JPS5853458B2 - High voltage cut-out fuse - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a high-voltage cut-out fuse in which a fusible material is stretched between a head terminal and a lead wire, and the outer periphery is surrounded by an arc-extinguishing tube whose one end is sealed with the head terminal. be.

Conventional high-voltage cutout fuses have the disadvantage that when a large current is applied during a short circuit, the fusible material gasifies in a very short period of time at the beginning of the short circuit, causing the pressure inside the fuse cylinder to rise rapidly. Therefore, the blocking ability was limited.

In other words, when a conventional high-voltage cut-out fuse is ignited by a large current, the pressure inside the fuse cylinder rises rapidly, and the fuse cylinder cannot withstand this shocking pressure rise, and it breaks and continues to flow, making it impossible to shut off. The arc extinguishing tube may be damaged due to a sudden rise in pressure, reducing its arc extinguishing ability, or the arc extinguishing tube may be torn apart or blown out due to the sudden release of internally generated gas through the fuse barrel opening. When the arc extinguishing ability is significantly reduced due to the leakage, if the current reaches zero point in this state, it will continue to flow inside the fuse cylinder, which naturally leads to the failure to interrupt the current.

In addition, when internally generated gas is released to the outside at high speed, a phenomenon can be seen where the gas enters the interior from the bottom of the cutout due to collision with the outside air, but this gas is ionized and has extremely poor electrical insulation. As a result, the dielectric strength between the external electrodes of the fuse cylinder or between the cutout switch electrodes was reduced, and there was a risk that a follow-on current would occur between these electrodes, making it impossible to shut off.

Therefore, it is an object of the present invention to provide a high-voltage cut-out fuse that suppresses a steep rise in internal pressure even when a short-circuit large current is applied, and furthermore, attempts to provide a high-voltage cut-out fuse that can gradually increase pressure and sufficiently increase dielectric strength.

This invention surrounds the outer periphery of the fusible body part with a pipe of good electrical conductor, thereby preventing a steep rise in internal pressure, and changing the cross section of the pipe of this good electrical conductor to adjust its fusing I2t. This is characterized by an improvement in dielectric strength.

The explanation will be given below according to the drawings. In Fig. 1, 1 is a head terminal, 2 is a lead wire, 3 is a fusible body stretched between the head terminal 1 and the lead wire 2, 4 is a fastener, and 5 is a fusible body 3. A pipe of good electrical conductivity surrounds the outer periphery of the head terminal 1 and is electrically connected to the head terminal 1.

6 is an arc extinguishing tube whose one end is sealed with the head terminal 1 and surrounds the outer periphery of the pipe 5; 7 is a tube clasp.

When the outer periphery of the fusible body 3 is surrounded by the pipe 5 which is a good electrical conductor in this way, the operating state in the case of a short circuit and a large current is as follows.

When a short-circuit large current passes, the fusible body is arced and gas is generated when the passing I2t coincides with the fusing 2t of the fusible body 3.

At this time, arc discharge occurs between the head terminal 1 and the fastener 4, the pressure inside the pipe 5 increases, and the voltage drop between the head terminal 1 and the fastener 4 increases due to the large arc resistance. It's getting thicker.

This voltage drop will be applied between the pipe 5 and the fastener 4, and since the gap between the poles, that is, between the end of the pipe and the fastener 4, is narrow and filled with generated gas, it can be quickly removed. Arc discharge starts, and the arc discharge inside the pipe 5 stops.

In the end, the transition of arc discharge took place, but by the time the transition occurred, the internal pressure had only increased slightly, and after the transition, the arc electrode was connected to the clamp 4 and the end of the pipe. Since the electrode position is close to the opening side, the pressure of the generated gas does not increase much, and therefore the gas is released quickly.

In this case, since the pressure inside the fuse cylinder is low and the gas discharge speed is slow, the arc extinguishing tube 6 is not damaged at all, and the generated gas is also prevented from entering the cutout.

As mentioned above, if the outer circumference 4 of the fusible body 3 is covered with the pipe 5 of a good electrical conductor electrically connected to the head terminal 1, a sudden increase in internal pressure can be suppressed and a favorable result can be obtained. If the current reaches zero point while the pressure inside the cylinder is low, even if the arc extinguishing tube 6 has sufficient arc extinguishing ability, there is a possibility that it will not be possible to shut off.

Therefore, in this invention, the pressure is gradually increased until the current zero point is reached, the dielectric strength is sufficiently increased, and the
As shown in FIG. 1, the cross-sectional area of the pipe 5, which is a good electrical conductor, is minimized at point A at the end, and the connections between points B and C and the head terminal 1 are taken. The cross-sectional area gradually increases as it goes toward the head terminal 1, and therefore, the 1st direction of fusing 2t gradually increases as it goes toward the head terminal 1, and by moving the gas generation position toward the 0 point, the desired insulation can be achieved. It has gained strength.

