JPS6191902A - barista - 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 The present invention relates to a varistor element (characteristic element) used in a delta power surge arrester that protects various equipment in a factory from lightning surges.

Conventional configuration and its problems The main performances required of varistor elements (characteristic elements) used in power surge arresters that protect various equipment in factories from lightning surges are limited voltage characteristics, energized life characteristics, and discharge withstand capacity. It is. Among these, the varistor element conventionally used to improve the discharge withstand capacity, that is, the magnitude of the lightning surge absorption capacity, has a structure as shown in Figure 1, where (1) is the varistor cable body, 2) is a side surface high resistance layer, and the varistor element is made by applying an oxide paste as a side surface high resistance layer (2) to the side surface of the varistor element body (1), which is a molded body, and drying it.
Manufactured by firing at ~1300°C.

The oxide paste is bismuth oxide (Bi, 0.), N
It is made from an oxide such as antimony I chloride (sbzol) or silicon oxide (Sin2) and an organic binder such as ethyl cellulose or n-butyl acetate.

When a surge current due to a lightning surge flows through the varistor body (1), a non-uniform electric field is generated on the side surface of the varistor body (1), causing discharge from locations where the electric field strength is high.

Otherwise, proceed to creepage connection.

When the side high resistance layer (2) is formed on the side surface of the varistor body (1), a high resistance layer is connected in parallel to the non-uniform electric field, which makes the electric field uniform and makes it difficult to discharge. Therefore,
When a lightning surge enters the varistor body (1), the value of the discharged surge current increases. Figure 2 shows the side high resistance layer (2
) with and without the side high resistance layer (2
), creeping discharge occurs at around 20 KA, but when the side high resistance layer (2) is formed, the discharge withstand capacity reaches a high value (
40KA), and a side high-resistance layer (2
) has been effective. However, the side high resistance layer (2)
The oxide paste is in paste form and is transferred to the varistor body (1) using a roller, etc., dried, and then fired, so if the varistor body (1) is not formed uniformly during molding, the oxide paste may be transferred unevenly. After drying, the edges may chip due to handling errors, and the thickness of the side high-resistance layer (2) may change depending on the viscosity of the oxide paste, resulting in chipping, changes in thickness, and unevenness of the oxide paste. There is a problem in that the application causes variations in the discharge withstand capacity of the varistor elements and deteriorates their performance.

OBJECTS OF THE INVENTION The present invention was made in order to solve the above-mentioned conventional problems, and an object of the present invention is to provide a varistor element that has a high discharge withstand capacity and uniform characteristics.

Structure of the Invention In order to achieve the above object, the present invention provides a voltage per unit thickness of a varistor element, that is, voltage/thickness (hereinafter V 1/
A varistor sheet with a higher V 1/wn than wn (referred to as wn) is attached to the side surface of the varistor body and fired, thereby improving the discharge withstand capacity of the varistor body.

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 3 and 4. Figure 3 shows the varistor element, (3) is the varistor element, (4) is V, / nyn is the varistor element (
This is a varistor sheet with higher v1/W11 than 3).

The varistor element of the present invention can be produced by wrapping a sheet of ethyl cellulose or the like having a composition similar to that of the varistor body (3) around the side surface of the molded body of the varistor body (3), and firing it. Manufactured. Since the varistor sheet (4) attached to the side uses a material with a higher V 1/an than the varistor body (3), a high resistance element is connected in parallel to the side of the varistor body (3). When a surge current due to a lightning surge flows, the electric field on the side surface of the varistor body (3) becomes uniform, similar to the conventional oxide paste side high-resistance layer (2) shown in Figure 1. .

FIG. 4 shows the implementation results of the varistor element according to the present invention,
It shows the magnitude of withstand current for five samples. That is, the discharge withstand capacity of the varistor elements is high in all samples (50 KA), and the variation in discharge withstand capacity among the varistor elements is also small. This is because by using the varistor sheet (4) as the side high resistance layer, the sheet can be made uniform with a tolerance of several μm for a thickness of 100 μm. Further, since the varistor sheet (4) is simply wrapped around the varistor body (3), the manufacturing process is simplified and handling is also facilitated.

As described in detail, according to the present invention, the manufacturing process is simplified, the discharge resistance is high, and the characteristic element, that is, the varistor element, used in a power surge arrester that protects various equipment in a factory from lightning surges. Moreover, it is possible to provide a varistor element having uniform characteristics.

[Brief explanation of drawings]

Figures 1 and 2 illustrate conventional varistor elements, where Figure 1 (a) is a plan view of the varistor element, Figure 1 (b) is a front sectional view, and Figure 2 (a) is a side view with high resistance. FIG. 2(b) is a diagram showing the experimental results of the discharge withstand capacity when there is no layer, FIG. 2(b) is a diagram showing the experimental results of the discharge withstand capacity when there is a side high resistance layer, and FIGS. One embodiment of the varistor element is shown, FIG. 3(a) is a plan view of the varistor element, and FIG. 3(b) is a plan view of the varistor element.
) is a front sectional view, and FIG. 4 is a diagram showing the experimental results of discharge withstand capacity. (3)...Ballista body, (4)...Ballista seat agent - Yoshihiro Morimoto Figure 1r, 7) Figure 2 (a) (Noshin Special 1c)
Ito^1o Shi-C Kenju~ri Figure 3 (a) (b Figure 4 Sample No.

Claims (1)

[Claims] 1. A varistor in which a varistor sheet with a voltage per unit thickness higher than the voltage per unit thickness of the varistor element is attached to the side of the varistor element and fired.