Interview Questions.

Question 1. What Is Meant By System?

Answer :

A gadget is described as any bodily object contains of diverse additives which might be inter related with each different with the aid of some characteristics.

Example: Automobile.

Question 2. What Is Meant By Control System?

Answer :

It is viable to differ any of the traits of components in a system in keeping with the necessities, and then the system is referred to as a controllable machine or control system.

For example recall an car, where the velocity may be various with the aid of adjusting the accelerator to the preferred degree.

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Question 3. What Are The Major Types Of Control System?

Answer :

The main forms of manage systems are:

Open loop manipulate machine.
Closed loop manipulate system.
Question 4. What Is Time Invariant System?

Answer :

If system's output characteristics do no longer change with time, then it's far called as time invariant gadget.

A linear time invariant system can be represented by way of regular co-green differential equations.

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Question 5. What Is Meant By Analogous Systems?

Answer :

The systems for which the differential equations have similar form are referred to as analogous gadget.

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Question 6. What Are The Advantages And Disadvantages Of Open Loop Control Systems?

Answer :

Advantages:

Open loop manage is an awful lot less complicated and much less luxurious.
No sensors are had to manipulate the variables.
Disadvantages:

No correct manage.
There is no compensation for any disturbances getting into the device since it has fixed input.
Question 7. What Are The Advantages And Disadvantages Of Closed Loop Control System?

Answer :

Advantages:

More correct control.
It compensates for disturbances.
Desired response can be received with the aid of appropriate design.
Disadvantages:

More complex and pricey.
Reduces the benefit of the device.
If the closed loop gadget is not nicely designed, the remarks may cause an oscillatory machine.
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Question 8. What Is An Order Of A System?

Answer :

The order of the differential equation governing the gadget is called as the order of a gadget.
From the transfer feature of the given gadget, we can gain the order of the system.

Question nine. What Are Analog Input/output & Digital Input/output?

Answer :

4-20 mA indicators from instrument (transmitters) are analog input to manipulate gadget.
4-20 mA alerts to instrument (I/p & electro pneumatic positioner) are analog output from manage device.
Volt unfastened (24V) contact (NO/NC) by using gadgets (all sort of switches, ex. Limit switch, press,temp,go with the flow,level switch) are virtual input to govern machine.
All powered alerts (24V, 48V, 110V….) from device to devices (SOV) are Digital outputs.
Question 10. Types Of Instrument Cables?

Answer :

IS cables & NIS cables.
IS – Intrinsic safety & NIS – Non Intrinsic protection.
Which cable to use, relies upon upon dangers circumstance.
Question eleven. Instrument Jb’s?

Answer :

Instrument JB’s relying upon hazards place category.
JB’s also may be IS or NIS.
For IS sign IS JB’s used for NIS sign NIS JB’s used.
For analog I/p & o/p signal we are able to use equal JB.
But for Digital I/p & o/p we have to use separate JB’s. Because virtual outputs are powered signal, with the aid of incorrect connection there may be probabilities to harm the cardboard.
For DCS I/p & o/p and PLC I/p & o/p we used separate JB’s.
Question 12. What Is Open Loop & Close Loop?

Answer :

OPEN LOOP: This is not anything however to sense the process indicators from the sector and to ship it to the manipulate room for operator monitoring handiest.

CLOSE LOOP: This is measuring the procedure indicators for operator’s motion. Means Tx feel the process and send it to the control room. Where the PID controller takes control motion and that given to the final manage detail as in line with the process requirement.

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Question 13. What Is Dcs & Plc?

Answer :

Distributed control machine (DCS) and Programmable good judgment controller. These are the control systems which handles fields I/Os.

