LAB MANUAL(Instrument and Measure)

LAB MANUAL

INSTRUMENTATION & MEASURE

ForB.E (EE)Name:Roll Number:Class:Batch:Semester:Department :

Hamdard Institute of Engineering & Technology Hamdard University Karachi , Islamabad Campusnbb Instrumentation and Measure Contents CON TENTS Lab No.PageNo.DatedRemarksList of ExperimentsMeasurement of self-inductance by three ammetermethod.113Measurement of capacitance by three voltmetermethod.2Measurement of real power and power factor byAnalog wattmeter and power factor meter.Measurement of electrical energy by electronicwattmeter and energy meter.34610Analyze a bridge rectifier circuit with the help of acathode ray oscilloscope.561316Analyze the voltage and current waveforms of aninductive load with the help of a cathoderayoscilloscope and a current transformer.To plot the characteristic curve of a photo resistorby varying illumination.789192427To plot the characteristic curve of photo diode byvarying illumination.To plot the characteristic curve of a phototransistorby varying illumination.1) Plot the characteristic curve of silicon transduceron a graph paper.2) Also determine STT linearity10113036To plot the characteristic curve of J-type Thermo-couple and to determine thermo conditioner couplelinearity.To Plot the characteristic curve ofresistance on a graph paper.To study the characteristic curve of a pressuretransducerthermo12133944To design and construct a 4 bit R- 2R ladder DAC(digital to analog conversion) circuit. Plot the curve.1446 Revised 2012 NF

Instrumentation and Measure

Measurement of self-inductance LAB SESSION 01 OBJECT:Measurement of self-inductance by three ammeter method.APPARATUS:Inductor of any suitable value.Resistance of any suitable value.Power supplyConnecting Wires150 Volts AC SupplyAmmeter and voltmeter DIAGRAM:VsFig no: 1bTHEORY:Connect all the components as shown in fig no: 1a. From the vector diagram in fig no: 1b, wehave(I )2 = (I 1+ I2 cos ) 2 + (I2sin ) 2I2=I12+2I1I2 cos+I22cos2+I22sin2I2=I12+2I1I2 cos+I22cos= (I2-I12-I22)/(2I1 I2) ......................................................(1)1


Measurement of self-inductance Also,Cos = r r +(2fL)2 2Thus eq (1) becomes L= (1/2f) 4r2I12I22r2(I2-I1 -I2 )22 2The dc resistance r of the coil can be measured by using the following two methods:1. It can be measured on direct current.2. Since R is known and cos can be determined by using eq(1),so from the vectordiagram in fig no:1b, we havecos =(I1r) / (I2R)r=(I2R cos) /I1OBSERVATIONS:S. No.VI1I2I3CALCULATIONS:RESULT:(1) Dc resistance r of the coil is found to be: ____________________(2) Self inductance L of the coil is found to be: __________________EXCERCISE:(a) With the help of above observations and eq(1), calculate the power absorbed by thecoil.(b) Perform a simple experiment to measure mutual inductance.2


Measurement of capacitance LAB SESSION 02 OBJECT:Measurement of capacitance by three voltmeter method.APPARATUS:Capacitor of any suitable value.Resistance of any suitable value.Power supplyConnecting Wires150 Volts AC SupplyAmmeter and voltmeterDIAGRAM: 3


Measurement of capacitance THEORY:Connect all the components as shown in fig no: 2a. From the vector diagram in fig no: 2b, we have(Vs )2 = (V 1+ V2 cos ) 2 + (V2sin ) 2Vs2=V1 +2V1V2 cos+V22cos +V22sin222Vs2=V12+2V1V2 cos+V22Cos=(Vs2-V12-V22)/(2V1V2)...............................................(1)Also,cos=r(1/r2)+(2fc)2Thus eq(1) becomes,r= (Vs2-V12-V22)/(2V1V2) .................................(2)(1/r2)+(2fc)2The leakage resistance r of the capacitor can be measured by using the following twomethods:1. It can be measured on direct current.2. Since R is known and cos can be determined by using eq(1),so from the vectordiagram in fig no:2b, we havecos =(V1R) / (V2 r)r=(V1R) / (V2cos)OBSERVATIONS:S. No.IVsV1V24

Measurement of capacitance CALCULATIONS:RESULT:The leakage resistance of the capacitor is found to be=---------------- The capacitance is found to be=----------------------- EXCERCISE:With the help of above observations and eq(1), calculate the power absorbed by the capacitor.5


Measurement of Real Power LAB SESSION 03 OBJECT: -Measurement of real power and power factor by Analog wattmeter and power factormeter.APPARATUS: -Resistive load.Voltmeter.Ammeter.Wattmeter.Power supply 220 VConnecting wiresTHEORY:Wattmeter:The wattmeter is a measuring instrument use to measure electric power.The wattmeter is consists of a Pressure Coil and Current Coil. The current coil of theinstrument carries the load current, while the pressure coil carries the current proportional to,and in phase with the voltage. The deflection of the wattmeter depends upon the currentin these two coils and upon the power factor. Inductance in the pressure coil circuitshould be divided as far as possible, since it causes the pressure coil current to lag behind theapplied voltage. A high non-inductive resistance is connected in series with the pressurecoil in order that the resultant of the coil itself shall be small in comparison, with theresistance of the whole pressure coil circuit taken by the pressure coil shall be small.Power Factor Meter:The instrument is based on the dynamometer principle with spring control. Theinstrument has a stationary coil, which has a uniform field. There are two moving voltagecoils having resitance, (R ) and inductance (L) in series. When the reistive load isincreased or decreased the pointer shows the power factor, either leading or lagging.PROCEDURE:1. Connect the voltmeter in parallel with the source.2. Connect the ammeter in series with the source.6


