projects in electrical instrumentation

8/8/2019 Projects in Electrical Instrumentation

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EXPERT SYSTEMS AND SOLUTIONS

Email: [email protected]

[email protected]

Cell: 9952749533www.researchprojects.info

PAIYANOOR, OMR, CHENNAI

Call For Research Projects Final

year students of B.E in EEE, ECE, EI,

M.E (Power Systems), M.E (Applied

Electronics), M.E (Power Electronics)

Ph.D Electrical and Electronics.

Students can assemble their hardware in our

Research labs. Experts will be guiding theprojects.


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UNITUNIT--22

ELECTRICAL ANDELECTRICAL AND

ELECTRONIC INSTRUMENTSELECTRONIC INSTRUMENTS


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INSTRUMENTS

PRIMARY INSTRUMENTS SECONDARY INSTRUMENTS

ACCORDING TO THE NATURE ACCORDING TO THE PRINCIPLE

INDICATING INSTRUMENT

INTEGRATING INSTRUMENT

RECORDING INSTRUMENT

(i) MAGNETIC EFFECT

(ii) HEATING EFFECT

(iii) INDUCTION EFFECT

(iv) ELECTROSTATIC EFFECT


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PRIMARY INSTRUMENT:PRIMARY INSTRUMENT:

The measured quantity is mentioned throughThe measured quantity is mentioned through

its physical quantity.its physical quantity.

EX:EX:Tangent GalvanometerTangent Galvanometer

SECONDARY INSTRUMENT:SECONDARY INSTRUMENT:

The measured quantity is mentioned DirectlyThe measured quantity is mentioned Directly


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ClassificationClassification

Electrical instruments classified according toElectrical instruments classified according to

the kind of currentthe kind of current

(i) Direct Current(i) Direct Current (ii) Alternating Current(ii) Alternating Current

(iii) Both AC & DC.(iii) Both AC & DC.

(Universal Instrument)(Universal Instrument)


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According to the OperationAccording to the Operation

Electrical instrument is divided into two types.Electrical instrument is divided into two types.i) Analog Instruments.i) Analog Instruments.

(ii) Digital Instruments.(ii) Digital Instruments.


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AnalogInstrumentsAnalogInstruments

AnalogAnalog instrumentsinstruments areare nothingnothing butbut itsits outputoutput

isis thethe deflectiondeflection ofof pointer,pointer, whichwhich isis

proportionalproportional toto itsits inputinput.. ItIt isis thethe devicedevice whichwhich thethe outputoutput oror displaydisplay isis aa

continuouscontinuous functionfunction ofof timetime andand aa constantconstant

relationrelation toto itsits inputinput..


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Analog Instrument ClassificationAnalog Instrument Classification

Indicating Instrument :Indicating Instrument :

Indicate the magnitude of a quantityIndicate the magnitude of a quantity

Using Dial and a pointerUsing Dial and a pointer

Recording InstrumentRecording Instrument

Continuous record of the quantity being measuredContinuous record of the quantity being measuredover a specified period.over a specified period.

It records the variation .It records the variation .

Integrating Instrument:Integrating Instrument:

Totalize the events over a specified period of time.Totalize the events over a specified period of time.


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According to the Comparison:According to the Comparison:

DirectDirect MeasuringMeasuring InstrumentInstrument::

The measured quantity displayed directly.The measured quantity displayed directly. InIn DirectDirect MeasuringMeasuring InstrumentInstrument::

The measured quantity compared with theThe measured quantity compared with the

standard Value.standard Value.


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Digital InstrumentsDigital Instruments DigitalDigital InstrumentsInstruments areare itsits outputoutput isis inin decimaldecimal

formform

ItIt operateoperate withwith 00 andand 11ss..


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MeasuringInstrumentsMeasuringInstruments


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Ammeter and voltmeter is used to measure the voltage and current.Ammeter and voltmeter is used to measure the voltage and current.

Types of Ammeter &Voltmeter instrumentsTypes of Ammeter &Voltmeter instruments

PermanentPermanent MagnetMagnet MovingMoving coilcoil (PMMC)(PMMC)

DC ONLYDC ONLY

MovingMoving IronIron--AttractionAttraction && RepulsiveRepulsive..

Either AC or DCEither AC or DC

ElectroElectro--dynamometerdynamometer


HotHot wirewire


ThermocoupleThermocouple --



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InductionInduction

AC ONLYAC ONLY

ElectrostaticElectrostatic Either AC or DCEither AC or DC

RectifierRectifier..



