JPH03250523A - Three-phase gang breaking fuse element and gang fuse - Google Patents

Abstract

PURPOSE:To prevent the phase missing operation and generation of abnormal voltage by fixing shaft bearing parts of electroconductive arms to a resistance by the use of a low melting point metal, and giving each arm a resilient force to prompt the arm end into rotating in the direction of connecting with another phase adjoining. CONSTITUTION:Electroconductive arms 4a, 4b, 4c are supported by a resistor at shaft bearing parts 5a, 5b, 5c and secured to the resistor with low melting point alloy 6a, 6b, 6c. Therein a resilient force is given which prompts the arm end into rotation in such a direction as connecting with another phase adjoining when this alloy melts. When therefore an overcurrent in the small and middle amperage ranges flow for ex. through resistance 3a, the alloy piece 6a is melted by the heat emanated by the resistor 3a, and the arm 4a having received spring force rotates and its end contacts another phase adjoining, to cause generation of inter-phase short-circuiting. This eliminates impedance on the secondary side of fuse and increases the short-circuiting current, and a three-phase arc short-circuit is generated in the weld-cut parts 2a, 2b, 2c. Thus the three phases are weld-cut approx. simultaneously, and breaking is obtained simultaneously.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a fuse used to protect low-voltage distribution lines such as three-phase three-wire and three-phase four-wire systems, particularly for open phase protection or abnormal voltage protection. This invention relates to a three-phase simultaneous cut-off fuse element used as a fuse element and a three-phase simultaneous cut-off fuse using this fuse element.

[Prior Art] As this type of fuse element and fuse, one shown in FIG. 6, for example, has been provided in the past.

That is, the inside of the sealed cylinder 13 is partitioned by the partition wall 14 and the blocking part 1
5 and an arc short circuit part 16, and both ends are connected to the terminal 17 to form fusible bodies 18a and 18b.

18c is built in, and when one of the fusible elements, for example, the fusible element 18a, is fused, the metal vapor or arc generated thereby short-circuits the other phases arranged close to each other, causing a large current to flow through the interrupting part 15. It is designed to break the circuit.

[Problems to be Solved by the Invention] Generally, when a fuse blows, an arc is generated between the electrodes, and metal vapor is filled. If the fuses of each phase are arranged close to each other, metal vapor will fill between the phases, causing dielectric breakdown between the different phases and causing an arc short circuit. However, this operation is not always reliable, and there may be cases where arc short circuits do not occur between different phases. In other words, in a relatively large current range, a large amount of metal vapor is generated, the insulation between different phases is easily destroyed, and an arc short circuit definitely occurs, but in a medium current range it becomes accidental, and in an overload and small current range, an arc short circuit occurs. arc short circuit can hardly be expected. Therefore, even if one phase is blown out, the other phases are not blown out, resulting in open phase operation or abnormal voltage generation, and there is a risk that the three-phase fuse will malfunction.

Therefore, the object of the present invention is to provide a fuse element for simultaneously interrupting three phases, which can surely blow out the other two phases when the - phase blows out, thereby preventing open-phase operation and generation of abnormal voltage. The purpose of the present invention is to provide a three-phase simultaneous cutoff fuse using a fuse element.

[Means for Solving the Problems] In order to achieve the above object, in the present invention, when one of the -phase resistors in the three-phase fuse element abnormally heats up, the conductive arm pivotally supported on this resistor A short-circuit method is adopted in which the three phases are rotated and come into contact with other adjacent phases, causing a short circuit between the phases, and the three phases are fused out almost simultaneously.

That is, in the fuse element for simultaneously interrupting three phases according to the present invention, a resistor having a fused section with a cross-sectional area that matches the rated current is connected between three pairs of connection terminals, and a resistor is connected at a position closer to the secondary side than the fused section. In this method, a conductive arm is provided that can rotate around each resistor, and the pivot portion of this conductive arm is fixed to the resistor with a low melting point metal. The structure is such that it has an elastic force that rotates in the direction in which it comes into contact with.

