JP2017131017A - Electronic circuit, electronic apparatus, and deterioration determination method of lightning surge protection element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic circuit capable of determining degradation level of a lightning surge protection element with a simple configuration.SOLUTION: The electronic circuit includes: a lightning surge protection element the input end of which is connected to a first terminal; and an element array of a plurality of melting elements each having an electrical property different from each other, which are connected in parallel to each other between the output end of the lightning surge protection element and a second terminal. A first melting element in the element array melts at predetermined upper limit surge current value which is a discharge tolerance or less of the lightning surge protection element, and only a second melting element melts at a predetermined lower limit surge current value flowing through the element array.SELECTED DRAWING: Figure 9

Description

  The present invention relates to an electronic circuit, an electronic device, and a method for determining deterioration of a lightning surge protection element.

  When using an Internet service, an Internet connection provider lends a communication device such as a modem, a home gateway, and a VoIP (Voice over Internet Protocol) adapter to the user. Since these communication devices are connected to outdoor lines, they are susceptible to lightning surges.

  For this reason, communication devices take measures against lightning surges by using lightning surge protection elements such as varistors for communication lines. However, every time the communication device receives a lightning surge, the lightning surge protection element deteriorates and eventually loses the protection function against the lightning surge, leading to a failure of the communication device.

  However, there has been a problem that users of communication devices and Internet connection providers are not aware of the lightning surge protection element being deteriorated if the communication device is operating normally. Therefore, when the communication device is returned from the user, the Internet connection operator lends it to the next user without replacing the protection element even if the lightning surge protection element is deteriorated. .

  And if a communication device whose lightning surge protection element has already deteriorated is lent to a new user and the communication device is damaged by a lightning surge, the lightning surge protection element will not function immediately and the communication device will break down. There was a problem that. In this case, since the rented communication device immediately broke down for the new user, the user might have a bad impression on the renting company.

  Therefore, if the Internet communication provider can determine the degree of deterioration of the lightning surge protection element of the communication device, it is possible to eliminate the communication device having the lightning surge protection element deteriorated and rent out again.

  The electronic devices shown in Patent Document 1 and Patent Document 2 are provided with a circuit for detecting a surge waveform, a surge current value, and the like received by the lightning surge protection element, and based on the detection result of the surge and the characteristics of the lightning surge protection element. The life of the lightning surge protection element is judged.

  In addition, the electronic device disclosed in Patent Document 3 detects a degree of deterioration of the lightning surge protection element by forming a special circuit for detecting a surge current in a pattern of a printed circuit board and processing it with another electronic circuit. .

  Further, in paragraph [0020] and FIG. 3 of Patent Document 4, a circuit for grasping an overvoltage history by connecting a plurality of Zener diodes with different Zener voltages in series to a fuse having the same fusing current is shown. Yes.

JP 2004-273362 A JP 2014-228298 A JP 2009-222663 A JP 2007-53876 A

  However, the electronic devices disclosed in Patent Document 1, Patent Document 2, and Patent Document 3 have a complicated circuit configuration in order to realize a determination circuit that detects a lightning surge and a circuit that stores a history. As a result, the cost of the electronic devices shown in these patent documents is high.

  Further, in the circuit shown in FIG. 3 of Patent Document 4, the element that bypasses the surge current is not a SPD but a Zener diode, so that even if it can cope with a low voltage surge, it becomes a high voltage like a lightning surge. It is considered that there is no element that can be used. If there is a Zener diode that can withstand the lightning surge voltage, and the circuit shown in FIG. 3 of Patent Document 4 is inserted between the output terminal of the SPD and the FG, the maximum value of the overvoltage can be grasped. However, the history corresponding to the number of overvoltages cannot be grasped. For this reason, it is not always appropriate to use the circuit shown in FIG. 3 of Patent Document 4 to determine the degree of SPD degradation.

  An object of the electronic circuit and the electronic apparatus of the present invention is to enable determination of the degree of deterioration of a lightning surge protection element with a simple configuration.

