JP2010027237A - Fuse equipped with alarm contact - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuse equipped with an alarm contact capable of reducing a current flowing in an alarm contact display wire even in a high-frequency region, and improving high-frequency current characteristics without cutting off the alarm contact display wire by high-frequency components contained in a commercial current. <P>SOLUTION: The fuse equipped with the alarm contact includes: a fuse element equipped with an inductor and a parasitic resistor; the alarm contact display wire which is connected to the fuse element in parallel, bypasses the high-frequency component of a lightning surge current flowing in the fuse element, and includes the inductor and the parasitic resistor; and an additional circuit set so that a ratio of impedance to combine the additional circuit with the alarm contact display wire and the impedance of the fuse element becomes 100 times or more in 1 MHz. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuse with a fusing alarm contact of a device that receives power supply, and more particularly to a fuse with an alarm contact that improves high-frequency current characteristics of a lightning surge current.

  A conventional circuit breaker with lightning protection has a terminal connected to a protected element, a fuse element 101 which is a coil for detecting an overcurrent, and a lightning surge current to flow through the circuit breaker as shown in FIG. An alarm contact display line 102 that is a bypass circuit that bypasses a high-frequency component and is configured by a combination of an inductance and a resistance or a resistance, and an alarm contact 103 are provided (see Patent Document 1).

FIG. 2 shows a circuit diagram of a circuit 200 which is an example of an equivalent circuit that realizes the configuration 100 shown in FIG.
In FIG. 2, the fuse element 101 includes an inductance L6 (10 nH) and a parasitic resistance R6 (0.3 mΩ), and the alarm contact display line 102 includes an inductance L7 (100 nH) and a parasitic resistance R7 (0.3Ω). It consists of. In the prior art shown in FIGS. 1 and 2, the high frequency component of the lightning surge current is prevented from flowing through the fuse element 101 by flowing the high frequency component of the lightning surge current through the alarm contact display line.

JP 2004-253222 A

  However, in the above prior art, the impedance of the fuse element increases due to the high frequency component contained in the commercial current, so that a large amount of current flows through the alarm contact display lines connected in parallel, and the alarm contact display lines are blown first. There was a problem of end up. Accordingly, an object of the present invention is to provide a fuse with an alarm contact that controls the current distribution between the fuse element and the alarm contact display line in the high frequency region and improves the high frequency current characteristics.

  In order to solve the above problems, a fuse with an alarm contact according to the present invention is connected in parallel to a terminal connected to a protected element, a fuse element for detecting an overcurrent having an inductor and a parasitic resistance, and the fuse element. A fuse with an alarm contact that bypasses a high-frequency component of a lightning surge current flowing through the fuse element and has an alarm contact display line having an inductor and a parasitic resistance, the inductor having a parasitic resistance, and the alarm contact display An additional circuit arranged in series with the line, the additional circuit being set so that the ratio of the impedance of the additional circuit and the alarm contact display line combined with the impedance of the fuse element is 100 times or more at 1 MHz Is further provided.

  In the fuse with an alarm contact of the present invention, the inductor of the additional circuit may be formed by winding the alarm contact display line in a coil shape.

  According to the fuse with an alarm contact of the present invention, the alarm contact ratio between the alarm contact line and the fuse element is set to 100 times or more in the high frequency region of 1 MHz, so that the alarm contact is cut off at the same time as in the past and the alarm is also generated in the high frequency region. The current flowing through the contact display line can be reduced, and the alarm contact display line is not interrupted by the high-frequency component included in the commercial current, so that the high-frequency current characteristics can be improved.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 3 is a block diagram showing a configuration 300 that is an example of a fuse with an alarm contact according to an embodiment of the present invention.
In FIG. 3, a configuration 300 includes a fuse element 301 that detects an overcurrent, a high-frequency component of a lightning surge current that is connected in parallel to the fuse element, and the bypass alarm contact display line 302 and the fuse element 301 cut off the high-frequency component of the lightning surge current that flows through the fuse element. The alarm contact 303 and an additional circuit 304 are provided to notify an alarm when the alarm is issued.

FIG. 4 is a circuit diagram showing a circuit 400 which is an example of an equivalent circuit for realizing the configuration 300 shown in FIG.
In FIG. 4, the fuse element 301 includes an inductor L6 (10 nH) and a parasitic resistance R6 (0.3 mΩ), and the alarm contact display line 302 includes an inductor L7 (100 nH) and a parasitic resistance R7 (0.3Ω). The additional circuit 304 includes an inductor L8 (1 μH) and a parasitic resistance R8 (6Ω). Here, the inductors L6 and L7 and the parasitic resistances R6 and R7 are the same as the circuit 200 according to the prior art shown in FIG. The inductor L8 has a larger inductance than the inductor L6 of the fuse element 301 in order to increase the impedance value in the high frequency region, and similarly, the parasitic resistance R8 has a larger resistance value than the parasitic resistance R6. Yes.