The operation in this respect will be explained below.

Passage ■2 t increases with the passage of time, so if fusing ■2 t is varied as described above, passage ■
Points having a direct melt cut almost equal to 2 t become gasified one after another, and point B is reached one after another.

By this time, the fastener 4 and the lead wire 2 have been ejected into the fuse tube material, so the arc electrode is at point B in the fuse tube and the fuse tube material, or from the moment the arc current transfers. Until this state is reached, the arc electrode in the fuse cylinder has moved from point A to point B, and therefore the gas generation position has also moved from point A to point B.

Here, for example, fusing I at each cross section between point A and point B
If the increase rate of 2t is increased, the time required to reach point B from point A becomes longer, and therefore the moving speed of the gas generation position becomes slower accordingly.

Furthermore, by reducing the rate of increase in the fusing I2t, the moving speed can be increased, and the moving speed can be freely adjusted.

Fuse operation I2 If the direction of t is equal to the fusing at point B ■2 t, the moving distance of the gas generation position is from point A to point B, and if the direction of fusing at point C is equal to t ,
The moving distance is approximately from point A to point C, and the moving distance of the gas generation position can also be freely selected.

In this way, mark the gas generation position inside the fuse cylinder, and
The pressure inside the fuse cylinder will increase according to the moving speed of the gas, and the pressure increase rate can be adjusted and the gas generation position will be adjusted until sufficient dielectric strength is obtained at the current zero point. It will be possible to move the shrine.

Further, since the fuse cylinder pressure and the arc voltage have an approximately proportional relationship, as is conventionally known, it is also possible to freely control the arc voltage.

In other words, it is possible to create the best arc voltage waveform according to the properties of the fuse tube and the performance of the arc extinguishing tube, greatly increasing the breaking ability of the high voltage cutout fuse, and making it a revolutionary high voltage cutout fuse. It's something you can get.

Furthermore, by controlling the arc voltage waveform, arc energy and arc power can be suppressed to a minimum, minimizing damage to the arc extinguishing tube and fuse cylinder, and furthermore, the gas generation position can be changed from point A to point B. Since the gas moves from point to point C, there is a fresh arc extinguishing tube around the gas generation position that does not reduce the arc extinguishing ability during arc generation, which also has the advantage of greatly increasing arc extinguishing power. There is.

In the example shown in FIG. 2, the vicinity of point A of the pipe 5 is connected to one end of the insulating tube 8, and the pipe 5. The space formed by the arc-extinguishing tube 6, the cylinder stopper 7, and the insulating tube 8 is filled with an arc-extinguishing agent 9, and 10 is a stopper to prevent the arc-extinguishing agent from flowing out.

In addition to the above-mentioned effects, this example has the following effects.

That is, as a disadvantage, first of all, in the case of a small current interruption, the fusible body 3 is interrupted and arced, generating gas.

Subsequently, as described above, the arc electrode migrates, and eventually the inner wall near point A of the pipe 5 and the fastener 4 or the flexible body remaining connected to the inner wall near point A and the fastener. This results in some arc discharge.

Due to the pressure rise of the gas generated by this arc discharge and the indicator spring of the fuse tube, the fastener 4 and lead wire 2 move toward the opening side, and the arc is extinguished by the arc extinguishing effect of the insulating tube 8 and the slit effect. Complete.

In the case of a short circuit large current, first, when the arc current moves to point A, the arc extinguisher 9 near point A immediately cools the arc electrode,
The arc extinguishing agent that has absorbed heat together with the plug 10 and the insulating tube 8 is released to the outside air while preventing the growth of the arc.

Since the arc temperature is lowered by this discharge action, the growth of the arc is further suppressed.

When the arc electrode reaches point B, the arc extinguishing agent from point A to point B has been released, but there is fresh arc extinguishing agent near point B that does not reduce the arc extinguishing ability. The same effect as point A can be obtained.

In this way, the same effect as at point A can be obtained throughout the arc generation from arc initiation to arc extinguishment, and the interrupting ability can be further improved.

Note that the same effect can be obtained by filling the inside of the pipe 5 and the insulating tube 8 with arc extinguishing agent.

It is also possible to fill the arc extinguishing agent both inside and outside the thermal chamber for even greater effectiveness.