  In order to achieve the above object, an electronic circuit of the present invention includes a lightning surge protection element having an input terminal connected to a first terminal, and an electrical circuit between an output terminal of the lightning surge protection element and a second terminal. A plurality of fusing elements having different characteristics are connected in parallel, and the first fusing element in the element arrangement has a predetermined upper limit surge current value that is less than or equal to the discharge tolerance of the lightning surge protection element. As for the second fusing element in the element arrangement, only the second fusing element is fused at a predetermined lower limit surge current value flowing in the element arrangement.

  In order to achieve the above object, an electronic device according to the present invention includes a lightning surge protection element having an input terminal connected to a first terminal, and an electric terminal between the output terminal and the second terminal of the lightning surge protection element. A plurality of fusing elements having different characteristics are connected in parallel, and the first fusing element in the element arrangement has a predetermined upper limit surge current value that is less than or equal to the discharge tolerance of the lightning surge protection element. The second fusing element in the element arrangement is fused with a first electronic circuit in which only the second fusing element is blown at a predetermined lower limit surge current value flowing through the element arrangement, and the first electron The circuit further comprises a first electronic circuit connected to the first terminal and the second terminal of the circuit.

  In order to achieve the above object, a method for determining deterioration of a lightning surge protection element according to the present invention includes a lightning surge protection element having an input terminal connected to a first terminal, an output terminal of the lightning surge protection element, and a second terminal. And an element array in which a plurality of fusing elements having different electrical properties are connected in parallel between the terminals of the first fusing element of the element arrangement, the discharge tolerance of the lightning surge protection element Fusing with a predetermined upper limit surge current value that is the following, the second fusing element of the element arrangement, fusing only the second fusing element with a predetermined lower limit surge current value flowing through the element arrangement, The deterioration of the lightning surge protection element is determined according to the fusing state of the plurality of fusing elements.

  According to the electronic circuit and the electronic apparatus of the present invention, it is possible to determine the degree of deterioration of the lightning surge protection element with a simple configuration.

It is a figure which shows the structural example of 1st Embodiment. It is a figure which shows operation | movement of 1st Embodiment. It is a figure which shows operation | movement of 1st Embodiment. It is a figure which shows the structural example of 2nd Embodiment. It is a figure which shows operation | movement of 2nd Embodiment. It is a figure which shows operation | movement of 2nd Embodiment. It is a figure which shows operation | movement of 2nd Embodiment. It is a figure which shows the modification of 1st Embodiment. It is a figure which shows the structural example of 3rd Embodiment.

[First Embodiment]
Next, a first embodiment of the present invention will be described in detail with reference to FIGS.
[Description of configuration]
FIG. 1 shows the configuration of the first embodiment.

  The electronic device 10 includes an SPD (Surge Protective Device; lightning surge protection element, surge protection device, lightning arrester) 21, a communication circuit 22, and a plurality of fuse resistors 31 to 3n. The electronic device 10 includes a communication terminal 11 connected to a communication line and an FG (frame ground) 12.

  The SPD 21 is a metal oxide varistor or the like, and is a component that bypasses a surge current when a high potential difference occurs between both terminals of the component, resulting in a short circuit state.

  The communication circuit 22 is an electronic circuit for communication.

  The fuse resistors 31 to 3n have a fusing characteristic in the resistor, and are components that are disconnected when a current exceeding the fusing power flows. In the present embodiment, the fuse resistors 31 to 3n have different resistance values, but have the same rated power.

  The communication line terminal 11 and the FG 12 are connected to the communication circuit 22. One terminal of the SPD 21 is connected to the communication line terminal 21, and the opposite terminal of the SPD 21 is connected to one terminal of all the fuse resistors 31 to 3n. The fuse resistors 31 to 3n are connected in parallel, and the terminal on the side not connected to the SPD 21 is connected to the FG 12.