  Here, the inductor L8 is described as an independent element, but may be formed by winding a part of the alarm contact display line 302 in a coil shape. Further, although the inductors L7 and L8 and R6 and R8 are described as separate elements, they may be combined into one element and have the same characteristics as described above.

FIG. 5 is a diagram showing frequency characteristics of the current flowing through the fuse element and the current flowing through the alarm contact display line in the circuits shown in FIGS. 2 and 4.
5A shows the current flowing through the fuse element 101 in the case of the circuit constant of the circuit 200 shown in FIG. 2, and FIG. 5B shows the alarm contact display in the case of the circuit constant of the circuit 200 shown in FIG. 4C shows the current flowing through the line 102, (C) shows the current flowing through the fuse element 301 in the case of the circuit constant of the circuit 400 shown in FIG. 4, and (D) shows the case of the circuit constant of the circuit 400 shown in FIG. Shows the current flowing through the alarm contact display line 102. As can be seen from FIG. 5, by adopting the configuration of the present embodiment, it is possible to reduce the current flowing through the alarm contact display line 302 in the higher frequency region than in the prior art.

FIG. 6 is a diagram illustrating frequency characteristics of the impedance obtained by combining the additional circuit 304 and the alarm contact display line 302 and the impedance of the fuse element 301 when various constants are used for the additional circuit 304.
6, (1) indicates the impedance of the fuse element 301, (2) indicates the impedance of the prior art alarm contact display line 102 shown in FIG. 2 when nothing is added as the additional circuit 304, (3) shows the case where R8 (0.3Ω) and L8 (1 μH) are added as the additional circuit 304, and (4) shows that R8 (0.3Ω) and L8 (10 μH) are added as the additional circuit 304. Show the case. Here, the effect of the present invention can be obtained if the ratio of the impedance of the additional circuit 304 combined with the alarm contact display line 302 and the impedance of the fuse element 301 is set to be 100 times or more at 1 MHz. Therefore, the additional circuit 304 can be used as long as it is a constant shown in (3) and (4) of FIG.

  As described above, according to the fuse with an alarm contact of the present invention, in the high frequency region, the ratio of the impedance of the additional circuit 304 and the alarm contact display line 302 combined with the impedance of the fuse element 301 is 100 times or more at 1 MHz. Thus, the current flowing through the additional circuit 304 and the alarm contact display line 302 can be reduced even in the high frequency region with the same alarm contact cutoff time as in the prior art, and the alarm contact display line 302 is generated by the high frequency component included in the commercial current. Is not cut off, and the high-frequency current characteristics can be improved.

It is a block diagram which shows the structure 100 which is an example of the fuse with an alarm contact by a prior art. FIG. 2 is a circuit diagram showing a circuit 200 that is an example of an equivalent circuit that realizes the configuration 100 shown in FIG. 1. 1 is a structural diagram illustrating a configuration 300 that is an example of a fuse with an alarm contact according to an embodiment of the present invention. FIG. FIG. 4 is a circuit diagram showing a circuit 400 which is an example of an equivalent circuit for realizing the configuration 300 shown in FIG. 3. 5 is a diagram showing frequency characteristics of currents flowing through fuse elements 101 and 301 and currents flowing through alarm contact display lines 102 and 302 in circuits 200 and 400 shown in FIGS. 2 and 4. FIG. It is a figure which shows the frequency characteristic of the impedance which combined the additional circuit 304 and the alarm contact display line 302 at the time of using various constants for the additional circuit 304, and the impedance of the fuse element 301.

Explanation of symbols

101, 301 Fuse element 102, 302 Alarm contact display line 103, 303 Alarm contact 104, 304 Additional circuit

Claims (2)

A terminal connected to the protected element;
A fuse element for detecting an overcurrent having an inductor and a parasitic resistance;
In the fuse with an alarm contact, which is connected in parallel to the fuse element, bypasses a high-frequency component of a lightning surge current flowing through the fuse element, and includes an alarm contact display line having an inductor and a parasitic resistance,
An additional circuit having an inductor and a parasitic resistance and arranged in series with the alarm contact display line, wherein the ratio of the impedance of the fuse element combined with the additional circuit and the alarm contact display line is 1 MHz A fuse with an alarm contact, further comprising an additional circuit set to be 100 times or more.   The fuse with an alarm contact according to claim 1, wherein the inductor of the additional circuit is formed by winding the alarm contact display line in a coil shape.

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