Admittance—Frequency Response in Zinc Oxide Varistor Ceramics |
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Authors: | Mohammad A Alim |
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Affiliation: | McGraw-Edison Power Systems Division, Cooper Industries, Inc., Franksville, Wisconsin 53126 |
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Abstract: | The lumped parameter/complex plane analysis technique revealed several contributions to the terminal admittance of the ZnO—Bi2O3 based varistor grain-boundary ac response. The terminal capacitance has been elucidated via the multiple trapping phenomena, a barrier layer polarization, and a resonance effect in the frequency range 10?2≤ f ≤ 109 Hz. The characterization of the trapping relaxation behavior near ~ 105 Hz (~ 10?6 s) provided a better understanding of a previously reported loss-peak. The possible nonuniformity in this trapping activity associated with its conductance term observed via the depression angle of a semicircular relaxation in the complex capacitance ( C *) plane has been postulated. |
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Keywords: | varistors zinc oxide grain boundaries bismuth oxide polarization |
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