JP2014007134A - High breaking capacity fuse - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high breaking capacity fuse which ensures whole region breaking and high manufacturing work efficiency without using an arc-extinguishing agent.SOLUTION: Upon melting of a current fuse, an abnormal overload current is shunted to an auxiliary fuse-element 2 connected in parallel with a main fuse-element 1, and to the side of a current limit resistor 3 connected in series with the auxiliary fuse-element 2. Since the auxiliary fuse-element 2 is blown out with an overload current limited by the current limit resistor 3 after blowing out the main fuse-element 1, blowout interval of the fuse-element is widened quickly from a large current such as short circuit current to a small fusion current close to the rated current, and the current can be interrupted safely. Furthermore, blowout can be confirmed visually without using an arc-extinguishing agent, and the manufacturing work can be facilitated.

Description

  The present invention relates to a current fuse, and more particularly, to an improvement in a high breaking capacity fuse that requires breaking of a large current.

  Conventionally, when trying to cut off a large current due to a short-circuit accident, etc., a fuse with a large rated current that increases the amount of metal in the fusible body generates more ionized gas after the fusible member is blown, and arc discharge is likely to continue. Arc energy may increase, causing the fuse itself to break and fail to shut down.

  For this reason, a high breaking capacity fuse that requires breaking of a large current is a method in which a cylinder containing a fusible material is filled with a sand-like arc-extinguishing agent to absorb and cool arc heat to achieve arc breaking by suppressing arc growth. It is common to take

  On the other hand, by filling the arc-extinguishing agent against overcurrent interruption due to an accident, it is not possible to visually confirm whether or not the fusible body has melted. An overcurrent protection device (for example, Patent Document 1) in which a second fusible body formed as a load protection means is connected in parallel, or a sealed current having a structure in which an overload current is shunted to a high resistance wire connected in parallel to the fusible body There is a fuse (for example, Patent Document 2).

Special table 2009-540777 gazette Japanese Utility Model Publication No. 5-84005

  Although the arc extinguishing agent filled in the overcurrent protection device described in Patent Document 1 and a general high-breaking fuse is excellent in arc extinguishing performance as its name suggests, the filling operation is difficult due to the sandy state. There is a problem that the control of the particle size and the difference in filling density in the cylinder cause a large variation in the arc extinguishing performance and the interruption performance becomes unstable.

  In addition, when the arc-extinguishing agent is filled like the overcurrent protection device described in Patent Document 1 or a general high-breaking fuse, the fusing interval of the fusible body is quickly set for fusing for a small fusing current close to the rated current. The arc discharge time becomes longer, resulting in a larger arc energy, and a smaller fusing current is more difficult to cut off than a large current such as a short circuit (small fusing close to the rated current from a large current) There is a problem that it is difficult to cut off the entire region, that is, to cut off the current.

  Moreover, in order to solve the problem that the presence or absence of fusing cannot be visually confirmed by filling the arc-extinguishing agent, there is a problem that a complicated display mechanism like the overcurrent protection device described in Patent Document 1 must be provided.

  Furthermore, since the first fusible body of the overcurrent protection device described in Patent Document 1 is subjected to a tensile force by a mechanical trip (spring) because of the display mechanism, the usable material and wire diameter are limited, and the fusible body. Although the wire diameter of the wire cannot be reduced and the amount of metal after melting the fusible body is increased, the arc is likely to continue, and the impedance of the resistor (body) connected to the first fusible body is considered, but the resistance The fusing Joule integral value of the (body) is not considered, and the resistance (body) may blow out first in the case of a large abnormal current affected by the magnitude of the fusing joule integral value. If it melts (breaks), a large amount of metal vapor constituting the resistance (body) is generated, and there is a problem that it is difficult to shut off without an arc-extinguishing agent.

  On the other hand, in the sealed current fuse described in Patent Document 2, there is one in which a high resistance wire is connected in parallel to the fusible body. The role of the high resistance wire is high when the fusible body is blown by overload current. The resistance wire is also red-hot fused to indicate that the fusible material has melted while leaving a scorch on the thermal paper, and is not intended to improve the shut-off performance.

  The present invention does not use the arc-extinguishing agent that is used as a matter of course for large current interruptions in order to solve the conventional problems. A current limiting resistor that is arranged in parallel with the fusible body and has a cross-sectional area larger than that of the auxiliary fusible body, limits the large short-circuit current, plays a role of arc resistance, and suppresses the arc current. By cutting the current with an auxiliary fusible material made of a material that is thinner and has less metal content and less ionized gas after fusing, it can be used in all areas from large current interruption to small fusing current close to the rated current without using an arc-extinguishing agent. It is characterized by safely achieving current interruption.

