Voltage stable nonlinear resistor containing minor amounts of aluminum and selected alkali metal additives

Claim 2

A sintered high voltage resistor body which can exhibit long lasting nonlinear V-I characteristics, consisting essentially of at least about 90 mole % of ZnO and up to about 10 mole % of additional metal oxides effective to provide electrical nonlinearity within the resistor and including the combination of from about 0.002 mole % to about 0.02 mole % of aluminum oxide and a total amount of from about 0.003 mole % to about 0.2 mole % of at least one alkali metal oxide selected from the group consisting of sodium oxide, potassium oxide, rubidium oxide, and cesium oxide, as essential ingredients, where all the oxides are homogeneously distributed through the resistor body.

Claim 3

The sintered nonlinear resistor of claim 1, where the amount of alkali metal oxide present is from about 0.003 mole % to about 0.125 mole %, Zno is present from about 90 mole % to about 97 mole %, the additional metal oxides are effective to provide electrical nonlinearity completely within the bulk of the resistor and are selected from the group consisting of Bi 2 O 3 , Co 3 O 4 , MnO 2 , Sb 2 O 3 , SiO 2 , and ZrO 2 , and mixtures thereof, where the resistor is characterized as having the ability to retain its initial nonlinear V-I characteristics and its initial resistive current values during extended use.

Claim 4

The sintered nonlinear resistor of claim 1, where the alkali metal oxide is sodium oxide.

Claim 5

The sintered nonlinear resistor of claim 1, where the alkali metal oxide is potassium oxide.

Claim 6

The sintered nonlinear resistor of claim 1, where the alkali metal oxide is rubidium oxide.

Claim 7

The sintered nonlinear resistor of claim 1, where the alkali metal oxide is cesium oxide.

Claim 8

A plurality of the sintered nonlinear resistors of claim 1, where the resistors have flat parallel surfaces with electrodes applied to said surfaces, said resistors being enveloped in an insulator with their electrode surfaces electrically contacting each other without air gaps therebetween, to provide a gapless lightning arrester.

Claim 9

A sintered high voltage bulk-type resistor body which can exhibit long lasting nonlinear V-I characteristics, consisting essentially of at least about 90 mole % of ZnO and up to about 10 mole % of additional metal oxides selected from the group consisting of Bi 2 O 3 , Co 3 O 4 , MnO 2 , Sb 2 O 3 , SiO 2 and ZrO 2 , and mixtures thereof, and including the combination of from about 0.002 mole % to about 0.02 mole % of Al 2 O 3 and a total amount of from about 0.003 mole % to about 0.2 mole % of at least one alkali metal oxide selected from the group consisting of Na 2 O, K 2 O, Rb 2 O and Cs 2 O, as essential ingredients, where all the oxides are homogeneously distributed through the resistor body.

Claim 10

A sintered high voltage bulk-type resistor body which can exhibit long lasting nonlinear V-I characteristics, consisting essentially of at least about 90 mole % of ZnO and up to about 10 mole % of additional metal oxides selected from the group consisting of Bi 2 O 3 , Co 3 O 4 , MnO 2 , Sb 2 O 3 , SiO 2 and ZrO 2 , and mixtures thereof, and including the combination of from about 0.002 mole % to about 0.02 mole % of Al 2 O 3 and a total amount of from about 0.003 mole % to about 0.2 mole % of at least one alkali metal oxide selected from the group consisting of Na 2 O, K 2 O, Rb 2 O and Cs 2 O, as essential ingredients, where all the oxides are homogeneously distributed through the resistor body.

Claim 11

The sintered nonlinear resistor of claim 8, where the amount of alkali metal oxide present is from about 0.003 mole % to about 0.125 mole %, ZnO is present from about 90 mole % to about 97 mole %, and where the resistor is characterized as having the ability to retain its initial nonlinear V-I characteristics and its initial resistive current values during extended use.

Claim 12

The sintered nonlinear resistor of claim 8, where the alkali metal oxide is Na 2 O.

Claim 13

The sintered nonlinear resistor of claim 8, where the alkali metal oxide is K 2 O.

Claim 14

The sintered nonlinear resistor of claim 8, where the alkali metal oxide is Rb 2 O.

Claim 15

The sintered nonlinear resistor of claim 8, where the alkali metal oxide is Cs 2 O.

Claim 16

The sintered nonlinear resistor of claim 8, where the amount of Bi 2 O 3 present is from about 0.5 mole % to about 3 mole %, the amount each of Co 3 O 4 , MnO 2 and Sb 2 O 3 present is from about 0.5 mole % to about 1.5 mole %, and the amount of SiO 2 and ZrO 2 present is from about 0.05 mole % to about 0.8 mole %.

Claim 17

The sintered nonlinear resistor of claim 8, having a thickness of over about 0.4 cm. and having flat parallel surfaces with electrodes applied to said surfaces.

Claim 18

A plurality of the sintered nonlinear resistors of claim 8, where the resistors have flat parallel surfaces with electrodes applied to said surfaces, said resistors being enveloped in an insulator with their electrode surfaces electrically contacting each other without air gaps therebetween, to provide a gapless lightning arrester.