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제     목 EchemNews 59: Mutual Inductance Effect in EIS Experiment
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EChemNews
 No. 59 | 2007.8.6                                         주요내용: Mutual Inductance in EIS
 


EIS측정시 mutual inductance/Coupling/Shielding 영향에 관련한 응용 자료입니다.

EIS실험시 도움이 되시길 바라며 문의사항이 있으시면 연락주십시요

  • Experiment Artifacts while measuring impedances

    Experiment: Mutual Induction (High current applications)

    The main source of errors measuring impedances on high current applications is the so-called mutual induction: due to the (high) current through the cables and the alternating electrical field, an alternating magnetically field is induced. This alternating magnetic field reveals itself in an impedance spectrum as a parasitic, inductive contribution in the high frequency region.

    Background:

    The mutual induction effect may be reduced significantly but is not eliminated completely. Therefore, the current- as well as the potential conducting lines have to be drilled. As a result, the magnetic fields eliminate themselves best.

    Objective of the experiment:

    The contribution of the mutual induction effect is determined, measuring a 10 mΩ resistor using different arrangement of the measuring cables. In addition, a so-called coaxial shunt is measured. Due to the geometrical arrangement of the resistive layer of the latter one, almost all of the mutual induction effect is eliminated.

    Note:

    Provided you are not aware of the mutual induction effect and its origin, you will get impedance spectra which are hardly reproducible in the high frequency area because a change in the arrangement of the cables may result in a remarkable change in the magnetic effect.

    Experiment: Coupling Effect (High- and Low current application)

    Concerning a ‘conventional’ electrochemical setup with a three electrode arrangement, the low conductivity of the solution as well as the high input impedance of the reference electrode may be the source of undesired parasitic effects during an impedance measurement. Both contributions lead to a ‘pseudo-inductive’ behavior in the high frequency part of an impedance spectrum (coupling effect).

    Considering ‘classical’ electrochemical methods like cyclic voltammetry (CV), this effect is not recognizable due to the different time scale (CV is much ‘slower’).

    Goal of the experiment:

    The order of magnitude of the coupling effect as well as the frequency dependence has to be determined, using two different reference electrodes exhibiting different input resistances.

    Note :

    Similar to the mutual induction, the coupling effect can not be eliminated completely. But, taking appropriate steps, this effect can be shifted towards higher frequencies.

    Experiment: Shielding (Low current application)

    Measuring high Ohmic objects, for instance insulators, the main source of error is the so called electromagnetic pollution. This parasitic effect reveals itself in the low frequency region of an impedance spectrum. One can overcome this problem using an appropriate shielding. As a rule, one can profit by applying shielding techniques provided the current is in the order of magnitude of 1 µA or below.

    Goal of the experiment:

    Different stages of shielding are applied on measuring an equivalent circuit and the corresponding influence of electromagnetic pollution is checked on the impedance spectra.

    Note :

    One of the coworkers of Zahner-elektrik is involved in an international working group which deals with the standardization of impedance measurements on high Ohmic systems. During this standardization, a set of different equivalent circuits (dummy cells) is measured worldwide in a Round Robin test.

     

       

     



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    WonATech 취급품목

     

    수입품

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    • CER(Contact Electric Resistance) Measurement system
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    생산품

    • Automatic Battery Charge/Discharge Test System
    • Fuel Cell Test Station
    • Electronic load for fuel cell test
    • Multi-channel Potentiostat/Galvanostat
    • Potentiostat/Galvanostat
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    • EIS analysis software
       

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