INSTRUMENTATION ENGINEERING INTERVIEW QUESTIONS(PART 6)

PART 6

1. How can level control be installed in steam drum for measuring the level of steam drum?
2. What is ultrasonic flowmeter?
3. Differentiate between ultrasonic flowmeter and radar type flow meter.
4. What is the use of temprature compensation?
5. What is modbus?
6. How signals can be taken through modbus?
7. How earthing can be checked?
8. How many ohms are required for proper earthing?
9. Explain signal isolator.
10. Which wiring connection is preferred in motor for industrial use?
11. What do you mean by trim?
12. How DP Transmitter can be calibrated for crude application in floating roof tank?
13. What is the principle of capacitance type level transmitter?
14. How process line mpm calculation is done?
15. Explain PLC Level and its type?
16. What is procedure on mmwc in to tph?
17. How an rtd work, and what volts/current goes to a RTD to measure the resistance?
18. What is consistency transmitter and describe its working?
19. How to calculate MMWC values into tonnes?
20. How can I make calculation to Install level transmitter (DP) for open tank and close tank?
21. What is difference between DO and DI?
22. What is loop1 and loop2 in MTS LT?
23. How to calibration a control valve?
24. What is dry leg calibration and where is it used?
25. How flow can be measured with dp?
26. Why MMWC unit is used?
27. How HART protocol can be connected with control valves?
28. What is the meaning of slope in PH transmeter?
29. What is Difference between PLC and CNC?
30. If we have 450 mm height boiler drum level, so what is span & zero value for a dpt transmitter?

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INSTRUMENTATION ENGINEERING INTERVIEW QUESTIONS(PART 5)

PART 5

1.What is furnace draft control?
Balanced draft boilers are generally used negative furnace pressure. When both forced draft and induced draft are used together, at some point in the system the pressure will be same as that of atmosphere. Therefore the furnace pressure must be negative to prevent hot gas leakage. Excessive vacuum in the furnace however produces heat losses through air infiltration. The most desirable condition is that the one have a very slight negative pressure of the top of furnace.

2.What is intrinsically safe system?
Intrinsic safety is a technique for designing electrical equipment for safe use in locations made hazardous by the presence of flammable gas or vapours in the air. Intrinsically safe circuit is one in which any spark or thermal effect produce either normally or under specified fault conditions is incapable of causing ignition of a specified gas or vapour in air mixture at the most ignited concentration.

3.What is zener diode? What is voltage regulator?
The breakdown region of a p-n diode can be made very sharp and almost vertical diodes with almost vertical breakdown region are known a s zener diodes. A zener diode operating in the breakdown region is equivalent to a battery. Because of this current through zener diode can change but the voltage remains constant. It is this constant voltage that has made the zener diode an important device in voltage regulation.
Voltage regulator: The output remains constant despite changes in the input voltage due to zener effect.

4.What is force balance principle? State some of its’ advantages?
Force balance principle: A controller which generates an output signal by opposing torque. The input force is applied on the input bellows which moves the beam. This crackles nozzle back pressure. The nozzle back pressure is sensed by the balancing bellows which brings the beam to balance. The baffle movement is very less about 0.002 for full scale output.
Advantages:
1. Moving parts are fewer.
2. Baffle movement is negligible
3. Frictional losses are less

5.What is motion balance principle?
A controller which generates an output signal by motion of its parts. The increase in the baffle is to move towards the nozzle. The nozzle back pressure will increase. This increase in the back pressure acting on the balancing bellows, will expand the bellows. The nozzle is moved upward due to this. The nozzle will move until motion almost equals the input baffle motion.

6.How will you test a transistor with a multimeter?
1. Emitter +ve of meter and base -ve output =Low resistance
2. Emitter -ve of meter and base +ve output =High resistance
3. Collector +ve and base -ve output =Low
4. Collector -ve and base +ve output =Low
Emitter: Collector = High resistance
PNP: Opposite Results

7.Explain ratio control system?
A ratio control system is characterized by the fact that variations in the secondary variable don’t reflect back on the primary variable. A ratio control system is the system where secondary flow is hold in some proportion to a primary uncontrollable flow.
If we assume that the output of a primary transmitter is A. and the output of the secondary transmitter is B, and that the multiplication factor of the ratio relay is K, then for equilibrium conditions which means set valve is equal to measured valve, we find the following relation:
KA-B=0 or B/A = K where ‘K’ is the ratio setting off the relay.

