There is provided a varistor having high surge resisting capability in spite of its small size and a method of manufacturing the same. The varistor is mainly composed of zinc oxide and contains a composite oxide expressed by the chemical formula Zn.sub.2 SnO.sub.4. It is manufactured using a method wherein zinc oxide and tin oxide are mixed; the mixture is subjected to a thermal process thereafter to obtain a composite oxide expressed by the chemical formula Zn.sub.2 SnO.sub.4 ; and the composite oxide is combined with the zinc oxide which is the main component and a thermal process is performed to obtain a raw material for the varistor.

Applicant has discovered that aliovalently doped zinc-indium-oxide where In is 40-75% of the metal elements can achieve electrical conductivity comparable to wide band-gap semiconductors presently in use while exhibiting enhanced transparency in both the visible and infrared. The material can be doped to resistivity of less than 1 milliohm-cm by small quantifies of aliovalent dopants, such as tetravalent atoms. It can be deposited on glass substrates in amorphous and polycrystalline films.

Connectors with capacitors or resistors built in are very expensive and a custom design requires a considerable lead time. By building a circuit in modular form so that it connects to a standard cylindrical connector, both the cost and lead time are reduced drastically. Modules containing a variety of frequently used circuitry can be kept in inventory for at-will and immediate association with any standard circular connector, as desired. By having a variety of adapter collars in stock that mate with various kinds and constructions of cylindrical connectors, the suppression modules may be connected to a variety of differently constructed connectors. Many different configurations for the electrical circuitry in the module are possible. Many different configurations of the circuit module and interface collar are possible and can be designed to accommodate almost any connector configuration. By utilizing a terminating module as well, the connector with its circuit module attached can be utilized like and appears to be a single connector. A metal oxide varistor in compact plate form is uniquely suited for use in multi-pin connector bodies or in circuit modules.

An arresting insulator is provided which includes an insulator body made of an insulative material and a non-linear resistor. The insulator body includes a head for linking the insulator to an adjacent insulator, and a shed formed integrally with the head. The resistor is secured in the insulator body and has a non-linear relation between residual voltage and current. More specifically, the resistor has a characteristic that satisfies the equation: wherein V.sub.NmA is a threshold reference voltage that causes a current of at least N milliamps to start flowing across the resistor to cause the resistor to perform a surge absorbing function. N is an arbitrary value in the range of 1 to 10, and H is the axial length of the resistor along a direction of electric field in millimeters.

According to this invention, there is disclosed a compact power circuit breaker having a large breaking capacity and stable breaking performance due to a compact closing resistor unit having high performance. The power circuit breaker includes a main switching mechanism having an arc extinguishing function, an auxiliary switching mechanism parallelly connected to the main switching mechanism and having an arc extinguishing function, and a closing resistor unit connected in series with the auxiliary switching mechanism and incorporated with a resistor containing zinc oxide (ZnO) as a main component and titanium figured out as titanium oxide (TiO.sub.2) in an amount of 0.5 to 25 mol% and nickel figured out as nickel oxide (NiO) in an amount of 0.5 to 30 mol. % as sub-components.