Measurement of Real Power 3. Connect the wattmeter and power factor meter according to the instructions alreadywritten on the labeled diagram.4. Now vary the load, and measure voltage, current, power and power factoreach time.DIAGRAM7


Measurement of Real Power OBSERVATIONS:LoadPowerVICosReactive(Watt)(Volts)(Amp)Power2 BulbsON6 BulbsONInductiveload 1Inductiveload 2CALCULATION:8


Measurement of Real Power RESULTThe power & p.f by wattmeter has been measured.EXCERCISE:a) What changes do you see in the observation columns after increasing the resistive load andinductive load?b) After the last observation add a capacitive load. What will you conclude now?9


Measurement of Electrical Energy LAB SESSION 04 OBJECT: -Measurement of Electrical Energy by Electronic wattmeter and Energymeter(KWH).Also prove that E = P * t.APPARATUS: -1. Circuit board.2. Energy meter.3. Electronic wattmeter.4. Stop watch.5. Resistive Load.THEORY: -Single Phase Watt-Hour Meter: -Induction type meters are the most common form of AC meters. These meters measureelectric energy in kilowatt-hour. The principle of these meters is practically the same asthat of the induction wattcmeters. In these meters magnet and spindle is used.The watt-hour meter consist on two main coils:(i)(ii)Pressure coil.Current coil.The pressure coil is attached to the source while the current coil is attached to the load. Inkilowatt-hour meter the breaking magnet is provided to control the speed of the disc. Thebreaking magnet decreases the breaking torque.Features: -1. They are induction type of instruments.2. They are light in weight.3. Torque to weight ratio is very small.4. Temperature change has very small effect on the instrument.Electronic Wattmeter:An electronic wattmeter is a power-measuring instrument. This instrument consists of adeflection scale, voltage adjustment knob and current adjustment knob as well. Theelectronic wattmeter is connected to the supply and voltage and current knob areadjusted. The pointer shows the deflection, which is to be noted. The power is calculated asPower = deflection* Voltage range * Amperes range10


Measurement of Electrical Energy PROCEDURE: -1. First of all the connection is completed.2. The voltage knob is adjusted at 500 volts.3. The ampere knob is adjusted at 5 amp.4. Deflection is measured from deflection scale.5. Power is measured by above formula mentioned on Electronic Wattmeter.6. Initially reading of kWh meter is noted and after 15 minutes the final reading istaken.7. Change the time (which is in minute) into Hours.8. The energy measured by electronic wattmeter should be equal to kWh meter.PC2134C CPNPLACOADSUPPLYNFig no:1ELECTRONC WATTMETERAC SUPPLY Fig no:2 11


Measurement of Electrical Energy OBSERVATION: -S.NoPower (watt)TimekWh byKWh by observationsDeflect.x V x I (minutes) calculationsKWh = P xtInitialFinalDiff.CALCULATION:-RESULT: -It is observed that the energy measured by electronic wattmeter and kWh meter is12


Bridge Rectifier LAB SESSION 05 OBJECT:By making use of cathode ray osilloscope , study the bridge rectifier to :-(1) To calculate input frequency Vin(2 ) To calculate Vrms, Vavg, Irms & Iavg.APPARATUS:Vin = 24 VAC voltmeter (50V)DC Ammeter (5A)DC voltmeter (50 V)AC Ammeter (3A)Transformer step-down (220-24 volts)Oscilloscope (T/d = 5 s/div)Variable LoadR1 = 23 OhmR2 = 9.6 OhmR1// R2 =R3 = 6.77 OhmTHEORY:During the +ve, half cycle of input voltage the two diodes D1 & D2 are in conduction.D2 provides returning path to the current. In the negative half of the input voltage D3 &D4 become forward biased and they start conduction. The direction of current flowremains same during both conduction stages hence we get rectification in both cycles ofinput voltage.Formulae Used in the Calculation:1. f = 1/T2. Vdc = 0.636Vmax3. Vrms = 0.707Vmax13


Bridge Rectifier CIRCUIT DIAGRAM:WAVE FORMS:PROCEDURE:-Connect the circuit element according to the diagram.Now turn on the load R1 and note the values of Iavg, Irms, Vavg, and Vrms. Alsoobserve their waveforms on the Oscilloscope.14


Bridge Rectifier Now turn on R2 and repeat the above procedure.This time turn on both R1 & R2 simultaneously and measure the readings.Now Calculate the values of Iavg, Irms, Vavg, and Vrms.OBSERVATIONS:-The wave forms of the output voltage of a bridge rectifier are observed for agiven frequency.f = 1/T = 1/ ms = Hz VrmVavgIrmIavS.No LoadVmaxObs Cal Diff Obs CalDiff Obs Cal Diff Obs CalDiffNo1load2349.6 23 9.6parallelwith 23 RESULT :-We have noted the observations by and calculate the input frequency by making use ofCathode Ray Oscilloscope.15


Analysis of Waveforms with CRO LAB SESSION 06 OBJECT:Analyze the voltage and current waveforms of an inductive load with the help of a cathoderay oscilloscope and a current transformer.APPARATUS:Transformer as an inductive load.Resistive loadOscilloscopeCeramic resistor valued 1current transformerAC supplyAmmeter and voltmeterTHEORY:Transformers used in connection with instruments for measurement functions are referredto as instrument transformers. The type used for measurement of current is called aninstrument current transformers or C.T. Current transformers are used for extending therange of ammeters & the current coils of watt meters & energy meters.The primary winding of current transformer is to be connected in series with the componentfor which current is to be determined & the secondary is enclosed through a meteringcircuit or a low valued resistance, it must never be left opened.Oscilloscope in connection with CT can be utilized for viewing current waveforms on thescope. For this purpose the secondary of CT is terminated in a 1 resistance.Then the probe of Oscilloscope is connected across the secondary of CT. The waveformthus displayed will be of the current. A typical phase measurement is done by overlappingtwo signals so that they appear to have the same amplitude this can be done by taking oneor both of the vertical channels out of calibration and using the vertical position control toplace both waveforms on center screen.The phase shift between two sinusoidal waveforms can be computed fromxWhere,= the phase shift in degreest = time difference between corresponding points on the two waveforms, secT = time period of the waveforms, sec16

