Interview Questions.

Top 100+ Instrumentational Engineering Interview Questions And Answers


Top 100+ Instrumentational Engineering Interview Questions And Answers

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

Answer :

Different orifice plates are:

1. Concentric: These plates are used for ideal liquid in addition to gases and steam carrier. Concentric holes are found in these plates, thats why it is known as concentric orifice.

2. Segmental: This plate has hole inside the shape of segment of the circle. This plate is used for colloidal and sherry flow size.

Three. Eccentric: This plate has the eccentric holes. This plate is utilized in viscous and sherry glide size.

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

Answer :

An orifice tab is welded on the orifice plate which extends out of the road giving a demonstration of the orifice plate.

Digital Electronics Interview Questions
Question three. Why Is The Orifice Tab Provided?

Answer :

Following motives justify for supplying orifice tab:

1. Indication of orifice plate in a line
2. The orifice diameter is marked on it.
3. The fabric of the orifice plate.
4. The tag quantity of the orifice plate.
Five. To mark the inlet of an orifice.

Question four. Explain Bernoulli’s Theorem. State Its Application.?

Answer :

Bernoulli’s theorem states that the ‘total electricity of a liquid flowing from one point to any other remains regular’. It is relevant for non-compressible liquids. For one-of-a-kind types of liquid go with the flow Bernoulli’s equation adjustments. There is direct share between pace of fluid and its dynamic strain and its kinetic strength. It can be utilized in diverse actual lifestyles conditions like measuring strain on plane wing and calibrating the airspeed indicator. It can also be used to low stress inside the venturi tubes found in carburetor.

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

Answer :

D.P. Transmitter can be calibrated the usage of following steps:

1. Adjust zero of Xmtrs.

2. Perform static strain test: Give same strain on each aspects of transmitter. Zero ought to no longer shift both aspect. If the 0 shifts then perform static alignment.

3. Perform vacuum check: Apply same vacuum to both the edges. Zero must now not shift.

Four. Calibration system: Give 20 psi air supply to the transmitter and vent L.P. Side to environment. Connect output of the instrument to the usual test gauge. Adjust 0. Apply required stress to the excessive strain facet and regulate the span. Adjust 0 advantage if essential.

Programmable Logic Controller (PLC) Interview Questions
Question 6. How Is Flow Measured In Square Root?

Answer :

Flow varies directly because the rectangular root of pressure. Thus, F=K of rectangular root of applied strain. Since this drift varies as the rectangular root of differential strain. The pressure pen does now not immediately imply waft. Thus go with the flow can be decided by way of taking the square root of the pen. Assume the pen reads 50% of the chart. So, float can be calculated the use of the pen measure 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 consists of following components:

‘C’ type bourdon tube.
Connecting link
Sector gear
Pinion Gear
Hair spring
Use of hair spring: Hair spring is accountable for controlling torque. It is likewise used to do away with any play into linkages.

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

Answer :

In closed tank, backside of the tank is attached to the high strain side of the transmitter. Top of tank is hooked up to the decrease strain facet of the transmitter. In this manner vessel pressure may be measured.

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

Answer :

In open tank the lower strain aspect is vented to the atmosphere. All stress is applied to the high stress aspect. This vessel stress is measured through excessive stress facet.

DCS(allotted control gadget) Interview Questions
Question 10. Explain The Working Of An Electronic Level Troll?

Answer :

The variant in stage of buoyancy as a result of a trade in liquid level varies the net weight of the displacer growing or reducing the weight at the torque arm. This alternate is directly proportional to trade in level and unique gravity of the liquid.

The ensuing torque tube motion varies the angular movement of the rotor in RVDT offering a rotor trade proportional to the rotor displacement, that is converted and amplified to a D.C. Modern.

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

Answer :

Enraf level gauge is based at the ser powered null stability method. A displacer serves as continuous level sensing element. A  section ser motor managed by means of a capacitive balance system winds unwinds the the measuring wire till the tension in the weight springs is in balance with the burden of the displaced component immersed inside the liquid. The sensing machine in stability measures the 2 capacitance formed by the transferring vital sensing rod furnished by means of the 2 capacitor plates and the si plates.

Process Control and Instrumentation Interview Questions
Question 12. What Is The Constant Voltage Unit?

