Power dissipation of ZnO-based metal oxide varistors (MOVs) for electronic circuit protection

Power dissipation in the high-current (upturn) region of the current-voltage characteristic of ZnO-based metal oxide varistors (MOVs) has been observed to be influenced by the ZnO grain resistivity and nonlinearity. Power dissipation lower than 20 kW was observed in samples with lower grain resistivity values (less than 1 /spl Omega/cm) and higher coefficients of nonlinearity (/spl alpha/ above 3.2). High concentration of intrinsic defects in ZnO powder could be the underlying cause of the higher grain resistivity, lower /spl alpha/ and larger power dissipation.