MEI TeachingSlides

7/26/2019 MEI TeachingSlides

1/114

Dr. Nirmalya GhoshElectrical Engineering, IIT Kharagpur

Figures Courtesy:"Electronic Instrumentation and Measurements 3rd

Edition" book by a!id # $ell

Measurement and ElectronicInstruments (EE 21004)


2/114

2

Electrical Bridge ircuits

Measurement o! "esistance# Inductance# and

a$acitance

Measurement and Electronic Instruments(EE 21004)

2


3/114

%

"esistance Measurement&oltmeter and 'mmeter

Methodso connectionsase 1* &oltmeter across

load

Error in current measurement'$$lica+le* " ,, " &

ase 2* 'mmeter in seriesith load

Error in -oltage measurement'$$lica+le* " " '

/u+stitution Method


%


4/114

4

Bridge ircuits* BasicsNull detection method't +alanced condition

or resistance measurement/u$$ly and detector* dcMagnitudes are only +alanced

or inductance andca$acitance measurement/u$$ly and detector* acMagnitude and $hase +oth

+alanced

3241 ZZZZVV ba ==


4


5/114

heatstone Bridge* !orresistanceGal-anometer initially shunted

ith a lo resistance't +alance#Bridge 'ccuracy*

3error o! "* sum 3 errors o! (/# #5).

/ensiti-ity o! G.Bridge recision *

Bridge sensiti-ity de$ends on*/u$$ly -oltage* EGal-anometer resistance* rGurrent sensiti-ity o! Gal-anometer

'$$lica+le* 6 to 10126

Q

PSR=

Q

PSR =



6/114

7

Bridge /ensiti-ity

he-enin e8ui-alent circuitat G terminals

9" that $roduces smallest9IG to shi!t G $ointer +y 1 mmon scale (sensiti-ity o! G)

G

SR

G

BSR

rr

VV

I

SQRPr

QS

S

PR

REVV

+

=

+=

+

+=

||||


7


7/114

:

heatstone Bridge* limits;o resistance measurement

onnecting lead resistances4igh resistance measurementInsulation resistances&oltmeterigh -oltage D su$$ly&oltmeter across su$$ly (" "&)

Modi?ed heatstone Bridgeo se$arate out -olume current

and sur!ace currentGuard ires# guard rings

Measurement and Electronic Instruments(EE 21004):


8/114

@

=el-in Bridge* lo resistance;ead resistance A is remo-ed

i!

E8uate -oltages o! across G

'$$lica+ility* 10 6 to 1 6hermo


9/114

heatstone Bridge !or high "Insulations

Guard ire# guard rings/ur!ace resistances* +# cModi?ed heatstone

+ridgea+le !ault detection



10/114

10

Inductora$acitor* Basics

Measurement and Electronic Instruments(EE 21004)10

E

V

E

VQ

CRR

L

Q

R

EIVV

CL

CL

==

==

==

1

and

:resonanceAt


11/114

11

' Bridge* BalancingBoth magnitude and

$hase to +e +alancedo (or more) elements

are adFusted in turn anditerati-ely

Bridge sensiti-ityDe?ned and com$uted

similarly# +ut ithim$edances

De$ends on* E and9IG



12/114

12

/eries " Bridges/im$le a$acitance Bridge

De /auty +ridge

/eries


13/114


14/114

14

/chering Bridge' series " +ridge

/tandard lo D airmica 1o +alance# adFusta+le %

'$$lica+le*

/mall Hat lo E>igh & ca$acitance

Guard ring to isolate leaCagecurrent

Grounded screens* eliminate

stray Insulationdielectric material/u+stitution method

33

4

31

1

34

RCRCD

R

RCC

C

CRR

XX

XX

==

==

)1()2( SSX CCC =



15/114

1

ien Bridge

om+ination o! seriesal! Immeans IDislarge

Diode +iased +eyondCneein linear &


49/114

4

>al!


50/114

0

ull


51/114

1

Electrodynamometer*constructionermanent magnet is

su+stituted +ystationary ?eld coils/ame or diQerent currents

in mo-ing and stationarycoils

Interaction +eteenmagnetic ?elds

'ir dam$ing* Mo-ing-ane

'ir


52/114

2

Electrodynamometer*$eration

Magnetic ?eld $roduced +y current So* re$ulsi-e eQectluH direction* rightmeters.Measurement and Electronic Instruments (EE

21004)


53/114

%

Electrodynamic -oltmeter Kammeter &oltmeter

Need high resistance*'ll coils in series>igher /D current than in MM;oer coil resistance* ;oading eQect.