Basic distinction between DCS & PLC is:

DCS handles more nos of I/Os in place of PLC.
PLC is quicker machine than DCS.
DCS can handles good-looking quantity of I/Os so that may be used for total plant automation. Whereas PLC has very own boundaries so it usually used for small but for vital (Safety factor of view) devices, like boiler automations, Make-up compressor automations Etc.
In the above noted case the PLCs may be get related with the DCS with the assist of tender link. Generally this is used to make alert to both the operator.
As I heard the PLC used to deal with the DI/DO signals so it is able to take fast movements. Some of the time it's far used to deal with few nos of AI/AO.
DCS & PLC’s velocity relies upon at the experiment rate of I/Os.
For both the machine Marshalling panels, Consoles and different faculties of Ethernet Etc may be used in keeping with the need.
According to the Cause and effects diagrams the System programmer assigns the control movement block into the system, we are able to call them as memory assigning.
Question 14. While Making Datasheets Which Things Are To Be Considered?

Answer :

Basically it relies upon at the tool item for which you are preparing the datasheet. As an Example. Temperature detail. We have acquire following records to put together D/s.

Type of Temperature Sensor (T/C or RTD, in case of T/c ?which sort J,K,R,S and many others.)
Head details a: Screw-cap and chain, b: cloth, c: conduit connections, d: terminal block> unmarried or duplex.
Thermo nicely Details a: fabric, b: Construction, c: size, e: connection. Etc.   
In case of valve:

Process Details
Material of production (Valve body, Trim),
Operating action,
Type of working traits
Stroke time
Accessories connected Etc.
Question 15. What Are Temperature Elements?

Answer :

Thermocouples and rtds.

Question 16. What Is Cable Tray? Its Type? Its Size? Its Support?

Answer :

Cable tray is not anything but the manner or media via which we lay the sphere cables in plant.

There are two fundamental kinds:

Ladder type (made in Rungs kind construction)
Perforated Type(Solid sheath consist of Holes for air flow). Basically discussing approximately tray help than lets say it relies upon on the site conditions. Only care needs to be taken thinking about adequate area for laying cable, considering their bends.Etc.
Question 17. How To Decide Cable Tray Size?

Answer :

According to the no. Of cable occupancy inside the cable tray and available tray size we must pick it. They are to be had in all. Types eighty,one hundred fifty,300,450,six hundred & 900.

Question 18. What Is Meant By Instrument Location & Jb Location?

Answer :

This includes Instrument location considering the piping drawing given from piping dept. We identify the places of the instrument within the system layouts and placed the bubbles and elevation and JB nos for the area. Same manner depending upon the accessibility we decide the vicinity of JB and marking of it into the instrument vicinity plan is JB location. There isn't any need to make a extraordinary drawing for this.

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Question 19. While Locating Instrument & Jb Which Things We Have To Consider?

Answer :

Transmitter: Tube routing, preservation place, man approach, Valve : Hand wheel operations, Maintenance place, Etc. Loop energy indicators: Man approach Illumination from Electrical if device isn't always going to offer.

Question 20. What Is The Use For Cable Entry In Control Room? (sleeves & Mct)

Answer :

In the technique plant Control room constructed considering the non-unsafe region. So in case if hearth/Explosion takes location in the plant than that has to be confined from entering into the control room. So MCT (Multiple cables temporary) blocks are used. They are designed to maintain the fireplace for fixed time length. That block holds the cables which are moving into the CCR.

Question 21. What Is Control System?

Answer :

A control device is an association of physical components related or associated in such a way as to command, direct or modify in such a manner as to command, direct or modify itself or every other machine.

Control gadget may be of two viz. Open-loop manipulate system and closed-loop control system.

Question 22. What Is Feedback In Control System? What Are Its Characteristics?

Answer :

Feedback is that assets of a closed loop manage machine which permits the output or a few other managed variable of the system, to be as compared with the enter to the gadget, in order that the appropriate manipulate action can be fashioned as a few characteristic of the output and input.

A comments is said to exist in a device if the motive and effect between variables is interrelated.

The traits of remarks are: accelerated bandwidth, accelerated accuracy, reduced distortion and non linearity and tendency in the direction of oscillations or instability.

Question 23. What Is System Error?

Answer :

The system blunders is the proper price of the controlled variable minus the cost of the final controlled variable.

Question 24. What Are Control System Components?

