MEASUREMENTS& CONTROLSModule I 1.What is meant by measurements? Measurement is the process of determining or finding the size, quantity or degree of something .Accurate measurement is of very important in engineering2.What is an measuring instrument?Measuring instruments are measuring devices that transform the measured quantity into an information, either analog or digital. 3.What are the methods of measurements?There are two types of measurement methods. They are (1)Direct method (2)Indirect method4.What are the three stages of generalized measuring system? The three stages of generalized measurement system area. Detector-transducer elementb. Intermediate modifying stagec. Terminating stage5.What is meant by primary measurement? rimary measurement is one that can be made by direct observation !ith out involving any conversion of the measured quantity.6. What is meant by secondary measurement? "econdary measurement involves only one transformation to be done on the quantity under measurement.7. What is meant by tertiary measurement?Tertiary measurement involves t!o translations to be done on the quantity under measurement.8.what are the functions of the measuring instruments?The functions of the measuring instruments area. Indicating functionb. #ecording functionc. $ontrolling function.what are the applications of the measuring instruments?The applications of the measuring instruments area. Monitoring of processes and operationsb. $ontrol of processc. %&perimental engineering analysis!".#efine sensiti$ity."ensitivity '() refers to the ability of the measuring device to measure small differences in the quantity being measured. It is also defined as the ratio of the magnitude of response *o+p, to the magnitude of the quantity being measured.!!.What is span of an instrument? "pan is the algebraic difference bet!een the higher value and the lo!ervalue it can measure.!%.#efine &ange. The instrument is calibrated to read a value bet!een t!o limits, one isthe higher calibration value and the other is the lo!er calibration value. This region bet!een !hich the instrument is to operate is called the range.!3.What is reproducibility?It is defined as the degree of closeness !ith !hich a given value may berepeatedly measured under same loading conditions. erfect reproducibility means that the instrument has no drift.!4.What are the factors affecting &eadability? #eadability depends on a. -umber of graduationsb. "pacing of graduationc. "ize of pointerd. aralla& effects!5.What is meant by drift? If an instrument does not reproduce the same reading at different timesof measurement for the same input signal, it is said to have drift. If an instrument has prefect reproducibility, it is said to have no drift.!6.what does zero drift mean?If the !hole calibration gradually drifts due to slippage, permanent set or due to undue !arming up of electronic tube circuits zero drift sets in. this can be eliminated by zero setting..ero drift line

/+-ominal curve I+!6.what is meant by span drift? If there is proportional change in all along the up!ard scale the drift is called the span drift "pan drift /+nominal curve

I+ !7.what is meant by zonal drift?In case if drift occurs only over apportion of span of an instrument it iscalled as zonal drift. .onal drift /+ -ominal curve

