03T13:10:00.001-07:00

Interview Question: How to Calibrate Control Valve? Which Instrument is Used?

Interview Answer:

For the calibration of a control valve a loop calibrator or a pressure calibrator can be used between 3-15psi.Check the valve position for 3psi which is to be 0 for a NC type valves.In such manner check the valve position for various ranges(6psi,9psi,12psi & 15psi).the valve position should be 0 for 3psi and 50% for 9 psi and completely opened for15psi.

The same procedure is applicable for NO type valves.The valve is open for 3 psi and completely closed for 15psi.Any errors occurred may be rectified by Zero span adjustment.

Why is Flow measure in Square-root?

2009-07-03T12:59:00.001-07:00

Interview QUestion: Why is Flow measure in Square-root?

Answer: Where orifice plate is used to measure flow alone, the signal is square rooted. it is by the formula Q=K (squareroot of Differential pressure). If other types of FT are used then the signal from that FT need not to be square rooted.

Why SCAN time of DCS is more than PLC?

2009-06-18T22:13:00.001-07:00

Interview Question: Why SCAN time of DCS is more than PLC? or Why does PLC have scan time less than DCS.

If so,then why do we use DCS instead of PLC?

My Interview Answer:

Scan time of DCS is more than the scan time of PLC when the I/O's are digital.Whereas the scan time of DCS is less than the scan time of PLC when the I/O's are analog.Hence DCS is better when analog signals are considered whereas PLC is better when digital signals are considered.However DCS do handle both analog and digital signals. It can also have more no. of I/O's compared to PLC.About 1 lakh I/O’s are available in DCS. Hence we use DCS.

DIFFERENCE BETWEEN UPS and INVERTER?

2009-06-18T22:12:00.001-07:00

Interview Question: What is the difference between an UPS and an Inverter?

Answer:

Inverter is device which is convert dc supply to ac supply.It has two units 1. charging 2.inverter circuit(which covert dc supply into ac supply with the help mosfet or transistor).The proper meaning of inverter is a device which converts dc into ac.The inverter also contains a battery unit and an dc to to ac
conversion unit. when the power fails the inverter will deliver power from switching from main source to battery source. The switching time here is normally greater than 20 ms.

Ups : means uninterrupted power supply.The proper meaning of this is a device, which delivers power, even if the source power fails(Uninterrupted power supply).This is also contains the same thing as a inverter except here the switching time from main source to backup source is less than 10ms, so that the computer hard drives or insensitive power products should not be affected from this.Depending on the switching time there is a online ups and offline ups. off line ups is same as a inverter.

What is the difference between Volumetric flow meter and Mass flow meter?

2009-06-18T21:05:00.001-07:00

Interview Question: What is the difference between Volumetric flow meter and Mass flow meter?

Answer:

Volumetric flow meter gives flow rate in terms of volume viz liters/hr,gallon, m3/hr etc whereas mass flow meter gives direct mass flow rate viz kg/hr or tons/hr etc

mass = density* volume

volumetric flow = area*velocity

volumetric flow gives how much volume is passing through a given point,it does not give the real mass of fluid is passing.Mass flow is highly depends on the density as well as on temperature,change in these changes the mass flow.

Why transmitter signal range is from 4-20 mA only

2009-06-18T20:53:00.001-07:00

Interview Question: Why transmitter signal range is from 4-20 mA only? Why can’t it be from 0-100 or 0-20mA?

Answer:

Because if use 0-100% instead of 0 -20 mA ,and if there is any signal cable damage or open cable then it will show only 0%.So we will not be able to know any error in the reading.But in the case of 4-20mA, a zero mA value means error.

What is dead weight tester and where it is used?

2009-06-18T20:47:00.001-07:00

Interview Question :what is dead weight tester and where it is used?

Answer:

Dead weight tester is the test instruments, in which the required test instruments is checked against the standard weight.

Dead weight tester used for pressure gauge, pressure transmitter, pressure switch calibration in high range. (Kg\cm2or bar). it is used for industrial purpose in instrumentation department.

Electric Train Voltage Supplied?

2009-06-18T09:24:00.001-07:00

Question : Electric Train Voltage Supplied?

Answer:

ac voltage of 25kv

Electric Motor Efficiency

2009-06-18T09:05:00.001-07:00

Interview Question: What is the Efficiency in Electric motor ?

Answer:

Power
(hp)         Minimum Nominal Efficiency1) 
1 - 4        78.8 
5 - 9         84.0 
10 - 19      85.5 
20 - 49      88.5 
50 - 99      90.2 
100 - 124     91.7 
> 125        92.4 
as per NEMA

Electrical motor efficiency is the ratio between the shaft output power - and the electrical input power.Electrical Motor Efficiency when Shaft Output is measured in WattIf power output is measured in Watt (W), efficiency can be expressed as:m = Pout / Pin?

where

m = motor efficiency

Pout = shaft power out (Watt, W)

Pin = electric power in to the motor (Watt, W)

Electrical Motor Efficiency when Shaft Output is measured in Horsepower.

What would happen if a transformer is made to operate at 60Hz instead of 50Hz?

2009-06-18T09:01:00.001-07:00

Interview Question: What would happen if a transformer is made to operate at 60Hz instead of 50Hz?

Answers :There will be no effect on the secondary side voltage because in transformer frequency remains constant, but the hysteresis losses will increase when the transformer is made to operate at 60Hz.

PS:Eddy current loss is not dependent on frequency

Welcome to My Interviews Questions and Answers Blog

2009-06-18T08:57:00.001-07:00

Here, i’ll share all the questions which were asked to me at various interviews including the answers which were answered by me and also what I found after searching the web.