8.What is solenoid valve? Where it is used?
A solenoid is electrically operated valve. It consists of solenoid coil in which magnetic plunger moves. This plunger is connected to the plug and tends to open or close the valve. There are two types of solenoid valves:
1. Normally Open
2. Normally closed
Use: It is used for safety purpose in different electric work

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INSTRUMENTATION ENGINEERING INTERVIEW QUESTIONS(PART 4)


PART 4

1.What is the use of single seated valve?
The single seated valve is used on smaller sizes where an absolute shut off is required. The use of single seated valve is limited by pressure drop across the valve in the closed or almost closed position.

2.What is the use of double seated valve?
In double seated valves the upward and downward forces on the plug due to reduction of fluid pressure are nearly equalized. It is generally used on bigger size valves and high pressure systems. Actuator forces required are less.

3.What is the use of valve positioner?
Valve positioner can be used for following reasons:
1. Quick action
2. Valve hysterisis
3. Viscous liquids
4. Split range.
5. Line pressure changes on valve
6. Bench set not standard
7. Reverse valve operations

4.What are primary elements of measuring pressure? Which type of pressure can be measured by these elements?
Primary elements of measuring pressure are:
1. Bourdon Tube
2. Diaphragm
3. Capsule
4. Bellows
5. Pressure springs
These elements are known as elastic deformation pressure elements.

5.Name different types of bourdon tubes?
Types of bourdon tubes:
1. C type
2. Spiral
3. Helix

6.What are different types of control valves?
The commonly used control valves can be defined as follows:
a. Depending on Action:
Depending on action there are two types of control valves
1. Air to close
2. Air to close
b. Depending on body:
Depending on body there are 4 types of control valves
1. Globe valves single or double seated
2. Angle valves
3. Butterfly valves
4. Three way valves

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INSTRUMENTATION ENGINEERING INTERVIEW QUESTIONS(PART 3)

PART 3

1.How is automatic reference junction compensation carried out in temperature recorders?
In automatic reference junction compensation, variable nickel resistor is used. As the temperature changes, so does its resistance. This reference junction compensator is located, so that it will be at the temperature of the reference junction. The reference junction is at the poset where the dissimilar wire of the thermocouple is rejoined. This joint is invariably at the terminal strip of the instrument.

2.What are de-saturators?
When, in some processes, e.g. batch processes, long transient responses are expected during which a sustained deviation is present the controller integral action continuously drives the output to a minimum or maximum value. This phenomenon is called ‘integral saturation of the control unit’. When this condition is met, then this unit is de-saturated.

3.Explain the working of Rota meter.
Variable area meters are special form of head meters. Where in the area of flow restrictor is varied. So as to hold the differential pressure constant. The rota meter consists of a vertical tapered tube through which the metered fluid flows in upward direction. As the flow varies the ‘float’ rises or falls to vary the area of the passages that the differential across it balances the gravitational force on the ‘float’. The differential pressure is maintained constant. The position of the ‘float’ is the measure of the rate of flow.

4.What is the working principle of the magnetic meter?
An electric potential is developed when a conductor is moved across the magnetic field. In most electrical machinery the conductor is a wire. The principle is equally applicable to a moving, electrically conductive liquid. The primary device of commercial magnetic meters consist of straight cylindrical electrically insulated tube with a pair of electrodes nearly flush with the tube walls and located at opposite end of a tube diameter. This device is limited to electrically conducting liquids. The magnetic meter is particularly suited to measurement of slurries and dirty fluids.

5.Explain the mechanism behind the turbine meter?
Turbine meters consist of straight flow tube within which a turbine or fan is free to rotate about it s axis which is fixed along g the centre line of the tube. Mostly, a magnetic pick up system senses the rotation of the rotor through the tube walls. The turbine meter is a flow rate device
, since the rotor speed is directly proportional to the flow rate. The output is usually in the form of electric pulses from the magnetic pick up with a frequency proportional to the flow rate.

6.How would you choose differential range?
The most common range for differential range for liquid measurement is 0-100. This range is high enough to minimize the errors caused by unequal heads in the seal chambers. It is also dependent on the differences in the temperature of the load lines. The 100 range permits an increased in capacity up to 400. While decrease down up to 20 by merely changing the range tubes or range adjustments.

