JPS5848764Y2 - Generic Users - Google Patents

Description

[Detailed description of the invention] The present invention is a current-limiting fuse in which a fuse element consisting of a large current breaker section and a small current breaker section having an arc-extinguishing tube and a resistance wire for displaying a blowout are electrically arranged in parallel. It is related to.

Conventional general current-limiting fuses do not break currents below 3 to 5 times the rated current, and if the current is smaller than this, the arc time is long when breaking, so the resistance wire connected in parallel with the fuse element is The element was cut off within the arcing time, and the operating overvoltage due to the breaking of the resistance wire did not increase.

However, by using a small current interrupting part made of an element made of a low-alloy metal and covered with an arc-extinguishing tube such as Teflon, arc-extinguishing gas generated in the arc-extinguishing tube due to arc heat when the element is fused is used. In current limiting fuses, the pressure is released to the outside of the arc extinguishing tube, and this discharge cools the arc and extinguishes the arc in the slit. In this type of current limiting fuse, the fuse element extinguishes the slit arc at the current zero point, and then the current flows into the resistance wire. will be migrated.

In this case, the current in the fuse element is small, but the current capacity of the resistance wire is extremely small, so it becomes a limiting area, and a high operating overvoltage occurs, and this overvoltage causes the gap in the fuse element that was previously cut off to reoccur. There was a defect in which the arc extinguishing tube was damaged and could no longer be cut.

The present invention has been developed by forming the resistance wire of a current limiting fuse in a spiral shape to cut off a small current by extinguishing a small current, and by rolling an appropriate number of main parts to make a difference in cross-sectional area. It is an object of the present invention to provide a novel current-limiting fuse that can eliminate the defects of conventional current-limiting fuses and suppress the rise in operating overvoltage of a resistance wire by firing at a different time.

An example of means embodying the present invention will be explained below with reference to the drawings. In the drawing, 1 is an outer cylinder made of an insulating material, and cap-shaped electrodes 2 and 3 are fixed to both ends of the outer cylinder, as shown in Fig. 1. are doing.

Reference numeral 4 denotes a fuse element whose both ends are connected to the electrodes 2 and 3 and which is spirally wound in the middle, with a silver element 5
and a small current interrupting section located in the center thereof and consisting of a low alloy metal element 6 such as a gold-silicon alloy sufficiently covered with an arc extinguishing tube 7 such as Teflon. .

Reference numeral 8 denotes an insulating thin tube made of porcelain or resin fixed in a straight line between both electrodes 2 and 3 at the center of the fuselage element 1-4, and the inside thereof is shown in FIG. A spiral resistance wire 9 is inserted between the bush 11 and the electrode 2, and one end thereof is connected to the one electrode 2.

A metal spring case 10 is fitted and fixed to the end of the insulating thin tube 8 on the electrode 3 side, and a bushing 11 made of an insulating material is fixed to the inner end of the spring case 10.
As shown in the figure, a resistance wire 9 is introduced through the bushing 11 so that the spiral portion is held.

Reference numeral 12 denotes an indicator pin slidably provided in the spring case 10, to the inner end of which the other end of the resistance wire 9 introduced into the spring case 10 is fixed, and the indicator pin 12 and the spring case are connected to each other. Spring 13 interposed between the inner end of 10
is held in a compressed state, and the fuse is shown in its unblown state.

That is, the resistance wire 9 is connected to the conductive display pin 12 and the spring 13.
, are connected to the electrode 3 via the spring case 10, and are electrically connected in parallel to the fuse element 4.

Note that when the fuse element is fused and the resistance wire is fused, the outer end of the display pin 12 will protrude to the outside through the through hole formed in the center of the terminal 3 due to the biasing force of the spring 13. , indicates a blown fuse.

The spring case 10, the display pin 12, and the spring 13 form a fusing display device.

Reference numeral 14 denotes an arc agent filled in the outer cylinder 1 and the insulating thin tube 8.

Now, in the current limiting fuse configured as described above, the structure of the resistance wire 9 will be explained in detail with reference to FIGS. 2 and 3. As shown in FIG. 9a is wound spirally around the outer periphery of the bar 15 as shown in FIG. 3C, and the wound state is rolled by rolling rollers 16 and 17 as shown in FIG. 3C.

At this time, the portion rolled by the rolling rollers 16 and 17 spreads over the entire area (including the length direction) due to the malleability of the resistance wire 9, so its cross-sectional area is different from that after being rolled.