I+ !8. What is meant by repeatability? #epeatability is a measure of closeness !ith !hich a given input may be measured over again repeatability is defined as the variation of scale reading and it is random in nature.!.what is calibration? $alibration of a measuring instrument means introducing an accurately 0no!n sample of the variable that is to be measured and then chec0ing the system1s response then the measuring instrument is chec0ed !ith and ad2usted until its scale is introduced accurately for measuring.%". What are the different types of calibration?There are t!o types of calibration namelya. rimary calibrationb. "econdary calibration%!.What are the different types of secondary calibration? The different types of secondary calibration area. Direct calibrationb. "econdary calibration%%.what is meant by primary calibration? In primary calibration, a system is calibrated against a primary standard provided. 3or e.g. calibrating flo! meters.%3what is meant by secondary calibration? In secondary calibration, a device that has been calibrated by primary calibration is used.%4.What is meant by direct calibration? In direct calibration, a standard device is placed in series !ith the device to be calibrated is used and calibration is done by comparing readings of the t!o devices over the desired range.%5.what is meant by indirect calibration?This procedure is based on the equivalence of t!o different devices adopting some similarity concept. %.g. flo! measurement-requirement of similarity is 4#eynolds1s number should be equal1.%6.'ow are mechanical measurements classified? Mechanical measurements are broadly classified into t!o categoriesa. Mechanics typeb. o!er type%7.What are the three methods in mechanics type measurements? The three types of mechanic type measurements area. %mpirical methodb. #ational method c. %&perimental method%8.Write about rational method of measurements?#ational method of measurement is strictly based upon scientificla!s and relationships. These types of la!s are mainly available in mechanics and thermodynamics. 5hile in other areas there is scarcity for this type of la!s. 6ence in other areas it has limited scope.%.#efine (oading effect. "ensing element of the measuring instrument absorbs some energyhence the instrument does not give accurate readings, this effect is called loading effect.3".write down the classification of measuring instruments? Measuring instruments are broadly classified into a. Mechanical instrumentsb. %lectrical instrumentsc. %lectronic instruments3!.#efine error. %rror is defined as the difference bet!een the indicated quantity and the true value.3%. What is meant by fidelity?3idelity is the ability of the measuring instrument to reproduce the output in the same form as the input.33.#efine hysterisis. 5hen loaded energy is put into the stressed component is not recovered !hile unloading this property of the measuring instrument is called hysterisis.34.#efine dynamic error.The difference between the indicated quantity and the true value of the time varying quantity is called dynamic error.