Analysis of Waveforms with CRO DIAGRAM:PROCEDURE:1) Connect all the components as shown in fig no:1.2) Apply a suitable ac voltage to the primary of the two winding transformer.3) Record the ammeter and voltmeter readings. These will be the values for primarycurrent and voltage of the two winding transformer.4) Connect channel 1 of the scope to primary of the two winding transformer to seeprimary voltage waveform.5) Connect channel 2 of the two winding transformer as shown in fig no:1 to observe theprimary current waveform.6) Calculate the phase difference between the two waveforms as explained in the theoryportion of the experiment.7) Now remove the scope and resistor from the secondary of CT and connect anammeter. OBSERVATION:Rated primary current of CT: -----------Rated secondary current of CT: -----------S.NOSupply/PrimaryVoltagePrimary currentSecondarycurrent of CTCalculatedcurrent throughprimary of CT17

Analysis of Waveforms with CRO WAVEFORMS (Properly Labeled):CALCULATION:RESULT:The current and voltage waveforms of the inductive load have been analyzed and the phaseangle is found to be = _____________________.18

Characteristic curve of photo resistor LAB SESSION 07 OBJECT:To plot the characteristic curve of a photo resistor by varying levels ofillumination.EQUIPMENT REQUIRED:Module HolderLight Transducer and Control Module G13/EVLight Transducer Interface Unit TY13/EVPS1-PSU- Power supply unitMeasurement unit IU9/EV.Connecting wiresDIN CableTHEORY:Light Transducer:Transducers are devices that convert energy from one form to another. Here weuse this term to define those devices that transform physical quantity into an electricalone. A typical block diagram of a transducer may be represented asPhysical Quantity Electrical Quantity Transducer Light transducers are devices that transform the light radiation into an electricalquantity (resistance, current), where light radiation may be defined as that region of theelectromagnetic spectrum that includes the infrared, visible and ultraviolet components.A part of the light radiations can be detected by the human eye and is defined as visibleradiation or light.Interacting with a substance, the light radiation produces different effects. Amongwhich, there is the Photoelectric Effect which consists of the liberation of electrons byelectromagnetic radiation incident on a metal surface and in case of semiconductors, inthe generation of electron hole pairs.19

InstrumentationCharacteristic curve of photo resistorNED University of Engineering and Technology Department of Electrical Engineering 20

Characteristic curve of photo resistor The first phenomenon is called photoemission and is applied to phototubes,photomultipliers etc. The second phenomenon, i.e. photoelectric effect on semi-conductors can be further divided into two:(1) Photoconductive Effect:The conductivity of a semiconductor bar depends on the intensity of the lightradiation that strikes it.(2) Photoelectric effect on the junction (Photovoltaic Effect):The current across a reversely biased P-N junction depends on the intensity of thelight radiation. If the junction is not biased, an electromotive force is generated across it(Photovoltaic effect).Devices belonging to the first category are called photoresistors, while thosebelonging to the second are called photodiodes, photoelectric cells and phototransistors.Photoresistors:A photoresistor is a passive semiconductor component without a junction. The resistance illumination characteristic curve of a photoresistor may be given as R (Ohm) LUX 21

Characteristic curve of photo resistor When crossed by al light radiation it varies its resistance as a result of thephotoconductive effect. The resistance drops when the light increases. In darkconditions, the photoresistor practically acts as an insulting piece, as it has resistancevalues measured in M (dark resistance); if strongly illuminated it has very lowresistance values measured up to some tens of . The material used for a photo resistordetermines the wavelength at which the device presents the maximum sensitivity.The following materials are used as photosensible materials: crystals of cadmiumsulphide or lead for sensors within the visible range and crystal of cadmium selenidefor sensors in the infrared rangeThe photoresistor used in unit TY13/EV has the following main characteristics: Resistance (10.76 Lux): 100 K Resistance (1076 Lux): 2400 Minimum dark resistance: 4 M Maximum voltage peak: 250 V Maximum dissipable power: 100 mW. Maximum sensitivity: 0.55 mSIGNAL CONDITIONER:Usually the output, electrical quantity of a transducer cannot be directlymanipulated, for e.g., the output voltage range may not be the wished one, thesupplied signal power may be too low, the electrical quantity may not be the onerequested and so on. For these reasons, the transducer is never supplied alone butwith a signal conditioner. The signal conditioner is an instrument converting anelectrical quantity into another electrical one that is more suitable to the specificapplication.PROCEDURE:1.2.Connect jumper 2 to 11 as shown in the figure and connect module G13 to unitTY13/EV.Set the switch of the Photoresistor Conditioner block to position A so as toisolate the photoresistor from the circuit and measure its resistance (With switchI1 in the position A, the transducer is disconnected from the rest of the circuit sothat it can be analyzed without the influence of the other components.)Set the multimeter to measure the resistance and connect it between terminals 16and 17.3.4.5.6.7.Connect module G13 to all the necessary supplies.Set the lamp to the maximum distance with the slide.Set the potentiometer of the SET-POINT block to the maximum value (300 Lux).Move the lamp near the light transducers with the slide in correspondence to thedivisions shown on the panel of unit TY13/EV, read the resistance value indicatedby the multimeter and report them in table (column OHM).22