The fuse resistors 31 to 3n have the same rated power. The fuse resistors 31 to 3n are 10 ohms, the fuse resistor 32 is 100 ohms, and the fuse resistor 33 is 200 ohms. Details of the method of selecting the fuse resistors 31 to 3n will be described in the section of the operation description.
[Description of operation]
Next, the operation of the present embodiment will be described with reference to FIGS.
(Overview of operation)
FIG. 2 schematically shows a case where a lightning surge has entered from the communication line terminal 11 of the electronic device 10. When a lightning surge enters from the communication line terminal 11, a large potential difference is generated between the communication line terminal 11 and the FG 12. As a result, when the potential difference between the communication 11 side terminal and the fuse resistance side terminal of the SPD 21 exceeds the limit voltage (also referred to as a voltage protection level) of the SPD 21, the SPD 21 bypasses the surge current from the communication line terminal 11 to the fuse resistance side. The bypassed surge current flows to the FG 12 via the fuse resistors 31 to 3n connected in parallel.

  In SPD, a maximum current value capable of bypassing a surge current referred to as a discharge tolerance is determined. When a current exceeding the discharge tolerance flows through the SPD, the SPD is broken. The surge current that the SPD bypasses the surge current and the surge current disappears and can be restored is a current that is less than the discharge tolerance.

  The electronic device 10 of the present invention is a device that keeps a record of the number of times the surge current has passed through the SPD 21 in a region where the SPD 21 is not destroyed, by fusing one or a plurality of fuse resistors 31 to 3n sequentially. It is.

  Since the electronic device 10 of the present invention can determine the deterioration status of the SPD 21 based on the fusing status of the fuse resistors 31 to 3n, the case of the SPD 21 must be opened unless the case of the electronic device 10 is normally opened to check the internal circuit. The deterioration status cannot be judged.

  However, when an internet connection company re-rents an electronic device such as a modem to a new user, the case is often replaced with a new one by reusing the internal circuit board. In this case, since the case of the electronic device returned from the previous user is opened, it is possible to check the fusing state of the fuse resistor.

Even if the case is not replaced when reusing the electronic equipment, the fuse resistance can be blown out by attaching a lid that can be opened and closed to a part of the case so that the fuse resistance portion of the internal circuit board can be confirmed. The situation can be confirmed.
(Method of determining the resistance value of the fuse resistor)
Next, a method for determining the resistance values of the fuse resistors 31 to 3n will be described.

  First, the upper limit Imax and the lower limit Imin of the surge current value to be left as a history are determined. Imax is set to a value equal to or less than the discharge withstand capacity of the SPD 21.

  The fuse resistors 31 to 3n have the same rated power and different resistance values. In general, the power Pcut at which the fuse resistor blows is proportional to the rated power. Since all the fuse resistors 31 to 3n have the same rated power, the value of Pcut of each fuse resistor is the same.

  Since the fuse resistors 31 to 3n are connected in parallel, the voltages at both ends of each fuse resistor are the same. The value obtained by dividing the square of the voltage by the resistance value is the power consumed by each fuse resistor, and the voltage at both ends of each fuse resistor connected in parallel is the same. large. Therefore, among the fuse resistors connected in parallel, the fuse resistor having the lower resistance value reaches the power value Pcut at which the fuse resistor is blown at a lower voltage. Therefore, a resistor having a lower resistance value melts at a lower voltage than a resistor having a higher resistance value, and a resistor having a higher resistance value melts at a higher voltage than a resistor having a lower resistance value.

  Therefore, a method for determining the resistance value R3n of the fuse resistor 3n, which is the maximum resistance value among the fuse resistors 31 to 3n, will be described.

  The fuse resistance 3n is determined so as to blow as the last one at the upper limit surge current value Imax described above. That is, the resistance value R3n may be determined so as to satisfy the following equation using the power Pcut for fusing the fuse resistor and the upper limit surge current value Imax.

R3n ＝ Pcut ／ (Imax ^ 2)
Here, Imax ^ 2 represents the square of Imax.

  In this manner, the resistance value R3n of the fuse resistor 3n, which is the maximum resistance value among the fuse resistors 31 to 3n, is determined.

  Next, a method for determining the resistance values of the fuse resistors 31 to 3 (n-1) will be described. Here, the fuse resistance 3 (n-1) indicates a fuse resistance having a resistance value that is one order before the fuse resistance 3n having a resistance value that increases sequentially from the fuse resistance 31 and that has the maximum resistance value. The resistance values of the fuse resistor 32 to the fuse resistor 3 (n-1) are represented by a constant multiple of R31.