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INSTRUMENTATION ENGINEERING INTERVIEW QUESTIONS AND ANSWERS (PART 2)

PART 2

1. How D.P. transmitter can be applied to close tank?
In closed tank, bottom of the tank is connected to the high pressure side of the transmitter. Top of tank is connected to the lower pressure side of the transmitter. In this way vessel pressure can be measured.

2. How D.P. transmitter can be applied to open tank?
In open tank the lower pressure side is vented to the atmosphere. All pressure is applied to the high pressure side. This vessel pressure is measured through high pressure side.

3. Explain the working of an electronic level troll?
The variation in level of buoyancy resulting from a change in liquid level varies the net weight of the displacer increasing or decreasing the load on the torque arm. This change is directly proportional to change in level and specific gravity of the liquid. The resulting torque tube movement varies the angular motion of the rotor in RVDT providing a rotor change proportional to the rotor displacement, which is converted and amplified to a D.C. current.

4. Explain the working of an enraf level gauge?
Enraf level gauge is based on the ser powered null balance technique. A displacer serves as continuous level sensing element. A two phase ser motor controlled by a capacitive balance system winds unwinds the the measuring wire until the tension in the weight springs is in balance with the weight of the displaced part immersed in the liquid. The sensing system in balance measures the two capacitance formed by the moving central sensing rod provided by the two capacitor plates and the si plates.

5. What is the constant voltage unit?
The constant voltage circuit consists of a rectifier, CR and a filter capacitor. It is followed by two stages of zener regulation. Abridge configuration is provided to lamp line voltage zener regulation. Regulation 1 and regulation 2 provides relatively provide constant current. Resistors form a bridge that may remoment line voltage effects.

6. Explain the burnout feature.
Burnout provides the warnsug feature of driving indicator at the end of scale, if the input circuit is open. A burnout resistor is provided which develops a voltage drop between the measuring circuit and amplifier. The polarity of the signal determines the direction of the servo drive upon an open circuit in the input.
Upscale burnout: R value 10 M
Downscale burnout: R value 22 M

7. Why thermo wells are used? What materials are used in thermo wells?
In numerous applications, it is neither desirable nor practical to expose a temperature sensor directly to a material. Wells are therefore used to protect against damage corresion, arosion, aborsion and high pressure processes. A thermo well is also useful in protecting a sensor from physical damage during handling and normal operations.
Materials used in thermo wells: Stainless steel, Inconel, Monel, Alloy Steel, Hastelloy.

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IMPORTANT INTERVIEW QUESTIONS FOR INSTRUMENTATION ENGINEERING(PART 1)

 
Hello Friends, here i am posting about important interview part 1 questions which are mostly  asked by the all core companies  like HONEYWELL, SOLITONTECH , MAHINDRA SATYAM , L&T etc.  So please make use of it.  All the best!!!
PART 1
QUESTIONS:
  1. What are different types of orifice plates? State their uses.
  2. How do you identify an orifice in the pipeline?
  3. Why is the orifice tab provided?
  4. Explain Bernoulli’s theorem. State its application.
  5. How can a D.P. transmitter be calibrated?
  6. How is flow measured in square root?
  7. Name different parts of a pressure gauge. Explain the use of hair spring in the pressure gauge.
ANSWERS:
1. What are different types of orifice plates? State their uses.
Different orifice plates are:
 1. Concentric
 2. Segmental
 3. Eccentric
 Concentric: These plates are used for ideal liquid as well as gases and steam service. Concentric holes are present in these plates, thats why it is known as concentric orifice.
 Segmental: This plate has hole in the form of segment of the circle. This plate is used for colloidal and sherry flow measurement.
 Eccentric: This plate has the eccentric holes. This plate is used in viscous and sherry flow measurement.

2. How do you identify an orifice in the pipeline?
An orifice tab is welded on the orifice plate which extends out of the line giving an indication of the orifice plate.

3.Why is the orifice tab provided?
Following reasons justify for providing orifice tab:
1. Indication of orifice plate in a line
2. The orifice diameter is marked on it.
3. The material of the orifice plate.
4. The tag number of the orifice plate.
5. To mark the inlet of an orifice.

4. Explain Bernoulli’s theorem. State its application?
Bernoulli’s theorem states that the ‘total energy of a liquid flowing from one point to another remains constant’. It is applicable for non-compressible liquids. For different types of liquid flow Bernoulli’s equation changes. There is direct proportion between speed of fluid and its dynamic pressure and its kinetic energy. It can be used in various real life situations like measuring pressure on aircraft wing and calibrating the airspeed indicator. It can also be used to low pressure in the venturi tubes present in carburetor.