Characteristic curve of photo resistor 8.9.Plot a graph with illumination on the x-axis and resistance on the y- axis anddraw the points detected. The characteristic curve of the transducer isobtained by joining these points.Remove the multimeter form terminals 16 and 17 and set the switch of thePhotoresistor Conditioner block to B. Now insert the multimeter, selected asvoltmeter for DC voltage, between terminal 18 and ground.10. Repeat all the last measurements: in this case measure the response of thetransducer together with the signal conditioner.11. Plot a graph with illumination on the x-axis and voltage on the y-axis and drawthe points detected.12. The characteristic curve of the transducer together with its signal conditioner isobtained by joining these points.13. Confront the quality of the two graphs.OBSERVATION:S. No LUX OHM VOLT 57 123456789 68 83 104 133 177 248 370612 10 1200RESULT:The characteristic curve of photo resistor is drawn and studied.23

Characteristic curve of photo diode LAB SESSION 08 OBJECT:Plot the characteristic curve of photodiode at variation of illumination.EQUIPMENT REQUIRED:1.2.3.4.5.6.7.Module HolderLight Transducer and Control Module G13/EVLight Transducer Interface Unit TY13/EVPS1-PSU- Power supply unitMeasurement unit IU9/EV.Connecting wiresDIN CableTHEORY:The photodiode is a device, which is similar in structure to a commonsemiconductor diode, with a P-N junction, and, for this kind of use, it is reverse biased.In dark conditions the photodiode operates as a common semiconductor diode,while when the junction is crossed by a light radiation, the reverse current increases. Figshows a typical relation between illumination and reverse current together with thesymbol of the device.The reverse current of photodiodes can take values ranging inside some nA andsome tensofmA.Themostly usedsemiconductormaterialsaresilicon,germanium, gallium arsenide and other semiconductor compounds.If a photodiode, which is not biased and without load is illuminated, it is crossed bya voltage generated inside the junction by the interaction between the light radiation andthe semi conductive material (photovoltaic effect). If, then a load is applied to thephotodiode, there is a passage of current and in this way generation of electrical energytakes place. The said is the operating principle of Photovoltaic cells.The typical parameters of photodiodes, beside the characteristic curve are: The maximum reverse voltage that can be applied across it. The maximum power that can be dissipated. Maximum switching speed (rise and fall times).The photodiode used in unit TY13/EV is P-I-N silicon type and has the followingcharacteristics (see data sheet for details): Maximum reverse voltage: 32 volts DC Maximum sensitivity: 0.9 m Maximum dark current: 30 nA. Reverse current with illumination equal to 1mW/cm2: 50 A. No-load voltage (1000 lux): 350 mV Rise and fall times: 50 ns24

Characteristic curve of photo diode 19 Vout w/o conditioner 22 Vout w/ conditionerPROCEDURE1.2.Carry out the circuit of figure and connect module G-13 to unit TY13/EV as infigureSet the switch of the Photodiode Conditioner block to position A (with switch inposition A, the transducer is disconnected from the operational amplifier andconnected to resistor R7 so that it can be analyzed without the influence of theother components).3.Set the multimeter for voltage measurement and connect it between terminal 19and ground. In this case although a current is generated by the transducer, it ispreferable to measure the fall this current determines on the resistor R7 as thesame current is a very small.4.5.6.7.Connect module G13 to all the necessary supplies.Set the lamp to the maximum distance with the slide.Set the potentiometer of the SET-POINT block to the maximum value (300 Lux).Move the lamp near the light transducers with the slide and in correspondence to25

Characteristic curve of photo diode the divisions shown on the panel of unit TY13/EV, read the voltage valuesindicated by the multimeter and report them in table8.9.Plot a graph with illumination on the x-axis and voltage of the diode cathode onthe y-axis and draw the points detected.The characteristic curve of the transducer is obtained by joining these points.10. Remove the voltmeter from terminal 19, take the switch to B and insert thevoltmeter between terminals 22 and ground.11. Repeat all the last measurements: in this case measure the response of thetransducer together with the signal conditioner.12. Plot a graph with illumination on the x-axis and voltage on the y-axis and drawthe points detected.13. The characteristic curve of the transducer together with one of its signalconditioner is obtained by joining these points.14. Confront the quality of the two graphs.OBSERVATION S No LUX57 Vout (19)Vout (22)1 2 3 68 83 4 104 133 177 248 370 612 1200 3330 5 6 7 8 9 10 11 RESULT:The characteristic curve of photodiode is drawn and studied.26

Characteristic curve of photo transistor LAB SESSION 09 OBJECT:Plot the characteristic curve of Phototransistor at variation of illumination.EQUIPMENT REQUIRED:Module HolderLight Transducer and Control Module G13/EVLight Transducer Interface Unit TY13/EVPS1-PSU- Power supply unitMeasurement unit IU9/EV.Connecting wiresDIN CableTHEORY:PhototransistorThe phototransistor is a device with a structure similar to the one of a standardtransistor, but with a photo sensible base. It is generally NPN kind, it is powered with apositive voltage between collector and emitter while the base can be left open orconnected to the emitter with a resistor.In the second case, the sensitivity of the phototransistor can be adjusted by varyingthe value of the resistor used. In dark conditions, the current of the collector Ic isminimum and increases with illumination. Figure shows the symbol with the typicaldiagram of the connection of the phototransistor; furthermore it shows the characteristiccurve with the relation between the variations of Ic and the variations of the illumination.The main parameters of a phototransistor, in addition to the characteristic curve, are: The maximum dark current. The wavelength of maximum sensitivity. The switching speed (rise and fall times). The maximum admitted values of current, voltage and power.The phototransistor used in the equipment has the following main characteristics: Dark current: 20 A Rise time: 8 s Fall time: 6 s Vce max: 30 V DC27