  First, the resistance value R31 of the fuse resistor 31 which is the minimum resistance value among the fuse resistors 31 to 3n is determined.

  The resistance value R of the combined resistance of the fuse resistors 31 to 3n is a variable R31 of the fuse resistor 31, each resistance value of the fuse resistor 32 to the fuse resistor 3 (n-1) represented by a constant multiple of the variable R31, and The value is expressed as R3n. Therefore, the resistance value R of the combined resistance is represented by the variable R31.

  Therefore, when the previously determined lower limit surge current value Imin is passed through the combined resistance of the resistance value R, the voltage generated across the fuse resistors 31 to 3n is represented by V. Since the power consumption of the fuse resistor 31 is obtained by dividing the square of V by the resistance value R31 of the fuse resistor 31, the power consumption of the fuse resistor 31 is represented by a variable R31.

  Then, assuming that the power consumption of the fuse resistor 31 represented by the variable R31 is equal to the value of the power Pcut for fusing the fuse resistor, R31 is obtained as a numerical value by solving for the variable R31.

  In this manner, the resistance value R31 of the fuse resistor 31 which is the minimum resistance value among the fuse resistors 31 to 3n is determined.

  Further, the resistance values of the fuse resistor 32 to the fuse resistor 3 (n-1) can be obtained as a constant multiple of R31.

As described above, the resistance values of the fuse resistors 31 to 3n are determined.
(Determination method of resistance value when there are four fuse resistors)
The method for setting the resistance value of the fuse resistor described above will be described for the case of four fuse resistors.

  The upper limit of surge current is Imax and the lower limit of surge current is Imin.

  The fuse resistors connected in parallel are four having different resistance values, and the resistance values are R1, R2, R3, and R4. R1 <R2 <R3 <R4, where R2 = a × R1 and R3 = b × R1, where a and b are constants greater than 1.

  Also, let Pcut be the power at which the fuse resistor melts.

  First, the value of R4 is determined by the following equation.

Pcut = (Imax ^ 2) × R4
Next, the combined resistance R of the resistors connected in parallel is obtained by the following equation.

R = (R1, R2, R3, R4) / (R2, R3, R4 + R1, R3, R4 + R1, R2, R4 + R1, R2, R3)
Here, since R2 = a × R1 and R3 = b × R1, R is represented by one variable R1.

  Therefore, when Imin flows through the combined resistance R, the voltage V across the combined resistance R is expressed by the following equation.

V = Imin × R
Here, since Imin is a predetermined value and R is represented by one variable R1 as described above, V is also represented by one variable R1.

  Next, the power consumption P1 of R1 having the smallest resistance value is expressed by the following equation.

P1 = (V ^ 2) / R1
Here, since both V and R can be represented by one variable R1, P1 can also be represented by one variable R1.

  Then, by setting P1 = Pcut and solving for R1, the resistance value of the fuse resistor R1 can be obtained as a numerical value.

  R2 is obtained by R2 = a × R1, and R3 is obtained by R3 = b × R1.

As described above, when the values of the fuse resistors R1 to R4 are determined, among the four fuse resistors connected in parallel, the fuse resistor R1 having the smallest resistance value is blown with the smallest current, and is the most resistant. The fuse resistor R4, which has a large value, blows at the largest current. The method for determining the resistance value of the fuse resistor described above is an idea and the surge current is a transient phenomenon. It is necessary to confirm appropriately by experiment etc.

The surge current that blows the fuse resistor takes a value between Imin and Imax, and the fuse resistance is not always blown one by one every time a lightning surge enters, but the resistor with the smallest resistance value. Fusing in order.
(Details of operation)
As described above, the electronic device 10 in which the resistance values of the fuse resistors 31 to 3n are set will show the details of the operation when the lightning surge is received.

  In FIG. 2, the surge current flow when the electronic device 10 first receives a lightning surge is schematically indicated by a dotted arrow.

  In FIG. 2, when a lightning surge enters the communication line terminal 11, the SPD 21 operates and the communication circuit 22 is protected. However, since the SPD 21 was operated by a lightning surge, the component performance deteriorated. When a surge current flows through the fuse resistors 31 to 3n connected in parallel, the largest current flows through the fuse resistor 31 having the lowest resistance value among the fuse resistors connected in parallel. Therefore, the fuse resistor 31 first reaches the fusing power among the parallel-connected fuse resistors, and the fuse resistor 31 is blown first. Since the fuse resistor 31 is blown, it can be known that the SPD 21 has deteriorated due to a lightning surge.