5. How can a D.P. transmitter be calibrated?
D.P. transmitter can be calibrated using following steps:
1. Adjust zero of Xmtrs.
2. Perform static pressure test: Give equal pressure on both sides of transmitter. Zero should not shift either side. If the zero shifts then carry out static alignment.
3. Perform vacuum test: Apply equal vacuum to both the sides. Zero should not shift.
4. Calibration procedure: Give 20 psi air supply to the transmitter and vent L.P. side to atmosphere. Connect output of the instrument to the standard test gauge. Adjust zero. Apply required pressure to the high pressure side and adjust the span. Adjust zero gain if necessary.

6. How is flow measured in square root?
Flow varies directly as the square root of pressure. Thus, F=K of square root of applied pressure. Since this flow varies as the square root of differential pressure. The pressure pen does not directly indicate flow. Thus flow can be determined by taking the square root of the pen. Assume the pen reads 50% of the chart. So, flow can be calculated using the pen measure in the chart.

7. Name different parts of a pressure gauge. Explain the use of hair spring in the pressure gauge.
Pressure gauge includes following components:
1. ‘C’ type bourdon tube.
2.  Connecting link3.  Sector gear
4.  Pinion Gear
5.  Hair spring
6.  Pointer
7.  Dial
Use of hair spring: Hair spring is responsible for controlling torque. It is also used to eliminate any play into linkages.

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JOBS IN L&T(LARSEN AND TOUBRO)


Hello Friends, i am posting about  immediate job openings in mnc company for instrumentation engineers and electrical engineers. For 2012 batches and also 2013 passed out candidates also apply.  So please hurry up!!!!All the best
opening job for L&T company mumbai only 2012-2013 candidate:
Apply to this job:
Role:Instrumentation Engineer
Experience: 0 To 1 Years
Job Type: Full Time
Job location: Mumbai / Delhi, Gurgaon & Noida / Pune
Basic/UG qualification: B.E/B.Tech
PG Qualification: M.Tech
Key skills: Production
No. of vacancies: 10+
Website: www.larsentoubro.com
Contact person: Riyaj Sir-9730308819
Description:
Opening Job For BE(Instrumentation,Electrical,Mech,Civil)
ADDRESS:
Near Azad College USB/Atulya Careerline,
Rozabagh,
Aurangabad-431001
MOB-9730308819
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FINAL YEAR ENGINEERING PROJECTS FOR ICE & EIE STUDENTS:

Hello friends, i am publishing various project ideas for ICE and EIE students related to electronics from basic level to advanced level for electronics and instrumentation students. Here i am discussed about many concepts related to embedded, electrical, robotics, communication, solar and many other technologies.
 

List Of   Projects Ideas for Engineering Students:

