JPH025521Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a lightning arrester with a built-in fuse, and is designed to ensure that even if the lightning arrester fails, this failure will not lead to a power outage accident.

In recent years, gear press arresters using high nonlinear resistance elements (ZnO characteristic elements) whose main component is zinc oxide have been used.

FIG. 1 is a circuit diagram showing an installation mode of a gear press arrester according to the prior art using ZnO characteristic elements. As shown in the figure, the lightning arrester 1 connected to the low voltage side electric wire _l1 is connected to the ground via a fuse _F1 . Further, a high voltage cutout ₂ having a built-in fuse _F2 is interposed in the high voltage side electric wire l2. Furthermore, the transformer Tr converts the high voltage (6600V) on the wire _L2 side to the low voltage (210V or 210V) on the wire _L1 side.
105V).

In such a circuit, when the ZnO characteristic element of the lightning arrester 1 is destroyed, this characteristic element becomes a conductor, so that a ground fault current flows to the ground through the electric wire l ₁ , the lightning arrester 1 and the fuse F ₁ . In other words, an abnormality similar to a ground fault will occur. At this time, if the ground fault current continues to flow for a predetermined period of time, the fuse will
_F1 blows out, and the ground fault current stops flowing and the system returns to normal. The main reason why a ZnO characteristic element is destroyed is when the ZnO characteristic element is subjected to multiple surges, or even if it is subjected to a severe surge that exceeds the discharge withstand capacity even a few times, which can cause deterioration and lead to destruction. many.

By the way, as mentioned above, if fuse F ₁ and fuse F ₂ are not coordinated, fuse
When a ground fault current flows to _F1 and an abnormal current flows to fuse _F2 on the high voltage side, the fuse
Fuse _F2 blows out before _F1 blows out.
If such a situation occurs, the electric wire _l2 will be opened, resulting in a major accident called a power outage.

In view of the above-mentioned circumstances, the present invention aims to provide a lightning arrester with a built-in fuse that does not cause power outage accidents.

Embodiments of the present invention will be described in detail below with reference to the drawings. Note that the same parts as in the prior art are given the same reference numerals, and redundant explanations will be omitted.

FIG. 2 is a circuit diagram showing an installation mode of a lightning arrester according to an embodiment of the present invention, and FIG. 3 is a partially cutaway sectional view of this embodiment. As shown in both figures, in the lightning arrester 3 of this embodiment, not only the ZnO characteristic element 5 but also the fuse F ₃ are built into the insulating case 4. The lightning arrester 3 has an electric wire L ₁ attached to it using an L-shaped fitting 6 and a tightening connector 7. At this time, the fuse F ₂ of the high-voltage cutout 2, which is a protection device, and the fuse F ₃ of the lightning arrester 3 are coordinated, and the blowing time of the fuse F ₃ is
This is shorter than the operating time of the high-voltage cutout 2, in which _F2 is fused and the electric wire _L2 is opened. That is, when the characteristic element 5 is destroyed, the fuse F ₃
When a ground fault current begins to flow in the fuse _F2 , an abnormal current (an overcurrent) begins to flow in the fuse _F2 at the same time, but the fuse _F3 starts to blow out earlier than the fuse F2. There is. In other words, Fig. 4 shows the fusing characteristics of fuses F ₂ and F ₃ converted to low voltage side current, and as can be seen from this figure, the blowing time of fuse F ₃ is shorter than that of fuse F ₂ . be. Therefore, even if the characteristic element 5 is destroyed, there will be no power outage, and power can always be stably supplied.

In the above embodiment, the blowing time of fuse _F3 is the blowing time of fuse _F2 (high pressure cutout 2
However, even if a device other than high voltage cutout 2 is provided as a protection device, the protection device and fuse F ₃ should cooperate in the same manner as in the above embodiment. Needless to say, it would be better to take .

As specifically explained above in conjunction with the embodiments, according to the present invention, even if a characteristic element is destroyed, a power outage accident will not occur.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing the installation mode of a conventional lightning arrester, Fig. 2 is a circuit diagram showing the installation mode of a lightning arrester according to an embodiment of the present invention, and Fig. 3 is a partially cutaway cross-sectional view of the present embodiment. 4 are characteristic diagrams showing the fusing characteristics of the fuse. In the drawing, 1 and 3 are lightning arresters, 2 is a high voltage cutout, 5 is a characteristic element, ₁ and ₂ are electric wires, F ₁ , F ₂ , F ₃
is a fuse and Tr is a transformer.

Claims (1)

[Scope of Claim for Utility Model Registration] The low-voltage side system circuit and the high-voltage side system circuit are equipped with a protection device that opens the system circuit after a predetermined operating time has elapsed from the point at which abnormal current begins to flow. Among the system circuits that are electrically connected by the lightning arrester, if the lightning arrester is installed in the low-voltage system circuit and has a built-in fuse and does not have a gap, if the characteristic element of the lightning arrester is destroyed, a ground fault will occur at the fuse. A lightning arrester with a built-in fuse, characterized in that the fuse has a fusing characteristic in which the time from when current begins to flow until the fuse blows out is shorter than the operating time of the protection device.