  The present invention does not use the arc-extinguishing agent used in general high breaking capacity fuses. Accordingly, work performance management such as particle size control and packing density is not required, and the shut-off performance is stabilized. Moreover, there is no generation of powdery dust caused by handling a sand-like substance called arc extinguishing agent, and the fuse can be assembled without polluting the fuse assembly work environment.

  In addition, when an arc is generated due to a large abnormal current, the arc energy increases, and even if an arc extinguishing agent is used, a sturdy container is required, and as a result, it is necessary to use a material with high cost. By limiting the current with the current limiting resistor, the current limiting resistor plays the role of arc resistance and limiting the arc current, so that the arc energy can be kept small, and an inexpensive container can be used. The arcing agent filling work is not required, and the manufacturing cost can be reduced.

  Furthermore, since no arc-extinguishing agent is used, the presence or absence of fusing of the fusible body can be visually confirmed, and it is not necessary to provide a complicated mechanism for fusing display.

The perspective view of the high interruption | blocking capacity | capacitance fuse of this invention. The perspective view before incorporating the main soluble body, current limiting resistance, and auxiliary soluble body of FIG. 1 in an outer container. The perspective view of the other Example of this invention. The perspective view of the board | substrate with a terminal which mounted the main soluble body, current limiting resistance, and auxiliary | assistant soluble body of the other Example of this invention. Similar to FIG. Similar to FIG. Similar to FIG. The cut-off current waveform of the main soluble body only. The breaking current waveform of the present invention.

  The high breaking capacity fuse of the present invention will be described with reference to FIGS. In the figure, 1 is a main soluble body, 2 is an auxiliary soluble body, and 3 is a current limiting resistor. The auxiliary fusible body 2 and the current limiting resistor 3 are connected in series, and are connected to the main fusible body 1 in parallel.

  The auxiliary fusible body 2 has a current-carrying capacity (rated current) of 1/10 or less of that of the main fusible body 1, and the main fusible body 1 and the auxiliary fusible body 2 are transparent transparent inner containers as shown in FIGS. 7 is housed in an insulating transparent outer container 9 and is electrically conductive in which lead terminals 5 electrically and mechanically connected to the inner container 7 are fixed to both ends of the outer container 9. The container terminal 10 is joined.

  As another embodiment, the main fusible body 1 and the auxiliary fusible body 2 are accommodated in an insulating transparent inner container 7 as shown in FIGS. 3 to 7, or are accommodated in a surface mount container 8 as shown in FIG. Then, the soldered substrate 4 is put in an insulating transparent outer container 9, and the substrate terminals 11 at both ends of the substrate 4 are protruded from the insulating container terminals 10 fixed at both ends of the outer container 9. It may be a terminal to connect to.

  As another embodiment, as shown in FIGS. 6 and 7, a main soluble body 1 and an auxiliary soluble body 2 are stretched between elliptical openings 6 on a substrate 4 and soldered at both ends. In some cases, the substrate terminals 11 at both ends of the terminal 4 protrude from the insulating container terminal 10 and are connected to a circuit.

  The current limiting resistor 3 has a cross-sectional area having a larger fusing Joule integral value than the auxiliary fusible body, the length is 1/1000 or less of the current flowing through the auxiliary fusible body 2 and the auxiliary fusible body 1, and the auxiliary fusible body. In order to secure a length having a resistance value that limits the current 2 to a current value that can be interrupted without an arc-extinguishing agent, a resistance wire such as manganin or advance is wound around the ceramic rod as shown in FIGS. Alternatively, a resistor may be formed on the substrate 4 by a printing technique as shown in FIG.

  The high breaking capacity fuse of the present invention is equivalent to a current-carrying capacity of 29.9 A for the main fusible body at this time under the conditions of a rated current of 30 A, a circuit voltage of 250 V, and a short-circuit current (inherent current) of 5,000 A (an insertion angle of 30 °). The operation in the case where a current limiting resistor 5Ω having an auxiliary fusible body energizing capacity equivalent to 1A and a fusing Joule integral value larger than that of the auxiliary fusible body is arranged will be described.

  First, when a short-circuit current of 5,000 A flows, the main fusible body side is about 4,600 A, the auxiliary fusible body connected in parallel to the main fusible body and the current limiting resistor side is about 3.5 A (the total does not become 5,000 A). Current flows due to a shunt current (due to a current limiting effect due to the resistance of the fuse itself). The load factor with respect to the shunted current is about 15,400% of the rated current for the main fusible body and about 350% of the rated current for the auxiliary fusible body, and the main fusible body having a high load factor is blown first. When the main fusible body melts, all of the short-circuit current flows into the auxiliary fusible body side, but the current is limited to about 46 A by a current limiting resistor connected in series.

