Zinc oxide-praseodymium oxide elements for surge arrestors

Abstract

Zinc oxide elements have been developed, which contain praseodymium oxide rather than bismuth oxide as a principal additive component. These elements have been used to produce gapless surge arresters with rated voltages up to 360kV. The 2-phase microstructure of these elements increases the active area of grain boundaries which is the origin of non-linearity in V-I relation.Consequently the effective area of the electrodes is increased resulting in a higher apparent dielectric constant of the element by a factor of 1.5 and higher capability for short wave front discharge withstand. The absorption capability for long duration discharge was improved by obtaining higher resistance at the peripheral of the element than at the inner area.

Effect of TiO2 doping on microstructural and electrical properties of ZnO–Pr6O11-based varistor ceramics

“…ZnO ceramics containing Pr 6 O 11 and Co 3 O 4 exhibiting nonohmic current characteristics were first reported by Mukae et al [30,31]. Some of the most interesting challenges with ZnO-Pr 6 O 11 based varistor ceramics, that use praseodymium oxide (Pr 6 O 11 ) as the varistor-forming oxide, are reducing quantity of composition materials and improving the electrical properties of the ceramics for application to a practical line [29].…”

Microstructure and electrical properties of ZnO–Pr6O11–Bi2O3-based varistor ceramics with sintering changes

“…However, zinc oxide varistor exhibits much higher stability of electrical properties than zener diode. Therefore, zinc oxide ceramics are widely used in the field of overvoltage protection systems from electronic circuits to electric power systems [3][4][5]. Zinc oxide varistor ceramics are made by sintering zinc oxide powder incorporated with indispensable minor additives, such as Bi 2 O 3 and Pr 6 O 11 , and subordinate additives such as CoO, MnO 2 , Cr 2 O 3 , etc.…”

Microstructure and Electrical Properties of ZPCCYT Varistor Ceramics

“…ZnO-based varistor ceramics exhibit voltage-switching properties at a critical value in accordance with increasing voltage. Voltage-switching properties enable ZnO varistors to be used widely in the field of overvoltage protection systems from electronic circuits to electric power systems [1][2][3][4].…”