)art*+!, #raw the neat s-etch of generalized measurent system and e.plain its $arious elements? -eat s0etch !ith mar0ings-7mar0s 8asic transducer detectorstage-9mar0s Intermediate modifying stage-9mar0s Terminating stage-:mar0s %, +riefly discuss the $arious measurements methods and e.plain? Direct comparison method-7mar0sIndirect comparison method-7mar0s 3, +riefly discuss the $arious functions and applications of measuring instruments? 3unctions Indicating function-9mar0s #ecording function-:mar0s $ontrolling function-9mar0s Applications Monitoring of process and operation-:mar0s $ontrol of process and operations-9mar0s %&perimental engineering analysis-9mar0s4, /lassify the $arious type of error and e.plain them details?rror definition!2mar"#alibration error!2mar"$oading error!2mar"6uman errors!2mar"%nvironmental error!2mar"%&perimental error!2mar"#andom error!2mar"$haotic error !2mar"5, +riefly discuss on the calibration of temperature measuring de$ice with suitable e.ample? rimary calibration "0etch-9mar0s rinciple-:mar0s rocedure-9mar0s "econdary calibration "0etch-9mar0s rinciple-:mar0s rocedure-9mar0s Module IIPART A!. What are recorders?Recorder is used to produce a permaet record o! t"e si#al t"at is measured. Recorder is used to aal$%e "o& t"e si#al 'aries &it" time.%.What is a /&0?CRO is a 'ersatile read out de'ice used !or measuri# d$amic ad trasiet si#als. (asicall$ it is ideted !or 'ie&i#3.What is meant by 0scillograph ) A Oscillo#rap" is a &riti# istrumet. T"e displacemet is recorded directl$ o a paper. Oscillo#rap" is a lo& impedace de'ice.4.(ist some type of recorders) *i+ ,-.Recorder *ii+(rid#e t$pe recorder *iii+Ma#etic tape recorder5.What is meant by attenuation?Atteuatio are de'ices t"at are used to /ri# do& t"e 'olta#e coducted /et&ee t"e circuits t"at are co'erted to its iput termial.6.#efine 1ilters)T"e output si#al !rom trasducers is to /e reported !ait"!ull$ !or t"e purpose o! measuremet. 0ece u&ated si#als are elimiated /$ !ilters.1.define the term transducer? A trasducer is a eer#$ co'erti# de'ice it recei'es stimulatio !rom a p"$sical situatio o! t"e measurad ad co'erts it ito a de!iitel$ associated si#al.8.what is meant by loading?2uri# t"e act o! measurmet t"e measuri# istrumet ta3es eer#$ !rom t"e si#al source .due to t"is e!!ect t"e si#al source is distur/ed .T"is e!!ect is called as loadi#.What is primary transducer?A primar$ trasducer seses a p"$sical p"eomeo ad co'erts it ito a aalo#ous output.!".What is a secondary transducer?T"e aalo#ous output !rom t"e primar$ trasducer is co'erted ito a electric si#al /$ a secodar$ trasducer11.What is a passi$e transducer?A passi'e trasducer "as a au4illar$ source o! po&er &"ic" supplies a ma5or part o! t"e output &"ile t"e iput si#al supplies ol$ a isi#i!icat portioE#resisti'e trasducer!%.What is acti$e transducer ?A compoet &"ose output eer#$ is supplied etirel$ or almost etirel$ /$ its iput si#al is called as acti'e trasducer.16.what is electrical transducer?7"ile measuri# o.electric 8uatities 9a detector is used.t"is detector co'erts p"$sical8uatit$ ito displacemet.t"is displacemet ils #i'e as iput to a electrical trasducer &"ic" #i'es a electrical output!4.(ist some electrical transducer?A.reasistace trasducer/.capaciti'e trasducerc.iducti'e trasducerd.'olta#e trasducer1:.#efine analog and digital transducer?A aalo# trasducer is oe &"ic" produces t"e output o! cotiious !uctio o! time.A di#ital trasducer is oe &"ic" produces t"e output i discrete !uctio o! time.1;.What is meant by mechanical transducer?I mec"aical trasducer t"e detecta/le 'aria/le are mec"aical displacemet or 'elocit$.!7.#efine the term amplification?Ampli!icatio is t"e process o! icreasi# t"e &ee3 si#al ad t"e de'ice used !or t"is purpose is called as ampli!ier.1i#ures D. : *Mar3s+Applicatio D. 2 *Mar3s+3. With a neat diagram?e.plain the wor-ing of a prony bra-e for estimating power?Re!er D. Measuremet & cotrols /$ S.("as3ar P. NoD.16.2Priciple D. 2 *Mar3s+2escriptio D.6 *Mar3s+Operatios D. ? *Mar3s+>i#ures D. : *Mar3s+Applicatio D. 2 *Mar3s+4. 3.plain the wor-ing of a +owdon tube pressure gauge?Re!er D.Measuremet & cotrols /$ S.("as3arPriciple D. 2 *Mar3s+2escriptio D.6 *Mar3s+Operatios D. ? *Mar3s+>i#ures D. : *Mar3s+Applicatio D. 2 *Mar3s+5. 3.plain the wor-ing of a optical pyrometer?Re!er D. Measuremet & cotrols /$ S.("as3arPriciple D. 2 *Mar3s+2escriptio D.6 *Mar3s+Operatios D. ? *Mar3s+>i#ures D. : *Mar3s+Applicatio D. 2 *Mar3s+6. With a neat diagram e.plain the shadow graph method for $iewing flow phenomenia?Re!er D. Measuremet & cotrols /$ S.("as3arPriciple D. 2 *Mar3s+2escriptio D.6 *Mar3s+Operatios D. ? *Mar3s+>i#ures D. : *Mar3s+Applicatio D. 2 *Mar3s+ Module I@AINE TERMS CONTROLLE2 @ARIA(LE &CONTROLLE2 ME2IA) (a) #ontrolled variable&The quantity or condition characteri)ing a process whose value is held constant by a controller or is changed according to a certain algorithm designed with the interests of the nature of function the system is performing (b) #ontrolled medium& The process material in the control system in which the variable to the controlled e*ists. ?.NAME T0E T7O T-PES O> CONTROL S-STEMS) There are two types of control systems namely (a)+pen loop control system (feed bac" control system) (b)#losed loop control system(non! feed bac" control system)

:. LIST T0E (ASIC ELEMENTS O> A >EE2 (ACK CONTROL S-STEM)

