Voltage limiting composition and method of fabricating the same

Claim 1

A method of fabricating a voltage limiter especially suitable for use in gapless lightning arresters, said method comprising: (a) preparing a composition which is selected to consist essentially of the following ingredients by approximate mole %: ______________________________________ ZnO 93.5 Bi.sub.2 O.sub.3 3.0 Co.sub.3 O.sub.4 1.0 M.sub.n O.sub.2 1.0 Sb.sub.2 O.sub.3 1.0 SiO.sub.2 0.5 ______________________________________ (b) forming the composition into the desired shape; (c) sintering the formed composition for a predetermined period of time at a predetermined temperature such that the composition displays a microstructure including an array of ZnO grains which are separated from one another by an intergranular phase made up of the remaining ingredients of said compositions; and (d) the particular amount of ZnO, the particular amount and kinds of additives and the particular sintering time and temperature being such that for a sample 5 cm in diameter by 1 cm high the voltage limiting composition displays an energy absorption capability at least equal to about 50 joules/cm 3 and a nonlinear exponent α at least equal to about 35 as determined by the following equation for α: ##EQU2## where V 1 and V 2 are the respective voltages across said sample at currents I 1 and I 2 flowing therethrough and where I 1 and I 2 are 1 ma and 5000 amps, respectively.

Claim 2

A method of fabricating a voltage limiter especially suitable for use in gapless lightning arresters, said method comprising: (a) preparing a composition which is selected to consist essentially of the following ingredients by approximate mole %: ______________________________________ ZnO 93.5 Bi.sub.2 O.sub.3 3.0 Co.sub.3 O.sub.4 1.0 M.sub.n O.sub.2 1.0 Sb.sub.2 O.sub.3 1.0 SiO.sub.2 0.5 ______________________________________ (b) forming the composition into the desired shape; (c) sintering the formed composition for a predetermined period of time at a predetermined temperature such that the composition displays a microstructure including an array of ZnO grains which are separated from one another by an intergranular phase made up of the remaining ingredients of said compositions; and (d) the particular amount of ZnO, the particular amount and kinds of additives and the particular sintering time and temperature being such that for a sample 5 cm in diameter by 1 cm high the voltage limiting composition displays an energy absorption capability at least equal to about 50 joules/cm 3 and a nonlinear exponent α at least equal to about 35 as determined by the following equation for α: ##EQU2## where V 1 and V 2 are the respective voltages across said sample at currents I 1 and I 2 flowing therethrough and where I 1 and I 2 are 1 ma and 5000 amps, respectively.

Claim 7

A method of fabricating a voltage limiter especially suitable for use in gapless lightning arresters, said method comprising: (a) preparing a composition which is selected to consist essentially of the following ingredients by approximate mole %: ______________________________________ ZnO 93.5 Bi.sub.2 O.sub.3 3.0 Co.sub.3 O.sub.4 1.0 M.sub.n O.sub.2 1.0 Sb.sub.2 O.sub.3 1.0 SiO.sub.2 0.5 ______________________________________ (b) forming the composition into the desired shape; and (c) sintering the formed composition for about 1.50 hours at a temperature of about 1300° C. such that for a sample 5 cm in diameter by 1 cm high the voltage limiting composition displays an energy absorption capability at least equal to about 50 joules/cm 3 and a nonlinear exponent α at least equal to about 35 as determined by the following equation for α: ##EQU4## where V 1 and V 2 are the respective voltages across said sample at currents I 1 and I 2 flowing therethrough and where I 1 and I 2 are 1 ma and 5000 amps, respectively.

Claim 8

A method of fabricating a voltage limiter especially suitable for use in gapless lightning arresters, said method comprising: (a) preparing a composition which is selected to consist essentially of the following ingredients by approximate mole %: ______________________________________ ZnO 93.5 Bi.sub.2 O.sub.3 3.0 Co.sub.3 O.sub.4 1.0 M.sub.n O.sub.2 1.0 Sb.sub.2 O.sub.3 1.0 SiO.sub.2 0.5 ______________________________________ (b) forming the composition into the desired shape; and (c) sintering the formed composition for about 1.50 hours at a temperature of about 1300° C. such that for a sample 5 cm in diameter by 1 cm high the voltage limiting composition displays an energy absorption capability at least equal to about 50 joules/cm 3 and a nonlinear exponent α at least equal to about 35 as determined by the following equation for α: ##EQU4## where V 1 and V 2 are the respective voltages across said sample at currents I 1 and I 2 flowing therethrough and where I 1 and I 2 are 1 ma and 5000 amps, respectively.