  1.  Propeller display of Time / Message
  2.  Vehicle tracking By GPS – GSM
  3.  Auto Power Supply Control from 4 Different Sources: Solar, Mains, Generator & Inverter to Ensure No Break Power
  4. Ultra Fast Acting Electronic Circuit Breaker
  5. Automatic Irrigation System on Sensing Soil Moisture Content
  6. Automatic Star Delta Starter Using Relays and Adjustable Electronic Timer for Induction Motor
  7. Programmable Switching Control for Industrial Automation in Repetitive Nature of Work
  8. Automatic Wireless Health Monitoring System in Hospitals for Patients
  9. Precise Digital Temperature Control
  10. Optimum Energy Management System
  11. Security System Using Smart card Technology
  12. Line Following Robotic Vehicle
  13. TV Remote Operated Domestic Appliances Control
  14. Password Based Circuit Breaker
  15. Programmable Load Shedding Time Management for Utility Department
  16. Object Detection by Ultrasonic Means
  17. Tampered Energy Meter Information Conveyed to Concerned Authority by Wireless Communication
  18. Distance Measurement by Ultrasonic Sensor
  19. Portable Programmable Medication Reminder
  20. Programmable Energy Meter for Electrical Load Survey
  21. Networking of Multiple Microcontrollers
  22. SCADA (Supervisory Control & Data Acquisition) for Remote Industrial Plant
  23. Movement Sensed Automatic Door Opening System
  24. Pick N Place with Soft Catching Gripper
  25. Fire Fighting Robotic Vehicle
  26. War Field Spying Robot with Night Vision Wireless Camera
  27. Integrated Energy Management System Based on GSM Protocol with Acknowledgement Feature
  28. Underground Cable Fault Distance Locator
  29. Display of Dialed Telephone Numbers on Seven Segment Displays
  30. Non Contact Tachometer
  31. Line Following Robotic Vehicle Using Microcontroller
  32. Auto Selection of Any Available Phase, in 3 Phase Supply System
  33. Life Cycle Testing of Electrical Loads by Down Counter
  34. GSM Based Energy Meter Reading with Load Control
  35. Stamp Value Calculator for Postage Needs
  36. Railway Track Security System
  37. Thermistor Based Temperature Control
  38. Electronic Eye Controlled Security System
  39. Fastest Finger Press Quiz Buzzer
  40. Speed Checker to Detect Rash Driving on Highways
  41. Home Automation Using Digital Control
  42. Intelligent Overhead Tank Water Level Indicator
  43. Speed Synchronization of Multiple Motors in Industries
  44. Pre Stampede Monitoring and Alarm System
  45. Touch Screen Based Home Automation System
  46. Speed Checker to Detect Rash Driving on Highways
  47. RF Based Home Automation System
  48. Obstacle Avoidance Robotic Vehicle
  49. Auto Metro Train to Shuttle Between Stations
  50. Touch Screen Based Remote Controlled Robotic Vehicle for Stores Management
  51. Metal Detector Robotic Vehicle
  52. RFID Based Passport Details
  53. Beacon Flasher Using Microcontroller
  54. IR Controlled Robotic Vehicle
  55. Automatic Bell System for Institutions
  56. Cell Phone Controlled Robotic Vehicle
  57. RFID Based Device Control and Authentication Using PIC Microcontroller
  58. Solar Energy Measurement System
Those are the top IEEE projects for instrumentation and electrical branches. So please make use of it. If you have any doubts ask me by using the comment box.

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      Immediate Opening In Videcon Company For Instrumentation Engineers

      Hello Friends, i am posting about  immediate opening in videcon company for instrumentation engineers and electronics engineers. For 2012 batches and also 2013 passed out candidates also apply.  So please hurry up!!!!All the best

      Urgent opening for VIDECON LTD BE(EEE,ECE,EE)fresher 2011-13
      Apply to this job
      Role:
      Electronics / Instrumentation Engineer
      Experience:
       0 To 1 Years
      Job Type:
      Full Time
      Job location:
      Pune / Ahmedabad / Gandhinagar
      Basic/UG qualification:
      B.E/B.Tech
      PG Qualification: 
       M.Tech
      Key skills:
       GET
      No. of vacancies:
       10+
      Company name: *VIDECON LTD
      Contact person: 9730308819
      Address: 
      Near Azad College USB/Atulya Careerline,Rozabagh Aurangabad-431001
      MOB-9730308819
      Atulya Careerline
      Riyaj-9730308819
      APPLY NOW:
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      Internships Program For Instrumentation Engineers

      Hello Friends, i am posting a internships program for instrumentation engineers, and final year students who are looking for a company project with internship program. So please make use of it.

      Internships @ Solitontech | A Bangalore based Company

      What is this program about?
      At Soliton, they  are constantly working on challenging engineering projects and development activities in various cutting edge technologies. Through their  internship program they  invite undergraduate, postgraduate, and Ph.D engineering students from reputed universities across the globe to come and be a part of this exciting work and apply the theory that has been learned in school to develop innovative solutions for real world applications. The student gets a chance to work closely with practicing engineers in Machine Vision, Computer Vision & LabVIEW during their internship at Soliton. This work (excluding any confidential portions) may be submitted to the college as the student's final semester project or masters research thesis.

      What are the technologies that you can work on?
      • Computer Vision
      •  Machine Vision
      • Artificial Intelligence
      • Machine Learning
      •  Automation
      • DSP, FPGA
      •  LabVIEW.

      Interesting? So, who can apply?
      Students who are pursuing UG, PG & Ph.D courses in engineering can apply for an internship at Soliton. For UG, a minimum of 4 semesters should have been completed.

