Learnhow to usean impedancemeter!The fundamental measurement techniques
Overview
Impedance metersquantify impedancewhich is the resistance ofanalternating current(AC). Thispage gives a comprehensiveoutline of the fundamentals ofimpedance, ways to measureimpedance, and also howto utilize an impedance meter.
What isthe definition of impedance?
Let’s begin by delving into the concept ofimpedance. Ina word, impedanceisa term used to describeresistance to thecurrentthat isanAC current.
When you connect your electricproduct, motor,orotherequipment toanACenergy source,current will flowthrough thecircuitry of the device. Impedance isdeterminedthrough the division of the voltage insuch a circuit byits current. Inessence, the term “impedance” canbedefined as a limit on theflow of currentwithinanAC circuit. Impedance isrepresented byit’ssymbol “Z” and measured inohms(O) that is the sameinstrument used to measureDC resistance. Thegreater the impedancethemore resistance there isto theflow of current.
What is the measurement of impedance?
As impedance itself isn’tan obvious phenomenon, it isessential to utilize a measuringinstrumentto determineit. Instrumentsthat can measureimpedance include impedance meters,LCR meters and impedance analyzer. There aremanyways that impedance canbe measured.
Bridge method
Thismethod usesan abridge circuit to calculateanunknownresistance. It requiresbalance adjustment tobemade using a galvanometer.While the method offersan extremely high level of precision(about 0.1%) however, it’s not suitedto measurements with high speed.
I-V method
This methodcalculates impedance usingthe voltagesacross adetection resistor and an unknownimpedance. Itis also usedfor measuringany samplesthat are grounded.As the impedance rises,themethod becomes more vulnerabletothe effects ofthevoltmeter.
The method of RF I.V
This method followsthe samefundamental measurement principleas the I.V. method. Itpermits high-frequency measurementthrough a circuit thatcorresponds to the characteristic impedancea high-frequency coaxial cable anda high-frequency coaxial connector.It’s difficult to use thismethod to measure widebands becausethemeasurement frequency bandisrestricteddue to the transformer of the testing head.
Automatically balancedbridge methods
This method uses the samefundamental measurement concept asusing the bridge technique. Itoffers coverage overwide frequency bands(1between mHz and 100 MHz).However, that coveragedoes not extend to the higherfrequencies.A number ofLCR metersutilize this method.
Each impedance analyzer method has its uniquebenefits and disadvantages, and soyou’ll need to clearly definethe type of impedance thatyou’ll need to gaugebefore deciding on the besttechnique to choose.
The use of an impedance gauge
The methodemployed to measure impedancedepends on the device beingutilized.For instance, Hioki’s LCRMeter IM3523measures impedancewith a high degree ofprecision across a broad rangeofmeasurementfrequency settings.
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40 Hz measurement
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200Hertz measurement
Apart from normal measurement, this instrument canconstantly and rapidly measure variousparametersunder variousconditions(measurement frequency andsignal level).
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C-D+ESR Measurement of Capacitors
impedance analyzercan also saveas much as 60 setsof measurement conditionin addition to up to128adjustments for open/short correctionandlength correction for cables.It is possible to load groups of settingsquickly loaded in one goto boostefficiency.
Additionally, the instrument’s externalcontrol terminalspermit you to designautomatedtest lines more quickly.
Impedance measurement is unstable.measurement
Based on the measurement methodthat is being used, impedance metersmight return a different measurementevery time a measurement isconducted. Ifthemeasured values are not stable make sure you check the following factors:
Particular components with parasitic properties of the component beingmeasured
In addition to the designedvaluesfor reactance and resistancecomponentscan also be affected by parasitic elements thatcause variability in measuredvalues.Variations in thelength ofthe leads that are connectedtocomponents as well as thedistance between themmayresult in measured values varying.
Measurementof the environment
Impedance measurement results can beaffected by manyfactors, such asvariations in temperature notjustresistorsbut also inductors and capacitors along withprobe capacitance and stray capacitance.
Thisrequires stepssuch as maintaining a consistentmeasurement space and averaging severalmeasurements instead ofusing just onemeasurement todeterminetheamount.
DC bias
DC biasrefers to aminusculevoltage that is present in measuringdevicesand circuits.For instance, it happensin the case of wires and probes thataremade from different components. Theresultant thermal electromotive forcecan causeDC bias.
Summary
Impedance determines the degree of resistance toan AC current. Itsmeasurement requiresa dedicated instrument.There are many kindsofmeasurement methods so it’s essential to pickthebest one based onthe goal you intend to achieve and also on each method’sadvantages anddrawbacks.
Impedance measurement is extremelysensitive and susceptible to fluctuationsdue to various factors such asthe measurement environment, frequency as well asDC bias. Thisis why it is necessary to takeprocedures like averaging severalmeasurements.
Applications
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Impedance measurements of Smart Key/Immobilizer antenna
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MLCC
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Conductive polymer capacitors
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Tantalum capacitors
How to Use
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LCRmeter measurement principles
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How to Use an LCR Meter: Basic Knowledge