Interview Questions.

Top 100+ Field Instrumentation Interview Questions And Answers


Top 100+ Field Instrumentation Interview Questions And Answers

Question 1. What Are Different Types Of Orifice Plates? State Their Uses?

Answer :

Different orifice plates are:

Concentric: These plates are used for perfect liquid as well as gases and steam service. Concentric holes are found in these plates, thats why it's far called concentric orifice.

Segmental: This plate has hole within the shape of section 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 drift size.

Question 2. How Do You Identify An Orifice In The Pipeline?

Answer :

An orifice tab is welded at the orifice plate which extends out of the line giving an indication of the orifice plate.

Programmable Logic Controller (PLC) Interview Questions
Question three. Why Is The Orifice Tab Provided?

Answer :

Following motives justify for providing orifice tab:

Indication of orifice plate in a line
The orifice diameter is marked on it.
The material of the orifice plate.
The tag quantity of the orifice plate.
To mark the inlet of an orifice.
Question four. Explain Bernoulli’s Theorem. State Its Application?

Answer :

Bernoulli’s theorem states that the ‘total strength of a liquid flowing from one factor to every other stays constant’. It is relevant for non-compressible beverages. For one-of-a-kind sorts of liquid flow Bernoulli’s equation modifications. There is direct percentage among pace of fluid and its dynamic pressure and its kinetic electricity. It may be utilized in numerous actual lifestyles conditions like measuring strain on aircraft wing and calibrating the airspeed indicator. It also can be used to low pressure in the venturi tubes found in carburetor.

Question five. How Can A D.P. Transmitter Be Calibrated?

Answer :

D.P. Transmitter may be calibrated using following steps:

Adjust zero of Transmitter.
Perform static stress test: Give same strain on both aspects of transmitter. Zero ought to no longer shift both side. If the zero shifts then carry out static alignment.
Perform vacuum take a look at: Apply same vacuum to both the perimeters. Zero must no longer shift.
Calibration technique: Give 20 psi air supply to the transmitter and vent L.P. Aspect to environment. Connect output of the instrument to the same old take a look at gauge. Adjust 0. Apply required strain to the excessive strain side and regulate the span. Adjust 0 advantage if essential.
Instrumentational Engineering Interview Questions
Question 6. How Is Flow Measured In Square Root?

Answer :

Flow varies without delay because the rectangular root of strain. Thus, F=K of rectangular root of carried out strain. Since this float varies because the square root of differential stress. The strain pen does not at once suggest flow. Thus flow can be determined via taking the rectangular root of the pen. Assume the pen reads 50% of the chart. So, waft can be calculated the usage of the pen degree inside the chart.

Question 7. Name Different Parts Of A Pressure Gauge. Explain The Use Of Hair Spring In The Pressure Gauge?

Answer :

Pressure gauge includes following additives:

‘C’ type bourdon tube.
Connecting hyperlink
Sector gear
Pinion Gear
Hair spring
Use of hair spring: Hair spring is responsible for controlling torque. It is likewise used to cast off any play into linkages..

Emc Vmax Interview Questions
Question eight. How D.P. Transmitter Can Be Applied To Close Tank?

Answer :

In closed tank, bottom of the tank is connected to the excessive pressure facet of the transmitter. Top of tank is connected to the decrease pressure facet of the transmitter. In this manner vessel stress may be measured.

Question nine. How D.P. Transmitter Can Be Applied To Open Tank?

Answer :

In open tank the decrease stress facet is vented to the surroundings. All stress is applied to the high pressure side. This vessel pressure is measured via high stress facet.

Underground Cable Interview Questions
Question 10. Explain The Working Of An Electronic Level Troll?

Answer :

The version in degree of buoyancy because of a alternate in liquid stage varies the internet weight of the displacer increasing or reducing the load at the torque arm. This exchange is directly proportional to change in level and precise gravity of the liquid. The resulting torque tube movement varies the angular movement of the rotor in RVDT presenting a rotor alternate proportional to the rotor displacement, that's converted and amplified to a D.C. Current.

Question 11. Explain The Working Of An Enraf Level Gauge?

Answer :

Enraf level gauge is based totally at the ser powered null balance technique. A displacer serves as non-stop degree sensing element. A  segment ser motor controlled by a capacitive stability gadget winds unwinds the the measuring cord until the tension in the weight springs is in balance with the weight of the displaced part immersed within the liquid. The sensing gadget in balance measures the 2 capacitance fashioned by way of the transferring central sensing rod furnished by means of the two capacitor plates and the si plates.

Transducer Interview Questions
Question 12. What Is The Constant Voltage Unit?