Answer :

The constant voltage circuit includes a rectifier, CR and a filter out capacitor. It is observed by two stages of zener law. Abridge configuration is provided to lamp line voltage zener regulation. Regulation 1 and regulation 2 gives enormously provide steady present day. Resistors form a bridge that can remoment line voltage results.

Digital Electronics Interview Questions
Question 13. Explain The Burnout Feature.?

Answer :

Burnout presents the warnsug feature of riding indicator at the quit of scale, if the enter circuit is open. A burnout resistor is supplied which develops a voltage drop between the measuring circuit and amplifier. The polarity of the signal determines the direction of the servo power upon an open circuit in the input.

Upscale burnout: R value 10 M
Downscale burnout: R price 22 M

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

Answer :

In severa packages, it is neither suitable nor realistic to expose a temperature sensor immediately to a cloth. Wells are therefore used to shield against damage corresion, arosion, aborsion and excessive stress tactics. A thermo nicely is also beneficial in defensive a sensor from physical damage at some stage in managing and ordinary operations.
Materials used in thermo wells: Stainless steel, Inconel, Monel, Alloy Steel, Hastelloy

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

Answer :

In automatic reference junction compensation, variable nickel resistor is used. As the temperature adjustments, so does its resistance.

This reference junction compensator is positioned, with a view to be at the temperature of the reference junction. The reference junction is at the poset where the distinct wire of the thermocouple is rejoined. This joint is continuously at the terminal strip of the device.

Power Transmission Interview Questions
Question 16. What Are De-saturators?

Answer :

When, in some strategies, e.G. Batch tactics, long brief responses are expected all through which a sustained deviation is gift the controller necessary movement continuously drives the output to a minimal or maximum fee. This phenomenon is known as ‘crucial saturation of the control unit’. When this situation is met, then this unit is de-saturated.

Question 17. Explain The Working Of Rota Meter?

Answer :

Variable region meters are unique form of head meters. Where in the location of go with the flow restrictor is various. So as to hold the differential strain constant. The rota meter includes a vertical tapered tube through which the metered fluid flows in upward path. As the go with the flow varies the ‘glide’ rises or falls to differ the place of the passages that the differential throughout it balances the gravitational force on the ‘waft’. The differential stress is maintained regular. The function of the ‘waft’ is the degree of the price of go with the flow.

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

Answer :

An electric powered capability is evolved while a conductor is moved across the magnetic discipline. In maximum electric equipment the conductor is a cord. The principle is similarly applicable to a transferring, electrically conductive liquid.

The primary device of commercial magnetic meters include straight cylindrical electrically insulated tube with a couple of electrodes nearly flush with the tube walls and positioned at contrary end of a tube diameter. This tool is constrained to electrically carrying out liquids. The magnetic meter is specifically desirable to measurement of slurries and grimy fluids.

Programmable Logic Controller (PLC) Interview Questions
Question 19. Explain The Mechanism Behind The Turbine Meter?

Answer :

Turbine meters consist of immediately glide tube inside which a turbine or fan is loose to rotate about it s axis which is constant alongside g the centre line of the tube. Mostly, a magnetic choose up gadget senses the rotation of the rotor thru the tube partitions.

The turbine meter is a float rate device , since the rotor speed is without delay proportional to the go with the flow fee. The output is typically in the shape of electric pulses from the magnetic select up with a frequency proportional to the flow price.

Question 20. How Would You Choose Differential Range?

Answer :

The maximum commonplace range for differential range for liquid measurement is zero-one hundred. This range is high enough to minimize the errors due to unequal heads in the seal chambers. It is likewise depending on the differences in the temperature of the weight traces. The a hundred range lets in an elevated in potential up to 400. While decrease down up to twenty via simply converting the variety tubes or variety modifications.

Plc Scada 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 shut off is needed. The use of single seated valve is limited by using stress drop throughout the valve in the closed or nearly closed function.

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

Answer :

In double seated valves the upward and downward forces on the plug due to reduction of fluid stress are almost equalized. It is normally used on larger size valves and excessive strain structures. Actuator forces required are much less.

Question 23. What Is The Use Of Valve Positioner?

Answer :

Valve positioner can be used for following reasons:

Quick motion
Valve hysterisis
Viscous beverages
Split range.
Line stress modifications on valve
Bench set not general
Reverse valve operations
Field Instrumentation Interview Questions
Question 24. What Are Primary Elements Of Measuring Pressure? Which Type Of Pressure Can Be Measured By These Elements?