      When & how should you apply?
      Internships at Soliton are open all days across the year. Drop in a mail at internships@solitontech.com with your resume. They  will respond with suitable project titles for which the applicant has to do some preliminary research and submit a brief proposal. The resume, proposal, and references will be used for the selection process.
      APPLY NOW:
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      Jobs for instrumentation freshers

      Hello Friends, i am posting jobs for instrumentation freshers with high salary. So please make use of it. All the best.

      Instrumentation Engineer, Instrumentation Design Engineer
      by PGL INDIA in Pune, Chandigarh, Faridabad
      Experience: 0 to 5 yrs. | Salary: INR 6,00,000 - 11,00,000 P.A | Opening(s): 87
      Job Description:
      instrumentation engineer, instrumentation design engineer
      Salary:
      INR 6,00,000 - 11,00,000 P.A
      Industry:
      Consumer Electronics / Appliances / Durables
      Functional Area:
      Engineering Design, R&D
      Role Category:
      Engineering Design
      Role:
      Senior Design Engineer
      Keyskills:
      instrumentation engineer, instrumentation design engineer, design manager, structural design engineer, cad engineer, autocad, electrical design engineer, mechanical design engineer, electrical designer, instructional design, mechanical engineer
      Desired Candidate Profile Education:
      (UG - Any Graduate - Any Specialization, Graduation Not Required) AND (PG - Any Postgraduate - Any Specialization, Post Graduation Not Required) AND ( Doctorate - Any Doctorate - Any Specialization, Doctorate Not Required)
      Please refer to the Job description above
      Company Profile
      PGL INDIA
      PGL an ISO 9001:2000 Company Manufacturing Electronics and Home Appliances Products.
      APPLY NOW
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      Urgent requirement for instrumentation engineers

      Hello Friends, i am posting a jobs for instrumentation engineers in Thermal power plants. So, please make use of it for your bright future. All the best..

      Sr Engineer - Instrumentation (Utkal)
      Application deadline 2013-08-05
      Position description Position : Sr. Engineer - O&M (Instrumentation)
      Reports to : HOD - Instrumentation
      Location : UAIL, Tikri, Odisha
      Responsibilities To plan, organise, coordinate, supervise and control instrumentation maintenance of various equipments related to thermal power plant, prepare maintenance schedule, co-ordinate with the contractors / external agencies, Rectification planning for defects identified in Condition Monitoring, Updation in Defect Register & Maintenance management software, Spares & Consumables planning for the accountable area, Preparation of purchase requisition, Prepare MIS reports, within the guidelines of Wartsila policies with the objective of ensuring smooth running of power plant and meeting Customer expectations
      Requirements Graduate / Diploma Engineer in Instrumentation

      5 - 8 years of experience at thermal power plants

      Contact person to give further information Mr. Sudhakar Rao K
      Country India
      Job area Contract Delivery
      APPLY NOW
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      Anna University 4th Semster Transducer Engineering 2 marks - Unit 1

      Hello Friends, i am posting 4th Semester Transducer Engineering Unit - 1 2 Marks Questions and Answers for the past four years. Please make use of it and score well in your exam.

      UNIT 1

      TRANSDUCER ENGINEERING

      1) What is instrument ?
      It is a device for determining the value or magnitude of a quantity or variable.

      2) Add 826 ± 5 to 628 ± 3 ?
      N1 = 826 ± 5 ( = ± 0.605%)
      N2 = 628 ± 3 ( = ± 0.477%)
      Sum = 1,454 ± 8 (=± 0.55%)

      3) Subtract 628 ± 3 from 826 ± 5 ?
      N1 = 826 ± 5 ( = ± 0.605%)
      N2 = 628 ± 3 ( = ± 0.477%)
      Difference = 198 ± 8 (= ± 4.04%)

      4) List three sources of possible errors in instruments ?
      (i) Gross Error (ii) Systematic (iii) Random errors.

      5) Define Instrumental error ?
      These are the errors inherent in measuring instrument because of their mechanical structure.

      6) Define limiting error ?
      Components are guaranteed to be within a certain percentage of rated value. Thus the manufacturer has to specify the deviations from the nominal value of a particular quantity.

      7) Define probable error.?
      It is defined as r = ± 0.6745s where s is standard deviation.Probable error has been used in experimental work to some extent in past, but standard deviation is more convenient in statistical work.

      8) Define Environmental error ?
      These are due to conditions in the measuring device, including conditions in thearea surrounding the instrument, such as the effects of changes in temperature,humidity.