  About 46A, since the auxiliary fusible body and the current limiting resistor are connected in series, the current limiting resistor is larger when viewed as electric power, but the load factor is about 4,600% of the current-carrying capacity of the auxiliary fusible body. Because the current that blows in less than 1 millisecond, the heat dissipation is almost unaffected and the cross-sectional area is the time domain that affects the current carrying capacity. Under this condition, the cross-sectional area of the current limiting resistor is the fusing Joule integral value of the auxiliary fusible body By having a larger value, the auxiliary fusible body corresponding to 1A is not melted first, and the resistance wire of the current limiting resistor is not melted.

  After the main fusible body is melted, the short-circuit current of 5,000 A is limited by the current limiting resistor, and the auxiliary fusible body is equivalent to 1 A and has a small amount of metal. Although the arc continues until the present invention, the current limiting resistor plays the role of the arc resistance as shown in FIG. 9, and the current interruption is achieved quickly without generating large arc energy. (The peak of the current waveform is not 5,000 A due to the current limiting effect of the main soluble material)

  Next, in the case where the overload current is a minimum fusing current of 1.35 times the rated current indicated in the technical standards for electrical equipment for fuses, the main fusible body has an energizing capacity equivalent to 29.9 A and the auxiliary fusible body is energized. A description will be given of the operation in the case where a capacity equivalent to 1A and a current limiting resistor 5Ω are arranged.

  Under this condition, a fusing current of 40.5 A (30 A × 1.35) flows in a split manner to about 40.47 A on the main soluble body side and about 0.03 A on the auxiliary soluble body side. The load factor for the shunted current is about 134.9% of the rated current for the main fusible body and about 3% of the rated current for the auxiliary fusible body. .

  When the main fusible body melts, all of the overload current flows into the auxiliary fusible body. At this time, the current limiting resistance connected in series with the auxiliary fusible body causes the current to be about 21.6 A, and the load factor is about 2,160%. The auxiliary fusible body corresponding to 1A having a cross-sectional area with a smaller fusing Joule integral value than the current limiting resistance is fused. At this time, the auxiliary fusible body has a large load factor of about 2,160% and the arc-extinguishing agent does not surround the fusible body, so that the fusing interval can be expanded quickly and the arc-extinguishing agent-filled high breaking fuse Therefore, the entire region is cut off without causing the problem that the cutting current is more difficult to cut off.

  Furthermore, the current load factor when energizing 30A in the same setting as in the normal use state is about 100% for the main soluble body and about 2% or less for the auxiliary soluble body (as the ratio of the current flowing through the main soluble body and the auxiliary soluble body) Even if it is a thin auxiliary soluble body (less than about 1/1000 of the main soluble body), the current inflow is limited by the current limiting resistance, causing little thermal or mechanical damage. It does not cause any problems with respect to overall reliability.

  The present invention is applicable to a current fuse that protects an electric circuit through which a small abnormal current flows from a large short-circuit current interruption.

Explanation of sign

DESCRIPTION OF SYMBOLS 1 Main soluble body 2 Auxiliary soluble body 3 Current limiting resistor 4 Board | substrate 5 Lead terminal 6 Board | substrate opening part 7 Inner container 8 Surface mount type container 9 Outer container 10 Container terminal 11 Board terminal

Claims (7)

An auxiliary fusible body whose current-carrying capacity is 1/10 or less of that of the main fusible body in parallel with the main fusible body, and a fusing Joule integral value larger than that of the auxiliary fusible body. A high breaking capacity fuse characterized in that a current limiting resistor for limiting a current in use to 1/1000 or less is connected in series to an auxiliary fusible body and stored in an outer container. The auxiliary fusible body housed in the inner container and the current limiting resistor are arranged in series on the substrate in parallel with the main fusible body housed in the inner container, and the substrate is housed in the outer container. High breaking capacity fuse. The auxiliary fusible body housed in the inner container and the current limiting resistor of the winding structure are arranged in series on the substrate in parallel with the main fusible body housed in the inner container, and the substrate is housed in the outer container. Item 4. The high breaking capacity fuse according to item 1. The auxiliary fusible body is stretched around the substrate opening in parallel with the main fusible body, and the substrate disposed so that the current limiting resistance is in series with the auxiliary fusible body is housed in an outer container. High breaking capacity fuse. 2. The high shutoff according to claim 1, wherein the auxiliary fusible body and the current limiting resistor formed by the printing technique are arranged in parallel with the main fusible body in series on the substrate, and the substrate is housed in an outer container. Capacitive fuse. The inner container containing the main soluble body and the auxiliary soluble body is made of an insulating transparent material, and the inner container is stored in an outer container made of an insulating transparent material. 4. The high breaking capacity fuse according to claim 1, wherein the presence or absence of fusing can be visually confirmed. The board on which the main soluble body and the auxiliary soluble body are stretched is stored in an outer container made of an insulating transparent material, and the presence or absence of fusing of the main soluble body and the auxiliary soluble body can be visually confirmed. The high breaking capacity fuse according to claim 4 or 5.

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