The basic bloc"s of a feedbac" system are (a),eed bac" path(b),orward path(c)rror detecting device In general the forward path of a system will have the following elements!%mplifier !rror sensor!#ompensating networ"

;. 70AT ARE ERROR 2ETECTORS)

rror detector is a device which compares the feed bac" signal obtained from the output with the input (command) signal and determines there from the deviation "nown as actuating signal. 1. E,PLAIN T0E MEANING O> CONTROL ACTION. LIST T0E COMMON MO2ES O> CONTROL) The control action refers to the manner in which the control elements manipulateThe error signal into a manipulated variable to do the necessary corrective action.$isted below are the types of modes of control or control action or controllers.(a)proportional control(p) (b)integral control(i)(c)derivative control(d)(d)two position control(e)multi position(floating control) ELECTRICAL S-STEM)

The three basic elements of electrical system are resistor'inductor - capacitor1?. 2E>INE RESISTANCE9CAPACITANCE9IN2UCTANCE)

1esistance&it is that which opposes the flow in general. It is defined as the change in potential difference required to cause a unit change in flow rate 1 electrical/de0di/e0i#apacitance&% capacitor is a storing element. #apacitance is defined as change in quantity contain or stored per a unit change in some reference variable# ele/change in quantity demanded0change in a reference variable /q0eInductance&Inductance is that which opposes acceleration. It is defined as change in potential difference required to cause a unit change in acceleration1:.LIST T0E CLASSI>ICATIONS O> 0-2RRULIC S-STEMS AN2 E,PLAIN T0EM) 2ydraulic systems can be classified into two types'(a) liquid level system(b) hydraulic devices.$iquid level systems are those incorporated'storage tan"s and connecting pipesThe devices using incompressible oil as their wor"ing medium are hydraulic device 1;.70AT ARE PNEUMATIC S-STEMS) (ystems which use compressible fluids as wor"ing medium are called as pneumatic systems.%ir is an e*ample of such fluids.

13. D,I4 ((ITI.IT5 I4 1$%5 T#24+$+657 It is defined as the ability of the relayto select the fault within a desirable )one of protection.

18.92%T %1 T2 T9+ #$%((I,I#%TI+4 +, D# (1.+ :+T+1(7 D# servo motors is classified into two.(a) sliding contact motors with commutators and brushes.(b) ;rushless or contact less motors with transistor commutator.

They are again classified into.(a) I1#2+,,( (#+4D $%9 +, .+$T%67The law states that ?the algebraic sum of voltages around a closed loop is )ero@.2A.92%T I( % .+$T%6 16B$%T+17% voltage regulator is a electronic circuit where a stable D# voltage'independent of load current' temperature and %# line voltage varies.

A;I$ATI/- /3 $/-T#/; "="T%M: MA#("1.What is system?7"e a um/er o! elemets or compoets are coected i a se8uece a speci!ic!uctio 9t"e #roup t"us !ormed is called as a s$stem.2.What is meant by control system?I a s$stem &"e t"e output 8uatit$ is cotrolled /$ 'ar$i# t"e iput 8uatit$9t"e s$stem is called as cotroll s$stem.6./ommand signal of e.citation.T"e iput 8uatit$ to t"e s$stem is called commad si#al o! e4citatio.?.What is controlled $ariable or response?T"e output 8uatit$ !rom t"e s$stem is called 'aria/le or respose.:.Gi'e t"e application of control system?1. Go'eri# o! speed2. 3ietic ad process cotrol6. pressure9temperature9!luid le'el ad !lo& cotrol?. T"rust ad !li#"t cotrol:. P"oto electric cotrol;.What is gyroscope?T"e #$roscope cosist o! a &"eel or disc mouted o a a4le.T"e a4le is supported /$ /eari#s !i4ed o a !rame.&or3 called ier #im/al*li#a#e+.1.What is meant by photo electric control?P"oto diode sesor is a li#"t acti'ated diode coected i re'erse /ias.7"e li#"t !all o t"e diode9it #eates ellectric curret.