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ForcesForces

Deflecting Force.Deflecting Force. Controlling Force.Controlling Force.

Damping Force.Damping Force.


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Deflecting Force or operating ForceDeflecting Force or operating Force

It is a Force used to Create the Deflection.It is a Force used to Create the Deflection.

The Force Creating system is also called as aThe Force Creating system is also called as aDeflecting System or Moving system.Deflecting System or Moving system.

It is created by any one of the Electrical Effect.It is created by any one of the Electrical Effect.


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EXPLANATIONEXPLANATION

when we are giving the supply to the Meterwhen we are giving the supply to the Meter

the corresponding changes are occurredthe corresponding changes are occurred

through the needle.through the needle.

So the Electrical system makes the Deflection .So the Electrical system makes the Deflection .

Such type of system is called as DeflectingSuch type of system is called as Deflecting

SystemSystem


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Controlling ForceControlling Force

It is used to create the control.It is used to create the control.

Such type of system is called as ControllingSuch type of system is called as ControllingSystem.System.

It is also used for create the Balance.It is also used for create the Balance.

Types:Types:

Springcontrol system.Springcontrol system.

Gravity Control system.Gravity Control system.


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EXP

LANATIONEXP

LANATION After giving the supply through DeflectingAfter giving the supply through Deflecting

System. It creates the Deflection.System. It creates the Deflection.

Due to the deflection the needle wont comes toDue to the deflection the needle wont comes tothe rest position.the rest position.

By using the controlling force it creates theBy using the controlling force it creates the

balance in the System .balance in the System .


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Damping ForceDamping Force

It is a Force used to avoid the oscillation.It is a Force used to avoid the oscillation.

It gives the Faster Action.It gives the Faster Action.

Types:Types:

Air Friction DampingAir Friction Damping

Fluid Friction DampingFluid Friction Damping Eddy current Damping systemEddy current Damping system


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EXPLANATIONEXPLANATION

The deflecting system creates the deflection in theThe deflecting system creates the deflection in themeter .meter .

The controlling system makes the controlling force.The controlling system makes the controlling force.

The controlling force is used for Balancing andThe controlling force is used for Balancing andneedle fix it in a rest position.needle fix it in a rest position.

But Thats not happened faster .due to that theBut Thats not happened faster .due to that theneedles are oscillating in the system.needles are oscillating in the system.

Such type ofProblems are minimized by usingSuch type ofProblems are minimized by using

Damping Force.Damping Force.


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Moving CoilMoving Coil

(i)(i) PMMC TypePMMC Type


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Magnet Systems :Magnet Systems :

Old style magnet system consisted of relatively longOld style magnet system consisted of relatively longU shaped permanent magnets having soft iron poleU shaped permanent magnets having soft iron pole

pieces.pieces. Owing to development of materials like Alcomax andOwing to development of materials like Alcomax and

Alnico, which have a high coAlnico, which have a high co--ercive force, it isercive force, it ispossible to use smaller magnet lengths and high fieldpossible to use smaller magnet lengths and high field

intensities.intensities. The flux densities used in PMIMC instruments varyThe flux densities used in PMIMC instruments vary

from 0.1 Wb/m to 1 Wb/m.from 0.1 Wb/m to 1 Wb/m.


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Control:Control: When the coil is supported between two jewelWhen the coil is supported between two jewel

bearings two phosphor bronze hairspringsbearings two phosphor bronze hairspringsprovide the control torque.provide the control torque.

These springs also serve to lead current in andThese springs also serve to lead current in andout of the coil. The control torque is providedout of the coil. The control torque is providedby the ribbon suspension as shown.by the ribbon suspension as shown.

This method is comparatively new and isThis method is comparatively new and isclaimed to be advantageous as it eliminatesclaimed to be advantageous as it eliminatesbearing friction.bearing friction.


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DampingDamping ::

Damping torque is produced by movement ofDamping torque is produced by movement of

the aluminum former moving in the magneticthe aluminum former moving in the magneticfield of the permanent magnet.field of the permanent magnet.


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Errors in PMMCErrors in PMMC

(i) Hysteresis Error(i) Hysteresis Error

Due to the Iron Parts Used in the Meter.Due to the Iron Parts Used in the Meter.