Therefore, as shown in FIG. 2, the resistance wire 9 manufactured in this manner has a large number of rolled portions 9b with small cross-sectional areas formed on the opposing circumferential surfaces of the spiral portion, and there is a difference in cross-sectional area as a whole. It becomes what is given.

The operation of the current limiting fuse provided with the resistance wire configured as described above will now be described.

Now, the electrical path of the current limiting fuse shown in Figure 1 is normally terminal 2→
The fuse element 4 becomes the electrode 3.

Now, when a small current several times the rated current flows, the low alloy element 6 portion of the fuse element 4 is fused and the slit arc is extinguished, and then the current transfers to the resistance wire 9.
Current flows through the electrode 2 → resistance wire 9 → display pin 12 → spring 13 → spring case 10 → electrode 3.

At this time, the resistance wire 9 has many rolled portions 9b as described above.
are formed and have different cross-sectional areas, so the resistance wire 9 fuses and arcs first in the rolled portion 9b, which has a smaller cross-sectional area, and then the unrolled portion fuses and undergoes staggered firing. be done.

Therefore, when comparing the conventional resistance wire with no difference in cross-sectional area and the resistance wire 9 of the present invention with a difference in cross-sectional area, the fourth
As shown in Figure a, the overvoltage peak value is different from conventional A1 to A2 in this invention, by providing parts with different cross-sectional areas, when breaking the resistance wire, first Due to the staggered firing in which a section fuses and then a section with a larger cross-sectional area fuses, the overvoltage peak value is at two locations, the firing time is longer than in the conventional case, and the resistance wire is cut off. become.

Therefore, the peak value of the operating overvoltage is lower than the conventional one-point cut-off, and the passing current waveform is also different from the conventional B1 to the B1 of the present invention, as shown in Figure 4.
It becomes 2.

In this way, in the current limiting fuse of the present invention, the resistance wire 9 fires continuously with a delay, so that the arc duration becomes longer and the time for transition to a high resistance element becomes longer, and the operating overvoltage is suppressed. Unlike conventional current-limiting fuses, the cut-off part of the fuse element does not re-fire and become unable to shut off, and it has the major feature of being able to reliably cut off small currents.

Further, as shown in FIGS. 3a-c, the wire-like resistance wire 9a is wound around a bar 15 and rolled onto rolling rollers 16, 17.
If it is manufactured by a rolling method, it can be easily manufactured using relatively simple equipment.

Cap-shaped electrodes are provided at both ends of an outer cylinder made of an insulating material, and between the two electrodes are a large current breaker and an arc extinguishing tube wrapped around the outer circumference of the insulating thin tube arranged inside the outer cylinder. a fuse element consisting of a small current interrupting part having In the current limiting fuse, which is electrically connected in parallel and has an arc extinguishing agent inside the insulating capillary tube and between the capillary tube and the outer cylinder, a suitable number of locations of the spiral portion of the resistance wire are rolled to create a difference in cross-sectional area. Due to this, when a small current is cut off, the resistance wire fires continuously with a delay, prolonging the duration of the arc, and also prolonging the time it takes to transition to a high-resistance element, thereby suppressing the rise in operating overvoltage. - It is effective to ensure that there is no danger of the breakout-resistant part re-igniting and losing its ability to shut off, to prevent damage to the equipment caused by this, and to ensure reliability of protection, which is the mission of fuses. This is an excellent invention for industrial use as a current limiting fuse.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an embodiment of a current limiting fuse embodying the present invention; Fig. 2 is an enlarged side view of the main part showing only the resistance wire; Fig. 3 a, l). C is a road body explanatory diagram showing an example of the manufacturing method of the resistance wire, No. 4
Figures a and l) are diagrams showing voltage and current waveforms due to the conventional resistance wire and the resistance wire of the present invention. Fuse element...4, Resistance wire...
・9, Rolled part...9b0

Claims (1)

[Scope of utility model registration request] Cap-shaped electrodes are provided at both ends of an outer cylinder made of an insulating material, and between the two electrodes are a large current breaker and an arc extinguishing tube wrapped around the outer circumference of the insulating thin tube arranged inside the outer cylinder. a fuse element consisting of a small current interrupting part having In the current limiting fuse, which is electrically connected in parallel and has an arc extinguishing agent inside the insulating capillary tube and between the capillary tube and the outer cylinder, a suitable number of locations of the spiral portion of the resistance wire are rolled to create a difference in cross-sectional area. A current-limiting fuse characterized by the fact that it is attached.