  Next, FIG. 3 schematically shows a case where a lightning surge enters the electronic device 10 from the communication line terminal 11 again.

  In FIG. 3, when a lightning surge enters from the communication line terminal 11, the SPD 21 operates and the communication circuit 22 is protected. However, since the SPD 21 was operated by a lightning surge, the component performance was further deteriorated. When a surge current flows through the fuse resistors 32 to 3n connected in parallel, the largest current flows through the fuse resistor 32 having the lowest resistance value among the fuse resistors connected in parallel. Therefore, the fuse resistor 32 reaches the fusing power first among the fuse resistors connected in parallel, and the fuse resistor 32 is blown first.

  Then, it can be known that the fuse resistor 32 is further deteriorated from the state in which the SPD 21 is operated by a lightning surge and the fuse resistor 31 is blown because the fuse resistor 32 is blown.

  In this way, each time a lightning surge enters the electronic device 10, the fuse resistors are sequentially melted.

  As described above, one fuse current does not always blow one fuse resistor at a time. However, when a plurality of fuse resistors are blown by a single surge current, a surge current larger than the surge current at which one fuse resistor is blown flows into the SPD 21. Accordingly, since the SPD 21 is more deteriorated in a state where a plurality of fuses are blown than in a state where one fuse resistor is blown, it meets the original purpose of knowing the degree of deterioration of the SPD 21.

  In addition, each time the fuse resistor 32 is blown, the surge current for fusing gradually increases. However, the number of fuse resistors blown is deteriorated by SPD due to a lightning surge having a current value between Imin and Imax. This is a rough guide.

  Each time a lightning surge enters the communication line terminal, the fuse resistors 31 to 3n are blown in order from a small resistance value. Finally, the fuse resistor 3n is melted and the SPD 21 is disconnected from the electronic circuit of the electronic device 10.

As described above, according to the electronic apparatus 10 shown in the present embodiment, it is possible to determine the degree of deterioration of the SPD 21 with a simple configuration including only a fuse resistor.
[Second Embodiment]
Next, a second embodiment will be described with reference to FIGS.
[Description of configuration]
FIG. 4 shows the configuration of the second embodiment.

  In the electronic device 10 according to the first embodiment, the SPD 21 and the fuse resistors 31 to 3n are inserted between the communication line terminal 11 and the FG 12.

  In the electronic device 50 according to the present embodiment, the configurations of the SPD 21 and the fuse resistors 31 to 3n inserted between the communication line terminal 11 connected to the communication circuit 22 and the FG 12 are the same. However, in the electronic device 50, the SPD 23 and the fuse resistors 41 to 4 n are inserted between the FG 12 that is common to the AC power supply terminal 13 and the communication line terminal of the communication circuit 22.

  There may be a plurality of communication lines and AC power lines, and FIG. 4 shows one of them.

The method for setting the resistance values of the fuse resistors 31 to 3n and the fuse resistors 41 to 4n is the same as in the description of the first embodiment. However, since the communication line terminal 11 and the AC power supply terminal 13 have different voltages and currents to be handled in normal times when no surge is generated, the specifications of the surge current for operating the SPD are different for the communication line and the AC power supply. Therefore, since the upper limit and the lower limit of the surge current are set differently, the resistance values of the fuse resistors 31 to 3n and the resistance values of the fuse resistors 41 to 4n are different.
[Description of operation]
Next, the operation of the present embodiment will be described with reference to FIGS.

  First, a case where a lightning surge enters the communication line terminal 11 will be described. In FIG. 5, a dotted arrow schematically shows a surge current flow when the communication line terminal 11 first receives a lightning surge. Since the operation when a lightning surge enters the communication line terminal 11 is the same as the operation of the first embodiment, the description is omitted.

  As described above, when a lightning surge enters the communication line terminal 11, one or more of the fuse resistors 31 to 3n are blown, but no surge current flows through the fuse elements 41 to 4n. 4n is not melted.