Characteristic curve of photo transistor PROCEDURE:Carry out the circuit of figure and connect module G-13 to units TY13/EV asin figureSet the switch of the PHOTODIODE CONDITIONER block to the positionA, set the multimeter for D.C. current measurement and connect it betweenterminals 23 and ground.Connect module G13 to all the necessary supplies.Set the lamp to the maximum distance with the slide.Set the potentiometer of the SET-POINT block to the maximum value (300Lux).Move the lamp near the light transducers with the slide, and incorrespondence to the divisions shown on the panel of unit TY13/EV, read thecurrent values indicated by the multimeter and report them in tablePlot a graph with illumination on the x-axis and current on the y-axis anddraw the points detected.The characteristic curve of the transducer is obtained by joining these points.Set the switch to B and insert the multimeter, selected as voltmeter for D.C.voltage, between terminal 28 and ground.Repeat all the last measurements: in this case measure the response of thetransducer together with the one of the signal conditioner.Plot a graph with illumination on the x-axis and voltage on the y-axis anddraw the points detected.The characteristic curve of the transducer together with its signal conditioneris obtained by joining these points.Confront the quality of the two graphs.28

Characteristic curve of photo transistor OBSERVATION:RESULT:The characteristic curve of Phototransistor is drawn and studied.29

Characteristic curve of silicon transducer LAB SESSION 10OBJECT:(a)Plot the characteristic curve of Silicon transducer on a graph paper.(b) Also determine STT linearity.EQUIPMENT REQUIRED:1.2.3.4.5.6.7.Module HolderModule for transducer control G34/ EVPS1-PSU- Power supply unitTransducer attachment TY 34/EVMeasurement unit IU9/EV.Connecting wiresSTT DIN cable.THEORY:General concepts regarding transducers:Devices, which convert a physical quantity of one type into a physical quantity ofa different type, are generally referred to as Transducers. Here this term refers to aspecific type of device designed to transform a physical quantity into an electricalquantity, i.e. those that are designed to function as SINSORS. The general block diagramof a transducer is shown in fig. The electrical quantity output by a transducer may be avoltage, current, resistance etc.Physical Quantity Electrical Quantity Transducer Transducers are categorized as analog or digital according to the nature of theelectrical quantity, which they output. When a continuous physical quantity is input to ananalog transducer, the output is a continuous physical quantity that is proportional to theinput, while in case of a digital transducer the output is a series of digital signals.In general, this conversion absorbs a certain quantity of energy; as a result, thepresence of a transducer represents a disturbance to the process being analyzed.Each type of transducer has a series of characteristics, some of which are specificto that type of transducer, others being common to more than one type. These include:30

Characteristic curve of silicon transducer RangeThis is the interval between the minimum and maximum physical quantities that thetransducer can measure. Proportionality constantThe proportionality constant is the relationship between the values of the output and theinput quantities. Linearity errorThe linearity error is the shift from the proportionality constant between the input andoutput quantities and is expressed as a percentage of the maximum output value. Accuracy (measurement error)The accuracy of a transducer indicates the maximum difference between the measuredvalue and the true value. Accuracy is expressed as a percentage of the full-scale value. Speed of responseThis is the speed with which the output quantity follows the variations in the inputquantity. StabilityThe stability indicates the degree to which the relationship between input and outputremains constant in all operating conditions. RepeatabilityThis is the tolerance relative to the values for a given measurement (expressed as afraction of the precision)Determining the linearity of a transducerMost transducers are linear. One of the most important characteristics determinedexperimentally is the linearity. The procedure required to determine the linearity is thesame for all types of transducers. In order to plot the input/output characteristic curve of atransducer, it is necessary to measure the quantities output by the transducer in response toa series of input physical quantities. When these values have been plotted on a graph, theline that best represents the average measurement can be drawn. This is the best-fitstraight line for the transducer. Plot two lines equidistant from and parallel to the best-fit straight line; these lines must encompass all the values plotted on the graph.Next, plot a vertical line parallel to the y-axis. The points of intersection with theparallel external lines are called V1 and V2 (see fig). The percentage linearity of thetransducer with respect to the full-scale value is given by the following equation:Lin.[%] = 1V2 -V1 . 1002 Vf.s.31

Characteristic curve of silicon transducer Output V2 V1 Physical Quantity Signal conditionersIt is not normally possible to manipulate the electrical output of a transducerdirectly. For example, the range of output voltages may not be suitable, or the outputsignal may be too weak, or perhaps the electrical quantity is not the one required for thesystem, etc. For this reason, transducers are never installed without a device known assignal conditioner. A signal conditioner is a device (generally electronic), which convertsone physical quantity into another that is more suitable for the specific applicationIn most cases, the output is a voltage. The block diagram relative to the signalconditioner is shown in fig.ELECTRICAL QUANTITY ELECTRICAL QUANTITY SIGNAL CONDITIONER Temperature Transducers:When energy is supplied to a physical system in any form, the state of the systeminevitably changes. Temperature is one of the indicators, which represent the state of thesystem. The unit of temperature used in the international system is the Kelvin (K). In theKelvin temperature scale, absolute zero corresponds to 0 K (-273 degrees centigrade).32

Characteristic curve of silicon transducer Two other temperature scales are normally used: the Celsius or centigrade scale(C) and the Fahrenheit scale (F) the relationship between these scales is shown in fig.Note the difference in the intervals on the Fahrenheit scale.Conversion from Centigrade to Fahrenheit is base on the following equation:0F= 95 C + 320K0C0F0 -273.1 -460 273.1 273.1 12730 +32 100 1000+212 1832We will use the centigrade scale, which is perhaps the most practical of the three,as 0 C corresponds to the temperature of melting ice and 100 C to the boiling-point ofwater at sea-level. In industrial and domestic applications, temperature is measured withdifferent types of transducers of varying complexity and accuracy.The most commonly used are semiconductor transducers, thermo-resistances andthermocouples as these offer a high degree of accuracy together with simple constructionand ease of use. These types of transducers can also be very small, and are therefore easy toinsert directly into the process.Semiconductor Temperature Transducers (STT):Semiconductor temperature transducers are based on the high degree of sensitivity ofsemiconductor materials to temperature. The temperature coefficient of a semiconductortemperature transducer (STT) is much higher than that of a thermo-resistance, and it ismuch cheaper to produce. Its main disadvantage lies in a limited temperature range andlower linearity.Devices of this type may have one or two terminals and are classified as follows: Semiconductor resistive block Junction between two semiconductors doped P and N (diodes) Integrate circuitThe first type of devices are the most simple in structural terms, and may have a positiveof negative temperature coefficient of approximately 0.7% / C and linearity of 0.5 %with in a temperature range of -65 C to + 200 C.33