It is desirable that the fusing parts are arranged close to each other, but this can be easily achieved by partially bending the resistor. That is, the resistor may be partially bent at the portion where the three-phase fusing portions are located so that the three-phase fusing portions are arranged close to each other.

Further, it is also possible to forcibly and reliably perform interphase short-circuiting by an arc at such a fusing portion. That is, when bending the resistor, it is bent into a substantially U-shape,
If a fusing portion is provided in the horizontal portion of this U-shape, a force is applied to drive the arc in the direction of other phases according to Fleming's left-hand rule, so that short-circuiting between phases due to the arc can be performed forcibly and reliably. The approximately U-shaped bent portion is plate-shaped, and this U-shaped bent portion is shaped like a plate.
By creating a small hole in the horizontal part of the letter shape to form a fusing part, the initial firing point is limited and the arc is driven in the direction of the other phase in the same way as above, resulting in a forced and reliable short-circuit between phases. can be achieved.

A three-phase simultaneous cutoff fuse that uses such a fuse element has a three-phase sleeve for connecting lead wires at both ends of the sealed container, and connects the connection terminals at both ends to the sleeves for each phase to cut off the three phases simultaneously. Obtained by housing the fuse element in a closed container.

In this case, if you surround the connection end of the primary resistor with an insulating pipe that has one end fixed to the insulating members that make up both sides of the sealed container, the insulation resistance after disconnection will be stable and reliable disconnection will be achieved. .

The material for the resistor and the conductive arm is preferably copper or a copper alloy such as a copper-nickel alloy.

[Operation] In the three-phase simultaneous cutoff fuse element configured as described above, the conductive arm rotates in response to the elastic force caused by the melting of the low-melting point metal in the small and medium current range, and the arm Since the end contacts the other adjacent phase and causes a short circuit, the impedance on the secondary side of the fuse disappears, resulting in an increase in short circuit current, and a three-phase short circuit occurs at the fused part, and the three phases are fused at almost the same time, resulting in interlocking interruption. . In addition, in a large current region, the three-phase fusing portions are fused out almost simultaneously due to an arc short circuit.

When the resistor is partially bent and the three-phase fusing parts are placed close to each other, not only interlocking cutoff in a large current range but also interlocking cutoff in a small to medium current range accompanied by a short circuit due to a conductive arm can be made more reliable.

In addition, if the resistor is bent into a substantially U-shape and the fusing part is provided in the horizontal part of this U-shape, a magnetic field will be generated around the vertical part close to the fusing part, and Fleming's left hand Since a force according to the law acts to drive the arc to other phases, interlocking interruption due to three-phase arc short circuit becomes more reliable.

In addition, if the approximately U-shaped bent part is made into a plate shape and a small hole is provided in the horizontal part of this U-shaped part to form a fusing part, the initial firing point is limited and the same arc drive as above is possible. The force makes interlocking shutoff more reliable.

A three-phase simultaneous cutoff fuse configured using such a fuse element can reliably cut off three phases in conjunction with each other, and there is no risk of open phase operation or abnormal voltage generation.

A three-phase simultaneous cutoff fuse with an insulated pipe surrounding the connecting end of the primary resistor has a high insulation resistance after interlocking cutoff, and the cutoff effect is stable.

[Example code] The following will explain the embodiments shown in the accompanying drawings.

FIG. 1 is a perspective view showing an embodiment of a three-phase fuse element according to the present invention, in which 1a, 1b, and 1c are three pairs of connection terminals, and a cross-sectional area corresponding to the rated current is provided between each connection terminal. Resistors 3a, 3b having fusing parts 2a, 2b, 2c,
3c is connected.

4a, 4b, 4c are conductive arms rotatably provided around the respective resistors at positions on the secondary side (right side in the drawing) of the fusing part;
a low melting point alloy 6a,
6b, 6b are fixed to the resistor. In this fixed state, the resistor is not in contact with the adjacent resistor, but when the low melting point alloy melts, an elastic force is applied so that the end of the arm rotates in the direction of contacting the other phase adjacent to it. ing.