  Next, a case where a lightning surge enters the AC power supply terminal 13 will be described. In FIG. 6, a dotted arrow schematically shows a surge current flow when the AC power supply terminal 13 first receives a lightning surge. Since the operation of fusing the fuse resistors 41 to 4n is the same as the operation of fusing the fuse resistors 31 to 3n of the first embodiment, the description thereof is omitted.

  In this case, one or more of the fuse resistors 41 to 4n are blown, but since the surge current does not flow through the fuse elements 31 to 3n, the fuse elements 41 to 4n are not blown.

  Therefore, by checking whether the fuse resistors 31 to 3n are blown or whether the fuse resistors 41 to 4n are blown, it is confirmed whether the lightning surge intrusion route to the electronic device 50 is a communication line or an AC power source. It is possible.

  For example, if the fuse resistor 41 and the fuse resistor 42 are blown as shown in FIG. 7, it can be seen that a lightning surge has entered the electronic device 50 from the AC power source, and no lightning surge has entered the communication line. I understand that. Knowing the lightning surge intrusion route makes it easier to take measures to prevent lightning surges.

As described above, the electronic device 50 shown in the present embodiment can confirm the lightning surge intrusion route in addition to determining the degree of deterioration of the SPD 21 and the SPD 23 with a simple configuration of only the fuse resistor.
[Third Embodiment]
Next, a third embodiment will be described with reference to FIG.

  The electronic device 100 according to this embodiment includes a lightning surge protection element 111 having an input terminal connected to the first terminal 101, and electrical characteristics between the output terminal of the lightning surge protection element 111 and the second terminal 102. Different fusing elements 112 and fusing elements 113 connected in parallel. And the 1st fusing element 112 of the above-mentioned element arrangement blows out with the predetermined upper limit surge current value which is below the discharge tolerance of the above-mentioned lightning surge protection element 111. Also, the second fusing element 113 in the element array is blown only by the second fusing element 113 at a predetermined lower limit surge current value flowing through the element arrangement.

  As described above, according to the electronic apparatus 100 shown in the present embodiment, it is possible to determine the degree of deterioration of the lightning surge protection element 111 with a simple configuration including only the fusing element 112 and the fusing element 113.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to the above-described embodiments, and can be expanded or modified as follows.

  The communication circuit shown in the first and second embodiments may be an electronic circuit other than the communication circuit.

  Next, the configuration of a modification of the first embodiment is shown in FIG.

  In FIG. 8, the communication path by the combination of the communication line 1 and FG connected to the communication line terminal 1 (reference numeral 61), and the communication path by the combination of the communication line 2 and FG connected to the communication line terminal 2 (reference numeral 62). These two communication paths are formed. Thus, in the case of an electronic device having a plurality of communication lines, a configuration may be adopted in which the surge current of a lightning surge that has entered the communication line terminal 1 (reference numeral 61) is bypassed to the communication line terminal 2 (reference numeral 62).

  In the configuration of FIG. 8, the SPD 63 and the fuse resistors 71 to 7n are inserted between the communication line terminal 1 (reference numeral 61) and the communication line terminal 2 (reference numeral 62). According to this configuration, the history of lightning surge that has entered the communication line 1 can be confirmed by blowing the fuse resistors 71 to 7n, and the degree of deterioration of the SPD 63 can be determined.

  In the electronic devices of the first and second embodiments, the fuse resistors that blow when a certain power is exceeded are connected in parallel. However, the fuses that blow when a certain current is exceeded can also be realized in parallel. It is. In this case, the fusing current value of the fuse to be blown as the last one in the parallel fuse array is set to the value of Imax described in the first embodiment. In the parallel fuse array, the fusing current value of the fuse that blows as the first one flows to the fuse that blows as the first one as a shunt when the current Imin flows through the parallel fuse array. Set to be equal to the current value.