Characteristic curve of silicon transducer The law by which resistance varies with temperature is, in approximate terms, as follows:RT = Ro (1 + T)The transducer and signal conditioner are generally connected by two wires. As thetemperature to which these wires are subjected varies, the overall resistance on thetransducer and wires also varies. However the measurement error caused by the wires is,in most cases, negligible.The wires which carry the transducer output are always made using the same material andare always of the same length, and their resistance R is therefore identical. As a result,using a differential amplifier, it is possible to obtain a voltage, which varies only with theresistance R.PROCEDURE:1. Connect the transducers to module G34 inserting the DIN cables into the relatedplugs.2. Insert the required transducer and the mercury thermometer into the related holesof unit TY34.3. Connect HEATER and COOLER terminals of G34 to HEATER and COOLERterminals of TY34.4. Connect the output of the SET-POINT block terminal 2 to the set-point input ofthe ERROR AMPLIFIER block terminal 3 and Temperature meter input 10.5. Connect the output of the ERROR AMPLIFIER 5 to the input of the PIDcontroller 6.6. Connect the output of the PID CONTROLLER 9 to the input of the HEATERAMPLIFIER 11.7. Connect the output of the STT Conditioner 23 to the ERROR AMPLIFIERfeedback input 4.8. Set up the connection of the power supply with the console.9. Set potentiometers p2 and p3 on the PID CONTROLLER to the halfway position10. Connect the multimeter to the output of the signal conditioner, and set to 20V DC.11. Short Jack 7 & 8.12. Set Temperature meter switch at STT.13. Starting from ambient temperature (temperature of the surrounding), adjust the0Set-Point knob in order to increase the temperature of the oven in 10 C steps(i.e. bring the voltage on jack 2 to a value which corresponds to ambienttemperature, then increase this voltage by a quantity which corresponds to a010 C temperature increase). Measure the output voltage of the signalconditioner as soon as the temperaturesstabilized.Thereferencetemperature is given by a precision mercury thermometer (Centigrade Scale)14. N.B. Be careful to avoid exceeding the maximum temperature that thetransducer can withstand (1750C). For safety, do not exceed 1500C.15. Make a table listing the values measured and use these measurements to plot agraph with the temperature on the x-axis and the output voltage of the transduceron the y-axis.34

\Characteristic curve of silicon transducer OBSERVATION:Output Voltage of STT Sensor (V)S. No.T (C)12345678930 C40 C50 C60 C70 C80 C90 C 100 C 110 C 120 C 130 C 10 11RESULT:1. The characteristic curve of Silicon transducer is observed.2. The linearity of STT sensor is found to be%.35

Characteristic curve of J type thermo couple LAB SESSION 11OBJECT:Plot the characteristic curve of J type thermo couple and to determine thermo conditionerCouple linearity.EQUIPMENT REQUIRED:1.2.3.4.5.6.7.Module HolderModule for transducer control G34/ EVPS1-PSU- Power supply unitTransducer attachment TY 34/EVMeasurement unit IU9/EV.Connecting wiresThermo Couple DIN cable.THEORY:Thermocouple:Thermocouples consist of two different metallic conductors, which are joined at one endby a galvanic contact (i.e. soldered) as shown in fig below.The thermocouple (or hot junction) is introduced into the surrounding where thetemperature is to be measured (e.g. inside an oven) and the conductors are brought to thepoint of measurement (cold junction), which is at a different temperature (see fig.). Thiscircuit generates a thermoelectric E.M.F. (Electromotive force), which varies accordingto the difference between TC and TF (Seebeck effect)36

Characteristic curve of J type thermo couple Hot _Junction +mV compensation line cold junction By measuring this electromotive force, and as the temperature TF is a known quantity, itis possible to calculate the value to Tc. Since it is necessary to know the value of TF inorder to calculate Tc, it is necessary to extend the wires of the thermocouple withcompensating wires to a point at which the temperature is constant and known.The most important of the thermocouples available in the market are as follows:Fe-ConstantanNi-NiCrCu-Constantan(type J)(type K)(type T)The E.M.F. of the Fe-Constantan thermocouple (J type) is much greater than that of theother types; its linearity is good, and it is inexpensive. One disadvantage is that themaximum temperature is limited by the iron element (700-800 C).The thermocouple examined in this case is of the Fe-Constantan type (type J), and has thefollowing main characteristics:Transduction constant:Error:53 V/C2.2C in the 0 - 270C range0.75% in the 270 - 760C rangeProtected against atmospheric agents by metallic sheathPROCEDURE: Set up the apparatus as described in the previous experiment replacing the signalconditioner for the (STT) with the signal conditioner for the thermocouple. Starting from ambient temperature, adjust the Set-Point knob in order to increase thetemperature of the oven in 10C step (i.e. bring the voltage on jack 2 to a valuewhich corresponds to ambient temperature, then increase this voltage by a quantitywhich corresponds to a 10C temperature increase). Measure the output voltage ofthe signal conditioner as soon as the temperature is stabilized.If the temperature exceeds 150C, remove the semiconductor transducer in order toavoid the possibility of damages. The reference temperature is given by a precision mercury thermometer(Centigrade scale) Compile a Voltage/Temperature table and then plot the characteristic curve on agraph37