Multi$lier resistance'mmeter

ield coil current is measured Ihermal eQect not im$ortant

/hunt and /am$ing resistorhermal eQect im$ortant as in MM

DeSection tor8ue

Energy ()* 0. I!2;!P 0. Im2;mP I!ImMDJ I! ImdMd(theta) * heta J

deSection (in radians)Nonlinear scale

Measurement and Electronic Instruments (EE

21004)

i ( )


54/114

4

Mo-ing Iron (MI) Meters*construction

'ttraction ty$e

"e$ulsion ty$e

oncentric


55/114

MI instruments* or8ue# ros#ons

J 0. I2;DJ 0. I2d;d(theta) * heta J deSection (in radians)'d-antage

erminal non


56/114

Electrodynamic attmeterield (current) coils

single coil sym+olMo-ing (-oltage) coil

Multi$lier resistor to restrictcurrent

"e-ersed $olarity* still $ositi-e

rans!er instrumentali+rated in D* J & I (in atts)In '* actual J &rms Irmscos X


21004)

E


57/114

attmeter* Errors#com$ensation

Burdens o! the coilsom$ensated attmeter

ield coil* hicC co$$er ireom$ensating coil* hin# re-erseold


81/114

rigger le-el control andBlanCing

rigger control'dFusted +y "

a-e!orm cancommence atany le-el

BlanCingly


82/114

Dual trace "

Multi$le signals com$aredo sets o! -ertical deSection systemsb one

set !or horiontal


21004)@

DeSection system in dual trace


83/114

DeSection system in dual trace" Dual

+eam/$lit

+eam


21004)@7

/itched hannel Method


84/114

/itched hannel Method

/ingle


85/114

$ ymode Both signal

ith same

$eriod D shi!t addedintentionally

'lternatelyand re$eatedlydis$layed

>igh sitching!re8uency*dis$lays seem

simultaneous.EHce$t at lo

!re8uency

Measurement and Electronic Instruments (EE21004)@@

Dual trace dis$lay in ho$


86/114

Dual trace dis$lay in ho$mode 'lternate dis$lay

time slots'$$ear

simultaneous!or lo and mid

!re8uency

Measurement and Electronic Instruments (EE21004)@

scillosco$e controls


87/114

scillosco$e controls

/ingle +eam dual trace analog oscillosco$erigger


88/114

" +ased measurements

eaC


89/114

ulse measurements

ulse am$litude# $ulse idth# s$ace idth

"ise


90/114

scillosco$e ro+esy$ically " in$ut

im$edance* (i# "i) J1M6 %0 $

't normally o$erating!re8uencies*a$acitor reactance

-ery high&i J &s "i ("i P "s)

o a-oid signi?cantattenuation or $haseshi!t# signal!re8uency , (%dBcut


91/114

'ttenuator $ro+es

Generally 10*1 $ro+es ith "1 J M6/cre


92/114

ro+e cali+ration

E-ery $ro+e to adFusted hen ?rst use in a$articular "ront $anel control'cti-e $ro+es

E -oltage !olloers* Electronic am$li?ers toincrease $ro+e in$ut resistance and minimiein$ut ca$acitance.

Measurement and Electronic Instruments (EE21004)

Dis$lay o! de-ice


93/114

Dis$lay o! de-icecharacteristics

'B


94/114

A Dis$lays# L Dis$lays

;issaFou ?gures ne signal

/ame !re8uency# diQerent $hase DiQerent !re8uencies (ith ratio J rationalnum+er)

L


95/114

scillosco$e s$eci?cations/ensiti-ities

>oriontal-ertical2m&di- V 10&di-0. sdi- V 200 nsdi-

ro+e ratio (1*1# 10*1)ime


96/114

$ $

re8uency res$onse* 2 > V 100 M>'ttenuation !or in$ut circuit (am$li?ers)# $ro+e and oscillosco$eDeSection am$li?er cutoQs/ignal !re8uency* 10 !lo 'ND , !hi10hen i$ and o$ +oth dis$layed# " attenuations and $hase

MEI TeachingSlides

Documents

Transcript of MEI TeachingSlides