Therefore, when an overcurrent in the small to medium current range flows through the resistor 3a, for example, the low melting point alloy 6a melts due to the heat generated by the resistor 3.
The conductive arm 4a receives the spring force and rotates, and the end of the arm comes into contact with another phase adjacent to the conductive arm 4a, causing a short circuit between the phases. As a result, the impedance on the secondary side of the fuse disappears, so the short-circuit current increases, and a three-phase arc short circuit occurs at the fusing portions 2a, 2b, and 2c, so that the three phases are fused almost simultaneously and are interlocked to be cut off.

FIG. 2 is a perspective view showing an example of a three-phase simultaneous cutoff fuse together with the other side of the fuse element.
%3c is the fused part 2a with a cross-sectional area that corresponds to the rated current,
The resistors 2b and 2C, 4a, 4b, and 4C are conductive arms that are rotatably provided around the respective resistors at a position closer to the secondary side (on the right side of the drawing) than the fusing part, The shaft supports 5a, 5b, and 5c are pivotally supported by the resistor and are fixed to the resistor by low melting point alloys 6a, 6b, and 6b. In this example, resistors 3a, 3b, 3c
A bent type is used for the three-phase fusing parts 2a and 2b.
, 2c are arranged close to each other. Specifically, as shown in the figure, a part of the resistor is bent into a substantially U-shape,
This U-shaped horizontal portion is provided with a fusing portion. Reference numeral 7 denotes an insulating member on both sides constituting a part of the airtight container, and 8 a sleeve provided on the insulating member, which connects the connection terminals 1a, 1b, and 1c of the fuse elements of each phase at the inner end and at the outer end. I am trying to connect the lead wires. That is, the three-phase fuse element has a structure in which the connection terminals at both ends are connected to a sleeve and housed in a closed container. Reference numeral 9 denotes an insulating pipe whose one end is fixed to the insulating member 7, which is made of glass, porcelain, etc., and surrounds the connecting ends of the resistors 3a, 3b, and 3C on the negative side.
The wall thickness of the inner end protruding from the inner end is increased. This is to improve the insulation resistance after the interlocking disconnection is completed and to quickly and reliably complete the disconnection. That is, the fusing part 2a12bs2c
After the fuse is blown, the arc short circuit continues and the resistor melts in the direction of the primary side and penetrates into the inside of the insulated pipe. The arc is cooled by this, the insulation between phases and poles increases rapidly, and the arc is quickly extinguished. Furthermore, the reason for increasing the wall thickness at the inner end is to increase the creepage distance and to provide a shaded area where the blown arc does not directly hit the insulating member.

As mentioned above, a part of the resistor is bent into a substantially U shape, and this U
In fuse elements and fuses in which the fusing part is provided in the horizontal part of the letter shape, as shown in Fig. 3, when the current ■ flows, the fusing parts 2a, 2b, 2b,
A magnetic field H is formed around the vertical part near 2C, and a force F is applied to drive the arc generated at the fused part in the direction of the other phases, so that the interphase short circuit is forcibly and reliably performed.

FIG. 4 shows another example of the fuse element as well as the other side of the three-phase simultaneous cutoff fuse, and the structure of the resistor and the fusing part are slightly different from the example shown in FIG. 2 above.

That is, in this example, the primary sides of the resistors 3a, 3b, and 3C are plate-shaped, and the substantially U-shaped bent portion is also configured in a plate-like manner, and a small hole 10 is provided in the horizontal plate-shaped portion to form the fusing portions 2a, 2b, 2c
It consists of That is, the initial arcing part is limited by the small holes 10 to form the fusing part. If the portion located on the primary side of the resistor is made into a plate shape in this way, the penetration speed when an arc occurs can be changed by changing the plate thickness and plate width.

When the cross-sectional area is constant, reducing the plate thickness and increasing the plate width will increase the penetration rate, and conversely, making the plate into a round bar shape will slow down the penetration rate. In order to quickly complete the arc extinguishment after all three phases are melted using this, the conductive arm 4a is formed into a plate shape to speed up melting, and does not require melting.
The mounting portions 4b and 4c are round rod-shaped with minimal melting.