Answer :

The consistent voltage circuit consists of a rectifier, CR and a filter capacitor. It is followed with the aid of  stages of zener regulation. Abridge configuration is furnished to lamp line voltage zener law. Regulation 1 and law 2 provides particularly offer steady modern. Resistors form a bridge that may remoment line voltage results.

Programmable Logic Controller (PLC) Interview Questions
Question thirteen. Explain The Burnout Feature?

Answer :

Burnout offers the warnsug characteristic of riding indicator on the give up 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 pressure upon an open circuit inside the enter.

Upscale burnout: R fee 10 M

Downscale burnout: R fee 22 M

Question 14. Why Thermowells Are Used? What Materials Are Used In Thermo Wells?

Answer :

In severa programs, it's far neither proper nor realistic to expose a temperature sensor directly to a fabric. Wells are consequently used to protect towards damage corrosion, arosion, aborsion and excessive pressure approaches. A thermowell is also beneficial in shielding a sensor from physical damage at some point of dealing with and ordinary operations.

Materials utilized in thermowells: Stainless metallic, Inconel, Monel, Alloy Steel, Hastelloy

Question 15. How Is Automatic Reference Junction Compensation Carried Out In Temperature Recorders?

Answer :

In computerized reference junction reimbursement, variable nickel resistor is used. As the temperature adjustments, so does its resistance. This reference junction compensator is located, so one can be on the temperature of the reference junction. The reference junction is on the poset in which the diverse twine of the thermocouple is rejoined. This joint is forever on the terminal strip of the instrument.

EMC Interview Questions
Question sixteen. What Are De-saturators?

Answer :

When, in a few approaches, e.G. Batch tactics, lengthy transient responses are expected during which a sustained deviation is present the controller crucial action continuously drives the output to a minimum or maximum cost. This phenomenon is called ‘crucial saturation of the control unit’. When this circumstance is met, then this unit is de-saturated.

Question 17. Explain The Working Of Rotameter?

Answer :

Variable location meters are special shape of head meters. Where within the place of float restrictor is various. So as to keep the differential strain constant. The rota meter includes a vertical tapered tube thru which the metered fluid flows in upward direction. As the glide varies the ‘waft’ rises or falls to vary the area of the passages that the differential across it balances the gravitational pressure on the ‘flow’. The differential stress is maintained steady. The role of the ‘float’ is the degree of the charge of waft.

Analogue electronics Interview Questions
Question 18. What Is The Working Principle Of The Magnetic Meter?

Answer :

An electric powered ability is advanced when a conductor is moved across the magnetic area. In maximum electrical equipment the conductor is a cord. The precept is similarly applicable to a moving, electrically conductive liquid. The number one tool of industrial magnetic meters consist of directly cylindrical electrically insulated tube with a pair of electrodes almost flush with the tube partitions and positioned at opposite stop of a tube diameter. This tool is confined to electrically carrying out liquids. The magnetic meter is specially suited to dimension of slurries and grimy fluids.

Instrumentational Engineering Interview Questions
Question 19. Explain The Mechanism Behind The Turbine Meter?

Answer :

Turbine meters consist of directly drift tube within which a turbine or fan is unfastened to rotate approximately it s axis that's fixed along g the centre line of the tube. Mostly, a magnetic pick up device senses the rotation of the rotor thru the tube partitions. The turbine meter is a glide charge device, because the rotor velocity is immediately proportional to the waft rate. The output is usually inside the form of electrical pulses from the magnetic select up with a frequency proportional to the go with the flow price.

Question 20. How Would You Choose Differential Range?

Answer :

The most commonplace range for differential range for liquid measurement is 0-a hundred. This range is excessive sufficient to minimize the mistakes caused by unequal heads within the seal chambers. It is likewise depending on the differences in the temperature of the load traces. The one hundred variety allows an expanded in capacity up to four hundred. While decrease down up to 20 by using merely converting the variety tubes or variety changes.

Transformer Interview Questions
Question 21. What Is The Use Of Single Seated Valve?

Answer :

The unmarried seated valve is used on smaller sizes where an absolute close off is required. The use of unmarried seated valve is constrained through pressure drop across the valve within the closed or almost closed function.

Question 22. What Is The Use Of Double Seated Valve?

Answer :

In double seated valves the upward and downward forces at the plug due to reduction of fluid pressure are nearly equalized. It is generally used on larger size valves and high pressure systems. Actuator forces required are less.

Question 23. What Is The Use Of Valve Positioner?

Answer :

Valve positioner may be used for following reasons:

Quick movement
Valve hysteresis
Viscous drinks
Split range.
Line strain changes on valve
Bench set no longer general
Reverse valve operations
Profibus Interview Questions
Question 24. What Are Primary Elements Of Measuring Pressure? Which Type Of Pressure Can Be Measured By These Elements?