  Furthermore, even if a circuit in which a fuse and a resistor are connected in series is connected in parallel, the same effect as in the first and second embodiments can be obtained. That is, resistors having different resistance values are connected in series to a plurality of fuses of the same standard, and the series connection circuits are connected in parallel. In this case, the current flowing through each fuse is a shunt of the current flowing through the parallel connection, and the shunt is determined by the resistance value of each resistor. And by selecting the resistance value of each resistor appropriately based on the general relationship between the resistance value and the shunt current, each time surge current flows, it is blown in order from the fuse connected in series to the resistor with the lower resistance value. You can do it. The resistor needs to have sufficient power resistance characteristics so that the resistor is not damaged before the fuse is blown.

10 Electronic equipment 11 Communication line terminal 12 FG
13 AC power terminal 14 FG
21 SPD
22 Communication circuit 23 SPD
31, 32, 33, 34, 3n Fuse resistance 41, 42, 43, 44, 4n Fuse resistance 50 Electronic device 60 Electronic device 61 Communication line terminal 1
62 Communication line terminal 2
63 SPD
64 communication circuit 71, 72, 7n fuse resistor 100 electronic circuit 101 first terminal 102 second terminal 111 lightning surge protection element 112, 113 fusing element

Claims (10)

A lightning surge protection element having an input terminal connected to the first terminal;
An element arrangement in which a plurality of fusing elements having different electrical properties are connected in parallel between the output terminal of the lightning surge protection element and the second terminal;
The first fusing element of the element arrangement is blown at a predetermined upper limit surge current value that is equal to or lower than the discharge withstand capability of the lightning surge protection element,
The second fusing element in the element arrangement is an electronic circuit wherein only the second fusing element is blown at a predetermined lower limit surge current value flowing through the element arrangement. The electrical properties include electrical resistance values;
The plurality of fusing elements are fuse resistors having the same fusing power value,
The electrical resistance value of the first fusing element is a value obtained by dividing the fusing power value by the square of a predetermined upper limit surge current value that is equal to or less than the discharge tolerance of the lightning surge protection element,
The electric resistance value of the second fusing element is a value obtained by dividing a squared value obtained by multiplying the combined electric resistance value of the element arrangement and a predetermined lower limit surge current value by the fusing power value. The electronic circuit according to claim 1. The electrical properties include a fusing current value,
The electronic circuit according to claim 1, wherein the plurality of fusing elements are fuses.   The electronic circuit according to claim 1, wherein the second terminal is a ground potential.   5. The first electronic circuit which is the electronic circuit according to claim 1, and the second electronic connected to the first terminal and the second terminal of the first electronic circuit. An electronic device characterized by further comprising a circuit. At least one first electronic circuit which is the electronic circuit according to any one of claims 1 to 4,
A third electronic circuit connected to the plurality of terminals,
An electronic apparatus, wherein the first terminal and the second terminal of the first electronic circuit are connected to any two terminals of the plurality of terminals of the third electronic circuit. A lightning surge protection element having an input terminal connected to the first terminal;
In an electronic circuit comprising an element array in which a plurality of fusing elements having different electrical properties are connected in parallel between an output end of the lightning surge protection element and a second terminal,
The first fusing element of the element arrangement is blown at a predetermined upper limit surge current value that is equal to or lower than the discharge withstand capability of the lightning surge protection element,
The second fusing element in the element arrangement is blown only by the second fusing element at a predetermined lower limit surge current value flowing through the element arrangement,
A method of determining deterioration of a lightning surge protection element, wherein deterioration of the lightning surge protection element is determined according to a fusing state of the plurality of fusing elements. The electrical properties include electrical resistance values;
The plurality of fusing elements are fuse resistors having the same fusing power value,
The electrical resistance value of the first fusing element is a value obtained by dividing the fusing power value by the square of a predetermined upper limit surge current value that is equal to or less than the discharge tolerance of the lightning surge protection element,
The electric resistance value of the second fusing element is a value obtained by dividing a squared value obtained by multiplying the combined electric resistance value of the element arrangement and a predetermined lower limit surge current value by the fusing power value. The method for determining deterioration of a lightning surge protection element according to claim 7. The electrical properties include a fusing current value,
The method according to claim 7, wherein the plurality of fusing elements are fuses.   The method for determining deterioration of a lightning surge protection element according to any one of claims 7 to 9, wherein the second terminal is a ground potential.

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