文本综合thermocouple热电偶.pdfVIP

Usedtomeasure

temperature

Forfurther

informationgoto

thiswebsite

Thermocoupleshave

TWOtypesofwire

Theyarejoinedat

thehotend(thisis

thepointwherethe

temperatureistobe

measured

Thevoltagween

thewiresgivesa

measureofthe

temperature

difference

Keyideas

V=0

Thethermocoupleworksontheprinciple

thatwhenthereisatemperature

differencweentwopartsofametal,

thentherewillbeavoltagedifference

betweenthetwowires.

Refere

Simp

Thermocouplesummary

Athermocoupleisatemperaturesensor

thathasapairofdissimilarmetalsjoined

togetheratoneendandterminatedatthe

otherend.Thejoinedendiscalledthe

sensingjunctionorhotjunctionandthe

terminatedendiscalledthereference

junctionorcoldjunction.

Thetemperatureatthereferencejunction

iscalledreferencetemperatureandis

alwaysmaintainedconstant.

Summary

Whenthesensingjunctionandthe

referencejunctionareatdifferent

temperatures,apotentialdifferenceis

obtainedandthiscausesaflowofcurrent

inthecircuit.

Thethermoelectricvoltageproducedis

duetothedifferentbindingenergiesof

theelectronstothemetalions.

Thisvoltagedependsonthemetals

themselves,andinadditiononthe

temperature.

Thethermalvoltageisproducedonly

becauseoftheclosedcircuitbetweenthe

twometals.Thisphenomenoniscalled

“SeebeckEffect”.

Thewiresmustbeelectricallyseparated

beyondthemeasuringjunction.

Ifthereferencejunctioniskeptata

standardtemperature,usually0°C,thena

givenpairofmet