Answer :

Primary elements of measuring stress are:

Bourdon Tube
Pressure springs
These elements are known as elastic deformation strain elements.

Emc Vmax Interview Questions
Question 25. Name Different Types Of Bourdon Tubes?

Answer :

Types of bourdon tubes:

C type
Question 26. What Are Different Types Of Control Valves?

Answer :

The generally used manipulate valves can be described as follows:

a. Depending on Action: Depending on action there are two kinds of control valves

Air to open
Air to shut
b. Depending on frame: Depending on frame there are four varieties of manage valves

Globe valves unmarried or double seated
Angle valves
Butterfly valves
Three manner valves
Question 27. What Is Furnace Draft Control?

Answer :

Balanced draft boilers are commonly used poor furnace strain. When both pressured draft and brought on draft are used together, in some unspecified time in the future inside the device the stress may be identical as that of surroundings. Therefore the furnace pressure should be terrible to save you hot gas leakage. Excessive vacuum within the furnace but produces heat losses via air infiltration. The most appropriate situation is that the only have a very moderate terrible stress of the top of furnace.

Underground Cable Interview Questions
Question 28. What Is Intrinsically Safe System?

Answer :

Intrinsic safety is a technique for designing electric equipment for safe use in places made dangerous by using the presence of flammable gasoline or vapours in the air. Intrinsically secure circuit is one wherein any spark or thermal effect produce both commonly or underneath special fault conditions is incapable of inflicting ignition of a distinctive fuel or vapour in air aggregate on the maximum ignited attention.

Question 29. Hat Is Zener Diode? What Is Voltage Regulator?

Answer :

The breakdown region of a p-n diode may be made very sharp and almost vertical diodes with almost vertical breakdown location are regarded a s zener diodes. A zener diode operating inside the breakdown area is equal to a battery. Because of this modern thru zener diode can alternate however the voltage stays steady. It is this consistent voltage that has made the zener diode an essential tool in voltage law.

Question 30. What Is Zener Diode? What Is Voltage Regulator?

Answer :

The breakdown vicinity of a p-n diode may be made very sharp and nearly vertical diodes with almost vertical breakdown vicinity are regarded a s zener diodes. A zener diode running in the breakdown vicinity is equal to a battery. Because of this contemporary via zener diode can exchange but the voltage stays constant. It is that this steady voltage that has made the zener diode an essential tool in voltage regulation.

Voltage regulator: The output remains consistent regardless of changes inside the enter voltage because of zener effect.

Question 31. What Is Force Balance Principle? State Some Of Its’ Advantages?

Answer :

Force stability principle: A controller which generates an output signal via opposing torque. The input force is applied at the enter bellows which movements the beam. This crackles nozzle returned stress. The nozzle lower back stress is sensed by using the balancing bellows which brings the beam to stability. The baffle movement could be very much less approximately zero.002 for full scale output.


Moving elements are fewer.
Baffle motion is negligible
Frictional losses are less
Question 32. What Is Motion Balance Principle?

Answer :

A controller which generates an output signal by motion of its elements. The growth inside the baffle is to transport closer to the nozzle. The nozzle lower back pressure will boom. This increase inside the back stress acting on the balancing bellows, will make bigger the bellows. The nozzle is moved upward because of this. The nozzle will move till movement almost equals the enter baffle motion.

Question 33. How Will You Test A Transistor With A Multimeter?

Answer :

Emitter +ve of meter and base -ve output =Low resistance
Emitter -ve of meter and base +ve output =High resistance
Collector +ve and base -ve output =Low
Collector -ve and base +ve output =Low
Emitter: Collector = High resistance

PNP: Opposite Results

Transducer Interview Questions
Question 34. Explain Ratio Control System?

Answer :

A ratio manipulate gadget is characterised through the reality that versions inside the secondary variable don’t replicate lower back at the number one variable. A ratio manipulate machine is the machine in which secondary float is keep in a few proportion to a number one uncontrollable glide.

If we anticipate that the output of a primary transmitter is A. And the output of the secondary transmitter is B, and that the multiplication component of the ratio relay is K, then for equilibrium situations which means set valve is same to measured valve,

we discover the subsequent relation:

KA-B=0 or B/A = K wherein ‘K’ is the ratio placing off the relay.

Question 35. What Is Solenoid Valve? Where It Is Used?

Answer :

A solenoid is electrically operated valve. It consists of solenoid coil wherein magnetic plunger actions. This plunger is connected to the plug and has a tendency to open or close the valve.

There are two styles of solenoid valves:

Normally Open
Normally closed
Use: It is used for safety cause in exclusive electric powered work.