Answer :

Primary factors of measuring pressure are:

a. Bourdon Tube
b. Diaphragm
c. Capsule
d. Bellows
e. Pressure springs

These elements are referred to as elastic deformation pressure elements.

Power Electronics Interview Questions
Question 25. Name Different Types Of Bourdon Tubes?

Answer :

Types of bourdon tubes:

1. C type
2. Spiral
3. Helix

Question 26. What Are Different Types Of Control Valves?

Answer :

The normally used manage valves can be described as follows:

a. Depending on Action:

Depending on movement there are  types of manage valves
1. Air to close
2. Air to close

b. Depending on frame:

Depending on body there are four forms of manage valves

1. Globe valves single or double seated
2. Angle valves
3. Butterfly valves
four. Three manner valves

Transmission & Distribution Interview Questions
Question 27. What Is Furnace Draft Control?

Answer :

Balanced draft boilers are commonly used poor furnace strain. When each pressured draft and triggered draft are used collectively, in some unspecified time in the future in the gadget the stress will be same as that of ecosystem.

Therefore the furnace strain need to be poor to save you hot fuel leakage. Excessive vacuum in the furnace however produces heat losses thru air infiltration. The most suitable situation is that the only have a completely mild poor stress of the top of furnace.

DCS(dispensed control device) Interview Questions
Question 28. What Is Intrinsically Safe System?

Answer :

Intrinsic safety is a technique for designing electrical system for safe use in places made unsafe through the presence of flammable gasoline or vapours inside the air.

Intrinsically secure circuit is one wherein any spark or thermal impact produce both usually or below special fault conditions is incapable of inflicting ignition of a targeted fuel or vapour in air mixture on the maximum ignited attention.

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

Answer :

The breakdown place of a p-n diode may be made very sharp and almost vertical diodes with almost vertical breakdown location are acknowledged a s zener diodes. A zener diode working within the breakdown area is equal to a battery.

Because of this modern-day through zener diode can alternate but the voltage stays regular. It is this steady voltage that has made the zener diode an important tool in voltage regulation.

Voltage regulator: The output remains steady regardless of changes inside the enter voltage due to zener impact.

Question 30. What Is Force Balance Principle? State Some Of Its’ Advantages?

Answer :

Force balance principle: A controller which generates an output sign by opposing torque. The enter pressure is applied on the enter bellows which moves the beam. This crackles nozzle back stress. The nozzle lower back stress is sensed via the balancing bellows which brings the beam to stability. The baffle motion may be very less approximately zero.002 for full scale output.


a. Moving components are fewer.
B. Baffle movement is negligible
c. Frictional losses are less

Question 31. What Is Motion Balance Principle?

Answer :

A controller which generates an output signal by movement of its parts. The increase within the baffle is to transport toward the nozzle. The nozzle lower back pressure will growth.

This growth inside the lower back strain appearing at the balancing bellows, will expand the bellows. The nozzle is moved upward due to this. The nozzle will flow till motion almost equals the input baffle movement.

Question 32. How Will You Test A Transistor With A Multimeter?

Answer :

1. Emitter +ve of meter and base -ve output =Low resistance

2. Emitter -ve of meter and base +ve output =High resistance

three. Collector +ve and base -ve output =Low

four. Collector -ve and base +ve output =Low

Emitter: Collector = High resistance
PNP: Opposite Results

Question 33. Explain Ratio Control System?

Answer :

A ratio manipulate device is characterized via the truth that versions inside the secondary variable don’t mirror returned at the number one variable. A ratio manage system is the machine wherein secondary flow is hold in a few proportion to a number one uncontrollable flow.

If we assume that the output of a number one transmitter is A. And the output of the secondary transmitter is B, and that the multiplication element of the ratio relay is K, then for equilibrium situations this means that set valve is same to measured valve, we find the following relation:

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

Process Control and Instrumentation Interview Questions
Question 34. What Is Solenoid Valve? Where It Is Used?

Answer :

A solenoid is electrically operated valve. It includes solenoid coil in which magnetic plunger movements. This plunger is connected to the plug and tends to open or close the valve.

There are  varieties of solenoid valves:

1. Normally Open
2. Normally closed

Use: It is used for protection motive in one-of-a-kind electric paintings.