      9) Define arithmetic mean.?
      The best approximation method will be made when the number of readings would give the best result,
      X = arithmetic mean
      x1,x2,xn = readings taken

      10) Define average deviation.?
      By definition, average deviation is the sum of absolute values of the value deviations divided by the number of reading.

      11) Define units.?
      It is necessary to define a physical quantity both in kind and magnitude in order touche this information for further proceedings. The standard measure of each kind of physical quantity is named as the unit.

      12) Define Standards ?
      The physical embodiment of a unit of measurement is a standard. For example,the fundamental unit of mass in the international system is the kilogram and defined as the mass of a cubic decimeter of water at its temperature of maximum density of 4°c.

      13) Mention the purpose of the measurement.?

      • To understand an event or an operation.
      • To monitor an event or an operation.
      • To control an event or an operation.
      • To collect data for future analysis
      •  To validate an engineer design.

      14) What are the methods of measurement ?
      • Direct comparison method
      • Indirect comparison method

      15) Define ODDs ?

      The specification of limiting error is in itself uncertain because the manufacture himself is not sure about the accuracy because of the presence of random errors.

      16) Classify Standards ?
      •  International standards
      •  Primary standards
      •  Secondary standards
      •  Working standards

      17) Define transducer and give an example ?
      Transducer is a device which converts one form of energy into electrical energy. A thermocouple converts heat energy into electrical voltage.

      18) Classify transducer ?
      On the basis of transduction form used:
      • As primary and secondary transducers
      •  As active and passive transducers
      • As analog and digital transducers
      • As transducers and inverse transducers

      19) What is primary transducer?
      Bourdon tube acting as a primary transducer senses the pressure and converts the pressure into displacement. No output is given to the input of the bourdon tube. So it is called primary transducer. Mechanical device can act as a primary transducer.

      20) What is secondary transducer?
      The output of the Bourdon tube is given to the input of the LVDT. There are two stages of transduction, firstly the pressure is converted into a displacement by the Bourdon tube then the displacement is converted into analog voltage by LVDT. Here LVDT is called secondary transducer. Electrical device can act as a secondary transducer.

      21) What is passive transducer?
      In the absence of external power, transducer cannot work and it is called a passive transducer. Example: capacitive, inductive, resistance transducers.

      22) What is active transducer?
      In the absence of external power, transducer can work and it is called active transducer. Example velocity, temperature, light can be transduced with the help of an active transducer.

      23) What is analog transducer?
      These transducers convert the input quantity into an analog output which is a continuous function of time. Thus a strain gauge, an LVDT, a thermocouple or a thermistors may be called analog transducer, as they give an output which is a continuous function of time.

      24) Give the classification of units ?
      • Absolute units
      • Fundamental and derived units
      • Electromagnetic units
      • Electrostatic units

      25) Define Primary fundamental and auxiliary fundamental units ?
      Fundamental units in mechanics are measures of length, mass and time and those are fundamental to most other physical quantities and hence they are called Primary fundamental units.
      Measures of certain physical quantities in thermal, electrical and illumination fields are also represented by fundamental units and are used only where those disciplines are involved and hence called auxiliary fundamental units.

      26) Define unit of mass preserved at International Bureau of weights and measures at Severes near Paris ?
      The unit of mass is represented by a material standard: the mass of International prototype kilogram consisting of platinum Iridium hollow cylinder.

      27) Define static calibration ?
      It refers to a process in which all the inputs(desired,modifying,interfering) except one are kept at some constant values.

      28) Define Traceability ?
      The ability to trace the accuracy of the standard back to its ultimate source in fundamental standards of National Institute of Science and Technology is termed “Traceability”.

      29) What are random errors or residual errors?
      The happenings or disturbances about which we are unaware and lumped together are called random errors or residual errors.Since these errors remain even after the systematic errors are taken care of,they are called residual errors.

      30) Give one property of piezo-electric crystal ?
      When a force is applied to piezo-electric crystals, they produce an output voltage.

      31) Define an Inverse transducer. Give an example ?
      A device which converts an electrical quantity into a non-electrical quantity. A piezo-electric crystal acts as an inverse transducer because when a voltage is applied across its surfaces, it changes its dimensions causing a mechanical displacement.

      32) List the factors responsible in selection of a transducer ?
      • Operating principle
      • Sensitivity
      • Operating range.
      • Accuracy.

      If you have questions that you dont know the answer, you can use the comment box to ask me.

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