(ii)Temperature Error(ii)Temperature Error Due to TemperatureDue to Temperature

(iii) Stray magnetic Field Error(iii) Stray magnetic Field Error

Due to Stray Magnetic field.Due to Stray Magnetic field. It Opposes the Operating Magnetic Field.It Opposes the Operating Magnetic Field.


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ADVANTAGE:ADVANTAGE:

The scale is uniformly divided.The scale is uniformly divided.

The power consumption is very lowThe power consumption is very low

The torqueThe torque--weight ratio is high which gives a high accuracy. The accuracy is of theweight ratio is high which gives a high accuracy. The accuracy is of theorder of generally 2 percent of fullorder of generally 2 percent of full--scale deflection.scale deflection.

Using different values for shunts and multipliers may use a single instrument forUsing different values for shunts and multipliers may use a single instrument formany different current and voltage ranges.many different current and voltage ranges.

Since the operating forces are large on account of large flux densities, which maySince the operating forces are large on account of large flux densities, which maybe as high as 0.5 Wb/m, the errors due to stray magnetic fields are small.be as high as 0.5 Wb/m, the errors due to stray magnetic fields are small.

SelfSelf--shielding magnets make the core magnet mechanism particularly useful inshielding magnets make the core magnet mechanism particularly useful inaircraft and aerospace applications.aircraft and aerospace applications.

DISADVANTAGEDISADVANTAGE

These instruments are useful only for D.C.These instruments are useful only for D.C.

The torque reverses if the current reverses. If the instrument is connected to a.c., theThe torque reverses if the current reverses. If the instrument is connected to a.c., thepointer cannot follow the rapid reversals and the deflection corresponds to meanpointer cannot follow the rapid reversals and the deflection corresponds to mean

torque, which is zero. Hence these instruments cannot be used for a.c.torque, which is zero. Hence these instruments cannot be used for a.c. The cost of these instruments is higher than that of moving iron instruments.The cost of these instruments is higher than that of moving iron instruments.


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Moving IronMoving Iron

Attraction TypeAttraction Type


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Repulsive Type:Repulsive Type:


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DynamoMeter TypeDynamoMeter Type


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Digital VoltmeterDigital Voltmeter

A digital voltmeter (DVM) displays the value of a.c. or d.c. voltage being measured directlyA digital voltmeter (DVM) displays the value of a.c. or d.c. voltage being measured directlyas discrete numerals in the decimal number system.as discrete numerals in the decimal number system.

Numerical readout of DVMs is advantageous since it eliminates observational errorsNumerical readout of DVMs is advantageous since it eliminates observational errorscommitted by operators.committed by operators.

The errors on account of parallax and approximations are entirely eliminated.The errors on account of parallax and approximations are entirely eliminated.

The use of digital voltmeters increases tile speed with which readings can be taken.The use of digital voltmeters increases tile speed with which readings can be taken.

A digital voltmeter is a versatile and accurate voltmeter, which has many laboratoryA digital voltmeter is a versatile and accurate voltmeter, which has many laboratoryapplications.applications.

On account of developments in the integrated circuit (IC) technology, it has been possible toOn account of developments in the integrated circuit (IC) technology, it has been possible toreduce the size, power requirements and cost of digital voltmeters.reduce the size, power requirements and cost of digital voltmeters.

In fact, for the same accuracy, a digital voltmeter now is less costly than its analogIn fact, for the same accuracy, a digital voltmeter now is less costly than its analogcounterpart.counterpart.

The decrease in size of DVMs on account of use of ICs, the portability of the instruments hasThe decrease in size of DVMs on account of use of ICs, the portability of the instruments hasincreased.increased.


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Types:Types:

Ramp type DVMRamp type DVM

Integrating type DVMIntegrating type DVM

Potentiometric type DVMPotentiometric type DVM

Successive approximation type DVMSuccessive approximation type DVM

Continuous balance type DVMContinuous balance type DVM


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Ramp type DVMRamp type DVM

Sample

Gate

Gate Counter

D

I

S

P

L

A

Y

Ranging and Attenuator

Ranging and Attenuator

Clock

Oscillator

Input

Voltage

Input

Comparator

Ground

Comparator


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Integrating type DVMIntegrating type DVM


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Potentiometric type DVMPotentiometric type DVM


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WATTMETERWATTMETER


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Three phase WattmeterThree phase Wattmeter


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Instrument TransformerInstrument Transformer

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