FIG. 5 shows an example of a structure for applying an elastic force to a conductive arm to rotate it in the direction of short-circuiting with other phases.
An example is shown in which a spring bearing arm 11 is separately attached to the resistors 3a, 3b, 3C, and a compression coil spring 12 is held between the conductive arms 4a, 4b, 4c.

Note that this is merely an example, and the spring receiver does not need to be provided with an arm as long as it can apply rotational force to the conductive arm. For example, a structure in which a torsion coil spring is wound around a resistor, one end is in contact with the inner wall of a sealed container and the other end is in contact with a conductive arm, an auxiliary arm is provided protruding from the insulating member 7,
Various configurations can be adopted, such as a structure in which a tension coil spring is mounted.

[Effects of the Invention] As described above, the fuse element for simultaneous three-phase breaking and the three-phase simultaneous breaking fuse according to the present invention can simultaneously interrupt three phases in a large current range by an arc short circuit at the fusion part, and in a small to medium current range. By rotating the conductive arm due to the melting of the low melting point alloy, a short circuit between the phases is forcibly caused, and the fused part is fired by the short circuit large current, and the arc short circuit interrupts the three phases at the same time. It operates reliably and can prevent open-phase operation and abnormal voltage generation.

In the configuration in which the resistor is partially bent and the three-phase fusing portions are disposed close to each other, arc short-circuiting at the fusing portion is ensured.

Further, in a configuration in which the arc is bent into a substantially U-shape and a fusing portion is provided in the horizontal portion, a force that drives the arc to the other phase acts, further ensuring arc short-circuiting.

In other words, the present invention provides a three-phase simultaneous cutoff fuse element and a three-phase simultaneous cutoff fuse in which three phases are interlocked and cut off almost simultaneously. Ideal for protecting railway lines.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing an embodiment of a three-phase simultaneous cutoff fuse element according to the present invention, and Fig. 2 shows the other side of the fuse element and an example of a three-phase simultaneous cutoff fuse using this fuse element. FIG. 3 is a perspective view showing the structure of the fusing part in the same fuse element; FIG. 4 is a perspective view showing still another example of the fuse element and another embodiment of the three-phase simultaneous cutoff fuse; The figure is an explanatory view showing an example of applying a resilient force to a conductive arm, and FIG. 6 is a sectional view showing an example of a conventional three-phase simultaneous cutoff fuse. 1a, 1b, IC... Connection terminals 2a, 2b, 2
c... Fusing parts 3a, 3b, 3C... Resistance elements 4a, 4b, 4c... Conductive arms 5a, 5b
, 5C...Axis branch

Claims (6)

[Claims] (1) Connect a resistor with a fusing part with a cross-sectional area that matches the rated current between the three pairs of connection terminals, and each resistor can be rotated around its axis at a position closer to the secondary side than the fusing part. A conductive arm is provided, and the shaft portion of the conductive arm is fixed to the resistor using a low melting point metal, and an elastic force is applied to the conductive arm so that the end of the arm rotates in the direction of contacting the other phase adjacent to the conductive arm. Fuse element for simultaneous three-phase cutoff. (2) The fuse element for simultaneous three-phase cutoff according to claim 1, wherein the resistor is partially bent and the three-phase fusing parts are arranged close to each other. (3) A fuse element for simultaneously interrupting three phases according to claim 2, wherein a part of the resistor is bent into a substantially U-shape, and a fusing portion is provided in a horizontal portion of the U-shape. (4) The fuse element for simultaneously interrupting three phases according to claim 1, wherein the substantially U-shaped bent portion is plate-shaped, and the fusing portion is formed by providing a small hole in the horizontal portion of the U-shape. (5) In a three-phase simultaneous cut-off fuse using the three-phase simultaneous cut-off fuse element according to claim 1, 2, 3, or 4, three-phase sleeves for connecting lead wires are provided at both ends of the sealed container, and A three-phase simultaneous cut-off fuse with a connecting terminal connected to each phase sleeve and a three-phase simultaneous cut-off fuse element built into a sealed container. (6) The three-phase simultaneous cut-off fuse according to claim 5, wherein the connecting end of the primary resistor is surrounded by an insulating pipe whose one end is fixed to an insulating member forming both sides of the closed container.