JP2841521B2 - Varistor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a varistor, and more particularly to a surge absorbing varistor.

[Prior Art] As shown in FIG. 4, a conventional varistor is provided with electrodes 2a and 2b on two opposing surfaces of a varistor base 1, respectively.
Each of the electrodes 2a, 2b is provided with a lead 5a, 5b,
Although it has a function of absorbing the surge applied to 2a and 2b, when an excessive surge is applied, a part of the varistor base is melted and short-circuited.

As shown in FIG. 5, it is possible to cope with a short-circuit state by externally connecting a thermal fuse 7 in series. However, when a surge is applied next time, the surge absorbing function is not utilized and the load side is not used. It was the cause of failure.

[Problems to be solved by the invention]

In the above-mentioned conventional varistor, the application of an excessive surge causes the short-circuit state or the varistor with a built-in thermal fuse to be in an open state, making the protection function against the next surge impossible and losing its role as a surge protection element. There is a drawback to do.

In addition, since there is no external display when the thermal fuse is cut, there is also a disadvantage that the electronic circuit on the load side after the varistor is destroyed cannot be prevented beforehand.

[Means for solving the problem]

The varistor of the present invention has a disk-type first varistor element having electrodes on both surfaces, and has electrodes on both surfaces.
A second varistor element having an outer diameter smaller than that of the first varistor element mounted on the varistor element and having an electrode on a surface opposite to the electrode on the first varistor element mounting surface connected in series; It is characterized by having the electrode of the first varistor element on the mounting surface of the second varistor element and a thermal fuse whose both ends are connected to the electrode on the other surface of the second varistor element.

〔Example〕

 Next, the present invention will be described with reference to the drawings.

FIG. 1 is a partially cutaway perspective view of a first embodiment of the present invention, and FIG. 2 is an equivalent circuit diagram of the embodiment of FIG.

As shown in FIGS. 1 and 2, a varistor base having a smaller outer diameter than the varistor base 1 is provided on an electrode 2b of a varistor element Q1 in which electrodes 2a and 2b are provided on two opposing surfaces of a disk-shaped varistor base 1. A varistor element Q2 provided with electrodes 4a and 4b on two opposing surfaces of 3 is mounted, and the electrodes 2b and 4a are electrically connected to connect the varistor element Q1 and the varistor element Q2 in series.
The electrode 2b and the electrode 4b are connected by a thermal fuse 6 made of a thin metal wire such as Al or Zn, and leads 5a and 5b for connecting an external circuit are connected to the electrodes 2a and 4b.

FIG. 3 is an equivalent circuit diagram of the second embodiment of the present invention.
Varistor element of varistor configured in the same manner as the first embodiment
By connecting the neon tube 4 and the resistor 5 in series between the electrode 4a and the electrode 4b of Q2, when the thermal fuse 6 is blown or the varistor element Q1 is short-circuited, the neon tube is turned on and visually observed. There is an advantage that visibility is possible.

〔The invention's effect〕

As described above, according to the present invention, the second varistor element having a smaller outer diameter than the first varistor element is mounted on the disk-type first varistor element and connected in series. By connecting thermal fuses in parallel, the thermal fuses are blown when an excessive surge is applied,
There is an effect that short circuit of the varistor element can be prevented beforehand. Further, when the first varistor element is short-circuited due to an excessive surge, the second varistor element operates to provide an effect of protecting the electronic circuit on the load side.

[Brief description of the drawings]

FIG. 1 is a partially cutaway perspective view of a first embodiment of the present invention, and FIG.
FIG. 3 is an equivalent circuit diagram of the embodiment of FIG. 1, FIG. 3 is an equivalent circuit diagram of the second embodiment of the present invention, FIG. 4 is a side view of the first example of the conventional varistor, and FIG. It is a perspective view of the 2nd example of the conventional varistor. DESCRIPTION OF SYMBOLS 1 ... Varistor base, 2a, 2b ... Electrode, 3 ... Varistor base, 4a, 4b ... Electrode, 5a, 5b ... Lead, 6 ... Thermal fuse, 7 ... Neon tube, 8 ... Resistance 9: Thermal fuse, Q1: Varistor element, Q2: Varistor element.

Claims (1)

(57) [Claims] 1. A disk-shaped first varistor element having electrodes on both surfaces, and an electrode on both surfaces, mounted on the first varistor element and provided on the electrode on the first varistor element mounting surface. A second varistor element having an outer diameter smaller than that of the first varistor element in which electrodes on opposing surfaces are connected in series; and an electrode of the first varistor element on a mounting surface of the second varistor element, and A varistor comprising: a thermal fuse having both ends connected to an electrode on the other surface of the second varistor element.