lecture hv measurement++

7/30/2019 Lecture HV Measurement++

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TKE474

~ ~

Hi hVolta e

Measurement

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measurement

Measurement is the basis for theunderstanding of all kinds of deals.

Eq. Length based on the size of humanbod such as foot

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gathering physicalinformation/parameters than can

numbers.

The measuring process is one in which ther r f n r m n r

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Theneed

of

measurement.

To measure:

rmin h m ni rextent or degree of the condition

o sys em n erms o somestandard

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Measuringpurposes

in

Hig

Vo tage:

orderto

ensure

that

the

required

voltage

or

2. Checkon

the

applied

voltage

or

current

in

or ertoensuret att erequ re vo tageorcurrentwaveforms havebeenapplied.

3. Assessmentoftestresultforcompliance

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HighVoltageMeasurementTechniques

Themeasurementofvoltageandcurrentin

high

voltage

system:

Cannotbe

measured

directly

like

conventional

low

vo tagemeasur ngsystems Notonlyrms,peakvalue,shape/waveformsofsignal

shouldbemeasured

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HighVoltageMeasurementTechniques

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HighCurrentMeasurementTechniques

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MeasurementofHighDCVoltage

HighOhmic SeriesResistancewithMicroammeter

HighDC

voltage

measured

by

connectingaveryhighresistanceinserieswithamicroammeter

nl

thecurrent

Iflowin

throu h

thelargecalibratedresistanceRismeasuredbythemovingcoil

Thevoltageofthesourceisgivenby:

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ResistancePotentialDividers

Thehigh

voltage

magnitude

is

givenby:

2

21 )(V

R

RR

+

acrossthelowvoltagearmR2.

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MeasurementofRippleVoltageInd.c.Systems

Asimplemethodofmeasuringtheripplevoltageistouseacapacitanceresistance

componentoftheACvoltagebyblockingthe

DCcomponent.

IfV1 isthed.c.sourcevoltagewithrippleandV2 is

Cacting

as

the

blocking

capacitor,

then

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MeasurementofHighACandImpulseVoltage

1. SeriesImpedanceVoltmeter

2. Series

Capacitance

Voltmeter3. VoltageDivider4. o age rans ormer

Peakvaluemeasurement: Peakvoltmeter

p ere

gap

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Measurement

of

Hi h

AC

and

Im ulse

Volta e

1. SeriesImpedanceVoltmeter

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2. SeriesCapacitanceVoltmeter

AseriescapacitorisusedinsteadofaresistorforAChighvoltage

capacitancewithaamperemeter

ecurren C ow ng roug emeteris:

IC =j CV

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2. VoltageDivider

Resistivevo tage ivi er

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Measurement

of

Hi h

AC

and

Im ulse

Volta e

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Measurement

of

Hi h

AC

and

Im ulse

Volta e3. CapacitiveDivider

IC =j CV

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5. VoltageTransformer

Forveryhighvoltages,cascading

ofthe

transformers

is

possible.

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Measurement

of

Hi h

AC

and

Im ulse

Volta e

PeakVoltage

Disruptivedischarge

phenomena

within

electrical

insulations stemsorinsulationmaterialsareingeneralcausedbytheinstantaneousmaximum

fieldgradients

stressing

the

materials.

Themaximumamplitudeoftheinstantaneous

o age

may

n a e

e

rea own.

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PeakVoltmeter

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S here

Ga

Measurement

Simp espar gapsinsu ate yatmosp ericaircanbe

used

to

measure

the

amplitude

of

avoltage

.

themeasurementofpeakvalueofAC,DCandImpulsevoltagesandisusedforcheckingthe

voltmetersand

other

voltage

measuring

devicesusedinhighvoltagetestcircuits.

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S here

Ga

Measurement

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S here

Ga

Measurement

Thebreakdownvoltageofaspheregapincreaseswithincreaseinpressureanddecreaseswithincreaseintemperature.

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SphereGapMeasurement

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lecture hv measurement++

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