Characteristic curve of J type thermo couple Calculate the linearity of the thermocouple as described in the previous experiment.OBSERVATIONOutput Voltage of STT Sensor (V)S. No.T (C)123430 C40 C50 C60 C5678970 C80 C90 C100 C110 C120 C130 C 10 11RESULT:1.2.The characteristic curve of thermocouple is determined and studied.The linearity of thermocouple is found to be%.38

Characteristic curve of thermo resistance LAB SESSION 12OBJECT:(a)Plot the characteristic curve of thermo resistance on a graph paper.EQUIPMENT REQUIRED:1.2.3.4.5.6.7.Module HolderModule for transducer control G34/ EVPS1-PSU- Power supply unitTransducer attachment TY 34/EVMeasurement unit IU9/EV.Connecting wiresRTD DIN cable.THEORY:Signal conditioners:It is not normally possible to manipulate the electrical output of a transducerdirectly. For example, the range of output voltages may not be suitable, or the outputsignal may be too weak, or perhaps the electrical quantity is not the one required for thesystem, etc. For this reason, transducers are never installed without a device known assignal conditioner. A signal conditioner is a device (generally electronic), which convertsone physical quantity into another that is more suitable for the specific applicationIn most cases, the output is a voltage. The block diagram relative to the signalconditioner is shown in fig.ELECTRICALQUANTITYELECTRICALQUANTITYSignalconditionerTemperature Transducers:When energy is supplied to a physical system in any form, the state of the systeminevitably changes. Temperature is one of the indicators, which represent the state of thesystem. The unit of temperature used in the international system is the Kelvin (K). In theKelvin temperature scale, absolute zero corresponds to 0 K (-273 degrees centigrade).39

Characteristic curve of thermo resistance Two other temperature scales are normally used: the Celsius or centigrade scale(C) and the Fahrenheit scale (F) the relationship between these scales is shown in fig.Note the difference in the intervals on the Fahrenheit scale.Conversion from Centigrade to Fahrenheit is base on the following equation:0F= 95 C + 320K0C0F0 -273.1 -460 273.1 273.1 12730 +32 100 1000+212 1832We will use the centigrade scale, which is perhaps the most practical of the three,as 0 C corresponds to the temperature of melting ice and 100 C to the boiling-point ofwater at sea-level. In industrial and domestic applications, temperature is measured withdifferent types of transducers of varying complexity and accuracy.The most commonly used are semiconductor transducers, thermo-resistances andthermocouplesas these offer a high degree of accuracy together with simple construction and ease of use.These types of transducers can also be very small, and are therefore easy to insert directlyinto the process.THERMORESISTANCE (RTDs):Thermo resistance measure temperatures by detecting variations in the resistance of anelectrical conductor. The law by which resistance varies with temperature is, in approximateterms, as follows:RT = Ro (1+T)Where temperature coefficient is the average value over the measurement rangeThermo resistances are also known as resistance temperature detectors (RTDs), and havethe following electrical symbol.RTD40

Characteristic curve of thermo resistance These type of transducers have following main characteristics:Long term invariability of characteristicsReproducibility of characteristicsGood resistance variation with temperatureTwo type of thermo resistance are generally accepted as standard:Nickel thermo resistancePlatinum thermo resistanceThe nickel thermo resistance has temperature coefficient =6.17*10exp -3 C-1,and canbe used at temperature between -60 to +150degree centigradeThe platinum thermo resistance has temperature coefficient =3.85*10exp -3 C-1,and canbe used at temperature between -220 to +750degree centigradeThe catachrestic curve are shown as belowR(ohm)NickelPlatinum0T(0C)41

Characteristic curve of thermo resistance The most commonly used RTDs have resistance of 100ohm at 00C and a tolerance of0+0.1 C.These normally consist of wires (platinum or nickel) which are wound on an insulatingcylindrical or flat support. The support is in a material whish withstands hightemperatures (ceramic, glass, etc)This structure results in a fairly high thermal constant. In other words thermo resistance isrelatively slow to follow the variations in the process temperatures.The thermo resistance and the signal conditioner normally connected by two wires. Inorder to reduce the influence of these wires on the measurement as the ambienttemperature varies the three or four wires connection are use together with especialelectronic circuit, as in the semiconductor temperature transducer.The overheating generated by the measurement current causes an error whose entitydepends on the transmission of heat between the sensitive element, the protective sheath,and the ambient. For this reason, the measurement current is not normally in excess of10mA.These experiment use a Pt100 3 wire platinum thermo resistance, which has temperaturerange of 0 to 250 0C, excellent linearity and a low tolerance.PROCEDURE:1. Connect the transducers to module G34 inserting the DIN cables into the relatedplugs.2. Insert the required transducer and the mercury thermometer into the related holesof unit TY34.3. Connect HEATER and COOLER terminals of G34 to HEATER and COOLERTerminals of TY34.4. Connect the output of the SET-POINT block terminal 2 to the set-point input ofthe ERROR AMPLIFIER block terminal 3 and Temperature meter input 10.5. Connect the output of the ERROR AMPLIFIER 5 to the input of the PIDController 6.6. Connect the output of the PID CONTROLLER 9 to the input of the HEATERAMPLIFIER 11.7. Connect the output of the RTD Conditioner to the ERROR AMPLIFIERFeedback input 4.8. Set up the connection of the power supply with the console.9. Set potentiometers p2 and p3 on the PID CONTROLLER to the halfway position10. Connect the multi meter to the output of the signal conditioner, and set to 20VDC.11. Short Jack 7 & 8.12. Set Temperature meter switch at RTD.13. Starting from ambient temperature (temperature of the surrounding), adjust0the Set-Point knob in order to increase the temperature of the oven in 10 Csteps (i.e. bring the voltage on jack 2 to a value which corresponds to ambienttemperature, then increase this voltage by a quantity which corresponds to a010 C temperature increase). Measure the output voltage of the signalconditioner as soon as the temperaturesstabilized.Thereferencetemperature is given by a precision mercury thermometer (CentigradeScale).42

