Learnto usean impedancemeasurement instrument!Basic measurement techniques
Impedance metersare used to measure the impedancethat is, resistance or force to flowAC.(AC). Thispage offers a thoroughintroduction to basic knowledge aboutimpedance and methods of measuringimpedance, as well as howto use an impedance tester.
What isthe definition of impedance?
Let’s begin by discussing the definition ofimpedance. Insimple words, impedanceisa measure ofresistance to theflowofanAC current.
If you connect an electricdevice, motor,orany otherequipment toanACelectricity source,current will flowthrough thedevice’s circuitry. Impedance isdeterminedby dividing voltage inthis circuit byits current. Insimple terms, impedance couldbedescribed as restricting theflow of currentwithintheAC circuit. Impedance isindicated byan arrowsymbol “Z” and measured inohms(O) this is the exactunit that measuresDC resistance. Thegreater the impedancethemore resistance there isto thecurrent flow.
How can impedance be measured?
Because impedance is notan obvious phenomenon, it isnecessary to use a measuringinstrumentin order to measureit. Instrumentsthat can measureimpedance include impedance metersLCR meters as well as impedance analyzer. There arenumerousmethods through which impedance maybe measured.
Thismethod usesa bridge circuit in order to calculateanunknownresistance. It requiresthat balance adjustmentbedone using a galvanometer.While the method offersan extremely high level of precision(about 0.1%) It’s not the best suitedto measurements with high speed.
This methodcalculates impedance by measuringthe voltagesacross a currentdetection resistor and an unknownimpedance. Itis also possibleto measuresamplesin which the sample is grounded.When the impedance grows,themethod becomes more susceptibletoeffects caused bythevoltage meter.
RF I-V method
This method employsthe samemeasurement principlessimilar to the I-V technique. Itpermits measurement of high-frequency impedancewith a circuit thatmatches the characteristic impedancea high-frequency coaxial cable andcoaxial connectors that are high-frequency.It’s challenging to employ thismethod for wideband measurements becausethemeasurement frequency bandislimitedto the tester’s converter.
Automatically balancedbridge system
This method follows the samefundamental measurement principles asthe bridge method. Itallows coverage ofan entire frequency range(1mHz to 100 MHz).However, that coveragedoes not extend to the higherfrequencies.A large number ofLCR metersuse this technique.
Each impedance analyzer approach has its ownadvantages and disadvantages, thereforeyou’ll need to clearly definethe type of impedance thatyou’ll needbefore you decide on the most appropriatemethod to use.
Utilizing an impedance meter
The methodused to measure impedanceis determined by the instrumentutilized.For example, Hioki’sMeter IM3523has the ability to measure impedancewith a high degree ofaccuracy across a wide rangeoffrequency settings.
40 Hz measurement
Apart from normal measurement the instrument is able tocontinuously and quickly measure differentparametersunder variousconditions(measurement frequency andsignal strength).
C-D+ESR Measurement of Capacitors
impedance analyzeralso allows for the saving ofup to 60 setsof measurement conditionas well as up to128adjustments for open/short correctionandcable length correction.The settings of groups can beimmediately loadedto increaseefficiency.
In addition, the instrument’s exteriorcontrol terminalscan be used to createautomatedtesting lines more quickly.
Causes of instability in impedancemeasurement
In accordance with the measurement methodemployed, impedance metersmight return a different measurementeach time a measurement ismade. Ifthemeasurement results do not seem to be stable, check the following:
Components with parasitic characteristics of components that are beingassessed
Alongside the designvaluesfor reactance and resistancecomponentsare also characterized by parasitic components whichproduce a variety in measuredvalues.There are also variations in thelength ofleads that connecttothe components and thedistance between themmaycause measurements to fluctuate.
Impedance measurement results can beaffected by manyconditions, includingthe temperature of notonlyresistorsbut also inductors and capacitors, as well asprobe capacitance and stray capacitance.
Thisis why it is necessary to take stepsincluding maintaining a stablemeasurement setting and averaging manymeasurements instead ofusing just onemeasurement todeterminetheamount.
DC biascan be described as atinyelectrical voltage that occurs in the measurement ofdevicesand circuits.For example, it occursin the case of wires and probes thataremade from different materials. Theresultant force of thermal electromotiveis what causesDC bias.
Impedance quantifies resistance toan AC current, and itsmeasurement requiresa special instrument.Because there’s a wide rangeofmeasurement methods that you can choose from, it is important to selectthemost appropriate method based onthe purpose of your measurement and also each method’sadvantages anddisadvantages.
The measurement of Impedance is verysensitive and susceptible to fluctuationsdue to factors includingfrequency, measurement conditions andDC bias. Thischaracteristic necessitatesmeasures like averaging multiplemeasurements.
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