JPS61110985A - Surge absorber - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a surge absorber that is inserted into a power supply section of an electronic device and used to protect the electronic device from abnormal voltages such as lightning surges.

(Conventional structure and its problems) Voltage dependent non-linear resistance elements such as zinc oxide varistors will deteriorate if a voltage higher than the maximum surge withstand voltage is applied even temporarily for some reason, causing the varistor voltage to decrease. However, a thermal runaway state occurs and eventually a certain level of residual resistance is exhibited, but in this process the element body becomes overheated and there is a risk of smoke, ignition, etc. Therefore, in order to solve these problems, there are methods such as using a device with a larger than necessary surno withstand capacity, or connecting in series fuses that blow at less than the maximum surge withstand voltage, but both methods are inexpensive. requires an increase in the height and space.

(Objective of the Invention) The present invention solves the above-mentioned difficulties and provides a surge absorber that is small and free from the risk of short-circuit ignition due to thermal runaway.

(Structure of the Invention) In order to achieve the above object, the present invention provides the following advantages:
Two electrodes are placed on one surface of a plate-shaped voltage-dependent nonlinear resistance element at a certain distance from each other so that a square is formed at the tip, and this square gap is exposed. The structure is such that the coating is applied after the coating is applied. This results in
It effectively protects electronic equipment, etc. from abnormal voltages such as lightning surges, has a small size, and discharges voltages higher than the maximum surge withstand voltage of voltage-dependent nonlinear resistance elements through the soak/soak gap. Therefore, it is possible to provide a surge absorber that is free from the risk of short-circuit ignition due to thermal runaway.

(Explanation of Examples) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an equivalent circuit of the surge absorber according to the present invention, where 1 shows a zinc oxide varistor and 2 shows a varistor. FIG. 2 shows a surge absorber according to the present invention. It is an Ifi zinc oxide varistor, 2 is a snooker, f is two electrodes formed on the - side 3, 3
4 and 4' respectively. 5,5
' indicates an external lead. FIG. 3 is an external view of the completed product, in which the spark gap portion 2 is exposed and painted.

Although a zinc oxide varistor is used in the above embodiment, other plate-shaped voltage-dependent nonlinear resistance elements may be used. However, in order to improve the properties of the zinc oxide varistor, a single electrode facing the split electrode may be provided on the other surface of the zinc oxide varistor.

When an abnormal voltage higher than the rated voltage is applied to a zinc oxide varistor, a short circuit phenomenon occurs due to deterioration as a failure mode, resulting in a thermal runaway state. This is shown in FIG. VI indicates the peak value of the voltage across the zinc oxide varistor and the peak value of the flowing current, and T indicates time. a is the point at which the zinc oxide varistor is destroyed by short circuit, b
is the region of short-circuit current, and C is the voltage due to residual resistance.

In the surge absorber according to the present invention, an abnormally high lightning surge (40 to 100 kV
) can be discharged at the Snokouk gap, and short circuiting of the voltage-dependent nonlinear resistance element can be prevented. In addition, since the voltage is within the rated value for a very low surge voltage without discharge in the four-kilogram system, it is possible to effectively absorb it by the voltage-dependent non-linear resistance element.

(Effects of the Invention) As described above, according to the present invention, there is no risk of short circuit or fire due to thermal runaway phenomenon even with abnormal voltage exceeding the rating of the voltage-dependent nonlinear resistance element, and the safety is extremely high. Moreover, it is possible to provide a small-sized surge absorber that does not require an attached protection circuit.

[Brief explanation of drawings]

Fig. 1 is an equivalent circuit of a surge absorber according to the present invention, Fig. 2 is a block diagram of a surge absorber in an embodiment of the present invention, Fig. 3 is an outline drawing of a completed product in the same embodiment, and Fig. 4 is a diagram. FIG. 2 is an explanatory diagram showing temporal changes in voltage and current during thermal runaway of a zinc oxide varistor. 1...Zinc oxide varistor, 2...Snokukugya,
7°13.3'...electrode, 4,4'...tip, 5
,5'...External lead. Figure 1 Figure 2 Figure 3

Claims (3)

[Claims] (1) Two electrodes are provided at a certain distance from each other on one surface of a plate-shaped voltage-dependent nonlinear resistance element, a spark gap is provided at the tip of each electrode, and this spark gap is exposed and painted. A surge absorber characterized by (2) The surge absorber according to claim (1), wherein a single electrode is provided on the other surface of the voltage-dependent nonlinear resistance element. (3) The surge absorber according to claim (1) or (2), wherein the discharge starting voltage of the spark gap is lower than the maximum surge withstand voltage of the voltage-dependent nonlinear resistance element.