Characteristic curve of thermo resistance 14. Be careful to avoid exceeding the maximum temperature that the transducer00can withstand (175 C). For safety, do not exceed 150 C.15. Make a table listing the values measured and use these measurements to plot agraph with the temperature on the x-axis and the output voltage of the transduceron the y-axisOBSERVATION:Output Voltage ofRTD Sensor(V)S. No.T (C)1230403504605706807908100 C110 C120 C130 C91011RESULT:1. The characteristic curve of RTDs transducer is observed.43

characteristic curve of a pressure transducer LAB SESSION 13 OBJECTTo study the characteristic curve of a pressure transducer.APPARATUSModule holderTY 35/EV modulePower supply unitConnecting wiresTHEORYThe characteristic curve of a Transducer is the plot of the output versus input physicalquantity. Pressure is defined as the relationship between a force on a surface. Pressuremeasurement can be subdivided into three main categoriesAbsolute pressureRelative pressureDifferential pressureAbsolute pressure is the pressure measured with respect to an absolute vacuum.Relative pressure is the measurement of pressure in relation to local atmosphericpressure.Differential pressure is the difference between the sources of pressure.Each type of pressure requires different types of transducer. Various types of transducersdeveloped for the purpose of pressure measurement areL.V.D.TPotentiometerStrain gauge etc.In recent years the monolithic types of transducers have become available which performthe transduction function in a single device. These may be categorized asPiezoresistive transducersSemi conductor transducersCapacitive transducersThese transducers are more compact and simpler in construction and use; they also offerincreased accuracy and linearity. Their cost is also lower.In the module G-35 semiconductor transducer is used.PROCEDURE:1. Supply TY 35/EV, with 220 volts ac2. Power the circuit with plus minus 12 volts.3. Connect the out put of the set point to the input of the power amplifier (jack 14)4. Connect the output of the pressure transducer of the TY35/EV unit to the input ofthe signal conditioner5. Connect the appropriate power supply +24 volts dc to the module.6. Adjust the set point so that the pressure inside the tank raises gradually, andmeasure the output voltage of the CONDITIONER block.7. List the increasing pressure levels and the corresponding output voltages of theCONDITIONER block in a table.44

characteristic curve of a pressure transducer 8. Plot a graph with the pressures on the X-axis and the corresponding outputvoltages on the Y-axis.9. Draw a curve which best approximates the points plotted on the graph. This isthe characteristic curve of the Transducer.OBSERVATION:S. No.01P(Bar)0.0P(Kpa)0Vout(V)020.220030.440040.660050.880061.0100120140160180200071.2081.4091.6101.8112.0RESULT:The characteristic curve of the pressure Transducer is observed.45

To construct the circuit of R2R ladder DAC LAB SESSION 14OBJECT:To design and construct a 4 bit R 2R ladder DAC (digital to analog conversion) circuit.Also plot the characteristic curve.EQUIPMENT REQUIRED:Power supply (5 volts)Digital multi meterTHEORY:Real world systems are analog .Digital systems that interface with the real world do so byusing a Digital to analog converter. The basic function of digital to analog converter(DAC or D/A) is to covert digital representation of a number into its equivalent analogvoltage.There are three types of DACs namelyBinary weighted resistor methodR-2R Ladder DACSwitched capacitor DACAll the methods have their merits and demerits. Out of the three R-2R DAC is the onethat is widely being used. This method is the least expensive and relatively easy tomanufacture since only two valued resistors are required. The circuit of DAC converts adigital number into its analog form. If a 4 bit DAC is to be constructed then it would take15 steps to give the whole input values. If 5 volts is taken as an input voltage for highstate and 0 volts for zero state then the 4 bit DAC would convert it into5/15 =0.33 volts analogThe output voltage for the converter should be equal to the binary input multiplied by thestep value for e.g; for an input of 9 volts (1001) the output voltage should be9 x 0.33 = 2.97 volts.A simplified functional diagram of an 8-bit R-AR Ladder DAC is given asThe applications of a DAC include MP3s and CDs in which most modern audio signalsare stored in digital form and in order to be heard through speakers they must be46

To construct the circuit of R2R ladder DAC converted into an analog signal. DACs are therefore found in CD players, digital musicplayers, and PC sound cards.Similarly Video signals from a digital source, such as acomputer, must be converted to analog form if they are to be displayed on an analogmonitor.A video DAC is, therefore incorporated in any Digital Video Player to get analogoutputs.This circuit requires only two resister values R and 2R.the value of R typically rangesfrom 2.5 to 10 K ohm. Taking successive thevenin equivalent circuit for each bit of theladder, it is easy to show that the inputs are each reduced by a factor of 2 going fromMSB to LSB.The summing amplifier with the R-2R ladder of resistances shown in the figure producesthe outputWhere the D's take the value 0 or 1. The digital inputs could be TTL voltages which closethe switches on a logical 1 and leave it grounded for a logical 0. This is illustrated for 4bits, but can be extended to any number with just the resistance values R and 2R. Simplified circuit diagram of 4 bit R2R ladder PROCEDURE:Wire the circuit according to the circuit diagram. Take different analog output ondifferent binary combinations and plot the graph verses binary input against analogoutput.47

To construct the circuit of R2R ladder DAC OBSERVATION:Digital inputVoutD3D2D1D0RESULT:The circuit of R- 2 R ladder DAC has been constructed and the characteristic curve isobserved.48

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LAB MANUAL(Instrument and Measure)