An electro-static discharge protection device includes a ceramic base material, first and second outer electrodes on the outer surface of the ceramic base material, a hollow portion inside the ceramic base material, a first discharge electrode including a first end portion electrically connected to the first outer electrode and a second end portion in the hollow portion, a second discharge electrode including a first end portion electrically connected to the second outer electrode and a second end portion spaced apart from the first discharge electrode in the hollow portion, and a discharge supporting electrode including silicon carbide and between the second end portion of the first discharge electrode and the second end portion of the second discharge electrode. The elemental alkali metal in the ceramic base material is about 3 percent by weight or less.

An electro-static discharge protection device includes a ceramic base material, first and second outer electrodes on the outer surface of the ceramic base material, a hollow portion inside the ceramic base material, a first discharge electrode including a first end portion electrically connected to the first outer electrode and a second end portion in the hollow portion, a second discharge electrode including a first end portion electrically connected to the second outer electrode and a second end portion spaced apart from the first discharge electrode in the hollow portion, and a discharge supporting electrode including silicon carbide and between the second end portion of the first discharge electrode and the second end portion of the second discharge electrode. The elemental alkali metal in the ceramic base material is about 3 percent by weight or less.

An ESD protection device includes an insulating ceramic body including a cavity, first and second discharge electrodes disposed so as to partially face each other with the cavity interposed therebetween, and a supporting electrode disposed so as to be at least partially exposed to the cavity and to be electrically connected to the first and second discharge electrodes. A void isolated from the cavity is provided in at least a portion of a boundary region between at least one of the first and second discharge electrodes, the supporting electrode, and the insulating ceramic body.

An ESD protection device includes an insulating ceramic body including a cavity, first and second discharge electrodes disposed so as to partially face each other with the cavity interposed therebetween, and a supporting electrode disposed so as to be at least partially exposed to the cavity and to be electrically connected to the first and second discharge electrodes. A void isolated from the cavity is provided in at least a portion of a boundary region between at least one of the first and second discharge electrodes, the supporting electrode, and the insulating ceramic body.

An ESD protection device includes a bare unitary body, and a first discharge electrode and a second discharge electrode that are disposed inside the bare unitary body. The first discharge electrode and the second discharge electrode are opposed to each other with a gap interposed therebetween. The bare unitary body includes a cavity in which the gap between the first discharge electrode and the second discharge electrode is located, and to which the first discharge electrode and the second discharge electrode are exposed. A first space of the cavity on a side closer to the first discharge electrode is smaller than a second space of the cavity on a side closer to the second discharge electrode.

An ESD protection device includes a bare unitary body, and a first discharge electrode and a second discharge electrode that are disposed inside the bare unitary body. The first discharge electrode and the second discharge electrode are opposed to each other with a gap interposed therebetween. The bare unitary body includes a cavity in which the gap between the first discharge electrode and the second discharge electrode is located, and to which the first discharge electrode and the second discharge electrode are exposed. A first space of the cavity on a side closer to the first discharge electrode is smaller than a second space of the cavity on a side closer to the second discharge electrode.

An ESD protection device includes a multilayer substrate, first and second discharge electrodes, and a discharge auxiliary electrode. Discharge portions of the first and second discharge electrodes are opposed to each other in a lamination direction of insulating layers with the discharge auxiliary electrode interposed between both the discharge portions. A cavity is provided within the multilayer substrate in at least one of a region positioned adjacent to or in a vicinity of the discharge portion of the first discharge electrode on an opposite side to the discharge auxiliary electrode and a region positioned adjacent to or in a vicinity of the discharge portion of the second discharge electrode on an opposite side to the discharge auxiliary electrode.

An ESD protection device includes a multilayer substrate, first and second discharge electrodes, and a discharge auxiliary electrode. Discharge portions of the first and second discharge electrodes are opposed to each other in a lamination direction of insulating layers with the discharge auxiliary electrode interposed between both the discharge portions. A cavity is provided within the multilayer substrate in at least one of a region positioned adjacent to or in a vicinity of the discharge portion of the first discharge electrode on an opposite side to the discharge auxiliary electrode and a region positioned adjacent to or in a vicinity of the discharge portion of the second discharge electrode on an opposite side to the discharge auxiliary electrode.

A gas-filled spark gap 2 for the protection of an electrical installation includes a gastight casing 4 and two elongate electrodes 13, 14 delimiting between them an inter-electrode space. The inter-electrode space includes successively a striking chamber 17 and an arc-extinguishing chamber 20 for extinguishing the electrical arc. The arc-extinguishing chamber 20 includes mutually spaced divider plates 29. The gas-filled spark gap 2 also includes two connecting terminals 11, 12 accessible from outside the casing 4 and intended to enable electrical connection of the gas-filled spark gap 2 to the electrical installation. The two connecting terminals 11, 12 are respectively electrically connected to the two electrodes 13, 14. Finally, the gas-filled spark gap 2 includes an inert gas trapped in the casing 4.

An ESD protective device includes an element assembly with a hollow portion that includes inner surfaces including a first inner surface, a second inner surface, and a third inner surface inclined to a Z direction in a cross section including the Z direction. Accordingly, a surface area of the inner surfaces of the hollow portion is increased, the heat load on an auxiliary discharge electrode is reduced, and the deterioration of the auxiliary discharge electrode is significantly reduced or prevented.