Answer :

Various components employed on top of things structures are servo-vehicles, amplidyne, synchros, stepper automobiles, tachometers, gyroscopes etc.

Question 25. Which Types Of Servo Motors Generally Lend Themselves To Small Horse Power Requirements?

Answer :

Two section and shaded pole kind induction motor are used.

Question 26. Give One Advantage Of The Two Phase Servomotor Over The Shaded Pole Type?

Answer :

Better reaction to very small controls indicators.

Question 27. Why Are Drag-cup-creation Used In Rotors Of Certain Fhp Machines For Control Purposes?

Answer :

In drag-cup-production all heavy iron lamination remain desk bound and only a light cup rotates, so the inertia is quite small.

Question 28. Why Is Series Compensating Winding Employed In The Amplidynes?

Answer :

Compensating winding is attached in series with the electricity output brush terminals of the amplidynes to neutralize the armature response mmf installation by using the load cutting-edge and growth amplification factor.

Question 29. Why Area Commutating Poles Required In Amplidynes?

Answer :

Com mutating poles are required in amplidynes to present high-quality commutation.

Question 30. Why Amplidyne Are Not Extremely Over-compensated?

Answer :

In case of extreme over-repayment, undesirable self-excitation of the amplidyne that is spontaneous upward push in voltage and load cutting-edge at consistent control contemporary (or with the manage circuit open) can arise. Self-excitation can purpose sizable over-loading of the amplidyne and absolutely disrupt operation of gadget containing the amplidyne.

Question 31. Why Amplidynes Are Provided With Split-poles?

Answer :

Amplidynes are supplied with cut up-poles to offer space for inter poles.

Question 32. What Is Stepper Motor?

Answer :

A motor wherein the rotor turns in discrete moves is referred to as a stepper motor.

Question 33. What Are The Two Types Of Stepper Motors?

Answer :

Permanent –magnet type and variable reluctance type motor are stepper motor.

Question 34. For The Same Number Of Poles Which Stepper Motor Produces?

Answer :

Largest stepping perspective.
Smallest stepping angle.
Permanent magnet kind- biggest stepping attitude.
Variable reluctance kind-smallest stepping attitude.
Question 35. Where Is Stepper Motor Used?

Answer :

Super motors are utilized in commercial conditions which call for specific positioning of an item or unique control of velocity while not having to hotel to closed-loop remarks. ,, it is most critical question of manage device.

Question 36. How An Ac Tachometer Is Superior To Dc Tachometer?

Answer :

AC tachometer does now not cause any maintenance problem of commentators and brushes.

Question 37. What Is Transfer Function?

Answer :

It is the mathematical expression that relates the device output to the system input and so describes the conduct of a system. It is expressed as ratio of the Laplace transform of the output variable to the lap lace transform of the input variable with the belief that every one the initial conditions are 0.

Question 38. What Is Linear System?

Answer :

A linear machine is a device that follows the regulation of superposition and homogeneity.

Question 39. What Is Analogous System?

Answer :

Systems which might be ruled with the aid of the same forms of equations are referred to as analogous structures. Analogous systems may also have completely exceptional physical appearances. For instance, a given electric circuit inclusive of resistances, inductance and capacitance can be analogous to a mechanical system such as a appropriate aggregate of dash pots, weights and springs or it could be analogous to an acoustical device inclusive of the correct arrangement of best mesh displays, tubes and cavities.

Question forty. What Is Signal Flow Graph?

Answer :

A signal go with the flow graph is pictorial illustration of the simultaneous equations describing a device. It graphically presentations the transmission of alerts through the device, as does the block diagram.

Question 41. What Is Meant By Overshoot?

Answer :

Over shoot is maximum distinction between the brief and constant-nation solutions for a unit step characteristic input.

Question 42. Enlist The Applications Of Sampled Data Systems?

Answer :

Sampled data system finds programs in

High speed tin plate rolling mills the use of quantized facts for manipulate.
Numerically controlled system device operations.
Pulse controlled or digital managed electric drives.
Large complex systems the use of telemetry links based totally on pulse modulation (PM) translation of facts.