In any of the above embodiments, a pipe 5 of good electrical conductivity is provided separately from the head terminal 1, and this is electrically connected to the head terminal 1 to surround the outer periphery of the fermentable body. As shown in FIG. 3, the same effect can be obtained even if the head terminal 1 itself is integrated with the pipe 5, which is a good electrical conductor.

FIG. 4 also shows a second
This shows an example in which a good electrical conductor pipe 11 is provided, which is provided so as to surround the outer periphery of the conductive body 3, and whose cross-sectional thickness is maximum at the connection part with the lead wire 2 and gradually decreases toward the other end. That's what I do.

FIG. 5 shows a modification f! of the embodiment of FIG. j! In addition to using the head terminal 1 as shown in Fig. 3, the pipe 11', which is a good electrical conductor, is integrated with the fastener 4.In both cases, the arc moves well and the inside of the fuse cylinder is This has the advantage of being able to more effectively adjust the pressure rise.

When the breaking performance of the high voltage cutout fuse according to the present invention was tested, the results shown in Table 1 and FIG. 6 were obtained.

The circuit conditions used for the test are as follows.

Supply voltage near, 2KV Conventional breaking current: 8.6KA Short-circuit power factor: cosφ=0.05 Sample A is a conventional high-voltage cant-out fuse that does not connect a pipe that is a good electrical conductor, and simply connects a fusible body to the head terminal. The outer periphery is surrounded by an arc-extinguishing tube that is stretched between the lead wires and sealed at one end with a head terminal.

Samples F4B and F4C are high-voltage cut-out fuses based on the present invention, and sample B is the embodiment shown in FIG. Sample C is the embodiment shown in Fig. 4, that is, in addition to the embodiment shown in Fig. 1 above, the fastener is provided with a second electrically conductive pipe to surround the outer periphery of the fusible material. be.

As is clear from the oscillograms in Table 1 and Figure 6, the high-voltage cutout fuse according to the present invention has the ability to control all of the factors such as maximum arc energy, arc power, spike voltage, and spike voltage gradient, which greatly affect the breaking ability. The draw-in was suppressed compared to the conventional example, and it was confirmed that the interrupting ability was significantly improved because the pressure rise and arc energy inside the fuse cylinder that occurs when a short circuit interrupts a large current is reduced.

As described above, the high-voltage cutout fuse according to the present invention prevents a sudden rise in internal pressure even when short-circuited and large current is applied, and the reason for this improvement in interrupting ability is based on thermal theory. By increasing the pressure gradually until the current zero point is reached, the dielectric strength can be sufficiently increased, providing a highly reliable, high-performance, high-voltage cutout fuse that can also be expected to significantly improve the breaking ability. I got it.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing one embodiment of the high-voltage cut-out fuse according to the present invention, and FIGS. 2 to 5 are cross-sectional views showing the implementation rows at various locations. In the oscillogram shown, 6 times shows sample A, Figure B shows sample B, and Figure C shows sample CV. 1.1'... Head terminal, 2... 1 node wire, 3... Fusible body, 5... Good electrical conductor pipe, 6... ... Arc extinguishing tube, 8...
・Insulating tube, 9... Arc extinguishing agent, 10...
... Arc-extinguishing agent outflow prevention plug, 11, 11... Good electrical conductor pipe.

Claims (1)

[Scope of Claims] 1. A high-voltage cut-out fuse in which a fusible material is stretched between the lead wires of the head terminal and the outer periphery is surrounded by an arc-extinguishing tube whose one end is sealed with the head terminal. A high-voltage cut-out fuse characterized by surrounding the outer periphery of a fusible body part with a pipe of good electrical conductivity that is electrically connected to a pipe. 2. The high-voltage cut-out fuse according to claim 1, wherein the cross-sectional thickness of the electrically conductive pipe is maximum at the connection with the head terminal and gradually decreases toward the other end. 3. The high-pressure cut-out fuse according to claim 1 or 2, in which a pipe with good electrical conductivity and a head terminal are integrated. 4 Connect the insulating tube to the other end of the electrically conductive pipe,
A high-pressure cut-out fuse according to claim 2 or 3, wherein the inner or outer space of the pipe and the insulating tube or the rain space thereof is filled with an arc-extinguishing agent, and an arc-extinguishing agent outflow prevention plug is provided. 5. A second electrically conductive material, which surrounds the outer periphery of the fusible material and has a cross-sectional thickness of the pipe that is maximum at the connection part with the fastener and gradually decreases toward the other end, is attached to the fastener that connects the fusible body and the lead wire. A high-voltage cut-out fuse according to claim 2 or 3, which is formed by connecting a pipe and having an end facing the other electrically conductive pipe. 6. The high-voltage cutout fuse according to claim 5, wherein the second electrically conductive pipe and the fastener are integrated.